Comprehensive Physiology Wiley Online Library
For Librarians For Authors Editors About

Biology Of Sodium‐Absorbing Epithelial Cells: Dawning of a New Era

Stanley G. Schultz, Randall L. Hudson

10.1002/cphy.cp060402

Source: Supplement 19: Handbook of Physiology, The Gastrointestinal System, Intestinal Absorption and Secretion

Originally published: 1991

Published online: January 2011

Full Article on Wiley Online Library



Abstract

The sections in this article are:

1 Background
1.1 Birth of Modern Era of Epitheliology
1.2 Extensions and Modifications of Original Koefoed‐Johnsen—Ussing Model
1.3 Regulation of Intracellular Ion Composition and Volume
1.4 Glossary
2 Na+ Transport Pool
2.1 Intracellular Na+ Compartment
2.2 What is the Relation Between Cell Na+ Activity and Na+ Pump Rate?
3 Na+ Pump(S)
3.1 Na+‐K+‐ATPase
3.2 Na+‐ATPase: Is There a Second Na+ Pump?
3.3 Na+‐HCO−3 Cotransport Across Basolateral Membranes
3.4 Summary
4 Basolateral Membrane K+ Conductance
4.1 Parallelism Between Rate of Transcellular Na+ Transport and Basolateral Membrane K+ Conductance
4.2 Physiological Utility of Parallelism Between Pump Rate and K+ Conductance of Basolateral Membrane
4.3 What Intracellular Signal(s) is Responsible for Parallelism Between Transcellular Na+ Transport, Pump Rate, and K+ Conductance of Basolateral Membranes?
4.4 Summary
5 Volume Regulation
5.1 Are the Mechanisms Responsible for Pump‐Leak Parallelism and Volume Regulatory Decrease Related?
5.2 Is Na+ Pump Rate Affected by Cell Swelling?
5.3 How do Cells “Recognize” an Increase in Volume?
5.4 Summary
6 Regulation of Cell Ca2+
7 Summary: Toward A “New Biology” of Na+ ‐Absorbing Epithelial Cells
Figure 1. Figure 1.

Koefoed‐Johnsen—Ussing model for Na+ absorption by isolated frog skin. ICM, inner cellular membrane; OCM, outer cellular membrane; P, Na+‐K+ pump.

[From Koefoed‐Johnsen and Ussing 155.]
Figure 2. Figure 2.

Composite model of Na+‐absorbing epithelial cells illustrating 4 established mechanisms for Na+ entry across apical membrane and Na+‐K+ pump and K+ leak characteristic of basolateral membranes of all such cells studied to date. S, solute.
Figure 3. Figure 3.

Effect of HCO3− (plus CO2) on intracellular Na+ activity [(Na)c] in rabbit gallbladder epithelial cells determined by use of Na+‐selective microelectrodes. Bars, variance among different tissues. Transient increase was observed in every instance and is highly significant.

[Adapted from Moran et al. 201.]
Figure 4. Figure 4.

Relations among mucosal Na+ activity [(Na)m], short‐circuit current (Isc), and intracellular Na+ activity [(Na)c] in Necturus urinary bladder epithelial cells.

[Reprinted by permission of Thomas et al. 278 and Springer‐Verlag.]
Figure 5. Figure 5.

Relations among mucosal Na+ activity [(Na)m] and intracellular Na+ activity [(Na)c] from impalements of single cells when (Na)m was 3.8, 11.4, or 34.2 mM. Values of short‐circuit current (Isc) across these tissues when (Na)m was 34.2 mM are given in parentheses. Note there is no consistent relation between (Na)m and (Na)c or between (Na)c and Isc.

[Reprinted by permission of Thomas et al. 278 and Springer‐Verlag.]
Figure 6. Figure 6.

Relations among intracellular Na+ activity [(Na)c or acNa] and transcellular current (Ic) across isolated frog skin when mucosal Na+ activity [(Na)m] was varied between 0.1 and 110 mM. Note that, although in most individual tissues there is a relation between (Na)c and Ic, it is not possible to predict Ic from a knowledge of (Na)c and vice versa.

[Reprinted by permission of Garcia‐Diaz et al. 90 and Springer‐Verlag.]
Figure 7. Figure 7.

Rate of equilibration of 42K+ in solution bathing serosal surface of rabbit ileum with total exchangeable intracellular K+. Note that rate of equilibration is not affected by presence of glucose or alanine in mucosal bathing solution despite the fact that these solutes elicited a two‐ to fourfold increase in rate of Na+ absorption by this epithelium.

[From Nellans and Schultz 210.]
Figure 8. Figure 8.

Relation between pump‐mediated influx of 42K+ from inner bathing solution into epithelium of frog skin (IpK) and rate of pump‐mediated Na+ extrusion across basolateral (inner) membranes (IpNa). Dashed line, relation predicted for a fixed 3:2 stoichiometry.

[From Cox and Helman 38.]
Figure 9. Figure 9.

Relation between half‐time (t1/2) for inhibition of short‐circuit current (Isc) across rabbit descending colon and initial Isc. Latter was varied by addition of graded doses of amiloride or amphotericin B to mucosal bathing solution.
Figure 10. Figure 10.

Simplified cytokinetic model of recycling of basolateral membrane pump units (P) in epithelial cells. Nuc, nucleus; ER, endoplasmic reticulum; G, Golgi stack; Lys, lysosomes. These models include the possibility that some pump units in basolateral membrane are inactive.
Figure 11. Figure 11.

Relations between cell water content of renal cortical tissue slices and activities of Na+ ‐K+ ‐ATPase and Na+ ‐ATPase.

[From Proverbio 352.]
Figure 12. Figure 12.

Effects of addition of galactose to solution bathing mucosal surface of Necturus small intestine on electrical potential difference across apical membrane (ϕmc) and values of ratio of apical to basolateral slope resistances (rm/rs) in normal tissues (A) and tissues exposed to cyanide (1 mM) and iodoacetamide (1 mM) (B).

[Adapted from Gunter‐Smith et al. 116.]
Figure 13. Figure 13.

Effect of 5 mM Ba2+ in solution bathing serosal surface of Necturus small intestine on responses of electrical potential difference across apical membrane (ψmc) and of ratio of apical to basolateral slope resistances (rm/rs) to addition of galactose to mucosal bathing solution. Note that initially rm/rs is very low due to decrease in slope conductance of basolateral membrane to K (gsK) and that delayed increase in rm/rs and repolarization of ψmc after addition of galactose to mucosal solution are markedly blunted. Removal of Ba2+ results in an increase in rm/rs and a repolarization of ψmc.
Figure 14. Figure 14.

Parallelism between repolarization of electrical potential difference across apical membrane (ψmc) and increase in short‐circuit current (ISC) after addition of galactose (Gal) to solution bathing mucosal surface of Necturus small intestine.

[From Lapointe et al. 161.]
Figure 15. Figure 15.

Effect of ψmc (or ψcs) on open‐time probability (Po) and single‐channel current (Ic) of K+ channels from basolateral membranes of Necturus small intestine reconstituted into planar lipid bilayers.

[Adapted from Costantin et al. 319.]


Figure 1.

Koefoed‐Johnsen—Ussing model for Na+ absorption by isolated frog skin. ICM, inner cellular membrane; OCM, outer cellular membrane; P, Na+‐K+ pump.

[From Koefoed‐Johnsen and Ussing 155.]


Figure 2.

Composite model of Na+‐absorbing epithelial cells illustrating 4 established mechanisms for Na+ entry across apical membrane and Na+‐K+ pump and K+ leak characteristic of basolateral membranes of all such cells studied to date. S, solute.



Figure 3.

Effect of HCO3− (plus CO2) on intracellular Na+ activity [(Na)c] in rabbit gallbladder epithelial cells determined by use of Na+‐selective microelectrodes. Bars, variance among different tissues. Transient increase was observed in every instance and is highly significant.

[Adapted from Moran et al. 201.]


Figure 4.

Relations among mucosal Na+ activity [(Na)m], short‐circuit current (Isc), and intracellular Na+ activity [(Na)c] in Necturus urinary bladder epithelial cells.

[Reprinted by permission of Thomas et al. 278 and Springer‐Verlag.]


Figure 5.

Relations among mucosal Na+ activity [(Na)m] and intracellular Na+ activity [(Na)c] from impalements of single cells when (Na)m was 3.8, 11.4, or 34.2 mM. Values of short‐circuit current (Isc) across these tissues when (Na)m was 34.2 mM are given in parentheses. Note there is no consistent relation between (Na)m and (Na)c or between (Na)c and Isc.

[Reprinted by permission of Thomas et al. 278 and Springer‐Verlag.]


Figure 6.

Relations among intracellular Na+ activity [(Na)c or acNa] and transcellular current (Ic) across isolated frog skin when mucosal Na+ activity [(Na)m] was varied between 0.1 and 110 mM. Note that, although in most individual tissues there is a relation between (Na)c and Ic, it is not possible to predict Ic from a knowledge of (Na)c and vice versa.

[Reprinted by permission of Garcia‐Diaz et al. 90 and Springer‐Verlag.]


Figure 7.

Rate of equilibration of 42K+ in solution bathing serosal surface of rabbit ileum with total exchangeable intracellular K+. Note that rate of equilibration is not affected by presence of glucose or alanine in mucosal bathing solution despite the fact that these solutes elicited a two‐ to fourfold increase in rate of Na+ absorption by this epithelium.

[From Nellans and Schultz 210.]


Figure 8.

Relation between pump‐mediated influx of 42K+ from inner bathing solution into epithelium of frog skin (IpK) and rate of pump‐mediated Na+ extrusion across basolateral (inner) membranes (IpNa). Dashed line, relation predicted for a fixed 3:2 stoichiometry.

[From Cox and Helman 38.]


Figure 9.

Relation between half‐time (t1/2) for inhibition of short‐circuit current (Isc) across rabbit descending colon and initial Isc. Latter was varied by addition of graded doses of amiloride or amphotericin B to mucosal bathing solution.



Figure 10.

Simplified cytokinetic model of recycling of basolateral membrane pump units (P) in epithelial cells. Nuc, nucleus; ER, endoplasmic reticulum; G, Golgi stack; Lys, lysosomes. These models include the possibility that some pump units in basolateral membrane are inactive.



Figure 11.

Relations between cell water content of renal cortical tissue slices and activities of Na+ ‐K+ ‐ATPase and Na+ ‐ATPase.

[From Proverbio 352.]


Figure 12.

Effects of addition of galactose to solution bathing mucosal surface of Necturus small intestine on electrical potential difference across apical membrane (ϕmc) and values of ratio of apical to basolateral slope resistances (rm/rs) in normal tissues (A) and tissues exposed to cyanide (1 mM) and iodoacetamide (1 mM) (B).

[Adapted from Gunter‐Smith et al. 116.]


Figure 13.

Effect of 5 mM Ba2+ in solution bathing serosal surface of Necturus small intestine on responses of electrical potential difference across apical membrane (ψmc) and of ratio of apical to basolateral slope resistances (rm/rs) to addition of galactose to mucosal bathing solution. Note that initially rm/rs is very low due to decrease in slope conductance of basolateral membrane to K (gsK) and that delayed increase in rm/rs and repolarization of ψmc after addition of galactose to mucosal solution are markedly blunted. Removal of Ba2+ results in an increase in rm/rs and a repolarization of ψmc.



