Comprehensive Physiology Wiley Online Library
For Librarians For Authors Editors About

Vertebrate Cardiovascular Systems

W. Burggren, A. Farrell, H. Lillywhite

10.1002/cphy.cp130104

Source: Supplement 30: Handbook of Physiology, Comparative Physiology

Originally published: 1997

Published online: January 2011

Full Article on Wiley Online Library



Abstract

The sections in this article are:

1 Diversity of Vertebrate Cardiovascular Patterns
1.1 Vertebrate Origins and Driving Forces behind Cardiovascular Evolution
1.2 Cardiovascular Patterns in Vertebrates
2 Functional Properties of Vertebrate Hearts
2.1 Overview
2.2 Electrical Properties of Cardiac Cells
2.3 Excitation–Contraction Coupling
2.4 Mechanical Properties of Cardiac Muscle
2.5 Cardiac Output and Cardiac Performance
2.6 Coronary Circulations, Myocardial O2 Consumption, and Myocardial O2 Supply
3 Peripheral Circulation and Hemodynamics
3.1 Arterial Blood Pressure and Its Regulation
3.2 Blood Volume and Its Regulation
4 Cardiovascular Performance Under Special Conditions
4.1 Aerobic Exercise
4.2 Breath Holding and Diving
4.3 Reduced Metabolism
4.4 Digestive State
4.5 Responses to Gravity
4.6 Development of Cardiovascular Systems
5 Conclusions and Future Directions
5.1 Mechanistic Unknowns
5.2 Adaptive Unknowns
5.3 Integrative Unknowns
5.4 Developmental Unknowns
Figure 1. Figure 1.

Simplified phyletic scheme relating Urochordata, Cephalochordata, and Vertebrata.

from ref. 505, after ref. 523
Figure 2. Figure 2.

Circulatory pattern of urochordates. Anatomical location of heart in ascidian urochordate Clavelina. Small arrows show direction of blood flow when heart is pumping from posterior to anterior.

from ref. 505, after ref. 523
Figure 3. Figure 3.

Reversal of blood flow in tunicate circulation. This recording of in vivo electrical heart rate activity in Ciona intestinalis shows alternating periods in which blood is presumed to be pumped toward gills (Branchial) and toward viscera (Visceral).

from ref. 564
Figure 4. Figure 4.

Schematic representation of urochordate circulation. Contractile regions of vessels indicated by double‐lined walls.

from ref. 505
Figure 5. Figure 5.

Secondary circulation of fishes. A: Schematic representation of primary and secondary (shaded) circulation of a typical teleost fish. B: Scanning electron micrograph of a vascular corrosion cast of arteries from rainbow trout, Oncorbynchus mykiss.

from ref. 629
Figure 6. Figure 6.

Schematic of cardiovascular system in various air‐breathing fishes. Relative amounts of black and white hatching within blood vessels indicate approximate degrees of oxygenation of blood. A: General arrangement in strictly water‐breathing fishes. B: Air‐breathing organ derived from pharyngeal and/or opercular mucosa (for example, Monopterus, Electrophorus, Periopthalmus, Anabas). C: Gills, buccal mucosa, or elaborations of opercular cavity serving as air‐breathing organs (for example, Clarias, Saccobranchus). D: Gastrointestinal tract used as air‐breathing organ (for example, Hoplosternum, Plecostomus, Ancistrus, Misgurnus). E: Relatively simple air bladder used as air‐breathing organ (for example, Polypterus, Amia, Lepisosteus). F: Lung, structurally similar to that of amphibians, used for air breathing (for example, lungfishes Protopterus, Lepidosiren). Note that these fishes show major enhancement of the gas‐exchange circuit in the form of a pulmonary vein leading directly back to the heart.

from ref. 329
Figure 7. Figure 7.

Sagittal sections (ventral aspect) through heart and truncus of the African lungfish Protopterus and South American lungfish Neoceratodus.

from ref. 337, and ref. 242
Figure 8. Figure 8.

Functional morphology of typical anuran heart. Flow of oxygen‐rich blood shown by open arrows; flow of poorly oxygenated blood shown by black arrows.

from ref. 556
Figure 9. Figure 9.

Schematic diagram of anuran and urodele amphibian circulation. The major difference between the two is the presence in anurans of a cutaneous artery arising from the pulmocutaneous arch, which results in dual skin supply from pulmonary (pulmocutaneous artery) and systemic vertebral arteries.
Figure 10. Figure 10.

Circulation in squamate reptiles. A: Highly schematic diagram of heart of freshwater turtle Chrysemys scripta. Pathways for blood flow from ventricular cava to arterial arches indicated by solid arrows. B: Simultaneously recorded intracardiac and arterial pressures in anesthetized Chrysemys scripta.

modified from ref. 557. modified from ref. 557
Figure 11. Figure 11.

Circulation in varanid lizards. A: Heart of Varanus. Dashed arrows indicate intracardiac diastolic pattern of flow of oxygen‐rich blood from left atrium; solid arrows show flow of oxygen‐poor blood from right atrium. B: Simultaneously recorded intracardiac and arterial pressures in anesthetized savannah monitor lizard, Varanus exanthematicus.

from ref. 268. from ref. 84
Figure 12. Figure 12.

Schematic diagram of crocodilian heart and major artiers. Outflow channels of heart have been untwisted 180° to clarify the relationship with ventricles. CC, common carotid artery; FP, foramen of Panizza; LAo, left aorta; PA, pulmonary artery; LA, left atrium; LV, left ventricle; PV, pulmonary veins; RA, right atrium; RAo, right arota; RV, right ventricle; SC, subclavian artery, VC, vena cava.

after ref. 250
Figure 13. Figure 13.

Major factors influencing cardiac output and pressure generation in vertebrate hearts.
Figure 14. Figure 14.

Two proposed schemes for Ca2+ movements during excitation‐contraction coupling of vertebrate cardiac muscle. The major difference between the mammalian scheme (A) and the fish/amphibian scheme (B) is the absence of a significant role for sarcoplasmic reticulum (SR) calcium release in fish and amphibians. Relative intensity of arrows indicates relative roles of Ca2+ released from SR (60%–80%) and transcarcolemmal influx (20%–40%) in mammals. Dashed line in the fish/amphibian scheme suggests a possible physiological role for SR Ca2+ release under certain conditions and in certain species, such as tuna. For example, panel C shows that whereas ryanodine, a blocker of the SR calcium release channel, is without effect on ventricular strips from rainbow trout, contractility of atrial strips from skipjack tuna is reduced by ryanodine in a manner similar to that seen with mammalian cardiac muscle. SL, sarcolemma.

with permission from refs. 355,356,604
Figure 15. Figure 15.

Resting and maximum heart rates for selected adult vertebrates. Resting and maximum heart rates for mammalian species show an allometric relationship. In contrast, maximum heart rate for lower vertebrates, with the exception of tuna, shows an upper limit of around 120 bpm, which is independent of body mass. The bottom of each bar is resting value and the top is maximum value. Lower vertebrates (fishes, amphibians, and reptiles) are identified numerically. Key for lower vertebrates and experimental temperatures: 1. Scaphiopus, 24°C; 2, Bufo, 25°C; 3, Xenopus, 25°C; 4, Rana, 25°C; 5, Natrix, 25°C, 6, Myxine, 11°C; 7, Bufo, 20°C; 8, Salmo, 20°C; 9, Ophiosaurus, 25°C; 10, Rana, 20°C; 11, Salmo, 10°C; 12, Testudo, 25°C; 13, Gadus, 10°C; 14, Iguana, 35°C; 15, Varanus, 35°C; 16, Hemitripterus, 10°C; 17, Ophiodon, 10°C (from ref. 182).
Figure 16. Figure 16.

Force–frequency relationships for isolated ventricular and atrial strips (tuna only) from selected vertebrate hearts. As contraction frequency is increased, contractility either increases to an apex (for example, elasmobranchs, tuna, and frogs) or decreases (for example, teleosts except tuna).

adapted from refs. 157,158,356
Figure 17. Figure 17.

Homeometric regulation in isolated perfused hearts from selected fishes. As demonstrated by these examples for fish, hearts in general are able to intrinsically maintain resting stroke volume (with heart rate constant) despite being required to generate higher arterial pressures as vascular resistance is increased.

adapted from refs. 182,186,222
Figure 18. Figure 18.

Intrinsic and extrinsic regulation of cardiac stroke volume. A: In its normal state and without extrinsic input, an increase in cardiac filling pressure results in an increased stroke volume through the Frank‐Starling mechanism. Extrinsic mechanisms of cardiac stimulation and cardiac depression result in a family of curves such that stroke volume can be changed by moving between curves (for example, from A to A′ or from A to A′) as well as moving along a curve (for example, from A to B). The importance of the Frank‐Starling mechanism in the regulation of stroke volume in fishes is illustrated in panel B, which summarizes experiments where filling pressure was varied in perfused heart preparations. Typically, the filling pressure required to elicit physiological stroke volume is low and, because it is subambient in some species, a vis‐a‐fronte filling mechanism is indicated.

adapted from refs. 181,182
Figure 19. Figure 19.

Pressure‐volume loops for rainbow trout (A), leopard shark (B), and human (C) ventricles during resting and exercise states. Differences in the extent to which stroke volume increases during exercise are quite evident. Furthermore, the mechanism by which stroke volume increases may be different. In fish, there are increases in end‐diastolic volume. In humans, upright exercise increases end‐diastolic volume, whereas supine exercise increases end‐systolic volume.

adapted from ref. 181
Figure 20. Figure 20.

Changes in ventricular stroke volume, heart rate, and cardiac output in an unrestrained, freely diving freshwater turtle, Chrysemys scripta.

from ref. 330, after ref. 557
Figure 21. Figure 21.

Simultaneous measurements of cardiac output (Q), coronary blood flow (), and dorsal aorta (PDAo) in coho salmon. Heart rate (fH), total systemic resistance (Rsys), and coronary vascular resistance (Rcor) were derived from these measurements. A: Injection of isoproterenol into the dorsal aorta (at time zero) resulted in an increase in and coronary vasodilation without a significant change in driving pressure (PDAo). B: Phasic relationship between pressure and flows. Flow in the main coronary artery is biphasic and continuous throughout the cardiac cycle.

adapted from ref. 19 with permission
Figure 22. Figure 22.

Blood pressures in branchial (lined bar) v. systemic (open bar) and pulmonary (stippled bar) v. systemic (open bar) arteries of selected vertebrates. Height of vertical bar is equivalent to pulse pressure.

from ref. 183
Figure 23. Figure 23.

Relationships between mean arterial pressures, measured at the body center (hydrostatic indifferent point, see text), and head‐up tilt angle determined in species of snakes from different gravitational environments. Pressures at the body center are expected not to change with tilt angle if the arterial column acts as a passive system contained within a rigid tube 227.

after ref. 552
Figure 24. Figure 24.

Changes in blood pressure in ventral aorta, dorsal aorta, and subintestinal vein during and after moderate swimming activity in rainbow trout.

from ref. 584
Figure 25. Figure 25.

Pattern of arterial pressure, hematocrit (Hct), and blood volume in a single snake, Elaphe obsoleta, for an extended “recovery” period following 15 min of locomotion (stippled bar). During recovery the snake was held within an acrylic tube, where it rested in an extended position but was free to move forward or backward for a distance of several centimeters. Note that the movements of the snake (stars in top panel) elevated arterial pressure and prevented blood volume from returning to control level measured before exercise.

from ref. 408 with permission
Figure 26. Figure 26.

Schematic diagram of mechanisms participating in baroreflex regulation of cardiovascular variables in Bufo. “Classical” representation of negative feedback, which uses a hypothesized “set point” for arterial pressure and a medullary comparator. Response of heart and systemic vasculature to baroreceptor stimulation is reduction in heart rate and systemic resistance, which opposes elevations in central arterial pressure. However, pulmocutaneous arterial (PCA) resistance increases, probably because of vagally mediated constriction of the extrinsic pulmonary artery. This opposes regulation of PCA pressure and ultimately central arterial pressure but protects the pulmonary microcirculation from pressure elevations. Some relevant references are numbered 1,2,3,4,5,6,7,8: 1, 321; 2, 568; 3, 576; 4, 621; 5, 623; 6, 622; 7, 624; 8, 644.

modified from ref. 643
Figure 27. Figure 27.

Schematic of baroreceptor zones and their innervation in five classes of vertebrate, drawn to illustrate developmental origins from visceral arch arteries and associations with corresponding visceral arch nerves. Amphibian and mammalian examples adapted from reference 623; the remainder based on references in 30, 340, 624–627. Drawing is from Van Vliet and West 625. Abbreviations: A, aorta; AA, aortic arch; Abd A, abdominal aorta; CA, celiac artery; CL, carotid labyrinth, CN, carotid nerve; CS, carotid sinus; CSN, carotid sinus nerve; DA, dorsal aorta; DCA, dorsal carotid artery; EC, external carotid artery; IC, internal carotid artery; IN, innominate artery; ITN, inferior truncal nerve; LDA, ductus arteriosus or its ligament; NG, nodose ganglia; PA, pulmonary artery; PH1 and PH2, pharyngeal branches of the vagus nerve; PCA, pulmocutaneous artery; RLN, recurrent laryngeal nerve; SC, subclavian artery; SLN, superior laryngeal nerve; STN, superior truncal nerve; TA, truncus arteriosus; TG, truncal ganglia; VA, ventral aorta; VCA, ventral carotid artery; VG, vagal ganglia; V, VII, IX, and X, cranial nerves 5, 7, 9 (glossopharyngeal), and 10 (vagus); 1,2,3,4,5, and 6, visceral arch arteries 1–6. Stippled areas represent functionally identified baroreceptive zones. Shaded region in upper midline of each figure represents larynx and pharynx.
Figure 28. Figure 28.

Schematic representing NaCl and H2O intake and excretion. Renal excretion determined by arterial pressure (AP) and modulated by neural and endocrine factors. Resetting of reflex control systems regulating total peripheral resistance (TPR) and renal excretion is indicated (adapt) to emphasize short‐term role of these systems. Arterial pressure provides a continuous nonadaptive signal to kidney to maintain sodium and water balance. Bottom: Influence of changes of blood volume (BV) and/or vascular compliance (C) with resulting changes of cardiac output (CO) and/or arterial pressure on blood vessels and vascular resistance (TPR) of systemic circulation. Venous return‐cardiac output (Heart box) and pressure‐natriuresis (Kidney box) relationships are indicated. ALDO, aldosterone; ANF, atrial natriuretic factor; ANG II, angiotensin II; AVP, arginine vasopressin; EDLF, endogenous digitalis‐like factor; ICV, intracellular volume; ISFV, interstitial fluid volume.

from ref. 132
Figure 29. Figure 29.

Cardiovascular adjustments to exercise in selected vertebrates. This three‐dimensional treatment deals with stroke volume (ml/kg/beat), heart rate (bpm), and arterial‐mixed venous oxygen extraction (vol %). Resting conditions are heavily shaded, while exercising conditions are lightly stippled.

from ref. 234
Figure 30. Figure 30.

Changes in heart rate, stroke volume, and cardiac output in the domestic mallard before, during, and after a forced dive.

from ref. 208
Figure 31. Figure 31.

Distribution of O2 stores available at the beginning of a dive in a selection of amphibians, reptiles, birds, and mammals. Data are approximations derived from primary data from different studies on the same species.

from ref. 74
Figure 32. Figure 32.

Pulmonary oxygen metering in the turtle Chelodina longicollis. Left panel shows records of lung ventilation, intrapulmonary lung pressure, pulmonary flow, PO2 of lung gas, and PO2 and O2 saturation of systemic arterial blood at termination of a dive and during two brief lung ventilation bouts. Right panel shows same records taken between 9 and 16 min into a voluntary dive.

from ref. 92
Figure 33. Figure 33.

Major cardiovascular and respiratory events during the life cycle of fishes, amphibians, and reptiles. *Developmental stages that may or may not occur within the class.

from ref. 89
Figure 34. Figure 34.

Gross morphology of central venous circulation of larval and adult tiger salamanders (Ambystoma tigrinum).

from ref. 421
Figure 35. Figure 35.

Developmental changes in heart rate (20°–25°C) during development in four anuran amphibians. Data have been “normalized” with respect to development such that the earliest points are from when the heart first begins to beat and the last points are from the largest adults for which data are available. This distorts the abscissa such that a single vertical line at a given point on the developmental scale is not the same stage of development of all species. Major developmental landmarks indicated; H, hatching; AB, onset of air breathing; M, metamorphosis.

from ref. 77, which provides original sources of data
Figure 36. Figure 36.

Major developmental events in ontogeny of heart rate regulation in the bullfrog Rana catesbeiana.

from ref. 77
Figure 37. Figure 37.

Adrenergic and cholinergic effects on arterial blood pressure and heart rate in 15‐day‐old embryo of the domestic chicken. Top panels show influence of 1μg of epinephrine in 10 μl of saline (first arrow) followed by 50 μl of saline (second arrow) on central arterial blood pressure and heart rate. Effects at 30 s and 1, 2, 3, 5, and 10 min are shown. Bottom panel shows influence of 1μg of acetylcholine in 10 μl of saline (first arrow) followed by 50 μl of saline (second arrow) on central arterial blood pressure and heart rate.

from ref. 592
Figure 38. Figure 38.

Superimposed recordings of blood pressure from the ventricle (continuous line), conus arteriosus (broken line), and truncus arteriosus (broken and dotted line) from three larval stages and small adult bullfrogs (Rana catesbeiana). Taylor‐Kollros developmental stages.

from ref. 479
Figure 39. Figure 39.

Mean arterial blood pressure as a function of body mass and development in intact, undisturbed larvae and adults of the paradoxical frog, Pseudis paradoxsus. Gosner developmental stages.

from ref. 79
Figure 40. Figure 40.

Mean dorsal aortic blood flow (top) and vascular resistance (bottom) in stages 12–29 of chick embryo. Mean ± 1 SEM, n > 15 at each stage.

from ref. 123


Figure 1.

Simplified phyletic scheme relating Urochordata, Cephalochordata, and Vertebrata.

from ref. 505, after ref. 523


Figure 2.

Circulatory pattern of urochordates. Anatomical location of heart in ascidian urochordate Clavelina. Small arrows show direction of blood flow when heart is pumping from posterior to anterior.

from ref. 505, after ref. 523


Figure 3.

Reversal of blood flow in tunicate circulation. This recording of in vivo electrical heart rate activity in Ciona intestinalis shows alternating periods in which blood is presumed to be pumped toward gills (Branchial) and toward viscera (Visceral).

from ref. 564


Figure 4.

Schematic representation of urochordate circulation. Contractile regions of vessels indicated by double‐lined walls.

from ref. 505


Figure 5.

Secondary circulation of fishes. A: Schematic representation of primary and secondary (shaded) circulation of a typical teleost fish. B: Scanning electron micrograph of a vascular corrosion cast of arteries from rainbow trout, Oncorbynchus mykiss.

from ref. 629


Figure 6.

Schematic of cardiovascular system in various air‐breathing fishes. Relative amounts of black and white hatching within blood vessels indicate approximate degrees of oxygenation of blood. A: General arrangement in strictly water‐breathing fishes. B: Air‐breathing organ derived from pharyngeal and/or opercular mucosa (for example, Monopterus, Electrophorus, Periopthalmus, Anabas). C: Gills, buccal mucosa, or elaborations of opercular cavity serving as air‐breathing organs (for example, Clarias, Saccobranchus). D: Gastrointestinal tract used as air‐breathing organ (for example, Hoplosternum, Plecostomus, Ancistrus, Misgurnus). E: Relatively simple air bladder used as air‐breathing organ (for example, Polypterus, Amia, Lepisosteus). F: Lung, structurally similar to that of amphibians, used for air breathing (for example, lungfishes Protopterus, Lepidosiren). Note that these fishes show major enhancement of the gas‐exchange circuit in the form of a pulmonary vein leading directly back to the heart.

from ref. 329


Figure 7.

Sagittal sections (ventral aspect) through heart and truncus of the African lungfish Protopterus and South American lungfish Neoceratodus.

from ref. 337, and ref. 242


Figure 8.

Functional morphology of typical anuran heart. Flow of oxygen‐rich blood shown by open arrows; flow of poorly oxygenated blood shown by black arrows.

from ref. 556


Figure 9.

Schematic diagram of anuran and urodele amphibian circulation. The major difference between the two is the presence in anurans of a cutaneous artery arising from the pulmocutaneous arch, which results in dual skin supply from pulmonary (pulmocutaneous artery) and systemic vertebral arteries.



Figure 10.

Circulation in squamate reptiles. A: Highly schematic diagram of heart of freshwater turtle Chrysemys scripta. Pathways for blood flow from ventricular cava to arterial arches indicated by solid arrows. B: Simultaneously recorded intracardiac and arterial pressures in anesthetized Chrysemys scripta.

modified from ref. 557. modified from ref. 557


Figure 11.

Circulation in varanid lizards. A: Heart of Varanus. Dashed arrows indicate intracardiac diastolic pattern of flow of oxygen‐rich blood from left atrium; solid arrows show flow of oxygen‐poor blood from right atrium. B: Simultaneously recorded intracardiac and arterial pressures in anesthetized savannah monitor lizard, Varanus exanthematicus.

from ref. 268. from ref. 84


Figure 12.

