Skip to main content
NCBI home page
The Journal of General Physiology logoLink to The Journal of General Physiology
. 1983 May 1;81(5):667–685. doi: 10.1085/jgp.81.5.667

Sodium flux ratio through the amiloride-sensitive entry pathway in frog skin

PMCID: PMC2216559  PMID: 6602864

Abstract

The sodium flux ratio of the amiloride-sensitive Na+ channel in the apical membrane of in vitro Rana catesbeiana skin has been evaluated at different sodium concentrations and membrane potentials in sulfate Ringer solution. Amiloride-sensitive unidirectional influxes and effluxes were determined as the difference between bidirectional 22Na and 24Na fluxes simultaneously measured in the absence and presence of 10(-4) M amiloride in the external bathing solution. Amiloride- sensitive Na+ effluxes were induced by incorporation of cation- selective ionophores (amphotericin B or nystatin) into the normally Na+- impermeable basolateral membrane. Apical membrane potentials (Va) were measured with intracellular microelectrodes. We conclude that since the flux ratio exponent, n', is very close to 1, sodium movement through this channel can be explained by a free-diffusion model in which ions move independently. This result, however, does not necessarily preclude the possibility that this transport channel may contain one or more ion binding sites.

Full Text

The Full Text of this article is available as a PDF (1.3 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Begenisich T., Busath D. Sodium flux ratio in voltage-clamped squid giant axons. J Gen Physiol. 1981 May;77(5):489–502. doi: 10.1085/jgp.77.5.489. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Begenisich T., De Weer P. Potassium flux ratio in voltage-clamped squid giant axons. J Gen Physiol. 1980 Jul;76(1):83–98. doi: 10.1085/jgp.76.1.83. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Benos D. J., Mandel L. J., Balaban R. S. On the mechanism of the amiloride-sodium entry site interaction in anuran skin epithelia. J Gen Physiol. 1979 Mar;73(3):307–326. doi: 10.1085/jgp.73.3.307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Benos D. J., Mandel L. J., Simon S. A. Cationic selectivity and competition at the sodium entry site in frog skin. J Gen Physiol. 1980 Aug;76(2):233–247. doi: 10.1085/jgp.76.2.233. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Biber T. U., Mullen T. L. Effect of inhibitors on transepithelial efflux of Na and nonelectrolytes in frog skin. Am J Physiol. 1977 Jan;232(1):C67–C75. doi: 10.1152/ajpcell.1977.232.1.C67. [DOI] [PubMed] [Google Scholar]
  6. Biber T. U., Mullen T. L. Saturation kinetics of sodium efflux across isolated frog skin. Am J Physiol. 1976 Oct;231(4):995–1001. doi: 10.1152/ajplegacy.1976.231.4.995. [DOI] [PubMed] [Google Scholar]
  7. Boulpaep E. L., Sackin H. Equivalent electrical circuit analysis and rheogenic pumps in epithelia. Fed Proc. 1979 May;38(6):2030–2036. [PubMed] [Google Scholar]
  8. Cala P. M., Cogswell N., Mandel L. J. Binding of [3H]ouabain to split frog skin: the role of the Na,K-ATPase in the generation of short circuit current. J Gen Physiol. 1978 Apr;71(4):347–367. doi: 10.1085/jgp.71.4.347. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Dawson D. C., Al-Awquati Q. Induction of reverse flow of Na+ through the active transport pathway in toad urinary bladder. Biochim Biophys Acta. 1978 Apr 4;508(2):413–417. doi: 10.1016/0005-2736(78)90343-7. [DOI] [PubMed] [Google Scholar]