Figure 14.

Parallelism between repolarization of electrical potential difference across apical membrane (ψmc) and increase in short‐circuit current (ISC) after addition of galactose (Gal) to solution bathing mucosal surface of Necturus small intestine.

[From Lapointe et al. 161.]


Figure 15.

Effect of ψmc (or ψcs) on open‐time probability (Po) and single‐channel current (Ic) of K+ channels from basolateral membranes of Necturus small intestine reconstituted into planar lipid bilayers.

[Adapted from Costantin et al. 319.]
References
 1. Albus, H., R. Bakker, and J. S. Van Heukelom. Circuit analysis of membrane potential changes due to electrogenic sodium‐dependent sugar transport in goldfish intestinal epithelium. Pfluegers Arch. 398: 1–9, 1983.
 2. Alpern, R. J. Mechanism of basolateral membrane H+/OH−/HCO−3 transport in the rat proximal convoluted tubule. A sodium coupled electrogenic process. J. Gen. Physiol. 86: 613–636, 1985.
 3. Armstrong, W. M., J. F. Garcia‐Diaz, J. O'Doherty, and M. G. O'Regan. Transmucosal Na electrochemical potential difference and solute accumulation in epithelial cells of the small intestine. Federation Proc. 38: 2722–2728, 1979.
 4. Armstrong, W. M., D. L. Musselman, and H. C. Reitzug. Sodium, potassium and water content of isolated bullfrog small intestinal epithelia. Am. J. Physiol. 219: 1023–1026, 1970.
 5. Aronson, P. S. Identifying secondary active solute transport in epithelia. Am. J. Physiol. 240 (Renal Fluid Electrolyte Physiol. 9): F1–F11, 1981.
 6. Aronson, P. S., J. Nee, and M. A. Suhm. Modifier role of internal H+ in activating the Na+ ‐H+ exchanger in renal microvillus membrane vesicles. Nature Lond. 299: 161–163, 1982.
 7. Arruda, J. A., L. S. Sabatini, and C. Westenfelder. Serosal Na/Ca exchange and H and Na transport by the turtle and toad bladders. J. Membr. Biol. 70: 135–146, 1982.
 8. Bader, C. R., L. Bernheim, and D. Bertrand. Sodium‐activated potassium current in cultured avian neurones. Nature Lond. 317: 540–542, 1985.
 9. Bakker‐Grunwald, T. Potassium permeability and volume control in isolated rat hepatocytes. Biochim. Biophys. Acta 731: 239–242, 1983.
 10. Bear, C. E., and O. H. Petersen. L‐Alanine evokes opening of single Ca2+ ‐activated K+ channels in rat liver cells. Pfluegers Arch. 410: 342–344, 1987.
 11. Benos, D. J. Amiloride: a molecular probe of sodium transport in tissues and cells. Am. J. Physiol. 242 (Cell Physiol. 11): C131–C145, 1982.
 12. Benos, D. J., B. A. Hyde, and R. Latorre. Sodium flux ratio through the amiloride‐sensitive entry pathway in frog skin. J. Gen. Physiol. 81: 667–685, 1983.
 13. Birnbaumer, L., and A. M. Brown. G protein opening of K channels. Nature Lond. 327: 21–22, 1987.
 14. Blaustein, M. P. The interrelationship between sodium and calcium fluxes across cell membranes. Rev. Physiol. Biochem. Pharmacol. 70: 33–82, 1974.
 15. Boron, W. F., and E. L. Boulpaep. Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO3 transport. J. Gen. Physiol. 81: 53–94, 1983.
 16. Bregestovski, P., A. Redkozubov, and A. Alexeev. Elevation of intracellular calcium reduces voltage‐dependent potassium conductance in human T cells. Nature Lond. 319: 776–778, 1986.
 17. Breitwieser, G. E., and J. M. Russell. Sidedness of pH dependence of the sodium pump in dialyzed squid giant axons (Abstract). Biophys. J. 41: 71a, 1983.
 18. Brinley, F. J., Jr., and L. J. Mullins. Effects of membrane potential on sodium and potassium fluxes in squid axons. Ann. NY Acad. Sci. 242: 406–433, 1974.
 19. Brobrycki, V. A., J. W. Mills, A. D. C. Macknight, and D. R. Di Bona. Structural responses to voltage‐clamping in the toad urinary bladder. I. The principal role of granular cells in the active transport of sodium. J. Membr. Biol. 60: 21–35, 1981.
 20. Brown, C. D. A., and N. L. Simmons. K+ transport in “tight” epithelial monolayers of MDCK cells. Evidence for a calcium activated K+ channel. Biochim. Biophys. Acta 690: 95–105, 1982.
 21. Brown, P. D., and F. V. Sepulveda. Potassium movements associated with amino acid and sugar transport in enterocytes isolated from rabbit jejunum. J. Physiol. Lond. 363: 271–285, 1985.
 22. Cala, P. M., N. Cogswell, and L. J. Mandel. Binding of (3H)‐ouabain to split frog skins: the role of the Na,K‐ATPase in the generation of the short‐circuit current. J. Gen. Physiol. 71: 347–367, 1978.
 23. Cala, P. M., L. J. Mandel, and E. Murphy. Volume regulation by Amphiuma red blood cells: cytosolic free Ca and alkali metal‐H exchange. Am. J. Physiol. 250 (Cell Physiol. 19): C423–C429, 1986.
 24. Candia, O. A., and J. A. Zadunaisky. Potassium flux and sodium transport in the isolated frog skin. Biochim. Biophys. Acta 255: 517–529, 1972.
 25. Cannon, C., J. van Adelsberg, S. Kelly, and Q. Al‐Awqati. Carbon dioxide‐induced exocytotic insertion of H+ pumps in turtle‐bladder luminal membrane: role of cell pH and calcium. Nature Lond. 314: 443–446, 1985.
 26. Caplan, M. J., G. E. Palade, and J. D. Jamieson. Cell surface expression and activation of newly synthesized Na,K‐ATPase in MDCK cells. In: The Sodium Pump, edited by I. Glynn and C. Ellory, Cambridge, UK: Company of Biologists, 1985, p. 147–151.
 27. Carafoli, E. Plasma membrane Ca transport and Ca handling by intracellular stores: integrated picture with emphasis on regulation. In: Mechanisms of Intestinal Electrolyte Transport and Regulation by Calcium, edited by M. Donowitz and G. W. G. Sharp. New York: Liss, 1984, p. 121–134.
 28. Carafoli, E. Intracellular calcium homeostasis. Annu. Rev. Biochem. 56: 395–433, 1987.
 29. Cardinal, J., J.‐Y. Lapointe, and R. Laprade. Luminal and peritubular ionic substitutions and intracellular potential of the rabbit proximal convoluted tubule. Am. J. Physiol. 247 (Renal Fluid Electrolyte Physiol. 16): F352–F364, 1984.
 30. Chang, D., and D. C. Dawson. Digitonin‐permeabilized colonic cell layers: demonstration of calcium‐activated basolateral K+ and Cl− conductances. J. Gen. Physiol. 92: 281–306, 1988.
 31. Chapman, J. B. Thermodynamics and kinetics and electrogenic pumps. In: Electrogenic Transport: Fundamental Principles and Physiological Implications, edited by M. P. Blaustein and M. Lieberman. New York: Raven, 1984, p. 17–32.
 32. Chase, H. S., Jr. Does calcium couple the apical and basolateral membrane permeabilities in epithelia? Am. J. Physiol. 247 (Renal Fluid Electrolyte Physiol. 16): F869–F876, 1984.
 33. Chase, H. S., Jr., and Q. Al‐Awqati. Regulation of the sodium permeability of the luminal border of toad bladder by intracellular sodium and calcium. J. Gen. Physiol. 77: 693–712, 1981.
 34. Chase, H. S., Jr., and Q. Al‐Awqati. Calcium reduces the sodium permeability of luminal membrane vesicles from toad bladder: studies using a fast reaction apparatus. J. Gen. Physiol. 81: 643–665, 1983.
 35. Christensen, O. Mediation of cell volume regulation by Ca influx through stretch activated channels. Nature Lond. 330: 66–68, 1987.
 36. Christensen, O., and T. Zeuthen. Maxi K+ channels in leaky epithelia are regulated by intracellular Ca2+, pH and membrane potential. Pfluegers Arch. 408: 249–259, 1987.
 37. Civan, M. M. The sodium transport pool of epithelia tissues. In: Water Relations in Membrane Transport in Plants and Animals, edited by A. M. Jungries, T. K. Hodges, A. Kleinzeller, and S. G. Schultz. New York: Academic, 1977, p. 187–188.
 38. Civan, M. M. Epithelial Ions and Transport. New York: Wiley, 1983.
 39. Civan, M. M., E. J. Cragoe, Jr., and K. Peterson‐Yantorno. Intracellular pH in frog skin: effects of Na+, volume, and cAMP. Am. J. Physiol. 255 (Renal Fluid Electrolyte Physiol. 24): F126–F134, 1988.
 40. Claus, W., J. Durr, E. Skadhauge, and H. Hornicke. Effects of aldosterone and dexamethasone on apical membrane properties and Na‐transport of rabbit distal colon in vitro. Pfluegers Arch. 403: 186–192, 1985.
 41. Cook, D. L., and C. N. Hales. Intracellular ATP directly blocks K+ channels in pancreatic B‐cells. Nature Lond. 311: 271–273, 1984.
 42. Cook, D. L., M. Ikeuchi, and W. Y. Fujimoto. Lowering of pHi inhibits Ca2+ ‐activated K+ channels in pancreatic B‐cells. Nature Lond. 311: 269–271, 1984.
 43. Cook, J. S., E. H. Tate, and C. Shaffer. Uptake of [3H]ouabain from the cell surface into the lysosomal compartment of HeLa cells. J. Cell. Physiol. 110: 84–92, 1982.
 44. Cooper, K. E., J. M. Tang, J. L. Rae, and R. S. Eisenberg. A cation channel in frog lens epithelia responsive to pressure and calcium. J. Membr. Biol. 93: 259–269, 1986.
 45. Coronado, R. Recent advances in planar phospholipid bilayer techniques for monitoring ion channels. Annu. Rev. Biophys. Chem. 15: 259–277, 1986.
 46. Costantin, J., S. Alcalen, A. Otero, W. P. Dubinsky, and S. G. Schultz. Reconstitution of an inwardly rectifying potassium channel from the basolateral membranes of Necturus enterocytes into planar lipid bilayers. Proc. Natl. Acad. Sci. USA. In press.
 47. Cox, T. C., and S. I. Helman. Na+ and K+ transport at basolateral membranes of epithelial cells. I. Stoichiometry of the Na,K‐ATPase. J. Gen. Physiol. 87: 467–483, 1986.
 48. Cox, T. C., and S. I. Helman. Na+ and K+ transport at basolateral membranes of epithelial cells. III. Voltage independence of basolateral membrane Na+ efflux. J. Gen. Physiol. 87: 503–509, 1986.