Schematic diagram of crocodilian heart and major artiers. Outflow channels of heart have been untwisted 180° to clarify the relationship with ventricles. CC, common carotid artery; FP, foramen of Panizza; LAo, left aorta; PA, pulmonary artery; LA, left atrium; LV, left ventricle; PV, pulmonary veins; RA, right atrium; RAo, right arota; RV, right ventricle; SC, subclavian artery, VC, vena cava.

after ref. 250


Figure 13.

Major factors influencing cardiac output and pressure generation in vertebrate hearts.



Figure 14.

Two proposed schemes for Ca2+ movements during excitation‐contraction coupling of vertebrate cardiac muscle. The major difference between the mammalian scheme (A) and the fish/amphibian scheme (B) is the absence of a significant role for sarcoplasmic reticulum (SR) calcium release in fish and amphibians. Relative intensity of arrows indicates relative roles of Ca2+ released from SR (60%–80%) and transcarcolemmal influx (20%–40%) in mammals. Dashed line in the fish/amphibian scheme suggests a possible physiological role for SR Ca2+ release under certain conditions and in certain species, such as tuna. For example, panel C shows that whereas ryanodine, a blocker of the SR calcium release channel, is without effect on ventricular strips from rainbow trout, contractility of atrial strips from skipjack tuna is reduced by ryanodine in a manner similar to that seen with mammalian cardiac muscle. SL, sarcolemma.

with permission from refs. 355,356,604


Figure 15.

Resting and maximum heart rates for selected adult vertebrates. Resting and maximum heart rates for mammalian species show an allometric relationship. In contrast, maximum heart rate for lower vertebrates, with the exception of tuna, shows an upper limit of around 120 bpm, which is independent of body mass. The bottom of each bar is resting value and the top is maximum value. Lower vertebrates (fishes, amphibians, and reptiles) are identified numerically. Key for lower vertebrates and experimental temperatures: 1. Scaphiopus, 24°C; 2, Bufo, 25°C; 3, Xenopus, 25°C; 4, Rana, 25°C; 5, Natrix, 25°C, 6, Myxine, 11°C; 7, Bufo, 20°C; 8, Salmo, 20°C; 9, Ophiosaurus, 25°C; 10, Rana, 20°C; 11, Salmo, 10°C; 12, Testudo, 25°C; 13, Gadus, 10°C; 14, Iguana, 35°C; 15, Varanus, 35°C; 16, Hemitripterus, 10°C; 17, Ophiodon, 10°C (from ref. 182).



Figure 16.

Force–frequency relationships for isolated ventricular and atrial strips (tuna only) from selected vertebrate hearts. As contraction frequency is increased, contractility either increases to an apex (for example, elasmobranchs, tuna, and frogs) or decreases (for example, teleosts except tuna).

adapted from refs. 157,158,356


Figure 17.

Homeometric regulation in isolated perfused hearts from selected fishes. As demonstrated by these examples for fish, hearts in general are able to intrinsically maintain resting stroke volume (with heart rate constant) despite being required to generate higher arterial pressures as vascular resistance is increased.

adapted from refs. 182,186,222


Figure 18.

Intrinsic and extrinsic regulation of cardiac stroke volume. A: In its normal state and without extrinsic input, an increase in cardiac filling pressure results in an increased stroke volume through the Frank‐Starling mechanism. Extrinsic mechanisms of cardiac stimulation and cardiac depression result in a family of curves such that stroke volume can be changed by moving between curves (for example, from A to A′ or from A to A′) as well as moving along a curve (for example, from A to B). The importance of the Frank‐Starling mechanism in the regulation of stroke volume in fishes is illustrated in panel B, which summarizes experiments where filling pressure was varied in perfused heart preparations. Typically, the filling pressure required to elicit physiological stroke volume is low and, because it is subambient in some species, a vis‐a‐fronte filling mechanism is indicated.

adapted from refs. 181,182


Figure 19.

Pressure‐volume loops for rainbow trout (A), leopard shark (B), and human (C) ventricles during resting and exercise states. Differences in the extent to which stroke volume increases during exercise are quite evident. Furthermore, the mechanism by which stroke volume increases may be different. In fish, there are increases in end‐diastolic volume. In humans, upright exercise increases end‐diastolic volume, whereas supine exercise increases end‐systolic volume.

adapted from ref. 181


Figure 20.

Changes in ventricular stroke volume, heart rate, and cardiac output in an unrestrained, freely diving freshwater turtle, Chrysemys scripta.

from ref. 330, after ref. 557


Figure 21.

Simultaneous measurements of cardiac output (Q), coronary blood flow (), and dorsal aorta (PDAo) in coho salmon. Heart rate (fH), total systemic resistance (Rsys), and coronary vascular resistance (Rcor) were derived from these measurements. A: Injection of isoproterenol into the dorsal aorta (at time zero) resulted in an increase in and coronary vasodilation without a significant change in driving pressure (PDAo). B: Phasic relationship between pressure and flows. Flow in the main coronary artery is biphasic and continuous throughout the cardiac cycle.

adapted from ref. 19 with permission


Figure 22.

Blood pressures in branchial (lined bar) v. systemic (open bar) and pulmonary (stippled bar) v. systemic (open bar) arteries of selected vertebrates. Height of vertical bar is equivalent to pulse pressure.

from ref. 183


Figure 23.

Relationships between mean arterial pressures, measured at the body center (hydrostatic indifferent point, see text), and head‐up tilt angle determined in species of snakes from different gravitational environments. Pressures at the body center are expected not to change with tilt angle if the arterial column acts as a passive system contained within a rigid tube 227.

after ref. 552


Figure 24.

Changes in blood pressure in ventral aorta, dorsal aorta, and subintestinal vein during and after moderate swimming activity in rainbow trout.

from ref. 584


Figure 25.

Pattern of arterial pressure, hematocrit (Hct), and blood volume in a single snake, Elaphe obsoleta, for an extended “recovery” period following 15 min of locomotion (stippled bar). During recovery the snake was held within an acrylic tube, where it rested in an extended position but was free to move forward or backward for a distance of several centimeters. Note that the movements of the snake (stars in top panel) elevated arterial pressure and prevented blood volume from returning to control level measured before exercise.

from ref. 408 with permission


Figure 26.

Schematic diagram of mechanisms participating in baroreflex regulation of cardiovascular variables in Bufo. “Classical” representation of negative feedback, which uses a hypothesized “set point” for arterial pressure and a medullary comparator. Response of heart and systemic vasculature to baroreceptor stimulation is reduction in heart rate and systemic resistance, which opposes elevations in central arterial pressure. However, pulmocutaneous arterial (PCA) resistance increases, probably because of vagally mediated constriction of the extrinsic pulmonary artery. This opposes regulation of PCA pressure and ultimately central arterial pressure but protects the pulmonary microcirculation from pressure elevations. Some relevant references are numbered 1,2,3,4,5,6,7,8: 1, 321; 2, 568; 3, 576; 4, 621; 5, 623; 6, 622; 7, 624; 8, 644.

modified from ref. 643


Figure 27.

Schematic of baroreceptor zones and their innervation in five classes of vertebrate, drawn to illustrate developmental origins from visceral arch arteries and associations with corresponding visceral arch nerves. Amphibian and mammalian examples adapted from reference 623; the remainder based on references in 30, 340, 624–627. Drawing is from Van Vliet and West 625. Abbreviations: A, aorta; AA, aortic arch; Abd A, abdominal aorta; CA, celiac artery; CL, carotid labyrinth, CN, carotid nerve; CS, carotid sinus; CSN, carotid sinus nerve; DA, dorsal aorta; DCA, dorsal carotid artery; EC, external carotid artery; IC, internal carotid artery; IN, innominate artery; ITN, inferior truncal nerve; LDA, ductus arteriosus or its ligament; NG, nodose ganglia; PA, pulmonary artery; PH1 and PH2, pharyngeal branches of the vagus nerve; PCA, pulmocutaneous artery; RLN, recurrent laryngeal nerve; SC, subclavian artery; SLN, superior laryngeal nerve; STN, superior truncal nerve; TA, truncus arteriosus; TG, truncal ganglia; VA, ventral aorta; VCA, ventral carotid artery; VG, vagal ganglia; V, VII, IX, and X, cranial nerves 5, 7, 9 (glossopharyngeal), and 10 (vagus); 1,2,3,4,5, and 6, visceral arch arteries 1–6. Stippled areas represent functionally identified baroreceptive zones. Shaded region in upper midline of each figure represents larynx and pharynx.



Figure 28.

Schematic representing NaCl and H2O intake and excretion. Renal excretion determined by arterial pressure (AP) and modulated by neural and endocrine factors. Resetting of reflex control systems regulating total peripheral resistance (TPR) and renal excretion is indicated (adapt) to emphasize short‐term role of these systems. Arterial pressure provides a continuous nonadaptive signal to kidney to maintain sodium and water balance. Bottom: Influence of changes of blood volume (BV) and/or vascular compliance (C) with resulting changes of cardiac output (CO) and/or arterial pressure on blood vessels and vascular resistance (TPR) of systemic circulation. Venous return‐cardiac output (Heart box) and pressure‐natriuresis (Kidney box) relationships are indicated. ALDO, aldosterone; ANF, atrial natriuretic factor; ANG II, angiotensin II; AVP, arginine vasopressin; EDLF, endogenous digitalis‐like factor; ICV, intracellular volume; ISFV, interstitial fluid volume.

from ref. 132


Figure 29.

Cardiovascular adjustments to exercise in selected vertebrates. This three‐dimensional treatment deals with stroke volume (ml/kg/beat), heart rate (bpm), and arterial‐mixed venous oxygen extraction (vol %). Resting conditions are heavily shaded, while exercising conditions are lightly stippled.

from ref. 234


Figure 30.

Changes in heart rate, stroke volume, and cardiac output in the domestic mallard before, during, and after a forced dive.

from ref. 208


Figure 31.

Distribution of O2 stores available at the beginning of a dive in a selection of amphibians, reptiles, birds, and mammals. Data are approximations derived from primary data from different studies on the same species.

from ref. 74


Figure 32.

Pulmonary oxygen metering in the turtle Chelodina longicollis. Left panel shows records of lung ventilation, intrapulmonary lung pressure, pulmonary flow, PO2 of lung gas, and PO2 and O2 saturation of systemic arterial blood at termination of a dive and during two brief lung ventilation bouts. Right panel shows same records taken between 9 and 16 min into a voluntary dive.

from ref. 92


Figure 33.

Major cardiovascular and respiratory events during the life cycle of fishes, amphibians, and reptiles. *Developmental stages that may or may not occur within the class.

from ref. 89


Figure 34.

Gross morphology of central venous circulation of larval and adult tiger salamanders (Ambystoma tigrinum).

from ref. 421


Figure 35.

Developmental changes in heart rate (20°–25°C) during development in four anuran amphibians. Data have been “normalized” with respect to development such that the earliest points are from when the heart first begins to beat and the last points are from the largest adults for which data are available. This distorts the abscissa such that a single vertical line at a given point on the developmental scale is not the same stage of development of all species. Major developmental landmarks indicated; H, hatching; AB, onset of air breathing; M, metamorphosis.

from ref. 77, which provides original sources of data


Figure 36.

Major developmental events in ontogeny of heart rate regulation in the bullfrog Rana catesbeiana.

from ref. 77


Figure 37.

Adrenergic and cholinergic effects on arterial blood pressure and heart rate in 15‐day‐old embryo of the domestic chicken. Top panels show influence of 1μg of epinephrine in 10 μl of saline (first arrow) followed by 50 μl of saline (second arrow) on central arterial blood pressure and heart rate. Effects at 30 s and 1, 2, 3, 5, and 10 min are shown. Bottom panel shows influence of 1μg of acetylcholine in 10 μl of saline (first arrow) followed by 50 μl of saline (second arrow) on central arterial blood pressure and heart rate.

from ref. 592


Figure 38.

Superimposed recordings of blood pressure from the ventricle (continuous line), conus arteriosus (broken line), and truncus arteriosus (broken and dotted line) from three larval stages and small adult bullfrogs (Rana catesbeiana). Taylor‐Kollros developmental stages.

from ref. 479


Figure 39.

Mean arterial blood pressure as a function of body mass and development in intact, undisturbed larvae and adults of the paradoxical frog, Pseudis paradoxsus. Gosner developmental stages.

from ref. 79


Figure 40.

Mean dorsal aortic blood flow (top) and vascular resistance (bottom) in stages 12–29 of chick embryo. Mean ± 1 SEM, n > 15 at each stage.