  10. Essig A. Influence of cellular and paracellular conductance patterns on epithelial transport and metabolism. Biophys J. 1982 May;38(2):143–152. doi: 10.1016/S0006-3495(82)84541-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Fromm M., Schultz S. G. Potassium transport across rabbit descending colon in vitro: evidence for single-file diffusion through a paracellular pathway. J Membr Biol. 1981;63(1-2):93–98. doi: 10.1007/BF01969450. [DOI] [PubMed] [Google Scholar]
  12. Frömter E., Diamond J. Route of passive ion permeation in epithelia. Nat New Biol. 1972 Jan 5;235(53):9–13. doi: 10.1038/newbio235009a0. [DOI] [PubMed] [Google Scholar]
  13. Fuchs W., Larsen E. H., Lindemann B. Current-voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin. J Physiol. 1977 May;267(1):137–166. doi: 10.1113/jphysiol.1977.sp011805. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. HODGKIN A. L., HUXLEY A. F. The components of membrane conductance in the giant axon of Loligo. J Physiol. 1952 Apr;116(4):473–496. doi: 10.1113/jphysiol.1952.sp004718. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. HODGKIN A. L., KEYNES R. D. The potassium permeability of a giant nerve fibre. J Physiol. 1955 Apr 28;128(1):61–88. doi: 10.1113/jphysiol.1955.sp005291. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Heckmann K. Single file diffusion. Biomembranes. 1972;3:127–153. doi: 10.1007/978-1-4684-0961-1_9. [DOI] [PubMed] [Google Scholar]
  17. Helman S. I., Fisher R. S. Microelectrode studies of the active Na transport pathway of frog skin. J Gen Physiol. 1977 May;69(5):571–604. doi: 10.1085/jgp.69.5.571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Helman S. I., Miller D. A. Edge damage effect on measurements of urea and sodium flux in frog skin. Am J Physiol. 1974 May;226(5):1198–1203. doi: 10.1152/ajplegacy.1974.226.5.1198. [DOI] [PubMed] [Google Scholar]
  19. Hille B. Ionic selectivity, saturation, and block in sodium channels. A four-barrier model. J Gen Physiol. 1975 Nov;66(5):535–560. doi: 10.1085/jgp.66.5.535. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Hille B., Schwarz W. Potassium channels as multi-ion single-file pores. J Gen Physiol. 1978 Oct;72(4):409–442. doi: 10.1085/jgp.72.4.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Horowicz P., Gage P. W., Eisenberg R. S. The role of the electrochemical gradient in determining potassium fluxes in frog striated muscle. J Gen Physiol. 1968 May;51(5 Suppl):193S+–193S+. [PubMed] [Google Scholar]
  22. KOEFOED-JOHNSEN V., USSING H. H. The nature of the frog skin potential. Acta Physiol Scand. 1958 Jun 2;42(3-4):298–308. doi: 10.1111/j.1748-1716.1958.tb01563.x. [DOI] [PubMed] [Google Scholar]
  23. Labarca P., Canessa M., Leaf A. Metabolic cost of sodium transport in toad urinary bladder. J Membr Biol. 1977 Apr 22;32(3-4):383–401. doi: 10.1007/BF01905229. [DOI] [PubMed] [Google Scholar]
  24. Leblanc G., Morel F. Na and K movements across the membranes of frog skin epithelia associated with transient current changes. Pflugers Arch. 1975 Jul 21;358(2):159–177. doi: 10.1007/BF00583925. [DOI] [PubMed] [Google Scholar]
  25. Lindemann B., Van Driessche W. Sodium-specific membrane channels of frog skin are pores: current fluctuations reveal high turnover. Science. 1977 Jan 21;195(4275):292–294. doi: 10.1126/science.299785. [DOI] [PubMed] [Google Scholar]
  26. Läuger P. Ion transport through pores: a rate-theory analysis. Biochim Biophys Acta. 1973 Jul 6;311(3):423–441. doi: 10.1016/0005-2736(73)90323-4. [DOI] [PubMed] [Google Scholar]