 49. Cremaschi, D., S. Henin, and G. Meyer. Stimulation of HCO−3 of Na+ transport in rabbit gallbladder. J. Membr. Biol. 47: 145–170, 1979.
 50. Cremaschi, D., G. Meyer, S. Bermano, and M. Marcato. Different sodium chloride cotransport systems in the apical membrane of rabbit gallbladder epithelial cell. J. Membr. Biol. 73: 227–235, 1983.
 51. Csaky, T. Z., and G. Esposito. Osmotic swelling of intestinal epithelial cells during active sugar transport. Am. J. Physiol. 217: 753–755, 1969.
 52. Curran, P. F., and M. Cereijido. K fluxes in frog skin. J. Gen. Physiol. 48: 1011–1033, 1965.
 53. Davis, C. W., and A. L. Finn. Sodium transport effects on the basolateral membrane in toad urinary bladder. J. Gen. Physiol. 80: 733–751, 1982.
 54. Davis, C. W., and A. L. Finn. Sodium transport inhibition by amiloride reduces basolateral membrane potassium conductance in tight epithelia. Science Wash. DC 216: 525–527, 1982.
 55. Davis, C. W., and A. L. Finn. Effects of mucosal sodium removal on cell volume in Necturus gallbladder epithelium. Am. J. Physiol. 249 (Cell Physiol. 18): C304–C312, 1985.
 56. Davis, C. W., and A. L. Finn. Cell volume regulation in frog urinary bladder. Federation Proc. 44: 2520–2525, 1985.
 57. Davis, C. W., and A. L. Finn. Effects of transport inhibition on cell volume in frog urinary bladder (Abstract). Biophys. J. 47: 445a, 1985.
 58. Dawson, D. C. Properties of epithelial potassium channels. Curr. Top. Membr. Transp. 28: 41–71, 1987.
 59. Dawson, D. C., W. Van Driessche, and S. I. Helman. Osmotically induced basolateral K+ conductance in turtle colon: lidocaine‐induced K+ channel noise. Am. J. Physiol. 254 (Cell Physiol. 23): C165–C174, 1988.
 60. Del Castillo, J. R., and J. W. L. Robinson. Sodium transport in intestinal basolateral membrane vesicles. Experientia Basel 39: 631, 1983.
 61. Del Castillo, J. R., and J. W. L. Robinson. Na‐stimulated ATPase activities in basolateral plasma membranes from guinea‐pig small intestinal epithelial cells. Biochim. Biophys. Acta 812: 413–422, 1985.
 62. Dellasega, M., and J. J. Grantham. Regulation of renal tubule cell volume in hypotonic media. Am. J. Physiol. 224: 1288–1294, 1973.
 63. De Long, J., and M. M. Civan. Dissociation of cellular K+ accumulation from net Na+ transport by toad urinary bladder. J. Membr. Biol. 42: 19–43, 1978.
 64. De Long, J., and M. M. Civan. Apical sodium entry in split frog skin: current‐voltage relationship. J. Membr. Biol. 82: 25–40, 1984.
 65. De Los Rios, A. D., N. E. De Rose, and W. M. Armstrong. Cyclic AMP and intracellular ionic activities in Necturus gallbladder. J. Membr. Biol. 63: 25–30, 1981.
 66. Demarest, J. R., and A. L. Finn. Characterization of the basolateral membrane conductance of Necturus urinary bladder. J. Gen. Physiol. 89: 541–562, 1987.
 67. Demarest, J. R., and A. L. Finn. Interaction between the basolateral K and apical Na conductances in Necturus urinary bladder. J. Gen. Physiol. 89: 563–680, 1987.
 68. De Weer, P. Electrogenic pumps: theoretical and practical considerations. In: Electrogenic Transport: Fundamental Principles and Physiological Applications, edited by M. P. Blaustein and M. Lieberman. New York: Raven, 1984, p. 1–15.
 69. De Weer, P. Cellular sodium‐potassium transport. In: The Kidney: Physiology and Pathophysiology, edited by D. W. Seldin and G. Giebisch. New York: Raven, 1985, p. 31–48.
 70. De Weer, P., D. C. Gadsby, and R. F. Rakowski. Voltage‐dependence of the Na‐K pump. Annu. Rev. Physiol. 50: 225–241, 1988.
 71. De Weer, P., D. C. Gadsby, and R. F. Rakowshi. Overview: stoichiometry and voltage dependence of the Na/K pump. In: The Na+,K+ ‐Pump. Molecular Aspects, edited by J. C. Skou, J. G. Norby, A. B. Mausbach, and M. Esmann. New York: Liss, 1988, pt. A, p. 421–434.
 72. Diamond, J. M. Transport of salt and water in rabbit and guinea pig gallbladder. J. Gen. Physiol. 48: 1–14, 1964.
 73. Diamond, J. M. Transcellular cross‐talk between epithelial cell membranes. Nature Lond. 300: 683–685, 1982.
 74. Di Bona, D. R., and J. W. Mills. Distribution of Na‐pump sites in transporting epithelia. Federation Proc. 38: 134–143, 1979.
 75. Di Bona, D. R., B. Sherman, V. A. Brobrycki, J. W. Mills, and A. C. D. MacKnight. Structural responses to voltage‐clamping in the toad urinary bladder. II. Granular cells and the natriferic action of vasopressin. J. Membr. Biol. 60: 35–44, 1981.
 76. Donnan, F. G. Theorie der Membrangleichgewichte und Membranpotentiale bei Vorhandensein von nicht dialysierenden Elektrolyten. Ein beitrag zur physikalisch‐chemischen Physiologie. Z. Elektrochem. 17: 572–581, 1911.
 77. Donowitz, M., and M. J. Welsh. Ca and cyclic AMP in regulation of intestinal Na, K and Cl transport. Annu. Rev. Physiol. 48: 135–150, 1986.
 78. Du Bois‐Reymond, E. H. Vorlaufiger Abriss einer Untersuchung uber den sogen Froschstrom und uber die elektromotorischen Fische. Poggendorffs Ann. Phys. Chem. 58: 1–22, 1843.
 79. Du Bois‐Reymond, E. H. Untersuchungen über Tierische Elektrizitat. Berlin: Reimer, 1848.
 80. Dunne, M. J., I. Findlay, O. H. Petersen, and C. B. Wollheim. ATP‐sensitive K+ channels in an insulin‐secreting cell line are inhibited by D‐glyceraldehyde and activated by membrane permeabilization. J. Membr. Biol. 93: 271–279, 1986.
 81. Eaton, D. C. Intracellular sodium ion activity and sodium transport in rabbit urinary bladder. J. Physiol. Lond. 316: 527–544, 1981.
 82. Eaton, D. C., A. M. Frace, and S. U. Silverthorn. Active and passive Na fluxes across the basolateral membrane of rabbit urinary bladder. J. Membr. Biol. 67: 219–229, 1982.
 83. Eaton, D. C., K. L. Hamilton, and K. E. Johnson. Intracellular acidosis blocks the basolateral Na‐K pump in rabbit urinary bladder. Am. J. Physiol. 247 (Renal Fluid Electrolyte Physiol. 16): F946–F954, 1984.
 84. Erlij, D., and H. F. Schoen. Regulation of basolateral membrane permeability during changes in sodium transport across frog skin (Abstract). Federation Proc. 44: 1567a, 1985.
 85. Erlij, D., and W. Van Driessche. Noise analysis of inward and outward Na current in ouabain‐treated frog skins (Abstract). Federation Proc. 42: 1101a, 1983.
 86. Eskesen, K., and H. H. Ussing. Single‐file diffusion through K channels in frog skin. J. Membr. Biol. 91: 245–250, 1986.
 87. Ewald, D. A., A. Williams, and I. B. Levitan. Modulation of single Ca‐dependent K‐channel activity by protein phosphorylation. Nature Lond. 315: 503–506, 1985.
 88. Falke, L. D., and S. Misler. Activity of ion channels during volume regulation by clonal N1E115 neuroblastoma cells. Proc. Natl. Acad. Sci. USA. In press.
 89. Fambrough, D. M. The sodium pump becomes a family. Trends Neuro. Sci. 11: 325–328, 1988.
 90. Findlay, I., M. J. Dunne, and O. H. Petersen. High‐conductance K channels in pancreatic acinar cells can be activated and inactivated by internal calcium. J. Membr. Biol. 83: 169–175, 1985.
 91. Finn, A. L. Transepithelial potential difference in toad urinary bladder is not due to ionic diffusion. Nature Lond. 250: 495–496, 1974.
 92. Finn, A. L. Changing concepts of transepithelial sodium transport. Physiol. Rev. 56: 453–464, 1976.
 93. Finn, A. L., and L. Reuss. Effects of changes in the composition of the serosal solution on the electrical properties of the toad urinary bladder epithelium. J. Physiol. Lond. 250: 541–558, 1975.
 94. Fishman, J. B., and J. S. Cook. Recycling of surface sialoglycoconjugates in HTC and HeLa cells. J. Biol. Chem. 257: 8122–8129, 1982.
 95. Forte, T. M., T. E. Machen, and J. G. Forte. Ultrastructural changes in oxyntic cells associated with secretory function: membrane recycling hypothesis. Gastroenterology 73: 941–955, 1977.
 96. Foskett, J. K., and K. R. Spring. Involvement of calcium and cytoskeleton in gallbladder epithelial cell volume regulation. Am. J. Physiol. 248 (Cell Physiol. 17): C27–C36, 1985.
 97. Friedman, P. A., J. F. Figueiredo, T. Maack, and E. E. Windhager. Sodium‐calcium interactions in the renal proximal convoluted tubule of the rabbit. Am. J. Physiol. 240 (Renal Fluid Electrolyte Physiol. 9): F558–F568, 1981.
 98. Frizzell, R. A., M. Field, and S. G. Schultz. Sodium‐coupled chloride transport by epithelial tissues. Am. J. Physiol. 236 (Renal Fluid Electrolyte Physiol. 5): F1–F8, 1979.
 99. Frizzell, R. A., P. L. Smith, E. Vosburgh, and M. Field. Coupled sodium‐chloride influx across brush border of flounder intestine. J. Membr. Biol. 46: 27–40, 1979.
 100. Frömter, E., J. T. Higgins, and B. Gebler. Electrical properties of amphibian urinary bladder epithelia. IV. The current‐voltage relationship of the sodium channels in the apical cell membrane. In: Ion Transport by Epithelia, edited by S. G. Schultz. New York: Raven, 1981, p. 31–45.
 101. Fuchs, W., E. H. Larsen, and B. Lindemann. Current‐voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin. J. Physiol. Lond. 267: 137–166, 1977.
 102. Gadsby, D. C., J. Kimura, and A. Noma. Voltage dependence of Na/K pump current in isolated heart cells. Nature Lond. 315: 63–65, 1985.
 103. Garcia‐Diaz, J. F., and W. M. Armstrong. The steady‐state relationship between sodium and chloride transmembrane electrochemical potential differences in Necturus gallbladder. J. Membr. Biol. 55: 213–222, 1980.