from ref. 123
References
 1. Abboud, F. M., and M. D. Thames. Interaction of cardiovascular reflexes in circulatory control. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Bethesda, MD: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, chapt. 19, p. 675–753.
 2. Abdel‐Magied, E.T.M. Encapsulated sensory receptors in the wall of the avian common carotid artery. J. Anat. 127: 196, 1987.
 3. Abraham, A. Microscopic Innervation of the Heart and Blood Vessels in Vertebrates Including Man. Oxford: Pergamon, 1969.
 4. Abrahamsson, T., S. Holmgren, S. Nilsson, and K. Pettersson. On the chromaffin system of the African lungfish, Protopterus aethiopicus. Acta Physiol. Scand. 107: 135–139, 1979.
 5. Abrahamsson, T., S. Holmgren, S. Nilsson, and K. Pettersson. Adrenergic and cholinergic effects on the heart, the lung and the spleen of the African lungfish, Protopterus aethiopicus. Acta Physiol. Scand. 107: 141–147, 1979.
 6. Acierno, R. C., C. Agnisola, R. Venzi, and B. Tota. Performance of the isolated and perfused working heart of the teleost Conger conger: study of the inotropic effect of prostacyclin. J. Comp. Physiol. [B] 160: 365–371, 1990.
 7. Akers, T. K., and C. N. Peiss. Comparative study of effect of epinephrine on cardiovascular system of turtle, alligator, chicken and opossum. Proc. Soc. Exp. Biol. Med. 112: 396–399, 1963.
 8. Anderson, H. T., and A. S. Blix. Pharmacological exposure of components in the autonomic control of the diving reflex. Acta Physiol. Scand. 90: 381–386, 1974.
 9. Anderson, M. J. Initiation and reversal of heart beat in Ciona. J. Exp. Biol. 49: 363–385, 1968.
 10. Arlock, P. Electrical activity and mechanical response in the systemic heart and the portal vein heart of Myxine glutinosa. Comp. Biochem. Physiol. A 51: 521–522, 1975.
 11. Arthur, P. C., J. E. Keen, P. W. Hochachka, and A. P. Farrell. Metabolic state of the in situ perfused trout heart during severe hypoxia. Am. J. Physiol. 263 (Regulatory Integrative Comp. Physiol. 34): R798–R804, 1992.
 12. Ask, J. A. Comparative aspects of adrenergic receptors in hearts of lower vertebrates. Comp. Biochem. Physiol. A 76: 543–552, 1983.
 13. Ask, J. A., G. Stene‐Larsen, and K. B. Helle. Temperature effects on the beta2‐adrenoceptors of the trout atrium. J. Comp. Physiol. [B] 143: 161–168, 1981.
 14. Avolio, A. P., M. F. O'Rourke, B. T. Bulliman, M. E. Webster, and K. Mang. Systemic arterial hemodynamics in the diamond python Morelia spilotes. Am. J. Physiol. 243 (Regulatory Integrative Comp. Physiol. 14): R205–R212, 1982.
 15. Axelsson, M. The importance of nervous and humoral mechanisms in the control of cardiac performance in the Atlantic cod, Gadus morhua, at rest and during non‐exhaustive exercise. J. Exp. Biol. 137: 287–303, 1988.
 16. Axelsson, M., W. Davison, M. E. Forster, and A. P. Farrell. Cardiovascular responses of the red‐blooded Antarctic fishes, Pagothenia bernaccbii and P. borchgrevinki. J. Exp. Biol. 167: 179–201, 1992.
 17. Axelsson, M., W. R. Driedzic, A. P. Farrell, and S. Nilsson. Regulation of cardiac output and gut blood flow in the sea raven, Hemitripterus americanus. Fish Physiol. Biochem. 6: 315–326, 1989.
 18. Axelsson, M., F. Ehrenstrom, and S. Nilsson. Cholinergic and adrenergic influence on the teleost heart in vivo. Exp. Biol. 46: 179–186, 1987.
 19. Axelsson, M., and A. P. Farrell. Coronary blood flow in vivo in the coho salmon (Oncorhynchus kisutch). Am. J. Physiol. 264 (Regulatory Integrative Comp. Physiol. 35): R963–R971, 1993.
 20. Axelsson, M., A. P. Farrell, and S. Nilsson. Effects of hypoxia and drugs on the cardiovascular dynamics of the Atlantic hagfish Myxine glutinosa. J. Exp. Biol. 151: 297–316, 1990.
 21. Axelsson, M., and R. Fritsche. Effects of exercise, hypoxia and feeding on the gastrointestinal blood flow in the Atlantic cod Gadus morhua. J. Exp. Biol. 158: 181–198, 1991.
 22. Axelsson, M., R. Fritsche, S. Holmgren, D. Grove, and S. Nilsson. Effects of diving, feeding and drugs on the gastrointestinal blood flow in the estuarin crocodile, Crocodylus porosus. Acta Physiol. Scand. 142: 509–516, 1991.
 23. Axelsson, M., S. Holmgren, and S. Nilsson. Flow dynamics of the Crocodilian heart. Am. J. Physiol. 256 (Regulatory Integrative Comp. Physiol. 27): R875–R879, 1989.
 24. Axelsson, M., and S. Nilsson. Control of the heart in the mudpuppy, Necturus maculosus. Exp. Biol. 44: 229–239, 1985.
 25. Axelsson, M., and S. Nilsson. Blood pressure control during exercise in the Atlantic cod, Gadus morhua. J. Exp. Biol. 126: 225–236, 1986.
 26. Axelsson, M., I. Wahlqvist, and F. Ehrenstrom. Cardiovascular regulation in the mudpuppy Necturus maculosus at rest and during short term exercise. Exp. Biol. 48: 253–259, 1989.
 27. Backhouse, S. S., A. A. Harper, B. N. van Vliet, and N. H. West. Localization and conduction velocities of arterial baroreceptors in the anesthetized snake. J. Physiol. (Lond.) 418: 143.
 28. Badeer, H. S. Does gravitational pressure of blood hinder flow to the brain of the giraffe? Comp. Biochem. Physiol. A 83: 207–211, 1986.
 29. Baeyens, D. A., E. Price, C. J. Winters, and D. L. Vesely. Diving increases atrial natriuretic factor–like peptide in freshwater diving turtles. Comp. Biochem. Physiol. A 94: 515–518, 1989.
 30. Bagshaw, R. J. Evolution of cardiovascular baroreceptor control. Biol. Rev. 60: 121–162, 1985.
 31. Bailey, J. R., and W. R. Driedzic. Enhanced inotropic and chronotropic responsiveness of fish hearts following temperature acclimation. J. Exp. Biol. 149: 239–254, 1990.
 32. Baker, C. H., and J. W. Remington. Fluid shifts after hemorrhage. Am. J. Physiol. 201: 910–914, 1961.
 33. Barajas, L., and P. Wang. Demonstration of acetylcholinesterase in the adrenergic nerves of the renal glomerular arterioles. J. Ultrastruct. Res. 53: 244–253, 1975.
 34. Barnes, R. D. Invertebrate Zoology (4th ed.). Philadelphia: Saunders, 1987.
 35. Baudinette, R. V., A. L. Tonkin, J. Orbach, R. S. Seymour, and J. F. Wheeldrake. Cardiovascular function during treadmill exercise in the turkey. Comp. Biochem. Physiol. A 72: 327–332, 1982.
 36. Baumgarten, C. M., and H. A. Fozzard. The resting and pacemaker potentials. In: The Heart and Cardiovascular System, edited by H. A. Fozzard, E. Haber, R. B. Jennings, A. M. Katz, and H. E. Morgan. New York: Raven, 1986, chapt. 30, p. 601–626.
 37. Baustian, M. The contribution of lymphatic pathways during recovery from hemorrhage in the toad, Bufo marinus. Physiol. Zool. 61: 555–563, 1988.
 38. Belaud, A., and C. Peyraud. Etude preliminaire du debit coronaire sur coeur perfuse de poisson. J. Physiol. Paris 63: 165A, 1971.
 39. Bell, C., and C. Rome. Pharmacological investigations of the vasodilator nerves supplying the duck's foot. Br. J. Pharmacol. 82: 801–808, 1984.
 40. Benson, H. D., B. Shapiro, B. Tursky, and G. E. Schwartz. Decreased systolic pressure through operant conditioning techniques in patients with essential hypertension. Science 173: 740–742, 1971.
 41. Bentley, P. J. Actions of neurohypophyseal hormones in amphibians, reptiles, and birds. In: Handbook of Physiology. The Pituitary Gland and Its Neuroendocrine Control, edited by E. Knobil and W. H. Sawyer. Bethesda, MD: Am. Physiol. Soc., 1974, sect. 7, vol. IV, pt. 1, p. 545–563.
 42. Berger, P. J. The reptilian baroreceptor and its role in cardiovascular control. Am. Zool. 27: 111–120, 1987.
 43. Berger, P. J., and G. Burnstock. Autonomic nervous system. In: Biology of the Reptilia, edited by C. Gans. New York: Academic, 1979, vol. X, p. 1–57.
 44. Berger, P. J., B. K. Evans, and D. G. Smith. Localization of baroreceptors and gain of the baroreceptor‐heart rate reflex in the lizard Tracbydosaurus rugosus. J. Exp. Biol. 86: 197–209, 1980.
 45. Berger, P. J., I. L. Gibbins, D. K. Hards, and L. J. Crosby. The distribution and ultrastructure of sensory elements in the baroreceptor region of the truncus arteriosus of the lizard Tracbydosaurus rugosus. Cell Tissue Res. 226: 389–406, 1982.
 46. Bishop, V. S., A. Malliani, and P. Thoren. Cardiac mechanoreceptors. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Bethesda, MD: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, chapt. 15, p. 497–555.
 47. Bjerring, H. C. Facts and thoughts on pixcine phylogeny. In: Evolutionary Biology of Primitive Fishes, edited by R. E. Foreman, A. Gorbman, J. M. Dodd, and R. Olsson. New York: Plenum, 1985, p. 31–57.
 48. Blix, A. S., and B. Folkow. Cardiovascular adjustments to diving in mammals and birds. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Bethesda, MD: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, p. 917–945.
 49. Blomqvist, C. G., and H. L. Stone. Cardiovascular adjustments to gravitational stress. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Bethesda, MD: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, p. 1025–1063.
 50. Bloom, G., E. Ostlund, and R. Fange. Functional aspects of cyclosome hearts in relation to recent structural findings. In: The Biology of Myxine, edited by A. Brodal and R. Fange. Oslo: Universitetsforlaget, 1963, p. 316–339.
 51. Bloom, G., E. Ostlund, U. S. von Euler, F. Lishajko, M. Ritzen, and J. Adams‐Ray. Studies on catecholamine‐containing granules of specific cells in cyclostome hearts. Acta Physiol. Scand. 53 (Suppl. 185): 1–34, 1961.
 52. Bogdanov, O. V. Effect of damage to different parts of the central nervous system on the cardiac activity of the chick embryo. Bull. Exp. Biol. Med. 50: 889–891, 1961.
 53. Boutilier, R. G. Control of arrhythmic breathing in bimodal breathers: Amphibia. Can. J. Zool. 66: 6–19, 1988.
 54. Boutilier, R. G. Diving physiology: amphibians. In: Comparative Pulmonary Physiology: Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 677–695.
 55. Boutilier, R. G., M. G. Emilio, and G. Shelton. The effects of mechanical work on electrolyte and water distribution in amphibian skeletal muscle. J. Exp. Biol. 120: 333–350, 1986.
 56. Boutilier, R. G., D. G. McDonald, and D. P. Toews. The effects of enforced activity on ventilation, circulation, and acid‐base balance in the aquatic gill‐less urodele, Cryptobranchus alleganiensis: a comparison with the semiterrestrial anuran, Bufo marinus. J. Exp. Biol. 84: 289–302, 1980.
 57. Boutilier, R. G., and G. Shelton. Gas exchange, storage and transport in voluntarily diving Xenopus laevis. J. Exp. Biol. 126: 133–155, 1986.
 58. Boutilier, R. G., D. F. Stiffler, and D. P. Toews. Exchange of respiratory gases, ions, and water in amphibious and aquatic amphibians. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 81–124.
 59. Boyd, J. D. The nerve supply to the branchial arch arteries in Vipera berus. J. Anat. 76: 248–258, 1942.
 60. Brady, A. J. Physiology of the amphibian heart. In: Physiology of Amphibia, edited by J. A. Moore. New York: Academic, 1964, p. 211–246.
 61. Brady, A. J. Electrophysiology of cardiac muscle. In: The Mammalian Myocardium, edited by G. A. Langer and A. J. Brady. 1974, p. 135–161.
 62. Brady, A. J. Mechanics of the myocardium. In: The Mammalian Myocardium, edited by G. A. Langer and A. J. Brady. 1974, p. 163–192.
 63. Brady, A. J., and C. Dubkin. Coronary circulation in the turtle ventricle. Biochem. Physiol. 13: 119–128, 1964.
 64. Brenner, B. M., B. J. Ballerman, M. E. Gunning, and M. L. Zeidel. Diverse biological actions of atrial natriuretic peptide. Physiol. Rev. 70: 665–699, 1990.
 65. Bride, M. Establissement de I'innervation dans le coeur du tetard de Xenope et ses repercussions sur le fonctionnement de l'organe. C. R. Soc. Biol. Paris 169: 1265–1271, 1975.
 66. Brill, R. W., and P. G. Bushnell. Metabolic and cardiac scope of high energy demand teleosts—the tunas. Can. J. Zool. 69: 2002–2009, 1991.
 67. Burggren, W. W. Circulation during intermittent lung ventilation in the garter snake Thamnophis. Can. J. Zool. 55: 720–725, 1977.
 68. Burggren, W. W. The pulmonary circulation of the chelonian reptile: morphology, pharmacology and haemodynamics. J. Comp. Physiol. [B] 116: 303–324, 1977.
 69. Burggren, W. W. Influence of intermittent breathing on ventricular depolarization patterns in chelonian reptiles. J. Physiol. (Lond.) 278: 349–364, 1978.
 70. Burggren, W. W. Bimodal gas exchange during variation in environmental oxygen and carbon dioxide in the air breathing fish Trichogaster trichopterus. J. Exp. Biol. 82: 197–214, 1979.
 71. Burggren, W. W. Pulmonary plasma filtration in the turtle; a wet vertebrate lung? Science 215: 77–78, 1982.
 72. Burggren, W. W. Transition of respiratory processes during amphibian metamorphosis: from egg to adult. In: Respiration and Metabolism of Embryonic Vertebrates, edited by R. S. Seymour. Dordrech, the Netherlands: Junk, 1984, p. 31–53.
 73. Burggren, W. W. Form and function in reptilian circulations. Am. Zool. 27: 5–19, 1987.
 74. Burggren, W. W. Cardiovascular responses to diving and their relation to lung and blood oxygen stores in vertebrates. Can. J. Zool. 66: 20–28, 1988.
 75. Burggren, W. W. Role of the central circulation in regulation of cutaneous gas exchange. Am. Zool. 28: 985–998, 1988.
 76. Burggren, W. W. Lung structure and function. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 153–192.
 77. Burggren, W. W. Central cardiovascular function in amphibians: qualitative influences of phylogeny, ontogeny and seasonality. In: Mechanisms of Systemic Regulation: Respiration and Circulation, edited by N. Heisler. Berlin: Springer‐Verlag, 1995, vol. I, p. 175–197.
 78. Burggren, W. W., and W. E. Bemis. Studying physiological evolution; paradigms and pitfalls. In: Evolutionary Innovations: Patterns and Processes, edited by M. H. Nitecki. Oxford: Oxford University Press, 1990, p. 191–228.
 79. Burggren, W. W., J. E. Bicudo, M. L. Glass, and A. S. Abe. Development of blood pressure and cardiac reflexes in the frog Pseudis paradoxsus. Am. J. Physiol. 263 (Regulatory Integrative Comp. Physiol. 34): R602–R608, 1992.
 80. Burggren, W. W., and M. Doyle. Ontogeny of heart rate regulation in the bullfrog, Rana catesbeiana. Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol 22): R231–R239, 1986.
 81. Burggren, W. W., and M. Doyle. Ontogeny of regulation of gill and lung ventilation in the bullfrog, Rana catesbeiana. Respir. Physiol. 66: 279–291, 1986.
 82. Burggren, W. W., and M. Doyle. The action of acetylcholine upon heart rate changes markedly with development in the bullfrog. J. Exp. Zool. 240: 137–140, 1986.
 83. Burggren, W. W., and Fritsche, R. Cardiovascular measurements in animals in the milligram body mass range. Brazil J Med. Biol. Res. 28: 1291–1305, 1995.
 84. Burggren, W. W., and K. Johansen. Ventricular hemodynamics in the monitor lizard, Varanus exanthematicus, pulmonary and systemic pressure separation. J. Exp. Biol. 96: 343–353, 1982.
 85. Burggren, W. W., and K. Johansen. Circulation and respiration in lungfishes. In: The Biology and Evolution of Lungfishes, edited by W. Bemis, W. Burggren, and N. Kemp. New York: Alan R. Liss, 1986, p. 217–236.
 86. Burggren, W. W., K. Johansen, and B. R. McMahon. Respiration in primitive fishes. In: The Biology of Primitive Fishes, edited by R. E. Forman, A. Gorbman, J. M. Dodd, and R. Olsson. New York: Plenum, 1985, p. 217–252.
 87. Burggren, W. W., and J. J. Just. Developmental changes in physiological systems. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 467–530.
 88. Burggren, W. W., G. S. Moreira, and M. C. F. Santos. Specific dynamic action and the metabolism of the brachyuran land crabs Ocypode quadrata (Fabricius, 1787), Goniopsis cruentata (Latreille, 1803) and Cardisoma guanhumi (Latreille, 1825). J. Exp. Mar. Biol. Ecol. 169: 117–130, 1993.
 89. Burggren, W. W., and A. W. Pinder. Ontogeny of cardiovascular and respiratory physiology in lower vertebrates. Annu. Rev. Physiol. 53: 107–135, 1991.
 90. Burggren, W. W., and D. J. Randall. Oxygen uptake and transport during hypoxic exposure in the sturgeon Acipenser transmontanus. Respir. Physiol. 34: 171–183, 1978.
 91. Burggren, W. W., and G. Shelton. Gas exchange and transport during intermittent breathing in chelonian reptiles. J. Exp. Biol. 82: 75–92, 1979.
 92. Burggren, W. W., A. W. Smits, and B. Evans. Arterial oxygen homeostasis during diving in the turtle Chelodina longicollis. Physiol. Zool. 62: 668–686, 1989.
 93. Burggren, W. W., H. Tazawa, and D. P. Thompson. Genetic and maternal environmental influences on embryonic physiology: intraspecific variability in avian embryonic heart rates. Isr. J. Zool. 40: 351–362, 1994.
 94. Burggren, W. W., and P. Territo. Early development of blood oxygen transport. In: Hypoxia and Brain, edited by J. Houston and J. Coates. Burlington, VT: Queen City Printer, 1995, p. 45–56.
 95. Burggren, W. W., and S. Warburton. Patterns of form and function in developing hearts: Contributions from non‐mammalian vertebrates. Cardioscience 5: 183–191, 1994.
 96. Burton, A. C. Physiology and Biophysics of the Circulation. Chicago: Year Book Medical Publishers, 1972.
 97. Bushnell, P. G., D. R. Jones, and A. P. Farrell. The arterial system. In: Fish Physiology, edited by W. W. Hoar, D. J. Randall and A. P. Farrell. San Diego: Academic, 1992, vol. XIIA, p. 89–139.
 98. Butler, P. J. Respiratory cardiovascular control during diving in birds and mammals. J. Exp. Biol. 100: 95–221, 1986.
 99. Butler, P. J. The exercise response and the “classical” diving response during natural submersion in birds and mammals. Can. J. Zool. 66: 29–39, 1988.
 100. Butler, P. J. Respiratory adaptations to limited oxygen supply during diving in birds and mammals. In: Physiological Strategies for Gas Exchange and Metabolism. Society for Experimental Biology Seminar Series 41, edited by A. J. Woakes, M. K. Grieshaber, and C. R. Bridges. Cambridge: Cambridge University Press, 1991, p. 235–257.
 101. Butler, P. J., and J. D. Metcalfe. Cardiovascular and respiratory systems. In: Physiology of Elasmobranch Fishes, edited by T. J. Shuttleworth. Berlin: Springer‐Verlag, 1988, p. 1–47.
 102. Butler, P. J., W. K. Milsom, and A. J. Woakes. Respiratory, cardiovascular and metabolic adjustments during steady state swimming in the green turtle, Chelodina mydas. J. Comp. Physiol. [B] 154: 167–174, 1984.
 103. Butler, P. J., and E. W. Taylor. Response of the dogfish (Scyliorhinus canicula L.) to slowly induced and rapidly induced hypoxia. Comp. Biochem. Physiol. A 39: 307–323, 1971.
 104. Butler, P. J., E. W. Taylor, M. F. Capra, and W. Davison. The effect of hypoxia on the levels of circulating catecholamines in the dogfish (Scyliorhinus canicula) J. Comp. Physiol. [B] 127: 325–330, 1978.
 105. Butler, P. J., E. W. Taylor, and W. Davison. The effect of long term, moderate hypoxia on acid‐base balance, plasma catecholamines and possible anaerobic end products in the unrestrained dogfish: Scyliorhinus canicula. J. Comp. Physiol. [B] 132: 297–303, 1979.
 106. Butler, P. J., N. H. West, and D. R. Jones. Respiratory and cardiovascular responses of the pigeon to sustained level flight in a wind tunnel. J. Exp. Biol. 71: 7–26, 1977.
 107. Cain, J. R., U. K. Abbott, and V. L. Rogallo. Heart rate of the developing chick embryo. Proc. Soc. Exp. Biol. Med. 126: 507–510, 1967.
 108. Cameron, J. N. Morphometric and flow indicator studies of the teleost heart. Can. J. Zool. 53: 691–698, 1975.
 109. Cameron, J. S. Autonomic nervous tone and regulation of heart rate in the goldfish, Carassius auratus. Comp. Biochem. Physiol. [C] 63: 341–349, 1979.
