Effect of external potassium on the coupled sodium: Potassium transport ratio of axons
- 28 Downloads
Resting membrane potential and the current-voltage relation were measured in crayfish giant axons bathed in various potassium solutions with and without ouabain.
Ouabain caused a depolarization of the membrane at each [K] o used but did not affect membrane resistance.
The ouabain-sensitive transport current was least (3 μA/cm2) in 0 mM [K] o and greatest (7 μA/cm2) in 16.2 and 21.6 mM [K] o .
The assumption was made and some indirect evidence presented that axons equilibrated in various potassium solutions maintain constant internal sodium and potassium concentrations for up to 3 h.
On the basis of this assumption, the apparent ratio of coupled Na∶K transport was calculated. It was found to be least (−1.3/l) in 0 mM [K] o and to approach infinity in 16.2 and 21.6 mM [K] o .
The data indicate that the apparent variability of the Na∶K exchange ratio likely represents an intrinsic property of the exchange mechanism and is less likely to be explained by a fixed-ratio coupled Na∶K transport operating in parallel with electro-neutral Na∶Na or K∶K exchange.
Key wordsPotassium Coupled Na∶K transport Axon Procambarus clarkii
Unable to display preview. Download preview PDF.
- Abercrombie, R. F., DeWeer, P.: Electric current generated by squid giant axon sodium pump: external K and internal ADP effects. Am. J. Physiol.235, (1), C63-C68 (1978)Google Scholar
- Adrian, R. H.: The effect of internal and external potassium concentration on the membrane potential of frog muscle. J. Physiol. (Lond.)133, 631–658 (1956)Google Scholar
- Adrian, R. H., Slayman, C. L.: Membrane potential and conductance during transport of sodium, potassium and rubidium in frog muscle. J. Physiol. (Lond.)184, 970–1014 (1966)Google Scholar
- Baker, P. F., Blaustein, M. P., Keynes, R. D., Manil, J., Shaw, T. I., Steinhardt, R. A.: The ouabain-sensitive fluxes of sodium and potassium in squid giant axons. J. Physiol. (Lond.)200, 459–496 (1969)Google Scholar
- Begenisich, T., DeWeer, P.: Ionic interactions in the potassium channel of squid giant axons. Nature269, 710–711 (1977)Google Scholar
- Casteels, R., Kuriyama, H.: Membrane potential and ion content in the smooth muscle of the guinea-pig's Taenia Coli at different external potassium concentrations. J. Physiol. (Lond.)184, 120–130 (1966)Google Scholar
- Christoffersen, G. R. J., Skibsted, L. H.: Calcium ion activity in physiological salt solutions: Influence of anions substituted for chloride. Comp. Biochem. Physiol.52A, 317–322 (1975)Google Scholar
- Cooke, I. M., Leblanc, G., Tauc, L.: Sodium pump stoichiometry in Aplysia neurones from simultaneous current and tracer measurements. Nature251, 254–256 (1974)Google Scholar
- DeWeer, P.: Na+, K+ exchange and Na+, Na+ exchange in the giant axon of the squid. Ann. N. Y. Acad. Sci.242, 434–444 (1974)Google Scholar
- DeWeer, P., Geduldig, D.: Electrogenic sodium pump in squid grant axon. Science179, 1326–1328 (1973)Google Scholar
- Glynn, I. M., Karlish, S. J. D.: The sodium pump. Ann. Rev. Physiol.37, 13–55 (1975)Google Scholar
- Glynn, I. M., Karlish, S. J. D.: ATP hydrolysis associated with an uncoupled sodium flux through the sodium pump: Evidence for allosteric effects of intracellular ATP and extracellular sodium. J. Physiol. (Lond.)256, 465–496 (1976)Google Scholar
- Gorman, A. L. F., Marmor, M. F.: Contributions of the sodium pump and ionic gradients to the membrane potential of a molluscan neurone. J. Physiol. (Lond.)210, 897–917 (1970)Google Scholar
- Karlish, S. J. D., Glynn, I. M.: An uncoupled efflux of sodium ions from human red cells, probably associated with Na-dependent ATPase activity. Ann. N.Y. Acad. Sci.242, 461–470 (1974)Google Scholar
- Kennedy, B. G., DeWeer, P.: Relationship between Na∶K and Na∶Na exchange by the sodium pump of skeletal muscle. Nature268, 165–167 (1977)Google Scholar
- Lieberman, E. M.: Effect of extracellular potassium on the stead-state electrogenic Na−K transport system of the crayfish giant axon Society of Neuroscience Abstracts, Vol.III, abst. No. 688 (1977)Google Scholar
- Lieberman, E. M., Lane, T. G.: The influence of cardioactive steroids, metabolic inhibitors, temperature and sodium on membrane conductance and potential of crayfish giant axons. Pflügers Arch.366, 189–193 (1976)Google Scholar
- Lieberman, E. M., Nosek, T. M.: The influence of chloride on the ouabain-sensitive membrane potential and conductance of crayfish giant axons. Pflügers Arch.366, 195–202 (1976)Google Scholar
- Miura, D. S., Hoffman, B. F., Rosen, M. R.: The effect of extracellular potassium on the intracellular potassium ion activity and transmembrane potentials of beating canine cardiac Purkinje fibers. J. Gen. Physiol.69, 463–474 (1977)Google Scholar
- Moreton, R. B.: An application of the constant-field theory to the behavior of giant neurones of the snail,Helix aspersa. J. Exp. Biol.48, 611–623 (1968)Google Scholar
- Moreton, R. B.: An investigation of the electrogenic sodium pump in snail neurones, using the constant field theory. J. Exp. Biol.51, 181–201 (1969)Google Scholar
- Mullins, L. J., Brinley, F. J., Jr.: Potassum fluxes in dialyzed squid axons. J. Gen. Physiol.53, 704–740 (1969)Google Scholar
- Rang, H. P., Ritchie, J. M.: On the electrogenic sodium pump in mammalian nonmyelinated nerve fibers and its activation by various external cations. J. Physiol. (Lond.)196, 183–221 (1968)Google Scholar
- Simons, T. J. B.: Potassium: Potassium exchange catalysed by the sodium pump in human red cells. J. Physiol. (Lond.)237, 123–155 (1974)Google Scholar
- Thomas, R. C.: Electrogenic sodium pump in nerve and muscle cells. Physiol. Rev.52, 563–594 (1972)Google Scholar
- Van Harreveld, A.: Physiological saline for crayfish. Proc. Soc. Exp. Biol.34, 428–432 (1936)Google Scholar
- Wallin, B. G.: Intracellular ion concentrations in single crayfish axons. Acta Physiol. Scand.70, 419–430 (1967a)Google Scholar
- Wallin, B. G.: The relation between external potassium concentrations, membrane potential and internal ion concentrations in crayfish axons. Acta Physiol. Scand.70, 431–448, (1967b)Google Scholar
- Yamagishi, S., Grundfest, H.: Contributions of various ions to the resting and action potentials of crayfish medial giant axons. J. Membr. Biol.5, 345–365 (1971)Google Scholar