 104. Garcia‐Diaz, J. F., L. M. Baxendale, G. Klemperer, and A. Essig. Cell K activity in frog skin in the presence and absence of cell current. J. Membr. Biol. 85: 143–158, 1985.
 105. Garcia‐Diaz, J. F., G. Klemperer, L. M. Baxendale, and A. Essig. Cell sodium activity and sodium pump function in frog skin. J. Membr. Biol. 92: 37–46, 1986.
 106. Garcia‐Diaz, J. F., J. O'Doherty, and W. M. Armstrong. Potential profile, K+ and Na+ activities in Necturus small intestine (Abstract). Physiologist 21: 41, 1978.
 107. Gardos, G. The function of calcium in the potassium permeability of human erythrocytes. Biochim. Biophys. Acta 30: 653–654, 1958.
 108. Garrahan, P. J., and I. M. Glynn. Factors affecting the relative magnitudes of the sodium: potassium and sodium: sodium exchanges catalysed by the sodium pump. J. Physiol. Lond. 192: 189–216, 1967.
 109. Garrahan, P. J., and I. M. Glynn. The stoichiometry of the sodium pump. J. Physiol. Lond. 192: 217–235, 1967.
 110. Geck, P., and E. Heinz. The Na‐K‐2Cl cotransport system. J. Membr. Biol. 91: 97–105, 1986.
 111. Geering, K., M. Girardet, C. Bron, J.‐P. Kraehenbuhl, and B. C. Rossier. Hormonal regulation of (Na,K)‐ATPase biosynthesis in the toad bladder. J. Biol. Chem. 257: 10338–10343, 1982.
 112. Geering, K., M. Girardet, C. Bron, J.‐P. Kraehenbuhl, and B. C. Rossier. Enhancement of biosynthesis of Na,K‐ATPase in the toad urinary bladder by aldosterone but not by T3. Curr. Top. Membr. Transp. 19: 809–812, 1983.
 113. Germann, W. J., S. A. Ernst, and D. C. Dawson. Resting and osmotically induced basolateral K conductances in turtle colon. J. Gen. Physiol. 88: 253–274, 1986.
 114. Germann, W. J., M. E. Lowy, S. A. Ernst, and D. C. Dawson. Differentiation of two distinct K conductances in the basolateral membrane of turtle colon. J. Gen. Physiol. 88: 237–251, 1986.
 115. Ghijsen, W. E. J. M., M. D. De Jong, and C. H. van Os. Kinetic properties of Na/Ca exchange in basolateral plasma membranes of rat small intestine. Biochim. Biophys. Acta 730: 85–94, 1983.
 116. Giebisch, G., L. P. Sullivan, and G. Whittembury. Relationship between tubular net sodium reabsorption and peritubular potassium uptake in the perfused Necturus kidney. J. Physiol. Lond. 230: 51–74, 1973.
 117. Gluck, S., C. Cannon, and Q. Al‐Awqati. Exocytosis regulates urinary acidification by rapid insertion of H pumps into the luminal membrane. Proc. Natl. Acad. Sci. USA 79: 4327–4331, 1982.
 118. Glynn, I. M. The electrogenic sodium pump. In: Electrogenic Transport: Fundamental Principles and Physiological Applications, edited M. P. Blaustein and M. Lieberman. New York: Raven, 1984, p. 33–48.
 119. Glynn, I. M., and C. Ellory (editors). The Sodium Pump, Cambridge, UK: Company of Biologists, 1985.
 120. Glynn, I. M., J. F. Hoffman, and V. L. Lew. Some partial reactions of the sodium pump. Philos. Trans. R. Soc. Lond. A Math. Phys. Sci. 262: 91–102, 1971.
 121. Glynn, I. M., and S. J. D. Karlish. The sodium pump. Annu. Rev. Physiol. 37: 13–55, 1975.
 122. Gogelein, H., and R. Greger. Single channel recordings from basolateral and apical membranes of renal proximal tubule. Pfluegers Arch. 401: 424–426, 1984.
 123. Graf, J., and G. Giebisch. Intracellular sodium activity and sodium transport in Necturus gallbladder epithelium. J. Membr. Biol. 47: 327–355, 1979.
 124. Grantham, J. J., C. M. Lowe, M. Dellasega, and B. R. Cole. Effect of hypotonic medium on K and Na content of proximal renal tubules. Am. J. Physiol. 232 (Renal Fluid Electrolyte Physiol. 1): F42–F49, 1977.
 125. Grasset, E., P. Gunter‐Smith, and S. G. Schultz. Effects of Na‐coupled alanine transport on intracellular K activities and the K conductances of the basolateral membranes of Necturus small intestine. J. Membr. Biol. 71: 89–94, 1983.
 126. Grinstein, S., S. Cohen, B. Sarkadi, and A. Rothstein. Induction of 86Rb fluxes by Ca2+ and volume changes in thymocytes and their isolated membranes. J. Cell. Physiol. 116: 352–362, 1983.
 127. Grinstein, S., A. Dupre, and A. Rothstein. Volume regulation by human lymphocytes. Role of calcium. J. Gen. Physiol. 79: 849–868, 1982.
 128. Grinstein, S., and D. Erlij. Intracellular calcium and the regulation of sodium transport in the frog skin. Proc. R. Soc. Lond. B Biol. Sci. 202: 353–360, 1978.
 129. Grinstein, S., and A. Rothstein. Mechanisms of regulation of the Na+/H+ exchanger. J. Membr. Biol. 90: 1–12, 1986.
 130. Grinstein, S., A. Rothstein, B. Sarkadi, and E. W. Gelfand. Responses of lymphocytes to anisotonic media: volume‐regulating behavior. Am. J. Physiol. 246 (Cell Physiol. 15): C204–C215, 1984.
 131. Guggino, S. E., B. A. Suarez‐Ilsa, W. B. Guggino, and B. Sacktor. Forskolin and antidiuretic hormone stimulate a Ca2+ ‐activated K+ channel in cultured kidney cells. Am. J. Physiol. 249 (Renal Fluid Electrolyte Physiol. 18): F448–F455, 1985.
 132. Guharay, F., and F. Sachs. Stretch‐activated single ion channel currents in tissue‐cultured embryonic chick skeletal muscle. J. Physiol. Lond. 352: 685–701, 1984.
 133. Gullans, S. R., G. Capasso, M. J. Avison, and G. Giebisch. Calcium‐induced potassium efflux in suspensions of mammalian renal proximal tubules (Abstract). Biophys. J. 47: 12a, 1985.
 134. Gunter‐Smith, P., E. Grasset, and S. G. Schultz. Sodium‐coupled amino acid and sugar transport by Necturus small intestine. An equivalent electrical circuit analysis of a rheogenic co‐transport system. J. Membr. Biol. 66: 25–39, 1982.
 135. Halm, D. R., and D. C. Dawson. Cation activation of the basolateral sodium‐potassium pump in turtle colon. J. Gen. Physiol. 82: 315–329, 1983.
 136. Handler, J. S., A. S. Preston, F. M. Perkins, M. Matsumura, J. P. Johnson, and C. O. Watlington. The effect of adrenal steroid hormones on epithelia formed in culture by A6 cells. Ann. NY Acad. Sci. 372: 442–454, 1981.
 137. Handler, J. S., A. S. Preston, and R. E. Steele. Factors affecting the differentiation of epithelial transport and responsiveness to hormones. Federation Proc. 43: 2221–2224, 1984.
 138. Hanrahan, J. W., W. P. Alles, and S. A. Lewis. Basolateral anion and K channels from rabbit urinary bladder epithelium (Abstract). J. Gen. Physiol. 84: 30a, 1984.
 139. Hanrahan, J. W., N. K. Wills, J. E. Phillips, and S. A. Lewis. Basolateral K channels in an insect epithelium. Channel density, conductance and block by barium. J. Gen. Physiol. 87: 443–466, 1986.
 140. Hansen, U.‐P., D. Gradmann, D. Sanders, and C. L. Slayman. Interpretation of current‐voltage relationships for “active” ion transport systems. I. Steady‐state reaction‐kinetic analysis of class‐I mechanisms. J. Membr. Biol. 63: 165–190, 1981.
 141. Harvey, B. J., and R. P. Kernan. Sodium‐selective microelectrode study of apical permeability in frog skin: effects of sodium, amiloride and ouabain. J. Physiol. Lond. 356: 359–374, 1984.
 142. Hasuo, H., and K. Koketsu. Potential dependency of the electrogenic Na‐pump current in bullfrog atrial muscles. Jpn. J. Physiol. 35: 89–100, 1985.
 143. Hazama, A., and Y. Okada. Ca2+ sensitivity of volume‐regulatory K+ and Cl− channels in cultured human epithelial cells. J. Physiol. Lond. 402: 687–702, 1988.
 144. Heeswijk, M. P. E., J. A. M. Geertsen, and C. H. van Os. Kinetic properties of the ATP‐dependent Ca pump and the Na/Ca exchange system in the basolateral membranes from rat kidney cortex. J. Membr. Biol. 79: 19–31, 1984.
 145. Heintze, K., K.‐U. Petersen, and J. R. Wood. Effects of bicarbonate on fluid and electrolyte transport by guinea pig and rabbit gallbladder: stimulation of absorption. J. Membr. Biol. 62: 175–181, 1981.
 146. Helman, S. I., W. Nagel, and R. S. Fisher. Ouabain on active transepithelial Na transport in frog skin: studies with microelectrodes. J. Gen. Physiol. 74: 105–127, 1979.
 147. Helman, S. I., and S. M. Thompson. Interpretation and use of electrical equivalent circuits in studies of epithelial tissues. Am. J. Physiol. 243 (Renal Fluid Electrolyte Physiol. 12): F519–F531, 1982.
 148. Hempling, H. G., and D. Hare. The effect of glycine transport on potassium fluxes in the Ehrlich mouse ascites tumor cell. J. Biol. Chem. 236: 2498–2502, 1961.
 149. Higgins, J. T., Jr., B. Gebler, and E. Frömter. Electrical properties of amphibian urinary bladder epithelia. II. The cell potential profile in Necturus maculosus. Pfluegers Arch. 371: 87–97, 1977.
 150. Hildman, B., A. Schmidt, and H. Murer. Ca transport across basal‐lateral plasma membranes from rat small intestinal epithelial cells. J. Membr. Biol. 65: 55–62, 1982.
 151. Hille, B. Ionic Channels in Excitable Membranes. Sunderland, MA: Sinauer, 1984, p. 109–112.
 152. Hinrichsen, R. D., A. Burgess‐Cassler, B. C. Soltvedt, T. Hennesey, and C. Kung. Restoration by calmodulin of a Ca‐dependent K current missing in a mutant of Paramecium. Science Wash. DC 232: 503–506, 1986.
 153. Hodgkin, A. L., and R. D. Keynes. The potassium permeability of a giant nerve fiber. J. Physiol. Lond. 128: 61–88, 1955.
 154. Hoffman, J. F. Active transport of Na and K by red blood cells. In: Physiology of Membrane Disorders (2nd ed.), edited by T. E. Andreoli, J. F. Hoffman, D. D. Fanestil, and S. G. Schultz. New York: Plenum, 1986, p. 221–234.
 155. Hoffman, J. F., and B. Forbush III (editors). Structure, mechanism and function of the Na/K pump. In: Curr. Top. Membr. Transp. New York: Academic, 1983, vol. 19.