 110. Campbell, D. L., R. L. Rasmusson, and H. C. Strauss. Ionic current mechanisms generating vertebrate primary cardiac pacemaker activity at the single cell level: an integrative view. Annu. Rev. Physiol. 54: 279–302, 1992.
 111. Campbell, G., I. L. Gibbins, J. L. Morris, J. B. Furness, M. Costa, A. M. Oliver, A. M. Beardsley, and R. Murphy. Somatostatin is contained in and released from cholinergic nerves in the heart of the toad Bufo marinus. Neuroscience 7: 2013–2023, 1982.
 112. Canty, A. A., and A. P. Farrell. Intrinsic regulation of flow in an isolated tail preparation of the ocean pout (Macrozoarces americanus). Can. J. Zool. 63: 2013–2020, 1985.
 113. Capra, M. F., and G. H. Satchell. The differential hemodynamic responses of the elasmobranch, Squalus acanthias, to the naturally occurring catecholamines, adrenaline and noradrenaline. Comp. Biochem. Physiol. [C] 58: 41–47, 1977.
 114. Cech, J. J., D. M. Rowell, and J. S. Glasgow. Cardiovascular responses of the winter flounder Pseudopleuronectes americanus to hypoxia. Comp. Biochem. Physiol. A 57: 123–125, 1977.
 115. Chan, D. K. O. Comparative physiology of the vasomotor effects of neurohypophyseal peptides in the vertebrates. Am. Zool. 17: 751–762, 1977.
 116. Chan, D. K. O., and N. Y. S. Chow. The effects of acetylcholine, biogenic amines and other vasoactive agents on the cardiovascular functions of the eel, Anguilla japonica. J. Exp. Biol. 96: 13–26, 1976.
 117. Chapeau, C., J. Gutkowska, P. W. Schiller, R. W. Milne, G. Thibault, R. Garcia, J. Genest, and M. Cantin. Localization of immunoreactive synthetic atrial natriuretic factor (ANF) in the heart of various animal species. J. Histochem. Cytochem. 33: 541–550, 1985.
 118. Chapman, C. B., D. Jensen, and K. Wildenthal. On circulatory control mechanisms in the Pacific hagfish. Circ. Res. 12: 427–440, 1963.
 119. Cho, K. W., S. H. Kim, G. Y. Koh, and K. H. Seul. Renal and hormonal responses to atrial natriuretic peptide and turtle atrial extract in the freshwater turtle, Amyda japonica. J. Exp. Zool. 247: 139–145, 1988.
 120. Cipolle, M. D., and J. E. Zehr. Renin release in turtles: effects of volume depletion and furosemide administration. Am. J. Physiol. 249 (Regulatory Integrative Comp. Physiol. 20): R100–R105, 1985.
 121. Clark, E. B. Functional aspects of cardiac development. In: Growth of the Heart in Health and Disease, edited by R. Zak. New York: Raven, 1984, p. 377–386.
 122. Clark, E. B. Growth, morphogenesis and function: the dynamics of cardiac development. In: Fetal, Neonatal and Infant Heart Disease, edited by J. H. Moller, W. Neal and J. Lock. New York: Appleton‐Century‐Crofts, 1989, p. 1–17.
 123. Clark, E. B. Functional characteristics of the embryonic circulation. In: The Development of the Vascular System, edited by R. N. Feinberg, G. K. Sherer, and R. Auerbach. Basel: Karger, 1991, p. 125–135.
 124. Clark, E. B., and N. Hu. Developmental hemodynamic changes in the chick embryo stages 18 to 27. Circ. Res. 51: 810–815, 1982.
 125. Clark, E. B., N. Hu, J. L. Dummett, G. K. Vandekieft, C. Olson, and R. J. Tamanek. Ventricular function and morphology in the chick embryo stage 18 to 29. Am. J. Physiol. 250 (Heart Circ. Physiol. 21): H407–H413, 1986.
 126. Coleridge, H. M., J. C. G. Coleridge, and H. D. Schultz. Characteristic of C fiber baroreceptors in the carotid sinus of dogs. J. Physiol. (Lond.) 394: 291–313, 1987.
 127. Colin, D. A., and C. Leray. Interaction of adenosine and its phosphorylated derivatives with putative purinergic receptors in the gill vascular bed of rainbow trout. Pflugers Arch. 383: 35–40, 1979.
 128. Comeau, S., V. A. Lance, J. W. Hicks, and J. M. Conlon. Purification and biological activity of alligator bradykinin. Am. J. Physiol. 263 (Regulatory Integrative Comp. Physiol. 34): R400–R404, 1992.
 129. Cordeiro de Sousa, M. B., and A. Hoffmann. Autonomic adjustments during avoidance and orienting responses induced by electrical stimulation of the central nervous system in toads (Bufo paracnemis). J. Comp. Physiol. [B] 155: 381–386, 1985.
 130. Cossins, A. R., and K. Bowler. Temperature Biology of Animals. London: Chapman and Hall, 1987.
 131. Cowley, A. W., Jr. The concept of autoregulation of total blood flow and its role in hypertension. Am. J. Med. 68: 906–916, 1980.
 132. Cowley, A. W., Jr. Long‐term control of arterial blood pressure. Physiol. Rev. 72: 231–300, 1992.
 133. Cowley, A. W., Jr., C. Hinojosa‐Laborde, B. J. Barber, D. R. Harder, J. H. Lombard, and A. S. Greene. Short‐term autoregulation of systemic blood flow and cardiac output. News Physiol. Sci. 4: 219–225, 1989.
 134. Cuneo, R. C., E. A. Espiner, M. G. Nicholls, T. G. Yandle, S. L. Joyce, and N. L. Gilchrist. Renal, hemodynamic, and hormonal responses to atrial natriuretic peptide infusions in normal man, and effect of sodium intake. J. Clin. Endocrinol. Metab. 63: 946–953, 1986.
 135. Dantzler, W. H. Comparative Physiology of the Vertebrate Kidney. Berlin: Springer‐Verlag, 1988.
 136. Datta, J. S. Munshi, and G. M. Hughes. Air‐breathing Fishes of India. Rotterdam: A. A. Balkema, 1992, p. 338.
 137. Davie, P. S. Vascular responses of an eel tail preparation: alpha constriction and beta dilation. J. Exp. Biol. 90: 65–84, 1981.
 138. Davie, P. S., and C. Daxboeck. Anatomy and adrenergic pharmacology of the coronary vascular bed of the Pacific blue marlin (Makaira nigricans). Can. J. Zool. 62: 1886–1888, 1984.
 139. Davie, P. S., and A. P. Farrell. Cardiac performance of an isolated heart preparation from the dogfish (Squalus acanthias): the effects of hypoxia and coronary artery perfusion. Can. J. Zool. 69: 1822–1828, 1991.
 140. Davie, P. S., and A. P. Farrell. The coronary and luminal circulations of the myocardium of fishes. Can. J. Zool. 69: 1993–2001, 1991.
 141. Davie, P. S., M. E. Forster, B. Davison, and G. H. Satchell. Cardiac function in the New Zealand hagfish, Eptatretus cirrhatus. Physiol. Zool. 60: 233–240, 1987.
 142. Davie, P. S., and C. E. Franklin. Myocardial oxygen consumption and mechanical efficiency of a perfused dogfish heart preparation. J. Comp. Physiol. [B] 162: 256–262, 1992.
 143. Davie, P. S., and C. E. Franklin. Preliminary observations on blood flow in the coronary artery of two school sharks (Galeorhinus australis). Can. J. Zool. 71: 1238–1241, 1993.
 144. Davie, P. S., C. E. Franklin, and A. P. Farrell. The effect of hypoxia and coronary perfusion on the maximum performance of the hypoxic eel heart. J. Exp. Zool. 262: 113–121, 1992.
 145. Davies, P. J., and J. A. Donald. The distribution and colocalization of neuropeptides in perivascular nerves innervating the large arteries and veins of the snake, Elaphe obsoleta. Cell Tissue Res. 269: 495–504, 1992.
 146. Davies, R., and M. L. Forsling. Vasopressin release after postural changes and syncope. J. Endocrinol. 65: 59P–60P, 1975.
 147. Daxboeck, C., and G. F. Holeton. Oxygen receptors in the rainbow trout, Salmo gairdneri. Can. J. Zool. 56: 1254–1259, 1978.
 148. Daxboeck, C. R. Effect of coronary artery ablation on exercise performance in Salmo gairdneri. Can. J. Zool. 60: 375–381, 1982.
 149. Delaney, R. G., S. Lahiri, and A. P. Fishman. Aestivation of the African lungfish, Protopterus aethiopicus: Cardiovascular and respiratory functions. J. Exp. Biol. 61: 111–118, 1974.
 150. Djojosugito, A. M., B. Folkow, and A.G.B. Kovach. The mechanism behind the rapid blood restoration after hemorrhage in birds. Acta Physiol. Scand. 74: 114–122, 1968.
 151. Donald, J. A., and H. B. Lillywhite. Adrenergic innervation of the large arteries and veins of the semi‐arboreal ratsnake, Elaphe obsoleta. J. Morphol. 198: 25–31, 1988.
 152. Donald, J. A., and H. B. Lillywhite. Adrenergic nerves and 5‐hydroxytryptamine‐containing cells in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus. Cell Tissue Res. 256: 113–118, 1989.
 153. Donald, J. A., J. E. O'Shea, and H. B. Lillywhite. Neural regulation of the pulmonary vasculature in a semi‐arboreal snake, Elaphe obsoleta. J. Comp. Physiol. [B] 159: 677–685, 1990.
 154. Donald, J. A., J. E. O'Shea, and H. B. Lillywhite. Somatostatin and innervation of the heart of the snake Elaphe obsoleta. Am. J. Physiol. 258 (Regulatory Integrative Comp. Physiol. 29): R1001–R1007, 1990.
 155. Downing, S. E., and R. W. Torrance. Vagal baroreceptors of the bullfrog. J. Physiol. (Lond.) 156: 13, 1961.
 156. Downing, S. W. Baroreceptor regulation of the heart. In: Handbook of Physiology. The Heart, edited by R. M. Berne and N. Sperelakis. Bethesda, MD: Am. Physiol. Soc., 1979, sect. 2, vol. I, p. 621–652.
 157. Driedzic, W. R., and H. Gesser. Ca2+ protection from the negative inotropic effect of contraction frequency on teleost hearts. J. Comp. Physiol. [B] 156: 135–142, 1985.
 158. Driedzic, W. R., and H. Gesser. Differences in force‐frequency relationships and calcium dependency between elasmobranch and teleost hearts. J. Exp. Biol. 140: 227–241, 1988.
 159. Duff, D. W., and K. R. Olson. Response of rainbow trout to constant‐pressure and constant‐volume hemorrhage. Am. J. Physiol. 257 (Regulatory Integrative Comp. Physiol. 28): R1307–R1314, 1989.
 160. Dumsday, B. Resting heart rate of the toad Bufo marinus: A long‐term study of individual differences and environmental influences. Physiol. Zool. 63: 420–431, 1990.
 161. Durfee, W. K. Cardiovascular Reflex Mechanisms in the Fowl. New Brunswick, NJ: Rutgers University, 1963. Ph.D. Thesis.
 162. Dzau, V. J., D. W. Burt, and R. E. Pratt. Molecular biology of the renin‐angiotensin system. Am. J. Physiol. 255 (Renal Fluid Electrolyte Physiol. 26): F563–F573, 1988.
 163. Elger, M. The branchial circulation and the gill epithelia in the Atlantic hagfish, Myxine glutinosa L. Anat. Embryol. 175: 489–504, 1987.
 164. Eisner, R., A. S. Blix, and J. K. Kjekshus. Tissue perfusion and ischemia in diving seals. Physiologist 21: 33, 1978.
 165. Eisner, R., and B. Gooden. Diving and Asphyxia: A Comparative Study of Animals and Man. Cambridge: Cambridge University Press, 1983.
 166. Emery, S. H., C. Mangano, and V. Randazzo. Ventricle morphology in pelagic elasmobranch fishes. Comp. Biochem. Physiol. A 82: 635–643, 1985.
 167. Enermar, A., B. Flack, and R. Hakanson. Observations on the appearance of norepinephrine in the sympathetic nervous system of the chick embryo. Dev. Biol. 11: 268–283, 1965.
 168. Erlij, D., R. Centrangolo, and R. Valadez. Adrenotropic receptors in the frog. J. Pharmacol. Exp. Ther. 149: 65–70, 1965.
 169. Estavillo, J., and R. E. Burger. Avian cardiac receptors: activity changes by blood pressure, carbon dioxide, and pH. Am. J. Physiol. 225: 1067–1071, 1973.
 170. Evans, D. H. An emerging role for a cardiac peptide hormone in fish osmoregulation. Annu. Rev. Physiol. 52: 43–60, 1990.
 171. Evans, D. H., and Y. Takei. A putative role for natriuretic peptides in fish osmoregulation. News Physiol. Sci. 7: 15–19, 1992.
 172. Fara, J. W. Postprandial mesenteric hyperemia. In: Physiology of the Intestinal Circulation, edited by A. P. Shepherd and D. N. Granger. New York: Raven, 1984, p. 99–106.
 173. Faraci, F. M., H. W. Shirer, J. A. Orr, and J. W. Trank. Circulatory mechanoreceptors in the pond turtle Pseudemys scripta. Am. J. Physiol. 242 (Regulatory Integrative Comp. Physiol. 13): R216–R219, 1982.
 174. Farrell, A. P. Cardiovascular events associated with air breathing in two teleosts, Hoplerythrinus unitaenialus and Arapaima gigas. Can. J. Zool. 56: 953–958, 1978.
 175. Farrell, A. P. Cardiovascular changes in the lingcod (Ophiodon elongatus) following adrenergic and cholinergic drug infusions. J. Exp. Biol. 91: 293–305, 1981.
 176. Farrell, A. P. A review of cardiac performance in the teleost heart: intrinsic and humoral regulation. Can. J. Zool. 62: 523–536, 1984.
 177. Farrell, A. P. Cardiovascular and hemodynamic energetics of fishes. In: Circulation, Respiration and Metabolism, edited by R. Gilles. Berlin: Springer‐Verlag, 1985, p. 377–385.
 178. Farrell, A. P. Cardiovascular responses in the sea raven, Hemitripterus americanus, elicited by vascular compression. J. Exp. Biol. 122: 65–80, 1986.
 179. Farrell, A. P. Coronary flow in a perfused rainbow trout heart. J. Exp. Biol. 129: 107–123, 1987.
 180. Farrell, A. P. Comparative biology of the pulmonary circulation. In: The Pulmonary Circulation: Normal and Abnormal, edited by A. P. Fishman. Philadelphia: University of Pennsylvania Press, 1990, p. 17–30.
 181. Farrell, A. P. Circulation of body fluids. In: Comparative Animal Physiology, Environmental and Metabolic Animal Physiology (4th ed.), edited by C. L. Prosser. New York: Wiley‐Liss, 1991, p. 509–558.
 182. Farrell, A. P. From hagfish to tuna: a perspective on cardiac function in fish. Physiol. Zool. 64: 1137–1164, 1991.
 183. Farrell, A. P. Introduction to cardiac scope in lower vertebrates. Can. J. Zool. 69: 1981–1984, 1991.
 184. Farrell, A. P., and P. S. Davie. Coronary artery reactivity in the mako shark, Isurus oxyrinchus. Can. J. Zool. 69: 375–379, 1991.
 185. Farrell, A. P., and P. S. Davie. Coronary artery reactivity in the rough skate, Raja nasuta. Comp. Biochem. Physiol. [C] 99: 555–560, 1991.
 186. Farrell, A. P., P. S. Davie, C. E. Franklin, J. A. Johansen, and R. W. Brill. Cardiac physiology in tunas: I. In vitro perfused heart preparations from yellowfin and skipjack tunas. Can. J. Zool. 70: 1200–1210, 1992.
 187. Farrell, A. P., C. E. Franklin, P. G. Arthur, H. Thorarensen, and K. L. Cousins. Mechanical performance of an in situ perfused heart from the turtle Chrysemys scripta during normoxia and anoxia at 5° and 15°C. J. Exp. Biol. 191: 207–229, 1994.
 188. Farrell, A. P., and M. S. Graham. Effects of adrenergic drugs on the coronary circulation of Atlantic salmon (Salmo salar). Can. J. Zool. 64: 481–484, 1986.
 189. Farrell, A. P., A. M. Hammons, M. S. Graham, and G. F. Tibbits. Cardiac growth in rainbow trout, Salmo gairdneri. Can. J. Zool. 66: 2368–2373, 1988.
 190. Farrell, A. P., J. A. Johansen, and M. S. Graham. The role of the pericardium in cardiac performance of the trout (Salmo gairdneri). Physiol. Zool. 61: 213–221, 1988.
 191. Farrell, A. P., J. A. Johansen, and R. K. Suarez. Effects of exercise‐training on cardiac performance and muscle enzymes in rainbow trout, Oncorhynchus mykiss. Fish Physiol. Biochem. 9: 303–312, 1991.
 192. Farrell, A. P., and D. R. Jones. The heart. In: Fish Physiology, edited by W. W. Hoar, D. J. Randall, and A. P. Farrell. New York: Academic, 1992, vol. XII, pt. A, p. 1–88.
 193. Farrell, A. P., K. R. Macleod, and B. Chancey. Intrinsic mechanical properties of the perfused rainbow trout heart and the effects of catecholamines and extracellular calcium under control and acidotic conditions. J. Exp. Biol. 125: 319–345, 1986.
 194. Farrell, A. P., K. R. Macleod, and C. Scott. Cardiac performance of the trout (Salmo gairdneri) heart during acidosis: effects of low bicarbonate, lactate and Cortisol. Comp. Biochem. Physiol. A 91: 271–277, 1988.
 195. Farrell, A. P., R. L. Saunders, H. C. Freeman, and T. P. Mommsen. Arteriosclerosis in Atlantic salmon: effects of dietary cholesterol and maturation. Arteriosclerosis 6: 453–461, 1986.
 196. Farrell, A. P., S. Small, and M. S. Graham. Effect of heart rate and hypoxia on the performance of a perfused trout heart. Can. J. Zool. 67: 274–280, 1989.
 197. Farrell, A. P., and J. F. Steffensen. An analysis of the energetic cost of the branchial and cardiac pumps during sustained swimming in trout. Fish Physiol. Biochem. 4: 73–79, 1987.
 198. Farrell, A. P., and J. F. Steffensen. Coronary ligation reduces maximum sustained swimming speed in chinook salmon, Oncorhynchus tshawytscha. Comp. Biochem. Physiol. A 87: 35–37, 1987.
 199. Farrell, A. P., S. Wood, T. Hart, and W. R. Driedzic. Myocardial oxygen consumption in the sea raven, Hemitripterus americanus; the effects of volume loading, pressure loading and progressive hypoxia. J. Exp. Biol. 117: 237–250, 1985.
 200. Fedak, M. A., M. R. Pullen, and J. Kanwisher. Circulatory responses of seals to periodic breathing: heart rate and breathing during exercise and diving in the laboratory and open sea. Can. J. Zool. 66: 53–60, 1988.
 201. Feder, M. E., and W. W. Burggren. Cutaneous gas exchange in vertebrates: designs, patterns, control and implications. Biol. Rev. 60: 1–45, 1985.
 202. Feder, M. E., and W. W. Burggren. Skin breathing in vertebrates. Sci. Am. 235: 503–514, 1985.
 203. Feigl, E. O. Coronary physiology. Physiol. Rev. 63: 1–205, 1983.
 204. Fidone, S. J., and A. Sato. A study of chemoreceptor and baroreceptor A and C‐fibers in the cat carotid nerve. J. Physiol. (Lond.) 205: 527–548, 1969.
 205. Figge, F. H. J. The differential reaction of the blood vessels of a branchial arch of Amblystoma tigrinum (Colorado axolotl) I. The reaction to adrenalin, oxygen and carbon dioxide. Physiol. Zool. 9: 79–101, 1936.
 206. Fishman, A. P., R. G. Delaney, and P. Laurent. Circulatory adaptation to bimodal respiration in the dipnoan lungfish. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol. 59: 285–294, 1985.
 207. Fishman, A. P., R. J. Galante, and A. I. Pack. Diving physiology: lungfish. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 645–676.
 208. Folkow, B., N. J. Nilsson, and L. R. Yonce. Effects of diving on cardiac output in ducks. Acta Physiol. Scand. 70: 347–361, 1967.
 209. Forster, M. E. Performance of the heart of the hagfish, Eptatretus cirrhatus. Fish Physiol. Biochem. 6: 327–331, 1989.
 210. Forster, M. E. Myocardial oxygen consumption and lactate release by the hypoxic hagfish heart. J. Exp. Biol. 156: 583–590, 1991.
 211. Forster, M. E., M. Axelsson, A. P. Farrell, and S. Nilsson. Cardiac function and circulation in hagfishes. Can. J. Zool. 69: 1985–1992, 1991.
 212. Forster, M. E., P. S. Davie, W. Davison, G. H. Satchell, and R. M. G. Wells. Blood pressures and heart rates in swimming hagfish. Comp. Biochem. Physiol. A 89: 247–250, 1988.
 213. Forster, M. E., W. Davison, M. Axelsson, and A. P. H. Farrell. Cardiovascular responses to hypoxia in the New Zealand hagfish, Eptatretus cirrhatus. Respir. Physiol. 88: 373–386, 1992.
 214. Forster, M. E., W. Davison, G. H. Satchell, and H. H. Taylor. The subcutaneous sinus of the hagfish Eptatretus cirrhatus and its relation to the central circulating blood volume. Comp. Biochem. Physiol A 93: 607–612, 1989.
 215. Forster, M. E., and A. P. Farrell. The volumes of the chambers of the trout heart. Comp. Biochem. Physiol A 109: 127–132, 1994.
 216. Foxon, G. E. H. A description of the coronary arteries in dipnoan fishes and some remarks on their importance from the evolutionary standpoint. J. Anat. 84: 121–131, 1950.
 217. Foxon, G. E. H. Blood and respiration. In: Physiology of the Amphibia, edited by J. A. Moore. New York: Academic, 1964, p. 151–209.
 218. Fozzard, H. A., and M. F. Arnsdorf. Cardiac electrophysiology. In: The Heart and Cardiovascular System, edited by H. A. Fozzard, R. B. Jennings, A. M. Katz, and H. E. Morgan. New York: Raven, 1986, chapt. 1, p. 1–30.
 219. Franklin, C. E. Intrinsic properties of an in situ turtle heart (Emydura signata) preparation perfused via both atria. Comp. Biochem. Physiol. A 107: 501–507, 1994.
 220. Franklin, C. E., and M. Axelsson. The intrinsic properties of an in situ perfused crocodile heart. J. Exp. Biol. 186: 269–288, 1994.
 221. Franklin, C. E., and P. S. Davie. The pericardium facilitates pressure work in the eel heart. J. Fish Biol. 39: 559–564, 1991.