  27. MACROBBIE E. A., USSING H. H. Osmotic behaviour of the epithelial cells of frog skin. Acta Physiol Scand. 1961 Nov-Dec;53:348–365. doi: 10.1111/j.1748-1716.1961.tb02293.x. [DOI] [PubMed] [Google Scholar]
  28. Macknight A. D., DiBona D. R., Leaf A. Sodium transport across toad urinary bladder: a model "tight" epithelium. Physiol Rev. 1980 Jul;60(3):615–715. doi: 10.1152/physrev.1980.60.3.615. [DOI] [PubMed] [Google Scholar]
  29. Macknight A. D., Leaf A. The sodium transport pool. Am J Physiol. 1978 Jan;234(1):F1–F9. doi: 10.1152/ajprenal.1978.234.1.F1. [DOI] [PubMed] [Google Scholar]
  30. Morel F., Leblanc G. Transient current changes and Na compartimentalization in frog skin epithelium. Pflugers Arch. 1975 Jul 21;358(2):135–157. doi: 10.1007/BF00583924. [DOI] [PubMed] [Google Scholar]
  31. Nagel W., Garcia-Diaz J. F., Armstrong W. M. Intracellular ionic activities in frog skin. J Membr Biol. 1981;61(2):127–134. doi: 10.1007/BF02007639. [DOI] [PubMed] [Google Scholar]
  32. Nagel W. The intracellular electrical potential profile of the frog skin epithelium. Pflugers Arch. 1976 Sep 30;365(2-3):135–143. doi: 10.1007/BF01067010. [DOI] [PubMed] [Google Scholar]
  33. O'Neil R., Helman S. I. Influence of vasopressin and amiloride on shunt pathways of frog skin. Am J Physiol. 1976 Jul;231(1):164–173. doi: 10.1152/ajplegacy.1976.231.1.164. [DOI] [PubMed] [Google Scholar]
  34. Palmer L. G., Edelman I. S., Lindemann B. Current-voltage analysis of apical sodium transport in toad urinary bladder: effects of inhibitors of transport and metabolism. J Membr Biol. 1980 Nov 15;57(1):59–71. doi: 10.1007/BF01868986. [DOI] [PubMed] [Google Scholar]
  35. Palmer L. G. Na+ transport and flux ratio through apical Na+ channels in toad bladder. Nature. 1982 Jun 24;297(5868):688–690. doi: 10.1038/297688a0. [DOI] [PubMed] [Google Scholar]
  36. Rick R., Dörge A., Macknight A. D., Leaf A., Thurau K. Electron microprobe analysis of the different epithelial cells of toad urinary bladder. Electrolyte concentrations at different functional states of transepithelial sodium transport. J Membr Biol. 1978 Mar 10;39(2-3):257–271. doi: 10.1007/BF01870334. [DOI] [PubMed] [Google Scholar]
  37. Thompson S. M., Suzuki Y., Schultz S. G. The electrophysiology of rabbit descending colon. I. Instantaneous transepithelial current-voltage relations and the current-voltage relations of the Na-entry mechanism. J Membr Biol. 1982;66(1):41–54. doi: 10.1007/BF01868480. [DOI] [PubMed] [Google Scholar]
  38. Turnheim K., Frizzell R. A., Schultz S. G. Interaction between cell sodium and the amiloride-sensitive sodium entry step in rabbit colon. J Membr Biol. 1978 Mar 10;39(2-3):233–256. doi: 10.1007/BF01870333. [DOI] [PubMed] [Google Scholar]
  39. USSING H. H., ZERAHN K. Active transport of sodium as the source of electric current in the short-circuited isolated frog skin. Acta Physiol Scand. 1951 Aug 25;23(2-3):110–127. doi: 10.1111/j.1748-1716.1951.tb00800.x. [DOI] [PubMed] [Google Scholar]
  40. Van Driessche W., Lindemann B. Concentration dependence of currents through single sodium-selective pores in frog skin. Nature. 1979 Nov 29;282(5738):519–520. doi: 10.1038/282519a0. [DOI] [PubMed] [Google Scholar]
  41. Wolff D., Essig A. Kinetics of bidirectional active sodium fluxes in the toad bladder. Biochim Biophys Acta. 1977 Jul 14;468(2):271–283. doi: 10.1016/0005-2736(77)90120-1. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of General Physiology are provided here courtesy of The Rockefeller University Press

RESOURCES