 156. Hoffman, J. F., H. Kaplan, and T. J. Callahan. The Na: K pump in red cells is electrogenic. Federation Proc. 38: 2440–2441, 1979.
 157. Hoffman, J. F., B. G. Kennedy, and G. Lunn. Modulation of red cell Na/K pump rates. In: Erythrocyte Membranes. 2. Recent Clinical and Experimental Advances. New York: Liss, 1981, p. 5–9.
 158. Hoffmann, E. K. Control of cell volume. In: Transport of Ions and Water in Animal Cells, edited by B. L. Gupta, R. B. Moreton, J. L. Oschman, and B. J. Wall. London: Academic, 1977, p. 285–332.
 159. Hoffmann, E. K. Role of separate K and Cl channels and of Na/Cl transport in volume regulation in Ehrlich cells. Federation Proc. 44: 2513–2519, 1985.
 160. Hoffmann, E. K. Volume regulation in cultured cells. Curr. Top. Membr. Transp. 30: 125–180, 1987.
 161. Hoffmann, E. K., I. H. Lambert, and L. O. Simonsen. Separate Ca‐activated K and Cl transport pathways in Ehrlich ascites tumor cells. J. Membr. Biol. 91: 227–244, 1986.
 162. Hoffmann, E. K., L. O. Simonsen, and I. H. Lambert. Volume‐induced increase of K and Cl permeabilities in Ehrlich ascites tumor cells. J. Membr. Biol. 78: 211–222, 1984.
 163. Horisberger, J.‐D., and G. Giebisch. Voltage dependence of the basolateral membrane conductance in the Amphiuma collecting tubule. J. Membr. Biol. 105: 257–263, 1988.
 164. Howard, L. D., and R. Wondergem. Effects of anisosmotic medium on cell volume, transmembrane potential and intracellular K activity in mouse hepatocytes. J. Membr. Biol. 100: 53–61, 1987.
 165. Hudson, R. L., and S. G. Schultz. Effects of sodium‐coupled sugar transport on intracellular sodium activities and sodium‐pump activity in Necturus small intestine. Science Wash. DC 224: 1237–1239, 1984.
 166. Hudson, R. L., and S. G. Schultz. Sodium‐coupled glycine uptake by Ehrlich ascites tumor cells results in an increase in cell volume and plasma membrane channel activities. Proc. Natl. Acad. Sci. USA 85: 279–283, 1988.
 167. Hunter, M., K. Kawahara, and G. Giebisch. Potassium channels along the nephron. Federation Proc. 455: 2723–2726, 1986.
 168. Jentsch, T. J., S. K. Keller, M. Koch, and M. Wiederholt. Evidence for coupled transport of bicarbonate and sodium in cultured bovine corneal endothelial cells. J. Membr. Biol. 81: 189–204, 1984.
 169. Jorgensen, P. L. Sodium and potassium ion pump in kidney tubules. Physiol. Rev. 60: 864–917, 1980.
 170. Kachadorian, W. A., J. B. Wade, and V. A. Di Scala. Vasopressin: induced structural change in toad bladder luminal membrane. Science Wash. DC 190: 67–69, 1975.
 171. Kameyama, M., M. Kakei, R. Sato, T. Shibasaki, H. Matsuda, and H. Irisawa. Intracellular Na activates a K channel in mammalian cardiac cells. Nature Lond. 309: 354–356, 1984.
 172. Kanbe, M., and H. Kitasato. Stimulation of Na,K‐ATPase of frog skeletal muscle by insulin. Biochem. Biophys. Res. Commun. 134: 609–616, 1986.
 173. Karin, N. J., and J. S. Cook. Regulation of Na,K‐ATPase by its biosynthesis and turnover. Curr. Top. Membr. Transp. 19: 713–751, 1983.
 174. Kawahara, K., M. Hunter, and G. Giebisch. Potassium channels in Necturus proximal tubule. Am. J. Physiol. 253 (Renal Fluid Electrolyte Physiol. 22): F488–F494, 1987.
 175. Kelepouris, E., Z. S. Agus, and M. M. Civan. Intracellular calcium activity in split frog skin epithelium. Effect of cAMP. J. Membr. Biol. 88: 113–121, 1985.
 176. Kennedy, B. G., G. Lunn, and J. F. Hoffman. Effects of altering the ATP/ADP ratio on pump‐mediated Na/K and Na/Na exchanges in resealed human red blood cell ghosts. J. Gen. Physiol. 87: 47–72, 1986.
 177. Kirk, K. L., and D. C. Dawson. Basolateral potassium channel in turtle colon. Evidence for single‐file ion flow. J. Gen. Physiol. 82: 297–313, 1983.
 178. Kirk, K. L., D. R. Halm, and D. C. Dawson. Active sodium transport by turtle colon via an electrogenic Na‐K exchange pump. Nature Lond. 287: 237–239, 1980.
 179. Kleinzeller, A. Cellular transport of water. In: Metabolic Pathways. Metabolic Transport (3rd ed.), edited by L. E. Hokin. New York: Academic, 1972, vol. VI, p. 91–131.
 180. Koefoed‐Johnsen, V., and H. H. Ussing. The nature of the frog skin potential. Acta Physiol. Scand. 42: 298–308, 1958.
 181. Kregenow, F. M. Osmoregulatory salt transporting mechanisms: control of cell volume in anisotonic media. Annu. Rev Physiol. 43: 493–505, 1981.
 182. Kristensen, L. O. Energization of alanine transport in isolated rat hepatocytes. Electrogenic Na‐alanine co‐transport leading to increased K permeability. J. Biol. Chem. 255: 5236–5243, 1980.
 183. Kristensen, L. O. Associations between transports of alanine and cations across cell membranes in rat hepatocytes. Am. J. Physiol. 251 (Gastrointest. Liver Physiol. 14): G575–G584, 1986.
 184. Kristensen, L. O., and M. Folke. Volume‐regulatory K efflux during concentrative uptake of alanine in isolated rat hepatocytes. Biochem. J. 221: 265–268, 1984.
 185. Lafaire, A. V., and W. Schwarz. Voltage dependence of the rheogenic Na/K ATPase in the membrane of oocytes of Xenopus laevis. J. Membr. Biol. 91: 43–51, 1986.
 186. Lang, F., G. Messner, and W. Rehwald. Electrophysiology of sodium‐coupled transport in proximal renal tubules. Am. J. Physiol. 250 (Renal Fluid Electrolyte Physiol. 19): F953–F962, 1986.
 187. Lang, M. A., S. R. Caplan, and A. Essig. Sodium transport and oxygen consumption in toad bladder. Biochim. Biophys. Acta 464: 571–582, 1977.
 188. Lapointe, J.‐Y., R. L. Hudson, and S. G. Schultz. Current‐voltage relations of Na‐coupled sugar transport across the apical membrane of Necturus small intestine. J. Membr. Biol. 93: 205–219, 1986.
 189. Lapointe, J.‐Y., R. Laprade, and J. Cardinal. Transepithelial and cell membrane electrical resistances of the rabbit proximal convoluted tubule. Am. J. Physiol. 247 (Renal Fluid Electrolyte Physiol. 16): F637–F649, 1984.
 190. Larson, M., and K. R. Spring. Volume regulation in epithelia. Curr. Top. Membr. Transp. 30: 105–123, 1987.
 191. Latorre, R., and C. Miller. Conduction and selectivity in potassium channels. J. Membr. Biol. 71: 11–30, 1983.
 192. Lau, K. R., R. L. Hudson, and S. G. Schultz. Cell swelling induces a barium‐inhibitable potassium conductance in the basolateral membrane of Necturus small intestine. Proc. Natl. Acad. Sci. USA 81: 3591–3594, 1984.
 193. Lau, K. R., R. L. Hudson, and S. G. Schultz. Effect of hypertonicity on the increase in basolateral conductance of Necturus small intestine in response to Na‐sugar cotransport. Biochim. Biophys. Acta 855: 193–196, 1986.
 194. Leaf, A., L. B. Page, and J. Anderson. Respiration and active sodium transport of isolated toad bladder. J. Biol. Chem. 234: 1625–1629, 1959.
 195. Leaf, A., and A. Renshaw. The anaerobic active ion transport by isolated frog skin. Biochem. J. 65: 90–93, 1957.
 196. Lederer, W. J., and M. T. Nelson. Sodium pump stoichiometry determined by simultaneous measurements of sodium efflux and membrane current in barnacle muscle. J. Physiol. Lond. 348: 665–677, 1984.
 197. Lee, C. O., and W. M. Armstrong. Activities of sodium and potassium ions in epithelial cells of small intestine. Science Wash. DC 175: 1261–1264, 1972.
 198. Lee, C. O., A. Taylor, and E. E. Windhager. Cytosolic calcium ion activity in epithelial cells of Necturus kidney. Nature Lond. 287: 859–861, 1980.
 199. Lew, V. L., and L. Beauge. Passive cation fluxes in red cell membranes. In: Membrane Transport in Biology. Transport Across Single Biological Membranes, edited by D. C. Tosteson. Berlin: Springer‐Verlag, 1979, vol. II, p. 81–115.
 200. Lew, V. L., and H. G. Ferreira. Calcium transport and the properties of a calcium activated potassium channel in red cell membranes. Curr. Top. Membr. Transp. 10: 218–277, 1978.
 201. Lewis, S. A., A. G. Butt, M. J. Bowler, J. P. Leader, and A. D. C. Macknight. Effects of anions on cellular volume and transepithelial Na transport across toad urinary bladder. J. Membr. Biol. 83: 119–137, 1985.
 202. Lewis, S. A., and J. L. C. de Moura. Cytoplasmic vesicle fusion alters the permeability properties of the apical membrane of the rabbit urinary bladder epithelium (Abstract). Biophys. J. 37: 268a, 1982.
 203. Lewis, S. A., D. C. Eaton, and J. M. Diamond. The mechanism of Na transport by rabbit urinary bladder. J. Membr. Biol. 28: 41–70, 1976.
 204. Lewis, S. A., and N. K. Wills. Interaction between apical and baso‐lateral membranes during sodium transport across tight epithelia. In: Ion Transport by Epithelia, edited by S. G. Schultz. New York: Raven, 1981, p. 93–107.
 205. Lewis, S. A., and N. K. Wills. Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder. J. Physiol. Lond. 341: 169–184, 1983.
 206. Limbird, L. E. Receptors linked to inhibition of adenylate cyclase: additional signaling mechanisms. FASEB J. 2: 2686–2695, 1988.
 207. Lindemann, B. Fluctuation analysis of sodium channels in epithelia. Annu. Rev. Physiol. 46: 497–515, 1984.
 208. Lindemann, B., and W. Van Driessche. Sodium‐specific membrane channels of frog skin are pores: current fluctuations reveal high turnover. Science Wash. DC 195: 292–294, 1977.
 209. Lohr, J. W., and J. J. Grantham. Isovolumetric regulation of isolated S2 proximal tubules in anisotonic media. J. Clin. Invest. 78: 1165–1172, 1986.