 222. Franklin, C. E., and P. S. Davie. Myocardial power output of an isolated eel (Anguilla dieffenbachii) heart preparation in response to adrenaline. Comp. Biochem. Physiol. [C] 101: 293–298, 1992.
 223. Fritsche, R., and W. W. Burggren. Development of cardiovascular responses to hypoxia in larvae of the frog Xenopus laevis. Am. J. Physiol. (Regulatory Integrative Comp. Physiol.) (in press), 1996.
 224. Fritsche, R., and S. Nilsson. Cardiovascular responses to hypoxia in the Atlantic cod, Gadus morhua. Exp. Biol. 48: 153–160, 1989.
 225. Furness, J. B., J. L. Morris, I. L. Gibbins, and M. Costa. Chemical transmissions of neurons and plurichemical transmission. Annu. Rev. Pharmacol. Toxicol. 29: 289–306, 1989.
 226. Gannon, B. J., G. D. Campbell, and G. H. Satchell. Monoamine storage in relation to cardiac regulation in the Port Jackson shark Heterodontus portusjacksoni. Z. Zellforsch. 131: 437–450, 1972.
 227. Gauer, O. H., and H. L. Thron. Postural changes in the circulation. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Washington, DC: Am. Physiol. Soc., 1965, sect. 2, vol. III, p. 2409–2439.
 228. Geer, P. G., B. C. Wang, and K. L. Goetz. Blood pressure of sinoaortic‐denervated dogs is not increased by cardiac denervation. Proc. Soc. Exp. Biol. Med. 181: 33–40, 1986.
 229. Gesser, H. Effects of hypoxia and acidosis on fish heart performance. In: Circulation, Respiration and Metabolism, edited by R. Gilles. Berlin: Springer‐Verlag, 1985, p. 402–411.
 230. Gesser, H., P. Andresen, P. Brams, and J. Sund‐Laursen. Inotropic effects of adrenaline on the anoxic or hypercapnic myocardium of rainbow trout and eel. J. Comp. Physiol. [B] 147: 123–128, 1982.
 231. Gesser, H., and O. Poupa. Acidosis and cardiac muscle contractility: comparative aspects. Comp. Biochem. Physiol. A 76: 559–566, 1983.
 232. Gibbins, I. L., J. L. Morris, J. B. Furness, and M. Costa. Innervation of systemic blood vessels. In: Nonadrenergic Innervation of Blood Vessels, Regional Innervation, edited by G. Burnstock and S. G. Griffith. Boca Raton, FL: CRC, 1988, vol. II, p. 1–35.
 233. Girard, H. Arterial pressure in the chick embryo. Am. J. Physiol. 224: 454–460, 1973.
 234. Gleeson, T. T. Patterns of metabolic recovery from exercise in amphibians and reptiles. J. Exp. Biol. 160: 187–207, 1991.
 235. Gleeson, T. T., and K. M. Baldwin. Cardiovascular response to treadmill exercise in untrained rats. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol. 50: 1206–1211, 1981.
 236. Gleeson, T. T., and A. F. Bennett. Respiratory and cardiovascular adjustments to exercise in reptiles. In: Circulation, Respiration and Metabolism, edited by R. Giles. Berlin: Springer‐Verlag, 1985, p. 23–38.
 237. Gleeson, T. T., G. S. Mitchell, and A. F. Bennett. Cardiovascular responses to graded activity in the lizards Varanus and Iguana. Am. J. Physiol. 239 (Regulatory Integrative Comp. Physiol. 10): R174–R179, 1980.
 238. Goetz, R. H., and O. Budtz‐Olsen. Scientific safari—the circulation of the giraffe. S. Afr. Med. J. 29: 773–776, 1955.
 239. Goetz, R. H., and E. N. Keen. Some aspects of the cardiovascular system in the giraffe. Angiology 8: 542–564, 1957.
 240. Goetz, R. H., J. V. Warren, O. H. Gauer, J. L. Patterson, Jr., J. T. Doyle, E. N. Keen, and M. McGregor. Circulation of the giraffe. Circ. Res. 8: 1049–1058, 1960.
 241. Gooden, B. A. The effects of hypoxia on the vasoconstrictor response of isolated mesenteric arterial vasculature from chickens and ducklings. Comp. Biochem. Physiol. [C] 67: 219–222, 1980.
 242. Goodrich, E. S. Studies on the Structure and Function of Vertebrates. London: Macmillan, 1930.
 243. Gorbman, A., W. W. Dickhoff, S. R. Vigna, N. B. Clark, and C. L. Ralph. Comparative Endocrinology. New York: Wiley, 1983.
 244. Graham, J. B. Ecological and evolutionary aspects of integumentary respiration: body size, diffusion, and the invertebrata. Am. Zool. 28: 1031–1045, 1988.
 245. Graham, M. S., and A. P. Farrell. The effect of temperature acclimation and adrenaline on the performance of a perfused trout heart. Physiol. Zool. 62: 38–61, 1989.
 246. Graham, M. S., and A. P. Farrell. Myocardial oxygen consumption in trout acclimated to 5°C and 15°C. Physiol. Zool. 63: 536–554, 1990.
 247. Granger, J. P., T. J. Opgenorth, J. Salazar, J. C. Romero, and J. C. Burnett. Chronic hypotensive and renal effects of atrial natriuretic peptide. Hypertension 8 (Suppl. II): II‐112–II‐116, 1986.
 248. Grant, R. T., and M. Regnier. The comparative anatomy of the cardiac coronary vessels. Heart 14: 285–317, 1926.
 249. Greenfield, L. J., and A. G. Morrow. The cardiovascular hemodynamics of Crocodilia. J. Surg. Res. 1: 97–103, 1961.
 250. Grigg, G. Central cardiovascular anatomy and function in Crocodilia. In: Physiological Adaptations in Vertebrates: Respiration, Circulation and Metabolism, edited by S. C. Wood, R. E. Weber, A. R. Hargens, and R. W. Millard. New York: Marcel Dekker, 1992, p. 339–354.
 251. Grigg, G. C., and K. Johansen. Cardiovascular dynamics in Crocodylus porosus breathing air and during voluntary aerobic dives. J. Comp. Physiol. [B] 157: 381–392, 1987.
 252. Grodzinsky, Z. Susceptibility of the heart in the sea trout embryo Salmo trutta L. to small changes in temperature. Bull. Acad. Pol. Sci. BII 173–182, 1950.
 253. Grubb, B. R. Allometric relations of cardiovascular function in birds. Am. J. Physiol. 245 (Heart Circ. Physiol. 16): H567–H572, 1983.
 254. Grubb, B. R., D. D. Jorgensen, and M. Conner. Cardiovascular changes in the exercising emu. J. Exp. Biol. 104: 193–201, 1983.
 255. Gustafsson, D., J. Hillman, and J. Lundvall. Influences on central hemodynamics in hemorrhage of B2‐adrenergic vascular control mechanisms. Acta Physiol. Scand. 116: 181–188, 1982.
 256. Guyton, A. C., H. J. Granger, and T. G. Coleman. Autoregulation of the total systemic circulation and its relation to control of cardiac output and arterial pressure. Circ. Res. 28 (Suppl. I): 93–97, 1971.
 257. Haller, B. G. D., H. Zust, S. Shaw, M. P. Gnadinger, D. E. Uehlinger, and P. Weidmannu. Effects of posture and ageing on circulating atrial natriuretic peptide levels in man. J. Hypertens. 5: 551–556, 1987.
 258. Halpern, M. H., and M. M. May. Phylogenetic study of the extracardiac arteries to the heart. Am. J. Anat. 102: 469–480, 1958.
 259. Halpern, W., B. L. Pegrani, J. E. Brayden, K. Mackey, M. K. McLaughlin, and G. Osol. Review of endothelial release of vasoactive substances. In: Resistance Arteries, edited by W. Halpern, B. L. Pegram, J. E. Grayden, K. Mackey, M. K. McLaughlin, and G. Osol. Ithaca, NY: Perinatology, 1988, p. 3–187.
 260. Hansen, C. A., and B. D. Sidell. Atlantic hagfish cardiac muscle: metabolic basis of tolerance to anoxia. Am. J. Physiol. 244 (Regulatory Integrative Comp. Physiol. 15): R356–R362, 1983.
 261. Hargens, A. R., R. W. Millard, K. Pettersson, and K. Johansen. Gravitational haemodynamics and oedema prevention in the giraffe. Nature 329: 59–60, 1987.
 262. Harrison, S. M., and D. M. Bers. Influence of temperature on the calcium sensitivity of the myofilaments of skinned ventricular muscle from the rabbit. J. Gen. Physiol. 93: 411–428, 1989.
 263. Harrison, S. M., and D. M. Bers. Modification of temperature dependence of myofilament Ca sensitivity by troponin C replacement. Am. J. Physiol. 258 (Cell Physiol. 21): C282–C289, 1990.
 264. Harrison, S. M., and D. M. Bers. Temperature dependence of myofilament Ca sensitivity of rat, guinea pig and frog ventricular muscle. Am. J. Physiol. 258 (Cell Physiol. 21): C274–C281, 1990.
 265. Heatwole, H., and W. A. Dunson. Hematological parameters of some marine snakes. J. Exp. Mar. Biol. Ecol. 113: 289–300, 1987.
 266. Hedberg, A., and S. Nilsson. Vago‐sympathetic innervation of the heart of the puff‐adder, Bitis arietans. Comp. Biochem. Physiol. [C] 53: 3–8, 1975.
 267. Heisler, N., and M. Glass. Mechanisms and regulation of central vascular shunts in reptiles. In: Cardiovascular Shunts: Ontogenetic, Phylogenetic and Clinical Aspects. Alfred Benzon Symposium 21, edited by K. Johansen and W. W. Burggren. Copenhagen: Munksgaard, 1985, p. 163–178.
 268. Heisler, N., P. Neumann, and G. M. O. Maloiy. The mechanism of intracardiac shunting in the lizard Varanus exanthematicus. J. Exp. Biol. 105: 15–32, 1983.
 269. Helgason, S. S., and S. Nilsson. Drug effects on pre‐ and post‐branchial blood pressure and heart rate in a free‐swimming marine teleost, Gadus morhua. Acta Physiol. Scand. 88: 533–540, 1973.
 270. Helle, K. B. Structures of functional interest in the myocardium of lower vertebrates. Comp. Biochem. Physiol. A 76: 447–452, 1983.
 271. Hemmingsen, E. A., and E. L. Douglas. Respiratory and circulatory adaptations to the absence of hemoglobin in Chaenichthyid fishes. In: Adaptations within Antarctic Ecosystems, edited by G. A. Llano. Washington, DC: Smithsonian, 1977, p. 479–487.
 272. Hemmingsen, E. A., E. L. Douglas, K. Johansen, and R. W. Millard. Aortic blood flow and cardiac output in the hemoglobin‐free fish Chaenocephalus aceratus. Comp. Biochem. Physiol. [A] 43: 1045–1051, 1972.
 273. Henderson, I. W., N. Hazon, and K. Hughes. Hormones, ionic regulation and kidney function in fishes. Symp. Soc. Exp. Biol. 39: 245–265, 1985.
 274. Henry, J., O. Gauer, S. Kety, and K. Kramer. Factors maintaining cerebral circulation during gravitational stress. J. Clin. Invest. 30: 292–301, 1951.
 275. Herbert, C. V., and D. C. Jackson. Temperature effects on the responses to prolonged submergence in the turtle Chrysemys picta bellii. I. Blood acid‐base and ionic changes during and following anoxic submergence. Physiol. Zool. 58: 655–669, 1985.
 276. Herbert, C. V., and D. C. Jackson. Temperature effects on the responses to prolonged submergence in the turtle Chrysemys picta bellii. II. Metabolic rate, blood acid‐base and ionic changes, and cardiovascular function in aerated and anoxic water. Physiol. Zool. 58: 670–681, 1985.
 277. Herman, C. A. Endocrinology. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: Chicago University Press, 1992, p. 40–54.
 278. Herman, C. A., D. O. Robleto, P. L. Mata, and M. D. Lujan. Attenuated cardiovascular effects of prostaglandin I2 and prostaglandin F2 in cold‐acclimated American bullfrogs, Rana catesbeiana. J. Exp. Zool. 238: 167–174, 1986.
 279. Heron, A. C. Advantages of heart reversal in pelagic tunicates. J. Mar. Biol. Assoc. U.K. 55: 959–963, 1975.
 280. Heymans, C., and E. Neil. Reflexogenic Areas of the Cardiovascular System. Boston: Little, Brown, 1958.
 281. Hicks, J. W., and H. S. Badeer. Siphon mechanism in collapsible tubes: application to circulation of the giraffe head. Am. J. Physiol. 256 (Regulatory Integrative Comp. Physiol. 27): R567–R571, 1989.
 282. Hicks, J. W., and S. C. Wood. Oxygen homeostasis in lower vertebrates: the impact of external and internal hypoxia. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 311–342.
 283. Hillman, J. Further studies on beta‐adrenergic control of trans‐capillary fluid absorption from skeletal muscle to blood during hemorrhage. Acta Physiol. Scand. 112: 281–286, 1981.
 284. Hillman, J., D. Gustafsson, and J. Lundvall. β2‐Adrenergic control of plasma volume in hemorrhage. Acta Physiol. Scand. 116: 175–180, 1982.
 285. Hillman, J., and J. Lundvall. Classification of β‐adrenoceptors in the microcirculation of skeletal muscle. Acta Physiol. Scand. 113: 67–71, 1981.
 286. Hillman, S. S. Cardiovascular correlates of maximal oxygen consumption rates in Anuran amphibians. J. Comp. Physiol. [B] 109: 199–207, 1976.
 287. Hillman, S. S. Inotropic influences of dehydration and hyperosmolal solutions on amphibian cardiac muscle. J. Comp. Physiol. [B] 154: 325–328, 1984.
 288. Hillman, S. S. Dehydrational effects on cardiovascular and metabolic capacity in two amphibians. Physiol. Zool. 60: 608–613, 1987.
 289. Hillman, S. S. Cardiac scope in amphibians: transition to terrestrial life. Can. J. Zool. 69: 2010–2013, 1991.
 290. Hillman, S. S., and R. W. Sommerfeldt. Microsphere studies on amphibian systemic blood flow redistribution during dehydration, hypovolemia, and salt load. J. Exp. Zool. 218: 305–308, 1981.
 291. Hillman, S. S., and P. C. Withers. The hemodynamic consequences of hemorrhage and hypernatremia in two amphibians. J. Comp. Physiol. [B] 157: 807–812, 1988.
 292. Reference numbers not used.
 293. Hillman, S. S., P. C. Withers, M. S. Hedrick, and P. B. Kimmel. The effects of erythrocythemia on blood viscosity, systemic oxygen transport and maximal rates of oxygen consumption in an amphibian. J. Comp. Physiol. [B] 155: 577–581, 1985.
 294. Hillman, S. S., P. C. Withers, W. B. Palioca, and J. A. Ruben. Cardiovascular consequences of hypercalcemia during activity in two species of amphibian. J. Exp. Zool. 242: 303–308, 1987.
 295. Hillman, S. S., A. Zygmunt, and M. Baustian. Transcapillary fluid forces during dehydration in two amphibians. Physiol. Zool. 60: 339–345, 1987.
 296. Hinojosa‐Laborde, C., A. S. Greene, and A. W. Cowley, Jr. Autoregulation of the systemic circulation in conscious rats. Hypertension 11: 685–691, 1988.
 297. Hinojosa‐Laborde, C., A. S. Greene, and A. W. Cowley, Jr. Whole‐body autoregulation in conscious areflexic rats during hypoxia and hyperoxia. Am. J. Physiol. 256 (Heart Circ. Physiol. 27): H1023–H1029, 1989.
 298. Hinojosa‐Laborde, C., R. L. Thunhorst, and A. W. Cowley, Jr. Vasoconstriction during volume expansion is independent of central control. Hypertension 15: 712–717, 1990.
 299. Hirst, G. D. S., F. R. Edwards, N. J. Bramich, and M. F. Kiemm. Neural control of cardiac pacemaker potentials. News Physiol. Sci. 6: 185–190, 1991.
 300. Hochachka, P. W. Living without Oxygen. Cambridge, MA: Harvard University Press, 1980.
 301. Hoff, K. S., and S. D. Hillyard. Angiotensin II stimulates cutaneous drinking in a toad, Bufo punctatus: a new perspective on the evolution of thirst in terrestrial vertebrates. Physiol. Zool. 64: 1165–1172, 1991.
 302. Hohnke, L. A. Regulation of arterial pressure in the common green iguana. Am. J. Physiol. 228: 386–391, 1975.
 303. Hol, R., and K. Johansen. A cineradiographic study of the central circulation in the hagfish, Myxine glutinosa L. J. Exp. Biol. 37: 469–473, 1960.
 304. Holeton, G. F. Oxygen uptake and circulation by a hemoglobinless Antarctic fish (Chaenocephalus aceratus Lonnberg) compared with three red‐blooded Antarctic fish. Comp. Biochem. Physiol. 34: 457–471, 1970.
 305. Holeton, G. F. Respiratory and circulatory responses of rainbow trout larvae to carbon monoxide and to hypoxia. J. Exp. Biol. 55: 683–694, 1971.
 306. Holmgren, S. Regulation of the heart of a teleost, Gadus morhua, by autonomic nerves and circulating catecholamines. Acta Physiol. Scand. 99: 62–74, 1977.
 307. Hong, S. K. Diving physiology: man. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 787–802.
 308. Hou, P.‐C. L., and W. W. Burggren. Blood pressures and heart rate during larval development in the anuran amphibian Xenopus laevis. Am. J. Physiol. 267 (Regulatory Integrative Comp. Physiol. 38): R1120–R1125, 1994.
 309. Hou, P.‐C. L., and W. W. Burggren. Cardiac output and peripheral resistance during larval development in the anuran amphibian Xenopus laevis. Am. J. Physiol. 161 (Regulatory Integrative Comp. Physiol. 38): R1126–R1132, 1994.
 310. Hove‐Madsen, L., and H. Gesser. Force frequency relation in the myocardium of rainbow trout. J. Comp. Physiol. [B] 159: 61–69, 1989.
 311. Howe, R. S., W. W. Burggren, and S. J. Warburton. Fixed patterns of bradycardia during late embryonic development in domestic fowl with C locus pleiotropic mutations. Am. J. Physiol. 268: (Heart Circ. Physiol. 39): H56–H60, 1995.
 312. Hoyt, R. W., M. Eldridge, and S. C. Wood. Noninvasive pulsed Doppler determination of cardiac output in an unanesthetized neotenic salamander, Ambystoma tigrinum. J. Exp. Zool. 230: 491–493, 1984.
 313. Huang, T. F. The action potential of the myocardial cells of the golden carp. Jpn. J. Physiol. 23: 529–540, 1973.
 314. Hughes, A. F. W. The heart output of the chick embryo. J. R. Microsc. Soc. 69: 145–152, 1949.
 315. Hughes, G. M. General anatomy of the gills. In: Fish Physiology. Anatomy, Gas Transfer, and Acid‐Base Regulation, edited by W. W. Hoar and D. J. Randall. New York: Academic, 1984, vol. X, pt. A, p. 1–72.
 316. Hughes, G. M., Y. L. Bras‐Pennec, and J.‐P. Pennec. Relationships between swimming speed, oxygen consumption, plasma catecholamines and heart performance in rainbow trout (S. gairdneri R.). Exp. Biol. 48: 45–49, 1988.
 317. Hutchison, V. H., and R. K. Dupré. Thermoregulation. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 206–224.
 318. Irving, L., D. Y. Solandt, and O. M. Solandt. Nerve impulses from branchial pressure receptors in the dogfish. J. Physiol. (Lond.) 84: 187–190, 1935.
 319. Ishii, K., and K. Ishii. Glossopharyngeal innervation of chemo‐ and baroreceptors in the dorsal carotid artery of the tortoise Testudo hermanii. Respir. Physiol. 65: 295–302, 1986.
 320. Ishii, K., K. Ishii, and T. Kusakabe. Chemo‐ and baroreceptor innervation of the aortic trunk of the toad Bufo vulgaris. Respir. Physiol. 60: 365–375, 1985.
 321. Ishii, K., K. Ishii, and T. Kusakabe. Electrophysiological aspects of reflexogenic area in the chelonian, Geoclemmys reevesii. Respir. Physiol. 59: 45–54, 1985.
 322. Ishimatsu, A., G. K. Iwama, T. B. Bentley, and N. Heisler. Contribution of the secondary circulatory system to acid‐base regulation during hypercapnia in rainbow trout (Oncorhynchus mykiss). J. Exp. Biol. 170: 43–56, 1992.
 323. Jackson, D. C. Cardiovascular function in turtles during anoxia and acidosis: in vivo and in vitro studies. Am. Zool. 27: 49–58, 1987.
 324. Jamieson, B. G. Fish Evolution and Systematics: Evidence from Spermatozoa. Cambridge: Cambridge University Press, 1991, p. 319.
 325. Jensen, D. Cardioregulation in an aneural heart. Comp. Biochem. Physiol. 2: 181–201, 1961.
 326. Johansen, K. Circulation in the hagfish, Myxine glutinosa L. Biol. Bull. 118: 289–295, 1960.
 327. Johansen, K. Cardiovascular dynamics in the amphibian, Amphiuma tridactylum Cuvier. Acta Physiol. Scand. 60 (Suppl. 217): 1–82, 1963.
 328. Johansen, K. The cardiovascular system of Myxine glutinosa L. In: The Biology of Myxine, edited by A. Brodal and R. Fange. Oslo: Universitetsforlaget, 1963, p. 289–316.
 329. Johansen, K. Air breathing in fishes. In: Fish Physiology. The Nervous System, Circulation and Respiration, edited by W. W. Hoar and D. J. Randall. New York: Academic, 1970, vol. IV, p. 411.
 330. Johansen, K., and W. W. Burggren. Cardiovascular function in lower vertebrates. In: Hearts and Heart‐like Organs, edited by G. Bourne. New York: Academic, 1980, p. 61–117.
 331. Johansen, K., and W. W. Burggren. Venous return and cardiac filling in varanid lizards. J. Exp. Biol. 113: 389–399, 1984.
 332. Johansen, K., R. Fange, and M. W. Johannessen. Relations between blood, sinus fluid and lymph in Myxine glutinosa L. Comp. Biochem. Physiol. 7: 23–28, 1962.
 333. Johansen, K., D. Hanson, and C. Lenfant. Respiration in a primitive air breather, Amia calva. Respir. Physiol. 9: 157–186, 1970.
 334. Johansen, K., C. Lenfant, and D. Hanson. Cardiovascular dynamics in the lungfish. Z. Vergl. Physiol. 59: 157–186, 1968.
 335. Johansen, K., and O. B. Reite. Cardiovascular responses to vagal stimulation and cardioacceleration blockade in birds, duck (Anas boscas) and seagull (Larus argentatus). Comp. Biochem. Physiol. 12: 479–488, 1964.