 210. Lopes, A. G., and W. B. Guggino. Volume regulation in the early proximal tubule of the Necturus kidney. J. Membr. Biol. 97: 117–125, 1987.
 211. Lorenzen, M., C. O. Lee, and E. E. Windhager. Cytosolic Ca2+ and Na+ activities in perfused proximal tubules of Necturus kidney. Am. J. Physiol. 247 (Renal Fluid Electrolyte Physiol. 16): F93–F102, 1984.
 212. Lytton, J. Insulin affects the sodium affinity of the rat adipocyte (Na+, K+)‐ATPase. J. Biol. Chem. 260: 10075–10080, 1985.
 213. Lytton, J., J. C. Lin, and G. Guidotti. Identification of two molecular forms of (Na,K)‐ATPase in rat adipocytes. J. Biol. Chem. 260: 1177–1184, 1985.
 214. Macknight, A. D. C., D. R. Di Bona, and A. Leaf. Sodium transport across toad urinary bladder: model “tight” epithelium. Physiol. Rev. 60: 615–715, 1980.
 215. Macknight, A. D. C., and A. Leaf. Regulation of cellular volume. Physiol. Rev. 57: 510–573, 1977.
 216. Macknight, A. D. C., and A. Leaf. The sodium transport pool. Am. J. Physiol. 234 (Renal Fluid Electrolyte Physiol. 3): F1–F9, 1978.
 217. Macknight, A. D. C., and A. Leaf. Regulation of cellular volume. In: Physiology of Membrane Disorders (2nd ed.), edited by T. E. Andreoli, J. F. Hoffman, D. D. Fanestil, and S. G. Schultz. New York: Plenum, 1986, p. 311–328.
 218. MacRobbie, E. A. C., and H. H. Ussing. Osmotic behavior of the epithelial cells of frog skin. Acta Physiol. Scand. 53: 348–365, 1961.
 219. Marmor, M. F. The independence of electrogenic sodium transport and membrane potential in a molluscan neurone. J. Physiol. Lond. 218: 599–608, 1971.
 220. Martin, D. The effect of the bicarbonate ion on the gallbladder salt pump. J. Membr. Biol. 18: 219–230, 1974.
 221. Martin, D. W., and J. M. Diamond. Energetics of coupled active transport of sodium and chloride. J. Gen. Physiol. 50: 295–315, 1966.
 222. Marunaka, Y. Effects of external K concentration on the electrogenicity of the insulin‐stimulated Na,K‐pump in frog skeletal muscle. J. Membr. Biol. 91: 165–172, 1986.
 223. Marunaka, Y. Effects of internal Na and external K concentrations on Na/K coupling of the Na,K pump in frog skeletal muscle. J. Membr. Biol. 101: 19–31, 1988.
 224. Marver, D., S. Lear, L. T. Marver, P. Silva, and F. H. Epstein. Cyclic AMP‐dependent stimulation of Na,K‐ATPase in shark rectal gland. J. Membr. Biol. 94: 205–215, 1986.
 225. Matsumura, Y., B. Cohen, W. B. Guggino, and G. Giebisch. Regulation of the basolateral potassium conductance of the Necturus proximal tubule. J. Membr. Biol. 79: 153–161, 1984.
 226. Messner, G., A. Koller, and F. Lang. The effect of phenylalanine on intracellular pH and sodium activity in proximal convoluted tubule cells of the frog kidney. Pfluegers Arch. 404: 145–149, 1985.
 227. Messner, G., H. Oberleithner, and F. Lang. The effect of phenylalanine on the electrical properties of proximal tubule cells in the frog kidney. Pfluegers Arch. 404: 138–144, 1985.
 228. Messner, G., W. Wang, M. Paulmichl, H. Oberleithner, and F. Lang. Ouabain decreases apparent potassium‐conductance in proximal tubules of the amphibian kidney. Pfluegers Arch. 404: 131–137, 1985.
 229. Mills, J. W., S. A. Ernst, and D. R. Di Bona. Localization of Na‐pump sites in frog skin. J. Cell Biol. 73: 88–110, 1977.
 230. Mills, J. W., A. D. C. Macknight, J. A. Jarrell, J. M. Dayer, and D. A. Ausiello. Interaction of ouabain with the Na pump in intact epithelial cells. J. Cell Biol. 88: 637–643, 1981.
 231. Mircheff, A. K., C. N. Conteas, C. C. Lu, N. A. Santiago, G. M. Gray, and L. G. Lipson. Basal‐lateral and intracellular membrane populations of rat exorbital lacrimal gland. Am. J. Physiol. 245 (Gastrointest. Liver Physiol. 8): G133–G142, 1983.
 232. Mitchell, P. Translocation through natural membranes. Adv. Enzymol. Relat. Areas Mol. Biol. 29: 33–87, 1967.
 233. Moran, W. M., R. L. Hudson, and S. G. Schultz. Kinetics of the effect of amiloride on the permeability of the apical membrane of rabbit descending colon to sodium. J. Membr. Biol. 87: 55–65, 1985.
 234. Moran, W. M., R. L. Hudson, and S. G. Schultz. Transcellular sodium transport and intracellular sodium activities in rabbit gallbladder. Am. J. Physiol. 251 (Gastrointest. Liver Physiol. 14): G155–G159, 1986.
 235. Morris, A. P., D. V. Gallacher, and J. A. C. Lee. A large conductance, voltage‐ and calcium‐activated potassium channel in the basolateral membrane of rat enterocytes. FEBS Lett. 206: 87–92, 1986.
 236. Mullins, L. J., and F. J. Brinley, Jr. Potassium fluxes in dialyzed squid axon. J. Gen. Physiol. 53: 704–740, 1969.
 237. Mullins, L. J., and K. Noda. The influence of sodium‐free solutions on the membrane potential of frog muscle fibers. J. Gen. Physiol. 47: 117–132, 1963.
 238. Murphy, M. P., and M. D. Brand. Variable stoichiometry of proton pumping by the mitochondrial respiratory chain. Nature Lond. 329: 170–172, 1987.
 239. Nagel, W. Basolateral membrane ionic conductance in frog skin. Pfluegers Arch. 405, Suppl. 1: S39–S43, 1985.
 240. Nagel, W., J. F. Garcia‐Diaz, and W. M. Armstrong. Intracellular ionic activities in frog skin. J. Membr. Biol. 61: 127–134, 1981.
 241. Narvarte, J., and A. L. Finn. Microelectrode studies in toad urinary bladder epithelium. Effects of Na concentration changes in the mucosal solution on equivalent electromotive forces. J. Gen. Physiol. 75: 323–344, 1980.
 242. Navarro, J., and A. Essig. Voltage‐dependence of Ca uptake and ATP hydrolysis of reconstituted Ca‐ATPase vesicles. Biophys. J. 46: 709–717, 1984.
 243. Nellans, H. N., and A. L. Finn. Oxygen consumption and sodium transport in the toad urinary bladder. Am. J. Physiol. 227: 670–675, 1974.
 244. Nellans, H. N., and J. E. Popovitch. Calmodulin‐regulated, ATP‐driven calcium transport by basolateral membranes of rat small intestine. J. Biol. Chem. 256: 9932–9936, 1981.
 245. Nellans, H. N., and S. G. Schultz. Relations among transepithelial sodium transport, potassium exchange and cell volume in rabbit ileum. J. Gen. Physiol. 68: 441–463, 1976.
 246. Nestler, E. J., and P. Greengard. Protein Phosphorylation in the Nervous System. New York: Wiley, 1984.
 247. Nielsen, R. Effect of the polyene antibiotic filipin and the calcium ionophore A23187 on sodium transport in isolated frog skin (Rana temporaria). J. Membr. Biol. 40: 331–345, 1978.
 248. Nielsen, R. A 3 to 2 coupling of the Na‐K pump responsible for the transepithelial Na transport in frog skin disclosed by the effect of Ba. Acta Physiol. Scand. 107: 189–191, 1979.
 249. Nielsen, R. Coupled transepithelial sodium and potassium transport across isolated frog skin: effect of ouabain amiloride and the polyene antibiotic filipin. J. Membr. Biol. 51: 161–184, 1979.
 250. Noma, A. ATP‐regulated K channels in cardiac muscle. Nature Lond. 305: 147–148, 1983.
 251. Oberleithner, H., U. Kersting, and M. Hunter. Cytoplasmic pH determines K+ conductance in fused renal epithelial cells. Proc. Natl. Acad. Sci. USA 85: 8345–8349, 1988.
 252. Okada, Y., T. Yada, T. Ohno‐Shosaka, and S. Oiki. Evidence for the involvement of calmodulin in the operation of Ca‐activated K channels in mouse fibroblasts. J. Membr. Biol. 96: 121–128, 1987.
 253. O'Neil, R. G., and R. A. Hayhurst. Sodium‐dependent modulation of the renal Na‐K‐ATPase: influence of mineralo‐corticoids on the cortical collecting duct. J. Membr. Biol. 85: 169–179, 1985.
 254. Ottoson, D. Physiology of the Nervous System. New York: Oxford Univ. Press, 1983, p. 133–140.
 255. Palmer, L. G. Na transport and flux ratio through apical channels in toad bladder. Nature Lond. 297: 688–690, 1982.
 256. Palmer, L. G. Use of potassium depolarization to study apical transport properties in epithelia. Curr. Top. Membr. Transp. 20: 105–121, 1984.
 257. Palmer, L. G. Modulation of apical Na permeability of the toad urinary bladder by intracellular Na, Ca and H. J. Membr. Biol. 83: 57–69, 1985.
 258. Palmer, L. G., I. S. Edelman, and B. Lindemann. Current‐voltage analysis of apical sodium transport in toad urinary bladder: effects of inhibitors of transport and metabolism. J. Membr. Biol. 57: 59–71, 1980.
 259. Palmer, L. G., and G. Frindt. Effects of cell Ca and pH on Na channels from rat cortical collecting tubule. Am. J. Physiol. 253 (Renal Fluid Electrolyte Physiol. 22): F333–F339, 1987.
 260. Palmer, L. G., and N. Speez. Stimulation of apical Na permeability and basolateral Na pump of toad urinary bladder by aldosterone. Am. J. Physiol. 250 (Renal Fluid Electrolyte Physiol. 19): F273–F281, 1986.
 261. Park, C. S., and I. S. Edelman. Dual action of aldosterone on toad bladder: Na+ permeability and Na+ pump modulation. Am. J. Physiol. 246 (Renal Fluid Electrolyte Physiol. 15): F517–F525, 1984.
 262. Petersen, G. L., R. D. Ewing, S. R. Hootman, and F. P. Conte. Large scale partial purification and molecular and kinetic properties of the (Na + K)‐activated adenosine triphosphatase from Artermia salina nauplii. J. Biol. Chem. 253: 4762–4770, 1978.
 263. Petersen, K.‐U., and L. Reuss. Electrophysiological effects of proprionate and bicarbonate on gallbladder epithelium. Am. J. Physiol. 248 (Cell Physiol. 17): C58–C69, 1985.
 264. Petersen, O. H., and Y. Maruyama. Calcium‐activated potassium channels and their role in secretion. Nature Lond. 307: 693–696, 1984.
 265. Petty, K. J., J. P. Kokko, and D. Marver. Secondary effect of aldosterone on Na‐K ATPase activity in the rabbit cortical collecting tubule. J. Clin. Invest. 68: 1514–1521, 1981.
 266. Pfaffinger, P. J., J. F. Martin, D. D. Hunter, N. M. Nathanson, and B. Hille. GTP‐binding proteins couple cardiac muscarinic receptors to a K channel. Nature Lond. 317: 536–538, 1985.
 267. Pollack, L. R., E. H. Tate, and J. S. Cook. Turnover and regulation of Na‐K‐ATPase in HeLa cells. Am. J. Physiol. 241 (Cell Physiol. 10): C173–C183, 1981.
 268. Post, R. L., and P. C. Jolly. The linkage of sodium, potassium and ammonium active transport across the human erythrocyte membrane. Biochim. Biophys. Acta 25: 118–128, 1957.
 269. Proverbio, F. The second sodium pump and the maintenance of cell volume. Curr. Top. Membr. Transp. In press.
 270. Proverbio, F., M. Condrescu‐Guidi, and G. Whittembury. Ouabain‐insensitive Na stimulation of an Mg‐dependent ATPase in kidney tissue. Biochim. Biophys. Acta 394: 281–292, 1975.
 271. Proverbio, F., J. A. Duque, T. Proverbio, and R. Marin. Cell volume‐sensitive Na+ ‐ATPase in rat kidney cortex cell membranes. Biochim. Biophys. Acta 941: 107–110, 1988.
 272. Rasmussen, H., and P. Q. Barrett. Calcium messenger system: an integrated view. Physiol. Rev. 64: 938–984, 1984.
 273. Reuss, L. Mechanisms of sodium and chloride transport by gallbladder epithelium. Federation Proc. 38: 2733–2738, 1979.
 274. Reuss, L., and A. L. Finn. Dependence of serosal membrane potential on mucosal membrane potential in toad urinary bladder. Biophys. J. 15: 71–75, 1975.
 275. Reuss, L., and A. L. Finn. Electrical properties of the cellular transepithelial pathway in Necturus gallbladder. I. Circuit analysis and steady‐state effects of mucosal solution ionic substitutions. J. Membr. Biol. 25: 115–139, 1975.
 276. Reuss, L., and S. A. Weinman. Intracellular ionic activities and transmembrane electrochemical potential differences in gallbladder epithelium. J. Membr. Biol. 49: 345–362, 1979.
 277. Richards, N. W., and D. C. Dawson. Single potassium channels blocked by lidocaine and quinidine in isolated turtle colon epithelial cells. Am. J. Physiol. 251 (Cell Physiol. 20): C85–C89, 1986.
 278. Richards, N. W., and D. C. Dawson. Two types of Ca‐activated channels in isolated turtle colon epithelial cells. Biophys. J. 51: 344a, 1987.
 279. Rick, R., A. Dorge, A. D. C. Macknight, A. Leaf, and K. Thurau. Electron microprobe analysis of the different epithelial cells of toad urinary bladder: electrolyte concentrations at different function states of transepithelial Na transport. J. Membr. Biol. 39: 257–271, 1978.
 280. Rick, R., A. Dorge, E. von Arnim, and K. Thurau. Electron microprobe analysis of frog skin epithelium: evidence for a syncytial sodium transport compartment. J. Membr. Biol. 39: 313–331, 1978.
 281. Rick, R., C. Roloff, A. Dorge, F. X. Beck, and K. Thurau. Intracellular electrolyte concentrations in the frog skin epithelium: effect of vasopressin and dependence on the Na concentration in the bathing media. J. Membr. Biol. 78: 129–145, 1984.
 282. Robinson, B. A., and A. D. C. Macknight. Relationships between serosal medium potassium concentrations and sodium transport in toad urinary bladder. III. Exchangeability of epithelial cellular potassium. J. Membr. Biol. 26: 269–286, 1976.
 283. Rossier, B. C., K. Geering, and J.‐P. Kraehenbuhl. Mechanism of action of aldosterone: role of Na‐K‐ATPase. In: Nephrology, edited by R. R. Robinson. New York: Springer‐Verlag, 1984, p. 388–396.
 284. Roy, G., and R. Suave. Effect of anisotonic media on volume, ion and amino acid content and membrane potential of kidney cells (MDCK) in culture. J. Membr. Biol. 100: 83–96, 1987.
 285. Sachs, F. Mechanotransducing ion channels. In: Ionic Channels in Cells and Model Systems, edited by R. Latorre, New York, Plenum, 1986, p. 181–193.
 286. Sachs, F. Mechanical transduction: unification? News Physiol. Sci. 1: 98–100, 1986.
 287. Sackin, H. Stretch‐activated potassium channels in renal proximal tubule. Am. J. Physiol. 253 (Renal Fluid Electrolyte Physiol. 22): F1253–F1262, 1987.
 288. Sackin, H., and L. G. Palmer. Basolateral potassium channels in renal proximal tubule. Am. J. Physiol. 253 (Renal Fluid Electrolyte Physiol. 22): F476–F487, 1987.
 289. Sanders, M. J., and D. S. Misfeldt. Ouabain‐sensitive Rb(K) influx is linked to transepithelial Na transport in pig kidney cell line. Biochim. Biophys. Acta 685: 383–385, 1982.
 290. Sansom, S. C., and R. G. O'Neil. Effects of mineralocorticoids on transport properties of cortical collecting duct basolateral membrane. Am. J. Physiol. 251 (Renal Fluid Electrolyte Physiol. 20): F743–F757, 1986.
 291. Sarkadi, B., R. Cheung, E. Mack, S. Grinstein, E. W. Gelfand, and A. Rothstein. Cation and anion transport pathways in volume regulatory response of human lymphocytes to hyposmotic media. Am. J. Physiol. 248 (Cell Physiol. 17): C480–C487, 1985.
 292. Sarkadi, B., E. Mack, and A. Rothstein. Ionic events during the volume response of human peripheral blood lymphocytes to hypotonic media. I. Distinctions between volume‐activated C1 and K conductance pathways. J. Gen. Physiol. 83: 497–512, 1984.
 293. Sasaki, K., and M. Sato. A single GTP‐binding protein regulates K+ ‐channels coupled with dopamine, histamine and acetylcholine receptors. Nature Lond. 325: 259–262, 1987.
 294. Schoen, H. F., and D. Erlij. Current‐voltage relations of the apical and basolateral membranes of the frog skin. J. Gen. Physiol. 86: 257–287, 1985.
 295. Schoen, H. F., and D. Erlij. Basolateral membrane responses to transport modifiers in the frog skin epithelium. Pfluegers Arch. 405, Suppl. 1: S33–S38, 1985.
 296. Schoen, H. F., and D. Erlij. Coupling between rate of transepithelial transport and basolateral membrane conductance is nonobligatory (Abstract). Federation Proc. 45: 746a, 1986.
 297. Schultz, S. G. Electrical potential differences and electromotive forces in epithelial tissues. J. Gen. Physiol. 59: 794–798, 1972.
 298. Schultz, S. G. Sodium‐coupled solute transport by small intestine: a status report. Am. J. Physiol. 233 (Endocrinol. Metab. Gastrointest. Physiol. 2): E249–E254, 1977.
 299. Schultz, S. G. Basic Principles of Membrane Transport. Cambridge, UK: Cambridge Univ. Press, 1980.
 300. Schultz, S. G. Homocellular regulatory mechanisms in sodium‐transporting epithelia: avoidance of extinction by “flush‐through.” Am. J. Physiol. 241 (Renal Fluid Electrolyte Physiol. 10): F579–F590, 1981.
 301. Schultz, S. G. Homocellular regulatory mechanisms in sodium transporting epithelia: an extension of the Koefoed‐Johnson‐Ussing model. In: Seminars in Nephrology, edited N. Kurtzman, New York: Grune & Stratton, 1982, p. 7–20.
 302. Schultz, S. G. Basolateral membrane properties of sodium‐absorbing epithelia. In: Nephrology, edited by R. R. Robinson. New York: Springer‐Verlag, 1984, p. 7–20.
 303. Schultz, S. G. Cellular models of epithelial ion transport. In: Physiology of Membrane Disorders (2nd ed.), edited by T. E. Andreoli, J. F. Hoffman, D. F. Fanestil, and S. G. Schultz. New York: Plenum, 1986, p. 519–534.
 304. Schultz, S. G., R. E. Fuisz, and P. F. Curran. Amino acid and sugar transport in rabbit ileum. J. Gen. Physiol. 49: 849–866, 1966.
 305. Schultz, S. G., R. L. Hudson, and J.‐Y. Lapointe. Electrophysiological studies of sodium cotransport in epithelia: toward a cellular model. Ann. NY Acad. Sci. 456: 127–135, 1985.
 306. Schwartz, G. J., J. Barasch, and Q. Al‐Awqati. Plasticity of functional epithelial polarity. Nature Lond. 318: 368–371, 1985.
 307. Schwarz, W., and H. Passow. Ca2+ ‐activated K+ channels in erythrocytes and excitable cells. Annu. Rev. Physiol. 45: 359–374, 1983.
 308. Sepulveda, F. V., K. A. Burton, and P. D. Brown. Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells. J. Cell. Physiol. 111: 303–308, 1982.
 309. Sepulveda, F. V., and W. T. Mason. Single channel recordings obtained from basolateral membranes of isolated rabbit enterocytes. FEBS Lett. 191: 87–91, 1985.
 310. Sheppard, D. N., F. Giraldez, and F. V. Sepulveda. Kinetics of voltage and Ca2+ activation and Ba2+ blockade of a large‐conductance K+ channel from Necturus enterocytes. J. Membr. Biol. 105: 65–75, 1988.
 311. Shorofsky, S. R., M. Field, and H. A. Fozzard. Electro‐physiology of Cl secretion in canine trachea. J. Membr. Biol. 72: 105–115, 1983.
 312. Shuttleworth, T. J., and J. L. Thompson. The mechanism of cyclic AMP stimulation of secretion in the dogfish rectal gland. J. Comp. Physiol. 140: 209–216, 1980.
 313. Siebens, A. W. Cellular volume control. In: The Kidney. Physiology and Pathophysiology, edited by D. W. Seldin and G. Giebisch. New York: Raven, 1985, p. 91–115.
 314. Siebens, A. W., and F. M. Kregenow. Volume regulatory responses of Amphiuma red cells in anisotonic media. J. Gen. Physiol. 86: 527–564, 1985.
 315. Sigler, K., and K. Janacek. The effect of non‐electrolyte osmolarity on frog oocytes. II. Intracellular potential. Biochim. Biophys. Acta 241: 539–546, 1971.
 316. Silva, P., J. A. Epstein, A. Stevens, K. Spokes, and F. H. Epstein. Ouabain binding in rectal gland of Squalus acanthias. J. Membr. Biol. 75: 105–114, 1983.
 317. Sjodin, R. A., and L. A. Beauge. The ion selectivity and concentration dependence of cation coupled active sodium transport in squid axon. Curr. Mod. Biol. 1: 105–115, 1967.