 336. Johnson, P. C. Autoregulation of blood flow. Circ. Res. 59: 483–495, 1986.
 337. Jolie, M. Chordate Morphology. Huntington, NY: Krieger, 1973.
 338. Jones, D. R. Systemic arterial baroreceptors in ducks and the consequences of their denervation on some cardiovascular responses to diving. J. Physiol. 234: 499–518, 1973.
 339. Jones, D. R., and P. J. Butler. On the cardioinhibitory role of water immersion per se in ducklings during submersion. Can. J. Zool. 60: 830–832, 1982.
 340. Jones, D. R., R. A. Furilla, M. R. A. Heieis, G. R. J. Gabbott, and F. M. Smith. Forced and voluntary diving in ducks; cardiovascular adjustments and their control. Can. J. Zool. 66: 75–83, 1988.
 341. Jones, D. R., B. L. Langille, D. J. Randall, and G. Shelton. Blood flow in dorsal and ventral aortas of the cod, Gadus morhua. Am. J. Physiol. 226: 90–95, 1974.
 342. Jones, D. R., and W. K. Milsom. Peripheral receptors affecting breathing and cardiovascular function in non‐mammalian vertebrates. J. Exp. Biol. 100: 59–91, 1982.
 343. Jones, D. R., W. K. Milsom, and G. R. J. Gabbott. Role of central and peripheral chemoreceptors in diving responses of ducks. Am. J. Physiol. 243. (Regulatory Integrative Comp. Physiol. 14): R537–R545, 1982.
 344. Jones, D. R., W. K. Milsom, F. M. Smith, N. H. West, and O. S. Bamford. Diving responses in ducks after acute barodenervation. Am. J. Physiol. 245 (Regulatory Integrative Comp. Physiol. 16): R222–R229, 1983.
 345. Jones, D. R., W. K. Milsom, and N. H. West. Cardiac receptors in ducks; the effect of their stimulation and blockade on diving bradycardia. Am. J. Physiol. 238 (Regulatory Integrative Comp. Physiol. 9): R50–R56, 1980.
 346. Jones, D. R., and M. J. Purves. The carotid body in the duck and the consequence of its denervation upon the cardiac responses to immersion. J. Physiol. (Lond.) 211: 279–294, 1970.
 347. Jones, D. R., and D. J. Randall. The respiratory and circulatory systems during exercise. In: Fish Physiology. Locomotion. edited by W. S. Hoar and D. J. Randall. New York: Academic, 1978, vol. III, p. 425–501.
 348. Jones, D. R., and G. Shelton. Factors affecting diastolic blood pressures in the systemic and pulmocutaneous arches of anuran Amphibia. J. Exp. Biol. 57: 789–803, 1972.
 349. Jones, D. R., and G. Shelton. The physiology of the alligator heart: left aortic flow patterns and right‐to‐left shunts. J. Exp. Biol. 176: 247–269, 1993.
 350. Juhasz‐Nagy, A., M. Szentnanyi, M. Szabo, and B. Vamosi. Coronary circulation of the tortoise heart. Acta Physiol. Hung. 23: 33–48, 1963.
 351. Julius, S. The blood pressure seeking properties of the central nervous system. J. Hypertens. 6: 177–185, 1988.
 352. Just, J. J., R. N. Gatz, and E. C. Crawford. Changes in respiratory functions during metamorphosis of the bullfrog, Rana catesbeiana. Respir. Physiol. 17: 276–282, 1973.
 353. Katkov, V. E., and V. V. Chestukhin. Blood pressures and oxygenation in different cardiovascular compartments of a normal man during postural exposures. Aviat. Space Environ. Med. 51: 1234–1242, 1980.
 354. Katz, A. M. Physiology of the Heart (2nd ed.). New York: Raven, 1992, p. 687.
 355. Keen, J. E. Thermal Acclimation, Cardiac Performance and Adrenergic Sensitivity in Rainbow Trout. Burnaby, Canada: Simon Fraser University, 1992. Dissertation.
 356. Keen, J. E., A. P. Farrell, G. F. Tibbits, and R. W. Brill. Cardiac dynamics in tunas. II. Effect of ryanodine, calcium and adrenaline on force‐frequency relationships in arterial strips from skipjack tuna (Katsuwonus pelamis). Can. J. Zool. 70: 1211–1217, 1992.
 357. Keen, J. E., D. M. Vianzon, A. P. Farrell, and G. F. Tibbits. Thermal acclimation alters both adrenergic sensitivity and adrenoceptor density in cardiac tissue of rainbow trout. J. Exp. Biol. 181: 27–47, 1993.
 358. Keen, J. E., D. M. Vianzon, A. P. Farrell, and G. F. Tibbits. Effect of temperature and temperature acclimation on ryanodine sensitivity of the trout myocardium. J. Comp. Physiol. [B] 164: 438–443, 1995.
 359. Khalil, F., and S. Malek. The anatomy of the vagosympathetic system of Uromastyx aegyptia (Forskal) and the significance of its union on the heart beat. J. Comp. Neurol. 96: 497–517, 1952.
 360. Kimmel, P. Ontogeny of Cardiovascular Control Mechanisms in the Bullfrog, Rana catesbeiana. Amherst: University of Massachusetts, 1990. Dissertation.
 361. Kimmel, P. Adrenergic receptors and the regulation of vascular resistance in bullfrog tadpoles (Rana catesbeiana). J. Comp. Physiol. [B] 162: 455–462, 1992.
 362. King, D. Z., and A. S. King. A possible aortic vasoreceptor zone in the domestic fowl. J. Anat. 127: 195–196, 1978.
 363. Kirby, S., and G. Burnstock. Comparative pharmacological studies of isolated spiral strips of large arteries from lower vertebrates. Comp. Biochem. Physiol. 28: 307–320, 1969.
 364. Kirchheim, H. S. Systemic arterial baroreceptor reflexes. Physiol. Rev. 56: 100–176, 1976.
 365. Kirchheim, H. S. Cardiopulmonary–arterial baroreceptor interaction in the control of blood pressure. News Physiol. Sci. 4: 56–59, 1989.
 366. Kitoh, K., and M. Oguri. Differentiation of the compact layer in the heart ventricle of rainbow trout. Bull. Jpn. Soc. Sci. Fish 51: 539–542, 1985.
 367. Kjekshus, J. K., A. S. Blix, R. Eisner, R. Hol, and E. Amundse. Myocardial blood flow and metabolism in the diving seal. Am. J. Physiol. 242 (Regulatory Integrative Comp. Physiol. 13): R79–R104, 1982.
 368. Klotz, M. A. Cardiovascular Regulation in the Pond Turtles Pseudemys scripta elegans and Chrysemys picta: Presence of Cardiac Synchronous Activity in the Vagus Nerve. Lawrence: University of Kansas, 1979. M.A. Thesis.
 369. von Knebel, R., and T. Ockenga. Das Verhalten des zentralen Venendrucks beim Kipptischversuch. Z. Kreislaufforsch. 49: 235–250, 1960.
 370. Kolatat, T., K. Kramer, and N. Muhl. Über die Aktivitat sensibler Herzherven des Frosches und ihre Beziehungen zur Herzdynamik. Pflugers Arch. 264: 127–144, 1957.
 371. Kolok, A. M., M. Spooner, and A. P. Farrell. The effect of exercise on the cardiac output and blood flow distribution of the largescale sucker Catostomus macrocheilus. J. Exp. Biol. 183: 301–321, 1993.
 372. Kontani, H., and R. Koshiura. Action of divalent cations on the mechanoreceptor of isolated frog heart. Nippon Yakurigaku Zasshi 77: 177–185, 1981.
 373. Kontani, H., and R. Koshiura. Effects of local anesthetics, tetrodotoxin, aconitine, and verapamil on the mechanoreceptors of isolated frog heart. Jpn. J. Pharmacol. 33: 503–513, 1983.
 374. Kooyman, G. L. Diverse Divers. Berlin: Springer‐Verlag, 1989.
 375. Kooyman, G. L. Diving physiology: Marine mammals. In: Comparative Pulmonary Physiology: Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 721–734.
 376. Korner, P. I. Integrative neural cardiovascular control. Physiol. Rev. 51: 312–367, 1971.
 377. Korner, P. I. Central nervous control of autonomic cardiovascular function. In Handbook of Physiology. The Heart, edited by R. M. Berne. Washington, DC: Am. Physiol. Soc., 1979, sect. 2, vol. I, p. 691–739.
 378. Kovach, A. G. B., E. Szasz, and N. Pilmayer. Mortality of various avian and mammalian species following blood loss. Acta Physiol. Acad. Sci. Hung. 35: 109–116, 1969.
 379. Kozubowski, M. M. Cardiovascular Mechanoreceptors in the Rat Snake (Elaphe obsoleta) and the Rattlesnake (Crotalus viridis helleri): Location and Characteristics. Lawrence: University of Kansas, 1985. Dissertation.
 380. Krogh, A. The supply of oxygen to the tissues and the regulation of the capillary circulation. J. Physiol. (Lond.) 52: 457–474, 1918.
 381. Laffont, J., and R. Labat. Action de l'adrénaline sur la fréquence cardiaque de le carpe commune. Effet de la température du milieu sur l'intensité de la réaction. J. Physiol. (Paris) 58: 351–355, 1966.
 382. Lagerstrand, G., A. Mattisson, and O. Poupa. Studies on the calcium paradox phenomenon in cardiac muscle strips of poikilotherms. Comp. Biochem. Physiol. A 75: 601–614, 1983.
 383. Lai, N. C., J. B. Graham, and L. Burnett. Blood respiratory properties and the effect of swimming on blood gas transport in the leopard shark Triakis semifasciata. J. Exp. Biol. 151: 161–173, 1990.
 384. Lai, N. C., J. B. Graham, and W. R. Lowell. Elevated pericardial pressure and cardiac output in the leopard shark Triakis semifasciata during exercise: the role of the pericardioperitoneal canal. J. Exp. Biol. 147: 263–277, 1989.
 385. Lai, N. C., R. Shabetai, J. B. Graham, B. D. Hoit, K. S. Sunnerhagen, and V. Bhargava. Cardiac function of the leopard shark, Triakis semifaserata. J. Comp. Physiol. [B] 160: 259–268, 1990.
 386. Lansman, J. B., T. J. Hallaim, and T. J. Rink. Single stretch‐activated ion channels in vascular endothelial cells as mechano‐transducers? Nature 325: 8111–8113, 1987.
 387. Laughline, K. F., H. Lundy, and J. A. Tait. Chick embryo heart rate during the last week of incubation: population studies. Br. Poult. Sci. 17: 293–310, 1976.
 388. Laurent, P. Gill internal morphology. In: Fish Physiology, Anatomy, Gas Transfer, and Acid‐Base Regulation, edited by W. W. Hoar and D. J. Randall. New York: Academic, 1984, vol. X, Pt. A, p. 73–184.
 389. Laurent, P., S. Holmgren, and S. Nilsson. Nervous and humoral control of the fish heart: structure and function. Comp. Biochem. Physiol. A 76: 525–542, 1983.
 390. Laurent, P., and J. D. Rouzeau. Afferent neural activity from pseudobranch of teleosts. Effects of PO2, pH, osmotic pressure and Na+ ions. Respir. Physiol. 14: 307–331, 1972.
 391. LeGrande, M. C., G. H. Paff, and R. J. Boueck. Initiation of vagal control of heart rate in the embryonic chick. Anat. Rec. 155: 163–166.
 392. Liem, K. Larvae of air‐breathing fishes as counter‐current flow devices in hypoxic environments. Science 211: 1177–1179, 1981.
 393. Lihrmann, I., P. Netchitailo, M. Feuilloley, M. Cantin, C. Delarue, F. Leboulenger, A. Delean, and H. Vaudry. Effect of atrial natriuretic factor on corticosteroid production by perfused frog interrenal studies. Gen. Comp. Endocrinol. 71: 55–61, 1988.
 394. Lillo, R. S. Heart rate and blood pressure in bullfrogs during prolonged maintenance in water at low temperature. Comp. Biochem. Physiol. A 65: 251–253, 1980.
 395. Lillo, R. S., and D. R. Jones. Control of diving responses by carotid bodies and baroreceptors in ducks. Am. J. Physiol. 242 (Regulatory Integrative Comp. Physiol. 13): R105–R108, 1982.
 396. Lillywhite, H. B. Postural edema and blood pooling in snakes. Physiol. Zool. 58: 159–165, 1985.
 397. Lillywhite, H. B. Circulatory adaptations of snakes to gravity. Am. Zool. 27: 81–95, 1987.
 398. Lillywhite, H. B. Snakes, blood circulation and gravity. Sci. Am. 256: 92–98, 1988.
 399. Lillywhite, H. B. Orthostatic intolerance in viperid snakes. Physiol. Zool. 66: 1000–1014, 1993.
 400. Lillywhite, H. B. Evolution of cardiovascular adaptation to gravity. J. Gravitation Physiol. 2: 1–4, 1995.
 401. Lillywhite, H. B., R. A. Ackerman, and L. Palacios. Cardiorespiratory responses of snakes to experimental hemorrhage. J. Comp. Physiol. [B] 152: 59–65, 1983.
 402. Lillywhite, H. B., and J. A. Donald. Anterograde bias of blood flow in arboreal snakes. Am. Zool. 28: 86A, 1988.
 403. Lillywhite, H. B., and J. A. Donald. Pulmonary blood flow regulation in an aquatic snake. Science 245: 293–295, 1989.
 404. Lillywhite, H. B., and K. P. Gallagher. Hemodynamic adjustments to head‐up posture in the partly arboreal snake, Elaphe obsoleta. J. Exp. Zool. 235: 325–334, 1985.
 405. Lillywhite, H. B., and F. H. Pough. Control of arterial pressure in aquatic sea snakes. Am. J. Physiol. 244 (Regulatory Integrative Comp. Physiol. 15): R66–R73, 1983.
 406. Lillywhite, H. B., and R. S. Seymour. Regulation of arterial blood pressure in Australian tiger snakes. J. Exp. Biol. 75: 65–79, 1978.
 407. Lillywhite, H. B., and L. H. Smith. Haemodynamic adjustments to head‐up posture in the partly arboreal snake, Elaphe obsoleta. J. Exp. Biol. 94: 275–283, 1981.
 408. Lillywhite, H. B., and A. W. Smits. Lability of blood volume in snakes and its relation to activity and hypertension. J. Exp. Biol. 110: 267–274, 1984.
 409. Lillywhite, H. B., and A. W. Smits. Cardiovascular adaptations of viperid snakes. In: Biology of the Pitvipers, edited by J. A. Campbell and E. D. Brodie, Jr. Tyler, TX: Selva, 1992, p. 143–153.
 410. Lillywhite, H. B., A. W. Smits, and M. E. Feder. Body fluid volumes in the aquatic snake Acrochordus granulatus. J. Herpetol. 22: 434–438, 1988.
 411. Linde, B., and P. Hjemdahl. Effect of tilting on adipose vascular tissue resistance and sympathetic activity in humans. Am. J. Physiol. 242 (Heart Circ. Physiol. 13): H161–H167, 1982.
 412. Little, C. The Colonisation of Land. Cambridge: Cambridge University Press, 1983.
 413. Little, C. The Terrestrial Invasion. Cambridge: Cambridge University Press, 1990.
 414. Lu, H. H., G. Lange, and C. McC. Brooks. Factors controlling activity of pacemaker cells in the mammalian sino‐atrial node. In: Electrophysiology and Ultrastructure of the Heart, edited by T. Saro, V. Mizuhira, and K. Matsuda. New York: Grune and Stratton, 1967, p. 117–126.
 415. Ludbrook, J., and W. F. Graham. Circulatory responses to onset of exercise: role of arterial and cardiac baroreflexes. Am. J. Physiol. 248 (Heart Circ. Physiol. 19): H457–H467, 1985.
 416. Lundvall, J., and J. Hillman. Fluid transfer from skeletal muscle to blood during hemorrhage. Importance of beta‐adrenergic vascular mechanisms. Acta Physiol. Scand. 102: 450–458, 1978.
 417. Lutz, B. R. Reflex cardiac and respiratory inhibition in the elasmobranch, Scyllium canicula. Biol. Bull. 59: 170–178, 1930.
 418. Lutz, B. R., and L. C. Wyman. Reflex cardiac inhibition of branchiovascular origin in the elasmobranch, Squalus acanthias. Biol. Bull. 62: 10–16, 1932.
 419. MacDonald, T. F., A. Cavalie, W. Trautwein, and D. Pelzier. Voltage‐dependent properties of macroscopic and elemental calcium channel currents in guinea pig ventricular myocytes. Pflugers Arch. 406: 437–448, 1986.
 420. MacKinnon, M. R., and H. Heatwole. Comparative cardiac anatomy of the Reptilia. The coronary arterial circulation. J. Morphol. 170: 1–27, 1981.
 421. Malvin, G. M. Adrenoceptor types in the respiratory vasculature of the salamander gill. J. Comp. Physiol. [B] 155: 591–596, 1985.
 422. Malvin, G. M. Cardiovascular shunting during amphibian metamorphosis. In: Cardiovascular Shunts: Ontogenetic, Phylogenetic and Clinical Aspects. Alfred Benzon Symposium 21, edited by K. Johansen and W. W. Burggren. Copenhagen: Munksgaard, 1985, p. 163–178.
 423. Malvin, G. M. Vascular resistance and vasoactivity of gills and pulmonary artery of the salamander, Ambytoma tigrinum. J. Comp. Physiol. [B] 155: 241–249, 1985.
 424. Malvin, G. M. Gill structure and function: amphibian larvae. In: Comparative Pulmonary Physiology: Current Concepts. Lung Biology in Health and Disease, edited by S. C. Wood. New York: Marcel Dekker, 1989, vol. 39, p. 121–151.
 425. Malvin, R. L. Some comparative aspects of the renin‐angiotensin system. Physiologist 27: 367–373, 1984.
 426. Manwen, J., M. J. Wilhelm, R. E. Lang, T. Unger, K. Lindpaintner, and D. Ganten. Endogenous tissue renin‐angiotensin systems, from molecular biology to therapy. Am. J. Med. 84: 28–34, 1988.
 427. Mcallen, R. M. The inhibition of the baroreceptor input to the medulla by stimulation of the hypothalamic defence area [Abstract]. J. Physiol. (Lond.) 257: 45P, 1976.
 428. McDonald, G., and B. R. McMahon. Respiratory development in Arctic char Salvelinus alpinus under conditions of normoxia and chronic hypoxia. Can. J. Zool. 55: 1461–1467, 1977.
 429. McGinnis, C. H., and R. K. Ringer. Carotid sinus reflex in the chicken. Poult. Sci. 45: 402–404, 1966.
 430. McIndoe, R., and D. G. Smith. Functional morphology of gills in larval amphibians. In: Respiration and Metabolism of Embryonic Vertebrates, edited by R. S. Seymour. Dordrecht, the Netherlands: Junk, 1984, p. 55–69.
 431. McMahon, B. R., and L. E. Burnett. The crustacean open circulatory system: A reexamination. Physiol. Zool. 63: 35–71, 1990.
 432. Mendes, E. G. Contribuicâo para a fisiologia dos sistemas respiratorio e circulatório de Siphonops annulatus (Amphibia‐Gymnophiona). Bol. Fac. Filos. Cienc. Letras Univ. San Paulo Ser. Zool. 5: 283–304, 1945.
 433. Middler, S. A., C. R. Kleeman, and E. Edwards. Lymph mobilization following acute blood loss in the toad, Bufo marinus. Comp. Biochem. Physiol. 24: 343–353, 1968.
 434. Millard, N. The development of the arterial system of Xenopus laevis, including experiments on the destruction of larval aortic arches. Trans. R. Soc. S. Afr. 30: 217–234, 1945.
 435. Miller, R. R., W. H. Fennel, Y. B. Young, A. R. Palomo, and M. A. Quinones. Differential systemic arterial and venous actions and consequent cardiac effects of vasodilator drugs. Prog. Cardiovasc. Dis. 24: 353–369, 1982.
 436. Miller, V. M., and P. M. Vanhoutte. Endothelium‐dependent responses in isolated blood vessels of lower vertebrates. Blood Vessels 23: 225–235, 1986.
 437. Milligan, C. L., and A. P. Farrell. Lactate utilization by an in situ perfused trout heart: effects of workload and blockers of lactate transport. J. Exp. Biol. 155: 357–373, 1991.
 438. Mills, T. W. The innervation of the heart of the slider terrapin (Pseudemys rugosa). J. Physiol. (Lond.) 6: 248–286, 1885.
 439. Mizelle, H. L., D. A. Hildebrandt, C. A. Gaillard, M. W. Brands, J.‐P. Montani, M. J. Smith, Jr., and J. E. Hall. Atrial natriuretic peptide induces sustained natriuresis in conscious dogs. Am. J. Physiol. 258 (Regulatory Integrative Comp. Physiol. 29): R1445–R1452, 1990.
 440. Moalli, R., R. S. Meyers, D. C. Jackson, and R. W. Millard. Skin circulation in the frog, Rana catesbeiana: distribution and dynamics. Respir. Physiol. 40: 137–148, 1980.
 441. Morris, C. E., and W. J. Sigurdson. Stretch‐inactivated ion channels coexist with stretch‐activated ion channels. Science 243: 807–809, 1989.
 442. Morris, J. L. Seasonal variation in responses of the toad renal vasculature to adrenaline. Naunyn Schmiedebergs Arch. Pharmacol. 320: 246–254, 1982.
 443. Mott, J. C. Some factors affecting the blood circulation in the common eel (Anguilla anguilla). J. Physiol. (Lond.) 114: 387–398, 1951.
 444. Nakazawa, M., E. B. Clark, and N. Hu. Effect of environmental hypothermia in the stage 18, 21 and 24 chick embryo. Pediatr. Res. 20: 1213–1215, 1986.
 445. Navaratnam, V. Anatomy of the mammalian heart. In: Hearts and Heart‐like Organs, edited by G. H. Bourne. New York: Academic, 1980, vol. I, p. 349–374.
 446. Niijima, A. Experimental studies on the afferent innervation of the toad's heart. Jpn. J. Physiol. 20: 527–539, 1970.
 447. Nilsson, S. On the adrenergic system of ganoid fish: the Florida spotted gar, Lepisosteus platyrhincus (Holostei). Acta Physiol. Scand. 111: 447–454, 1981.
 448. Nilsson, S. Autonomic Nerve Function in the Vertebrates. New York: Springer‐Verlag, 1983.
 449. Nilsson, S., and S. Holmgren. Novel neurotransmitters in the autonomic nervous systems of nonmammalian vertebrates. Pharmacol. Ther. 41: 257–457, 1989.
 450. Nilsson, S., and S. Holmgren. Cardiovascular control by purines, 5‐hydroxytryptamine, and neuropeptides. In: Fish Physiology, edited by D. J. Randall and W. W. Hoar. New York: Academic, 1992, vol. XIIA, p. 89–139.
 451. Nilsson, S., S. Holmgren, and D. J. Grove. Effects of drugs and nerve stimulation on the spleen and arteries of two species of dogfish, Scyliorhinus canicula and Squalus acanthias. Acta Physiol. Scand. 95: 219–230, 1975.
 452. Nishimura, H. Physiological evolution of the renin‐angiotensin system. Jpn. Heart J. 19: 806–822, 1978.
 453. Nishimura, H. Evolution of the renin‐angiotensin system. In: The Renin‐Angiotensin System, edited by J. A. Johnson and R. R. Anderson. New York: Plenum, 1980, p. 29–77.
 454. Norris, D. O. Vertebrate Endocrinology (2nd ed.). Philadelphia: Lea & Febiger, 1985.
 455. Numao, Y., M. Siato, N. Terui, and M. Kumada. The aortic nerve‐sympathetic reflex in the rat. J. Autonom. Nerv. Syst. 13: 65–79, 1985.
 456. Oberg, B. Effects of cardiovascular reflexes on net capillary fluid transfer. Acta Physiol. Scand. 62 (Suppl. 229): 1–98, 1964.
 457. Ogilvy, C. S., and A. B. Dubois. Effect of tilting on blood pressure and interstitial fluid pressures of blue fish and smooth dogfish. Am. J. Physiol. 242 (Regulatory Integrative Comp. Physiol. 13): R70–R76, 1982.
 458. Ogilvy, C. S., P. G. Tremml, and A. B. Dubois. Pressor and hemodilution responses compensate for acute hemorrhage in bluefish. Comp. Biochem. Physiol. A 91: 807–813, 1988.
 459. Olson, K. R. Blood and extracellular fluid volume regulation: role of the renin angiotensin system, kallikrein‐kinin system and atrial natriuretic peptides. In: Fish Physiology, edited by W. S. Hoar, D. J. Randall, and A. P. Farrell. San Diego: Academic, 1992, vol. XII, pt. B, p. 136–232.
 460. Olson, K. R., D. W. Duff, A. P. Farrell, J. Keen, M. D. Kellogg, D. Kullman, and J. Villa. Cardiovascular effects of endothelin in trout. Am.J. Physiol. 260 (Heart Circ. Physiol. 31): H1214–H1223, 1991.
 461. Olson, K. R., K. B. Flint, and R. B. Budde. Vascular corrosion replicas of chemo‐baroreceptors in fish: the carotid labyrinth in Ictaluridae and Clariidae. Cell Tissue Res. 219: 535–541, 1981.
 462. Olson, K. R., and J. Villa. Evidence against nonprostanoid endothelium‐derived relaxing factor(s) in trout vessels. Am. J. Physiol. 260 (Regulatory Integrative Comp. Physiol. 31): R925–R933, 1991.
 463. Opdyke, D. F., J. R. McGreenhan, S. Messing, and N. E. Opdyke. Cardiovascular responses to spinal cord stimulation and autonomically active drugs in Squalus acanthias. Comp. Biochem. Physiol. A 42: 611–620, 1972.
 464. Orlando, K., and A. Pinder. Larval cardiorespiratory ontogeny and allometry in Xenopus laevis. Physiol. Zool. 68: 63–75, 1995.
 465. Ostadal, B., Z. Rychter, and O. Poupa. Comparative aspects of the development of the terminal vascular bed in the myocardium. Physiol. Bohemoslov. 19: 1–7, 1970.
 466. Ostadal, B., and T. H. Schiebler. Über die terminale Strombann in Fishherzen. Z. Anat. Entwickl. 134: 101–110, 1971.
 467. Owen, R. On the structure of the heart in the perennibranchiate Batrachia. Trans. Zool. Soc. Lond. 1: 213–220, 1834.
 468. Page, S. G., and R. Niedergerke. Structures of physiological interest in the frog heart ventricle. J. Cell. Sci. 11: 179–203, 1972.
 469. Paintal, A. S. Cardiovascular receptors. In: Handbook of Sensory Physiology. III. Enteroreceptors, edited by E. Neil. Berlin: Springer‐Verlag, 1972, p. 1–46.
 470. Pang, P. K. T. Osmoregulatory functions of neurohypophyseal hormones in fishes and amphibians. Am. Zool. 17: 739–749, 1977.
 471. Pang, P. K. T., M. Uchiyama, and W. H. Sawyer. Endocrine and neural control of amphibian renal functions. Federation Proc. 41: 2366–2370, 1982.
 472. Pang, P. K. T., M. Yang, C. Oguro, J. G. Phillips, and J. A. Yee. Hypotensive actions of parathyroid hormone preparations in vertebrates. Gen. Comp. Endocrinol. 41: 135–138, 1980.
 473. Panizza, B. Sulla structure del cuore e sulla circolazione del sangue del Crocodilus luciua. Bibl. Ital. 87: 87–91, 1833.
 474. Parker, G. H., and F. K. Davis. The blood vessels of the heart in Carcharias, Raja, Amia. Proc. Boston Soc. Nat. History 29: 163–178, 1899.
 475. Parkes, D. G., J. P. Coghlan, J. G. McDougall, and B. A. Scoggins. Long‐term hemodynamic actions of atrial natriuretic factor in conscious sheep. Am. J. Physiol. 254 (Heart Circ. Physiol. 25): H811–H815, 1988.
 476. Patterson, J. L., Jr., and J. L. Cannon. Postural changes in the cerebral circulation, studied by continuous oximetric and pressure‐recording techniques [Abstract]. J. Clin. Invest. 30: 664, 1951.
 477. Peach, M. J. Renin‐angiotensin: biochemistry and mechanisms of action. Physiol. Rev. 57: 313–370, 1979.
 478. Pelster, B., and W. E. Bemis. Ontogeny of heart function in the little skate, Raja erinacea. J. Exp. Biol. 156: 387–398, 1991.
 479. Pelster, B., and W. W. Burggren. Central arterial hemodynamics in larval bullfrogs (Rana catesbeiana): developmental and seasonal effects. Am. J. Physiol. 260 (Regulatory Integrative Comp. Physiol. 31): R240–R246, 1991.
 480. Pelster, B. and W. W. Burggren. Disruption of hemoglobin oxygen transport does not impact oxygen‐dependent physiological processes in developing embryos of zebrafish (Danio rerio). Circ. Res., 19: 358–362, 1996.
 481. Pelster, B., W. W. Burggren, S. Petrou, and I. Wahlqvist. Developmental changes in the acetylcholine influence on heart muscle of Rana catesbeiana: in situ and in vitro effects. J. Exp. Zool. 267: 1–8, 1993.
 482. Persson, P., H. Ehmke, H. Kirchheim, and H. Seller. Effect of sinoaortic denervation in comparison to cardiopulmonary deafferentation on long‐term blood pressure in conscious dogs. Pflugers Arch. 411: 160–166, 1988.
 483. Persson, P., H. Ehmke, and H. Kirchheim. Cardiopulmonary–arterial baroreceptor interaction in the control of blood pressure. News Physiol. Sci. 4: 56–59, 1989.
 484. Peters, R. H. The Ecological Implications of Body Size. Cambridge: Cambridge University Press, 1983.
 485. Pettersson, K., M. Axelsson, and S. Nilsson. Shunting of blood flow in the caiman. In: Physiological Adaptations in Vertebrates: Respiration, Circulation and Metabolism, edited by S. C. Wood, R. E. Weber, A. R. Hargens, and R. W. Millard. New York: Marcel Dekker, 1992, p. 355–362.
 486. Petterson, K., and S. Nilsson. Drug induced changes in cardiovascular parameters in the Atlantic cod, Gadus morhua. J. Comp. Physiol. 137: 131–138, 1980.
 487. Peyraud‐Waitzenegger, M., and P. Soulier. Ventilatory and circulatory adjustments in the European eel (Anguilla anguilla L.) exposed to short term hypoxia. Exp. Biol. 48: 107–122, 1989.
 488. Piiper, J., M. Meyer, H. Worth, and H. Willmer. Respiration and circulation during swimming activity in the dogfish Scyliorhinus stellaris. Respir. Physiol. 30: 221–239, 1977.
 489. Pinder, A. W., K. B. Storey, and G. R. Ultsch. Estivation and hibernation. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 250–274.
 490. Ploucha, J. M., and G. D. Fink. Hemodynamics of hemorrhage in the conscious rat and chicken. Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol. 22): R846–R850, 1986.
 491. Ploucha, J. M., J. B. Scott, and R. K. Ringer. Vascular and hematologic effects of hemorrhage in the chicken. Am. J. Physiol. 240 (Heart Circ. Physiol. 11): H9–H17, 1981.
 492. Poder, T. C., S. D. Silberberg, and D. Rampe. Contraction of reptile, amphibian, and fish blood vessels by endothelin‐1. Can. J. Physiol. Pharmacol. 69: 215–217, 1991.
 493. Poupa, O., J. A. Ask, and K. B. Helle. Absence of calcium paradox in the cardiac ventricle of the Atlantic hagfish (Myxine glutinosa). Comp. Biochem. Physiol. A 78: 181–183, 1984.
 494. Poupa, O., K. B. Helle, and L. M. Lomsky. Calcium paradox from cyclostome to man; a comparative study. Comp. Biochem. Physiol. A. 81: 801–805, 1985.
 495. Priede, I. G. The effect of swimming activity and section of the vagus nerves on heart rate in rainbow trout. J. Exp. Biol. 60: 305–319, 1974.
 496. Protas, L., and G. R. Leontieva. Ontogeny of cholinergic and adrenergic mechanisms in the frog (Rana temporaria) heart. Am. J. Physiol. 262 (Regulatory Integrative Comp. Physiol 33): R150–R161, 1992.
 497. Putnam, J. L. Septation in the ventricle of the heart of Siren intermedia, Copeia 1975: 773–774, 1975.
 498. Putnam, J. L., and J. F. Dunn. Septation in the ventricle of the heart of Necturus maculosus. Herpetologica 34: 292–297, 1978.
 499. Putnam, J. L. and J. B. Parkerson. Anatomy of the heart of the Amphibia. II. Cryptobranchus alleganiesis. Herpetologica 41: 287–298, 1985.
 500. Quillen, E. W., Jr., and A. W. Cowley, Jr. Influence of volume changes on osmolality–vasopressin relationships in conscious dogs. Am. J. Physiol. 244 (Heart Circ. Physiol. 15): H73–H79, 1983.
 501. Randall, D. J. The circulatory system. In: Fish Physiology, edited by W. S. Hoar and D. J. Randall. New York: Academic, 1970, vol. IV. p. 133–172.
 502. Randall, D. J., and C. Brauner. Effects of environmental factors on exercise in fish. J. Exp. Biol. 160: 113–126, 1991.
 503. Randall, D. J., W. W. Burggren, A. P. Farrell, and M. S. Haswell. Evolution of Air Breathing in Vertebrates. Cambridge: Cambridge University Press, 1980.
 504. Randall, D. J., J. N. Cameron, C. Daxboeck, and N. Smatersk. Aspects of bimodal gas exchange in the bowfin, Amia calva L. (Actinopterygii; Amiiformes). Respir. Physiol. 43: 339–348, 1981.
 505. Randall, D. J., and P. S. Davie. The hearts of urochordates and cephalochordates. In: Hearts and Heart‐like Organs, edited by G. H. Bourne. New York: Academic, 1980, vol. 1. p. 41–59.
 506. Randall, D. J., and C. Daxboeck. Cardiovascular changes in the rainbow trout (Salmo gairdneri, Richardson) during exercise. Can. J. Zool. 60: 1135–1140, 1992.
 507. Randall, D. J., and E. D. Stevens. The role of adrenergic receptors in cardiovascular changes associated with exercise in salmon. Comp. Biochem. Physiol. A 21: 415–424, 1967.
 508. Rasmusson, R. L., J. W. Clark, W. R. Giles, K. Robinson, and R. B. Clark. A mathematical model of electrophysiological activity in bullfrog atrial cells. Am. J. Physiol. 259 (Heart Circ. Physiol. 30): H370–H389, 1990.
 509. Reeves, R. B. Energy cost of work in aerobic and anaerobic turtle heart muscle. Am. J. Physiol. 205: 17–22, 1963.
 510. Reite, O. B. The evolution of vascular smooth muscle responses to histamine and 5‐hydroxytryptamine. III. Manifestation of dual actions of either amine in reptiles. Acta Physiol. Scand. 78: 213–231, 1970.
 511. Reuter, H. Calcium channel modulation by neurotransmitters, enzymes and drugs. Nature 301: 569–574, 1983.
 512. Rice, G. E. Plasma arginine vasotocin concentrations in the lizard Varanus gouldi (Gray) following water loading, salt loading and dehydration. Gen. Comp. Endocrinol. 47: 1–6, 1982.
 513. Ringer, S. A further contribution regarding the influence of the different constituents of the blood on the contraction of the heart. J. Physiol. (Lond.) 4: 29–42, 1883.
 514. Ristori, M. T. Reflexe de barosensibilité chez un poisson teleosteen (Cyprinus carpio L). C. R. Seances Soc. Biol. Fil. 164: 1512–1516, 1970.
 515. Ristori, M. T., and G. Dessaux. Sur l'existence d'un gradient de sensibilité dans les recepteurs branchiaux de Cyprinus carpio L. C. R. Seances Soc. Biol. Fil. 164: 1517–1519, 1970.
 516. Ristori, M. T., and P. Laurent. Plasma catecholamines and glucose during moderate exercise in the trout: comparison with bursts of violent activity. Exp. Biol. 44: 247–253, 1985.
 517. Robertson, D., G. A. Johnson, R. M. Robertson, A. S. Nies, D. G. Shand, and J. A. Oates. Comparative assessment of stimuli that release neuronal and adrenomedullary catecholamines in man. Circulation 59: 637–643, 1979.
 518. Robertson, O. H., M. A. Krupp, N. Thompson, S. F. Thomas, and S. Hane. Blood pressure and heart weight in immature and spawning Pacific salmon. Am. J. Physiol. 210: 957–964, 1966.
 519. Roman, R. J., M. L. Kaldunski, A. G. Scicli, and O. A. Carretero. Influence of kinins, angiotensin II on the regulation of papillary blood flow. Am. J. Physiol. 255 (Renal Fluid Electrolyte Physiol. 26): F690–F698, 1988.
 520. Rombough, P. J. Respiratory gas exchange, aerobic metabolism, and effects of hypoxia during early life. In: Fish Physiology, edited by W. W. Hoar and D. J. Randall. New York: Academic, 1988, vol. XIA, p. 59–161.
 521. Rombough, P. J., and B. M. Moroz. The scaling and potential importance of cutaneous and branchial surfaces in respiratory gas exchange in young Chinook salmon Oncorhynchus tshawytscha. J. Exp. Biol. 154: 1–12, 1990.
 522. Rome, L. C., E. D. Stevens, and H. B. John‐Alder. The influence of temperature and thermal acclimation on physiological function. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 183–205.
 523. Romer, A. S. The Vertebrate Body. Philadelphia: Saunders, 1955.
 524. Rowell, L. B. Human Cardiovascular Control. New York: Oxford University Press, 1993.
 525. Rowlatt, U. Functional and nonfunctional determinants of mammalian cardiac anatomy, parts I and II. In: Hearts and Heart‐like Organs, edited by G.H. Bourne. New York: Academic, 1980, vol. I, p. 259–300.
 526. Ruben, J. A., and A. F. Bennett. Intense exercise, bone structure and blood calcium levels in vertebrates. Nature 291: 411–413, 1981.
 527. Sabatier, A. Etudier sur le coeur et la circulation centrale dans la series des vertebres. Ann. Sci. Nat. Zool. Paleontol. Ser. 518: 1–89, 1873.
 528. Sagawa, K. Baroreflex control of systemic arterial pressure and vascular bed. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow, edited by J. T. Shepherd and F. M. Abboud. Washington, DC: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, chapt. 14, p. 453–496.
 529. Saint‐Aubain de, M. L. The morphology of amphibian skin before and after metamorphosis. Zoomorphology 100: 55–63, 1982.
 530. Saint‐Aubain de, M. L., and K. G. Wingstrand. A sphincter in the pulmonary artery of the frog Rana temporaria and its influence on blood flow in skin and lungs. Acta Zool. (Stockh.) 60: 163–172, 1979.
 531. Sanchez‐Quintana, D., and J. M. Hurle. Ventricular myocardial architecture in marine fishes. Anat. Rec. 217: 263–273, 1987.
 532. Sander‐Jensen, K., N. H. Secher, A. Astrup, N. J. Christensen, J. Giese, T. W. Schwartz, J. Warberg, and P. Bie. Hypotension induced by passive head‐up tilt: endocrine and circulatory mechanisms. Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol. 22): R742–R748, 1986.
 533. Sanford, B., and G. A. Stephens. The effects of adrenocorticotropin hormone and angiotensin II on adrenal corticosteroid secretions in the freshwater turtle Pseudemys scripta. Gen. Comp. Endocrinol. 72: 107–114, 1988.
 534. Santer, R. M. Morphology and innervation of the fish heart. In: Advances in Anatomy, Embryology and Cell Biology. Berlin: Springer‐Verlag, 1985, p. 1–102.
 535. Satchell, G. H. The response of the dogfish to anoxia. J. Exp. Biol. 38: 531–543, 1961.
 536. Satchell, G. H. Sites of cholinergic vasoconstriction in trout (Salmo gairdneri). Can. J. Zool. 56: 1678–1683, 1971.
 537. Satchell, G. H. The circulatory system of air‐breathing fish. In: Respiration of Amphibious Vertebrates, edited by G. M. Hughes. London: Academic, 1976, p. 105–123.
 538. Satchell, G. H. Physiology and Form of Fish Circulation. Cambridge: Cambridge University Press, 1991.
 539. Satchell, G. H. The venous system. In: Fish Physiology, edited by W. W. Hoar, D. J. Randall, and A. P. Farrell. New York: Academic, 1992, vol. XII, pt A., p. 141–183.
 540. Sawaya, P. Sôbre o veneo das glandulas cutaneas, a secreçâo e o coraçâo de Siphonops annulatus. Bol. Fac. Filos. Cienc. Letras Univ. San Paulo Ser. Zool. 4: 206–270, 1940.
 541. Sawyer, W. H. Evolution of active neurohypophysial principles among the vertebrates. Am. Zool. 17: 727–737, 1977.
 542. Scheuermann, D. W. Untersuchungen hinsichtlich der Innervation des Sinus venosus and des Aurikels von Protopterus annectens. Acta Morphol. Neerl. Scand. 17: 231–232, 1979.
 543. Schindler, S. L., and R. P. Gildersleeve. Comparison of recovery from hemorrhage in birds and mammals. Comp. Biochem. Physiol. 87: 533–542, 1987.
 544. Schlondorff, D., S. Roczniak, J. A. Satriano, and V. W. Folkert. Prostaglandin synthesis by isolated rat glomeruli: effect of angiotensin II. Am. J. Physiol. 238 (Renal Fluid Electrolyte Physiol. 9): F486–F495, 1980.
 545. Schmidt‐Nielsen, K. Scaling: Why Is Animal Size So Important? Cambridge: Cambridge University Press, 1984.
 546. Schultz, S. G. Volume preservation: then and now. News Physiol. Sci. 4: 169–172, 1989.
 547. Segar, W. E., and W. W. Moore. The regulation of antidiuretic hormone release in man. I. Effects of change in position and ambient temperature on blood ADH levels. J. Clin. Invest. 47: 2143–2151, 1968.
 548. Seymour, R. S. Scaling of cardiovascular physiology in snakes. Am. Zool. 27: 97–109, 1987.
 549. Seymour, R. S. Diving physiology: reptiles. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 697–720.
 550. Seymour, R. S., and S. J. Barker. Evolution of blood pressure regulation in snakes [Abstract]. Proc. Int. Union Physiol. Sci. 15: 312, 1983.
 551. Seymour, R. S., and K. Johansen. Blood flow uphill and downhill: does a siphon facilitate circulation above the heart? Comp. Biochem. Physiol. [A] 88: 167–170, 1987.
 552. Seymour, R. S., and H. B. Lillywhite. Blood pressure in snakes from different habitats. Nature 264: 664–666, 1976.
 553. Shabetai, R., D. C. Abel, J. B. Graham, V. Bhargava, R. S. Keyes, and K. Witztum. Function of the pericardium and pericardioperitoneal canal in elasmobranch fishes. Am. J. Physiol. 248 (Heart Circ. Physiol. 19): H198–H207, 1985.
 554. Shelton, G. The effect of lung ventilation on blood flow to the lungs and body of the amphibian, Xenopus laevis. Respir. Physiol. 9: 183–196, 1970.
 555. Shelton, G. The regulation of breathing. In: Fish Physiology, edited by W. S. Hoar and D. J. Randall. New York: Academic, 1970, p. 293–359.
 556. Shelton, G. Gas exchange, pulmonary blood supply, and the partially divided amphibian heart. In: Perspectives in Experimental Biology, edited by P. S. Davies. Oxford: Pergamon, 1976, p. 247–259.
 557. Shelton, G., and W. Burggren. Cardiovascular dynamics of the chelonia during apnoea and lung ventilation. J. Exp. Biol. 64: 323–343, 1976.
 558. Shelton, G., and D. R. Jones. Pressure and volume relationships in the ventricle, conus and arterial arches of the frog heart. J. Exp. Biol. 43: 479–488, 1965.
 559. Shelton, G., and D. R. Jones. The physiology of the alligator heart: the cardiac cycle. J. Exp. Biol. 158: 539–564, 1991.
 560. Shen, Y.‐T., A. W. Cowley, Jr., and S. F. Vatner. Relative roles of cardiac and arterial baroreceptors in vasopressin regulation during hemorrhage in conscious dogs. Circ. Res. 68: 1422–1436, 1990.
 561. Shoemaker, V. H., S. S. Hillman, S. D. Hillyard, D. C. Jackson, L. L. McCanahan, P. C. Withers, and M. L. Wygoda. Exchange of water, ions, and respiratory gases in terrestrial amphibians. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 125–150.
 562. Short, S., P. J. Butler, and E. W. Taylor. The relative importance of nervous humoral and intrinsic mechanisms in the regulation of heart rate and stroke volume in the dogfish (Scyliorhinus canicula L.). J. Exp. Biol. 70: 77–92, 1977.
 563. Short, S., E. W. Taylor, and P. J. Butler. The effectiveness of oxygen transfer during normoxia and hypoxia before and after cardiac vagotomy. J. Comp. Physiol. [B] 132: 289–295, 1979.
 564. Shumway, S. E. Respiration, pumping activity and heart rate in Ciona intestinalis exposed to fluctuating salinities. Marine Biol. 48: 235–242, 1978.
 565. Siebert, H. Thermal adaptation of heart rate and its parasympathetic control in the european eel Anguilla (L.) Contp. Biochem. Physiol. [C] 64: 275–278, 1979.