 318. Skou, J. C. The influence of some cations on adenosinetri‐phosphatase from peripheral nerves. Biochim. Biophys. Acta 23: 394–401, 1957.
 319. Skou, J. C. The (Na + K) activated enzyme system and its relationship to transport of sodium and potassium. Q. Rev. Biophys. 7: 401–434, 1975.
 320. Smith, P. L., and R. A. Frizzell. Chloride secretion by canine tracheal epithelium. IV. Basolateral membrane K permeability parallels secretion rate. J. Membr. Biol. 77: 187–199, 1984.
 321. Soltoff, S. P., and L. J. Mandel. Active ion transport in the renal proximal tubule. II. Ionic dependence of the Na pump. J. Gen. Physiol. 84: 623–642, 1984.
 322. Spring, K. R. Determinants of epithelial cell volume. Federation Proc. 44: 2526–2529, 1985.
 323. Sweander, K. J. Two molecular forms of (Na+ + K+)‐stimulated ATPase in brain. Separation, and difference in affinity for strophanthidin. J. Biol. Chem. 254: 6060–6067, 1979.
 324. Tamkun, M. M., and D. M. Fambrough. The (Na + K)‐ATPase of chick sensory neurons. Studies on the biosynthesis and intracellular transport. J. Biol. Chem. 261: 1009–1019, 1986.
 325. Taylor A. Role of cytosolic calcium and sodium‐calcium exchange in regulation of transepithelial sodium and water absorption. In: Ion Transport by Epithelia, edited by S. G. Schultz. New York: Raven, 1981, p. 233–259.
 326. Taylor, A., and E. E. Windhager. Possible role of cytosolic calcium and Na‐Ca exchange in regulation of transepithelial sodium transport. Am. J. Physiol. 236 (Renal Fluid Electrolyte Physiol. 5): F505–F512, 1979.
 327. Thomas, R. C. Electrogenic sodium pump in nerve and muscle cells. Physiol. Rev. 52: 563–594, 1972.
 328. Thomas, S. R., Y. Suzuki, S. M. Thompson, and S. G. Schultz. The electrophysiology of Necturus urinary bladder. I. “Instantaneous” current‐voltage relations in the presence of varying mucosal sodium concentrations. J. Membr. Biol. 73: 157–175, 1983.
 329. Thompson, S. M., Y. Suzuki, and S. G. Schultz. The electrophysiology of rabbit descending colon. I. Instantaneous transepithelial current‐voltage relations and the current‐voltage relation of the Na‐entry mechanism. J. Membr. Biol. 66: 41–54, 1982.
 330. Thurau, K., A. Dorge, J. Mason, F. Beck, and R. Rick. Intracellular elemental concentrations in renal tubular cells. An electron microprobe analysis. Klin. Wochenschr. 57: 993–999, 1979.
 331. Trachtenberg, M. C., D. J. Packey, and T. Sweeney. In vivo functioning of the Na,K‐activated ATPase. Curr. Top. Cell. Regul. 19: 159–217, 1981.
 332. Turnheim, K., R. A. Frizzell, and S. G. Schultz. Interaction between cell sodium and the amiloride‐sensitive sodium entry step in rabbit colon. J. Membr. Biol. 39: 233–256, 1978.
 333. Turnheim, K., R. L. Hudson, and S. G. Schultz. Cell Na activities and transcellular Na absorption by descending colon from normal and Na‐deprived rabbits. Pfluegers Arch. 410: 279–283, 1987.
 334. Turnheim, K., S. M. Thompson, and S. G. Schultz. Relation between intracellular sodium and active sodium transport in rabbit colon. J. Membr. Biol. 76: 299–309, 1983.
 335. Ussing, H. H. The distinction by means of tracers between active transport and diffusion. Acta Physiol. Scand. 19: 43–56, 1949.
 336. Ussing, H. H. The Alkali Metal Ions in Biology. Berlin: Springer‐Verlag, 1960.
 337. Ussing, H. H. Relationship between osmotic reactions and active sodium transport in the frog skin epithelium. Acta Physiol. Scand. 63: 141–155, 1965.
 338. Ussing, H. H. Volume regulation of frog skin epithelium. Acta Physiol. Scand. 114: 363–369, 1982.
 339. Ussing, H. H., and V. Koefoed‐Johnsen. Nature of the frog skin potential (Abstract). Comm. Int. Physiol. Congr., XXth, Brussels, 1956, p. 511.
 340. Valenzeno, D. P., and T. Hoshiko. Potassium reaccumulation by isolated frog skin epidermis. Biochim. Biophys. Acta 470: 273–289, 1977.
 341. Van Driessche, W., and B. Lindemann. Concentration dependence of currents through single sodium‐selective pores in frog skin. Nature Lond. 282: 519–520, 1979.
 342. Vestergaard‐Bogind, B., P. Stampe, and P. Christophersen. Single‐file diffusion through the Ca‐activated K channel of human red cells. J. Membr. Biol. 88: 67–75, 1985.
 343. Vieira, F. L., S. R. Caplan, and A. Essig. Energetics of sodium transport in frog skin. I. Oxygen consumption in the short‐circuited state. J. Gen. Physiol. 59: 60–76, 1972.
 344. Wade, J. B., R. G. O'Neil, J. L. Pryor, and E. L. Boulpaep. Modulation of cell membrane area in renal collecting tubules by corticosteroid hormones. J. Cell Biol. 81: 439–445, 1979.
 345. Wade, J. B., D. L. Stetson, and S. A. Lewis. ADH action: evidence for a membrane shuttle mechanism. Ann. NY Acad. Sci. 372: 106–117, 1981.
 346. Weber, K., and M. Osborn. The molecules of the cell matrix. Sci. Am. 253: 110–120, 1985.
 347. Welling, P. A., M. A. Linshaw, and L. P. Sullivan. Effect of barium on cell volume regulation in rabbit proximal straight tubules. Am. J. Physiol. 249 (Renal Fluid Electrolyte Physiol. 18): F20–F27, 1985.
 348. Welsh, M. J. Basolateral membrane potassium conductance is independent of sodium pump activity and membrane potential in canine tracheal epithelium. J. Membr. Biol. 84: 25–33, 1985.
 349. Welsh, M. J., and J. D. McCann. Intracellular calcium regulates potassium channels in a chloride‐secreting epithelium. Proc. Natl. Acad. Sci. USA 82: 8823–8826, 1985.
 350. Welsh, M. J., P. L. Smith, and R. A. Frizzell. Chloride secretion by canine tracheal mucosa. III. Membrane resistances and electromotive forces. J. Membr. Biol. 71: 209–218, 1983.
 351. White, J. F., K. Burnup, and D. Ellingsen. Effect of sugars and amino acids on amphibian intestinal Cl− transport and intracellular Na+, K+, and Cl− activity. Am. J. Physiol. 250 (Gastrointest. Liver Physiol. 13): G109–G117, 1986.
 352. White, J. F., and M. A. Imon. Effect of galactose on intracellular potential and sodium activity in urodele small intestine. Evidence for basolateral electrogenic transport. In: Intestinal Transport, edited by M. Gilles‐Baillien and R. Gilles. Berlin: Springer‐Verlag, 1983, p. 295–312.
 353. Whittembury, G. Relationship between sodium extrusion and electrical potentials in kidney cells. In: Electrophysiology of Epithelial Cells, edited by G. Giebisch, Stuttgart, FRG: Schattauer, 1971, p. 153–178.
 354. Whittembury, G., and F. Proverbio. Two modes of Na extrusion in cells from guinea pig kidney cortex slices. Pfluegers Arch. 316: 1–25, 1970.
 355. Widdicombe, J. H., C. B. Basbaum, and E. Highland. Sodium‐pump density of cells from dog tracheal mucosa. Am. J. Physiol. 248 (Cell Physiol. 17): C389–C398, 1985.
 356. Wills, N. K., and S. A. Lewis. Intracellular Na activity as a function of Na transport rate across a tight epithelium. Biophys. J. 30: 181–186, 1980.
 357. Wills, N. K., S. A. Lewis, and D. C. Eaton. Active and passive properties of rabbit descending colon: a microelectrode and nystatin study. J. Membr. Biol. 45: 81–108, 1979.
 358. Windhager, E. E., and A. Taylor. Regulatory role of intracellular calcium ions in epithelial Na transport. Annu. Rev. Physiol. 45: 519–532, 1983.
 359. Wolitzky, B. A., and D. M. Fambrough. Regulation of the (Na+ + K+)‐ATPase in cultured chick skeletal muscle. Modulation of expression by the demand for ion transport. J. Biol. Chem. 261: 9990–9999, 1986.
 360. Wong, S. M., and H. S. Chase, Jr. Role of intracellular calcium in cellular volume regulation. Am. J. Physiol. 250 (Cell Physiol. 19): C841–C852, 1986.
 361. Yang, J. M., C. O. Lee, and E. E. Windhager. Regulation of cytosolic free calcium in isolated perfused proximal tubules of Necturus. Am. J. Physiol. 225 (Renal Fluid Electrolyte Physiol. 24): F787–F799, 1988.
 362. Yatani, A., J. Codina, A. M. Brown, and L. Birnbaumer. Direct activation of mammalian atrial muscarinic potassium channels by GTP regulatory protein Gk. Science Wash. DC 235: 207–211, 1987.
 363. Yatani, A., J. Codina, Y. Imoto, J. P. Reeves, L. Birnhaumer, and A. M. Brown. A G protein directly regulates mammalian cardiac calcium channels. Science Wash. DC 238: 1288–1292, 1987.
 364. Yingst, D. R. Modulation of the Na,K‐ATPase by Ca and intracellular proteins. Annu. Rev. Physiol. 50: 291–303, 1988.
 365. Yingst, D. R., and J. F. Hoffman. Ca‐induced K transport in human red blood cell ghosts containing Arsenazo III. J. Gen. Physiol. 83: 19–45, 1984.
 366. Yiu, S. C., R. W. Lambert, M. E. Bradley, C. E. Ingham, K. L. Hales, R. L. Wood, and A. K. Mircheff. Stimulation‐associated redistribution of Na,K‐ATPase in rat lacrimal gland. J. Membr. Biol. 102: 185–194, 1988.
 367. Zerahn, K. Oxygen consumption and active sodium transport in the isolated and short‐circuited frog skin. Acta Physiol. Scand. 36: 300–318, 1956.

Contact Editor

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

* Required Field

Article Title: Biology Of Sodium‐Absorbing Epithelial Cells: Dawning of a New Era
 

How to Cite

Stanley G. Schultz, Randall L. Hudson. Biology Of Sodium‐Absorbing Epithelial Cells: Dawning of a New Era. Compr Physiol 2011, Supplement 19: Handbook of Physiology, The Gastrointestinal System, Intestinal Absorption and Secretion: 45-81. First published in print 1991. doi: 10.1002/cphy.cp060402