 566. Small, S. A., C. MacDonald, and A. P. Farrell. Vascular reactivity of the coronary artery in rainbow trout (Oncorhynchus mykiss). Am. J. Physiol. 258 (Regulatory Integrative Comp. Physiol. 29): R1402–R1410, 1990.
 567. Smith, D. G. Neural regulation of blood pressure in rainbow trout (Salmo gairdneri). Can. J. Zool. 56: 1678–1683, 1978.
 568. Smith, D. G., P. J. Berger, and B. K. Evans. Baroreceptor control of heart rate in the conscious toad, Bufo marinus. Am. J. Physiol. 241 (Regulatory Integrative Comp. Physiol. 12): R307–R311, 1981.
 569. Smith, D. G., S. Nilsson, I. Wahlqvist, and B. M. Eriksson. Nervous control of blood pressure in the Atlantic cod, Gadus morhua. J. Exp. Biol. 117: 335–347, 1985.
 570. Smith, F. M., and P. S. Davie. Effects of sectioning cranial nerves IX and X on the cardiac response to hypoxia in the coho salmon. Can. J. Zool. 62: 766–769, 1984.
 571. Smith, F. M., and D. R. Jones. Localization of receptors causing hypoxic bradycardia in trout (Salmo gairdneri). Can. J. Zool. 56: 1260–1265, 1978.
 572. Smith, J. J. (Ed). Circulatory Response to the Upright Posture. Boca Raton, FL: CRC, 1990.
 573. Smits, A. W. Fluid balance in vertebrate lungs. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 503–537.
 574. Smits, A. W., and M. M. Kozubowski. Partitioning of body fluids and cardiovascular responses to circulatory hypovolemia in the turtle, Pseudemys scripta elegans. J. Exp. Biol. 116: 237–250, 1985.
 575. Smits, A. W., and H. B. Lillywhite. Maintenance of blood volume in snakes: transcapillary shifts of extravascular fluids during acute hemorrhage. J. Comp. Physiol. [B] 155: 305–310, 1985.
 576. Smits, A. W., N. H. West, and W. W. Burggren. Pulmonary fluid balance following pulmocutaneous baroreceptor denervation in the toad. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol. 61: 331–337, 1986.
 577. Snyder, G. K. Respiratory adaptations in diving mammals. Respir. Physiol. 54: 269–294, 1983.
 578. Sommer, J. C., and E. A. Johnson. Ultrastructure of cardiac muscle. In: Handbook of Physiology. The Cardiovascular System. The Heart, edited by R. M. Berne. Washington, DC: Am. Physiol. Soc., 1979, sect. 2, vol. 1, p. 113–186.
 579. Steffensen, J. F., K. Johansen, C. D. Sindberg, J. H. Soernsen, and J. L. Moller. Ventilation and oxygen consumption in the hagfish, Myxine glutinosa L. J. Exp. Mar. Biol. Ecol. 84: 173–178, 1984.
 580. Steffensen, J. F., and J. P. Lomholt. The secondary vascular system. In: Fish Physiology, edited by W. W. Hoar, D. J. Randall, and A. P. Farrell. New York: Academic, 1992, vol. XII, A, p. 185–217.
 581. Steffensen, J. F., J. P. Lomholt, and W. O. P. Vogel. In vivo obserations on a specialized microvasculature, the primary and secondary vessels in fishes. Acta Zool. (Stockh.)) 67: 193–200, 1986.
 582. Stephens, G. A. Blockade of angiotensin pressor activity in the freshwater turtle. Gen. Comp. Endocrinol. 45: 364–371, 1981.
 583. Stephenson, R., and D. R. Jones. Diving physiology: birds. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood. New York: Marcel Dekker, 1989, p. 735–786.
 584. Stevens, E. D., and D. J. Randall. Changes in blood pressure, heart rate and breathing rate during moderate swimming activity in rainbow trout. J. Exp. Biol. 46: 307–315, 1967.
 585. Stinner, J. N. Cardiovascular and metabolic responses to temperature in Coluber constrictor. Am. J. Physiol. 253 (Regulatory Integrative Comp. Physiol. 24): R222–R227, 1987.
 586. Stinner, J. N. Blood pressure during routine activity, stress, and feeding in black racer snakes (Coluber constrictor). Am. J. Physiol. 264 (Regulatory Integrative Comp. Physiol. 35): R79–R84, 1993.
 587. Sturkie, P. D. Heart and circulation: anatomy, hemodynamics, blood pressure, blood flow. In: Avian Physiology (4th ed.), edited by P. D. Sturkie. New York: Springer‐Verlag, 1986, p. 130–166.
 588. Sudak, F. N., and C. G. Wilber. Cardiovascular responses to hemorrhage in the dogfish. Biol. Bull. 119: 342, 1960.
 589. Taha, A.A.M., E. M. Abdel‐Magied, and A. S. King. Ultrastructure of aortic and pulmonary baroreceptors in the domestic fowl. J. Anat. 137: 197–207, 1983.
 590. Taylor, E. W., and D. J. Barrett. Evidence of a respiratory role for the hypoxic bradycardia in the dogfish Scyliorhinus canicula L. Comp. Biochem. Physiol. [A] 80: 99–102, 1985.
 591. Taylor, E. W., S. Short, and P. J. Butler. The role of the cardiac vagus in the response of the dogfish (Scyliorhinus canicula) to hypoxia. J. Exp. Biol. 70: 57–75, 1977.
 592. Tazawa, H., Y. Hashimoto, and K. Doi. Blood pressure and heart rate of the chick embryo (Gallus domesticus) within the egg: responses to autonomic drugs. In: Phylogenetic Models in Functional Coupling of the CNS and the Cardiovascular System, edited by R. B. Hill, K. Kuwasawa, B. R. McMahon, and T. Kuramoto. Basel: Karger, 1992, p. 86–96.
 593. Tazawa, H., T. Hiraguchi, O. Kuroda, S. G. Tullett, and D. C. Deeming. Embryonic heart rate during development of domesticated birds. Physiol. Zool. 64: 1002–1022, 1991.
 594. Tazawa, H., O. Kuroda, and G. C. Whittow. Noninvasive determination of embryonic heart rate during hatching in the brown noddy (Anous stolidus). Auk 108: 594–601, 1991.
 595. Tazawa, H., M. Mochizuki, and J. Piiper. Respiratory gas transport by the incompletely separated double circulation in the bullfrog, Rana catesbeiana. Respir. Physiol. 36: 77–95, 1979.
 596. Reference number not used.
 597. Tazawa, H., and S. Nakagawa. Response of egg temperature, heart rate and blood pressure in the chick embryo to hypothermal stress. J. Comp. Physiol. [B] 155: 195–200, 1985.
 598. Tazawa, H., W. Watanabe, and W. W. Burggren. Embryonic heart rate in altricial birds, the pigeon (Columbia domestica) and the bank swallow (Riparia riparia). Physiol. Zool. 67: 1448–1460, 1994.
 599. Tcheng, K.‐T., S.‐K. Fu, and T.‐Y. Chen. Intravagal receptors and sensory neurons in birds. Sci. Sinica 14: 1323–1331, 1965.
 600. Thomas, D. P. and G. F. Fregin. Cardiorespiratory and metabolic responses to treadmill exercise in the horse. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol. 50: 864–868, 1981.
 601. Thorarensen, H. P. Gastrointestinal Blood Flow in Chinook Salmon (Oncorhynchus tshawytscha). Burnaby, Canada: Simon Fraser University, 1994. Dissertation.
 602. Thorarensen, H. P., P. Gallagher, A. Kiessling, and A. P. Farrell. Intestinal blood flow in swimming Chinook salmon, Oncorhynchus kisutch: the effects of hematocrit on blood flow distribution. J. Exp. Biol. 179: 115–129, 1993.
 603. Thoren, P. Role of cardiac vagal‐C‐fibers in cardiovascular control. Rev. Physiol. Biochem. Pharmacol. 86: 1–94, 1979.
 604. Tibbits, G. F., L. Hove‐Madsen, and D. M. Bers. Ca2+ transport and the regulation of cardiac contractility in teleosts: a comparison with higher vertebrates. Can. J. Zool. 69: 2014–2019, 1991.
 605. Tibbits, G. F., H. Kashihara, M. J. Thomas, J. E. Keen, and A. P. Farrell. Ca2+ transport in myocardial sarcolemma from rainbow trout. Am. J. Physiol. 259 (Regulatory Integrative Comp. Physiol. 30): R453–R460, 1990.
 606. Toews, D. P., and D. MacIntyre. Respiration and circulation in an apodan amphibian. Can. J. Zool. 56: 998–1004, 1978.
 607. Toews, D. P., G. Shelton, and D. J. Randall. Gas tensions in the lungs and major blood vessels of the urodele amphibian, Amphiuma tridactylum. J. Exp. Biol. 55: 47–61, 1971.
 608. Tota, B. Vascular and metabolic zonation in the ventricular myocardium of mammals and fishes. Comp. Biochem. Physiol. [A] 76: 423–437, 1983.
 609. Tota, B. Myoarchitecture and vascularization of the elasmo‐branch heart ventricle. J. Exp. Zool. (Suppl. 2): 122–135, 1989.
 610. Tota, B., R. Acierno, and C. Agnisola. Mechanical performance of the isolated and perfused heart of the haemoglobinless Antarctic icefish Chionodraco hamatus (Lonnberg): effects of loading conditions and temperature. Phil. Trans. R. Soc. Lond. B 332: 191–198, 1991.
 611. Tufts, B. L., D. C. Mense, and D. G. Randall. The effects of forced activity on circulating catecholamines and pH and water content of erythrocytes in the toad. J. Exp. Biol. 128: 411–418, 1987.
 612. Tummons, J. L. Nervous control of heart rate in domestic fowl. New Brunswick, NJ: Rutgers University, 1970. Dissertation.
 613. Tummons, J. L., and P. D. Sturkie. Nervous control of heart rate during excitement in the adult White Leghorn cock. Am. J. Physiol. 216: 1437–1440, 1969.
 614. Uchiyama, K., Y. Tsumuraya, A. Ishibiki, and K Okada. Electrophysiology and Ultrastructure of the Heart, edited by T. Saro, V. Mizuhira, and K. Matsuda. New York: Grune and Stratton, 1967, p. 109–115.
 615. Uchiyama, M., and P.K.T. Pang. Renal and vascular responses to AVT and its antagonistic analog (KB IV‐24) in the lungfish, mudpuppy, and bullfrog. In: Current Trends in Comparative Endocrinology, edited by B. Lofts and W. N. Holmes. Hong Kong: Hong Kong University Press, 1985, p. 929–932.
 616. Van Citters, R. L., D. L. Franklin, S. F. Vatner, T. Patrick, and J. V. Warren. Cerebral hemodynamics in the giraffe. Trans. Assoc. Am. Physicians 82: 293–304, 1969.
 617. Van Citters, R. L., S. Kemper, and D. L. Franklin. Blood pressure responses of wild giraffes studied by radio telemetry. Science 152: 384–386, 1966.
 618. Van Citters, R. L., S. Kemper, and D. L. Franklin. Blood flow and pressure in the giraffe carotid artery. Comp. Biochem. Physiol. A 24: 1035–1042, 1968.
 619. Van Mierop, L.H.S., and C. J. Bertuch, Jr. Development of arterial blood pressure in the chick embryo. Am. J. Physiol. 212: 43–48, 1967.
 620. Van Mierop, L.H.S., and L. M. Kutsche. Some aspects of comparative anatomy of the heart. In: Cardiovascular Shunts: Phylogenetic, Ontogenetic and Clinical Aspects, edited by K. Johansen and W. W. Burggren. Copenhagen: Munksgaard, 1985, p. 38–53.
 621. Van Vliet, B. N., and N. H. West. Cardiovascular responses to electrical stimulation of the recurrent laryngeal nerve in conscious toads (Bufo marinus). J. Comp. Physiol. [B] 156: 363–375, 1986.
 622. Van Vliet, B. N., and N. H. West. Response characteristics of pulmocutaneous arterial baroreceptors in the toad, Bufo marinus. J. Physiol. (Lond.) 388: 55–70, 1987.
 623. Van Vliet, B. N., and N. H. West. Responses to circulatory pressures, and conduction velocity of pulmocutaneous baroreceptors in Bufo marinus. J. Physiol. (Lond.) 388: 41–53, 1987.
 624. Van Vliet, B. N., and N. H. West. Cardiovascular responses to denervation of pulmocutaneous baroreceptors in toads. Am. J. Physiol. 256 (Regulatory Integrative Comp. Physiol. 27): R946–R954, 1989.
 625. Van Vliet, B. N., and N. H. West. Phylogenetic trends in the baroreceptor control of arterial blood pressure. Physiol. Zool. 67: 1284–1304, 1994.
 626. Vassort, G., O. Rougier, D. Gamier, M. P. Sauviat, E. Corabeouf, and Y. M. Gargouil. Effects of adrenaline on membrane inward currents during the cardiac action potential. Pflugers Arch. 309: 70–81, 1969.
 627. Versteeg, P.G.A., M.I.M. Noble, J. Stubbs, and G. Elzinga. The effect of cardiac denervation and beta blockade on control of cardiac output in exercising dogs. Eur. J. Appl. Physiol. 52: 62–68, 1983.
 628. Voboril, A., and T. H. Schiebler. Zur GefaBBversorgung von fischherzen. Z. Anat. Entwicklungsgesch 130: 1–8, 1970.
 629. Vogel, W. O. P. Systemic vascular anastomoses, primary and secondary vessels in fish, and the phylogeny of lymphatics. In: Cardiovascular Shunts: Phylogenetic, Ontogenetic and Clinical Aspects, edited by K. Johansen and W. W. Burggren. Copenhagen: Munksgaard, 1985, p. 143–151.
 630. Vornanen, M. Regulation of contractility of the fish (Carassius carassius L.) heart ventricle. Comp. Biochem. Physiol. [C] 94: 477–483, 1989.
 631. Wagman, A. J., and E. B. Clark. Frank‐Starling relationship in the developing cardiovascular system. In: Cardiovascular Morphogenesis, edited by V. Ferrans, G. Rosenquist, and C. Weinstein. New York: Elsevier, 1985, p. 245–252.
 632. Wahlqvist, I., and G. Campbell. Autonomic influences on heart rate and blood pressure in the toad, Bufo marinus, at rest and during exercise. J. Exp. Biol. 134: 377–396, 1988.
 633. Wahlqvist, I., and S. Nilsson. The role of sympathetic fibres and circulating catecholamines in controlling the blood pressure in the cod, Gadus morhua. Comp. Biochem. Physiol. [C] 57: 65–67, 1977.
 634. Wahlqvist, I., and S. Nilsson. Sympathetic nervous control of the vasculature in the tail of the Atlantic cod, Gadus morhua. J. Comp. Physiol. [B] 144: 153–156, 1981.
 635. Wang, T., W. W. Burggren, and E. Nobrega. Metabolic, ventilatory and acid‐base responses associated with specific dynamic action in the toad, Bufo marinus. Physiol. Zool. 68: 192–205, 1995.
 636. Weathers, W. W. Influence of temperature acclimation on oxygen consumption, haemodynamics and oxygen transport in bullfrogs. Aust. J. Zool. 24: 321–330, 1976.
 637. Webb, G.J.W. Comparative cardiac morphology of the Reptilia. III. The heart of crocodilians and a hypothesis on the completion of the intraventricular septum of crocodilians and birds. J. Morphol. 161: 221–240, 1979.
 638. Webb, G.J.W., H. Heatwole, and J. DeBavay. Comparative cardiac anatomy of the Reptilia: I. The chambers and septa of the varanid ventricle. J. Morphol. 134: 335–350, 1971.
 639. West, N. H., and W. W. Burggren. Control of pulmonary and cutaneous blood flow in the toad, Bufo marinus. Am. J. Physiol. 247 (Regulatory Integrative Comp. Physiol. 18): R884–R894, 1984.
 640. West, N. H., P. J. Butler, and R. M. Bevan. Pulmonary blood flow at rest and during swimming in the green turtle, Chelonia mydas. Physiol. Zool. 65: 287–310, 1992.
 641. West, N. H., A. W. Smits, and W. W. Burggren. Factors terminating nonventilatory periods in the turtle, Chelydra longicollis. Physiol. Zool. 62: 668–686, 1989.
 642. West, N. H., and B. N. Van Vliet. Open‐loop analysis of the pulmocutaneous baroreflex in the toad (Bufo marinus). Am. J. Physiol. 245: R642–R650, 1983.
 643. West, N. H., and B. N. Van Vliet. Sensory mechanisms regulating cardiovascular and respiratory systems. In: Environmental Physiology of the Amphibians, edited by M. E. Feder and W. W. Burggren. Chicago: University of Chicago Press, 1992, p. 151–182.
 644. White, F. C., R. Kelly, S. Kemper, P. T. Schumacker, K. R. Gallagher, and R. M. Laurs. Organ blood flow haemodynamics and metabolism of the albacore tuna Thunnus alalunga (Bonnaterre). Exp. Biol. 47: 161–169, 1988.
 645. White, F. N. Circulation in the reptilian heart (Caiman sclerops). Anat. Rec. 125: 417–432, 1956.
 646. White, F. N. Circulation in the reptilian heart (Squamata). Anat. Rec. 135: 129–134, 1959.
 647. White, F. N. Redistribution of cardiac output in the diving alligator. Copeia 3: 567–570, 1969.
 648. White, F. N. Central vascular shunts and their control in reptiles. Federation Proc. 29: 1149–1153, 1970.
 649. White, F. N. Circulation. In: Biology of the Reptilia, edited by C. Gans. New York: Academic, 1976, vol. 5, p. 275–334.
 650. White, F. N. Role of intracardiac shunts in pulmonary gas exchange in chelonian reptiles. In: Cardiovascular Shunts: Ontogenetic, Phylogenetic and Clinical Aspects. Alfred Benzon Symposium 21, edited by K. Johansen and W. W. Burggren. Copenhagen: Munksgaard, 1985, p. 296–309.
 651. White, F. N. Carbon dioxide homeostasis. In: Comparative Pulmonary Physiology; Current Concepts, edited by S. C. Wood, New York: Marcel Dekker, 1989, p. 503–537.
 652. White, F. N., and G. Ross. Circulatory changes during experimental diving in the turtle. Am. J. Physiol. 211: 15–18, 1966.
 653. Whittow, G. C. (Ed). Comparative Physiology Of Thermoregulation. Mammals. New York: Academic, 1971, vol. II.
 654. Withers, P. C. Comparative Animal Physiology. Philadelphia: Saunders, 1992.
 655. Withers, P. C., and S. S. Hillman. A steady‐state model of maximal oxygen and carbon dioxide transport in anuran amphibians. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol. 64: 860–868, 1988.
 656. Withers, P. C., S. S. Hillman, and P. B. Kimmel. Effects of activity, hemorrhage, and dehydration on plasma catecholamine levels in the marine toad Bufo marinus. Gen. Comp. Endocrinol. 72: 63–71, 1988.
 657. Withers, P. C., S. S. Hillman, L. A. Simmons, and A. C. Zygmunt. Cardiovascular adjustments to enforced activity in the anuran amphibian, Bufo marinus. Comp. Biochem. Physiol. A. 89: 45–49, 1988.
 658. Witschi, E. Development of Vertebrates. Philadelphia: Saunders, 1956.
 659. Wood, C. M. Mayer waves in the circulation of a teleost fish. J. Exp. Zool. 189: 267–274, 1974.
 660. Wood, C. M. Pharmacological properties of the adrenergic receptors regulating systemic vascular resistance in the rainbow trout. J. Comp. Physiol. [B] 107: 211–228, 1976.
 661. Wood, C. M. Cholinergic mechanisms and the response to ATP in the systemic vasculature of the rainbow trout. J. Comp. Physiol. [B] 122: 325–345, 1977.
 662. Wood, C. M., P. Pieprzak, and J. N. Trott. The influence of temperature and anaemia on the adrenergic and cholinergic mechanisms controlling heart rate in the rainbow trout. Can. J. Zool. 57: 2440–2447, 1979.
 663. Wood, C. M., and G. Shelton. Physical and adrenergic factors affecting systemic vascular resistance in the rainbow trout: a comparison with branchial vascular resistance. J. Exp. Biol. 63: 505–523, 1975.
 664. Wood, C. M., and G. Shelton. Cardiovascular dynamics and adrenergic responses of the rainbow trout in vivo. J. Exp. Biol. 87: 247–270, 1980.
 665. Wood, C. M., and G. Shelton. The reflex control of heart rate and cardiac output in the rainbow trout: interactive influences of hypoxia, haemorrhage and systemic vasomotor tone. J. Exp. Biol. 87: 271–284, 1980.
 666. Woods, J. J. Studies on the Distribution and Action of Serotonin in the Avian Cardiovascular System. New Brunswick, NJ: Rutgers University, 1971. Dissertation.
 667. Wright, G. M. Structure of the conus arteriosus and ventral aorta in the sea lamprey, Petromyzon marinus, and the Atlantic hagfish, Myxine glutinosa: microfibrils, a major component. Can. J. Zool. 62: 2445–2456, 1984.
 668. Yamaguchi, K., and H. Nishimura. Angiotensin H‐induced relaxation of fowl aorta. Am. J. Physiol. 255 (Regulatory Integrative Comp. Physiol. 26): R591–R599, 1988.
 669. Yamamoto, T. Observations on the fine structure of the cardia muscle cells in goldfish (Carassius auratus). In: Electrophysiology and Ultrastructure of the Heart, edited by T. Saro, V. Mizuhira, and K. Matsuda. New York: Grune and Stratton, 1967, p. 1–13.
 670. Yamauchi, A. Comparisons of the fine structure of receptor end‐organs in the heart and aorta. In: Cardiac Receptors, edited by R. Hainsworth, C. Kidd, and R. J. Linden. Cambridge: Cambridge University Press, 1979, p. 51–70.
 671. Zapol, W. M., G. C. Liggins, R. C. Schneider, J. Qvist, M. T. Snider, R. K. Creasy, and P. W. Hochachka. Regional blood flow during simulated diving in the conscious Weddell seal. J. Appl. Physiol.: Respir. Environ. Exerc. Physiol 47: 968–973, 1979.
 672. Zehr, J. E., D. J. Standen, and M. D. Cipolle. Characterization of angiotensin pressor responses in the turtle Pseudemys scripta. Am. J. Physiol. 240 (Regulatory Integrative Comp. Physiol. 11): R276–R281, 1981.

Contact Editor

Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Vertebrate Cardiovascular Systems
 

How to Cite

W. Burggren, A. Farrell, H. Lillywhite. Vertebrate Cardiovascular Systems. Compr Physiol 2011, Supplement 30: Handbook of Physiology, Comparative Physiology: 215-308. First published in print 1997. doi: 10.1002/cphy.cp130104