Abstract
We have investigated the potential dependence of the electrogenic sodium pump in Aplysia neurons by recording the potential and current induced by sudden change of the artificial sea water from one containing K+ at various concentrations to K+-free sea water in the presence or absence of ouabain. Both K+-free sea water and ouabain block sodium transport and result in a significant depolarization due to removal of a maintained outward current that is a result of transport of more Na+ out of the cell than K+ into the cell during pump operation. In the presence of ouabain there is, however, an inward current induced by changing external K+ concentration from zero to some value between 1 and 20 mM, and this current is greater with a greater K+ concentration gradient. The current induced by change from zero to 1 mM K+ does not show any potential dependence, although those currents induced by higher K+ concentrations are potential dependent. We conclude that the activity of the electrogenic sodium pump is not potential dependent, but that the potential independence is obscured if higher concentrations of K+ are used to activate the electrogenic sodium pump.
Similar content being viewed by others
References
Abercrombie, R. F., De Weer, P. (1978) Electric current generated by squid giant axon sodium pump: external K and internal ADP effects. Am. J. Physiol. 235, C63–C68.
Ayrapetyan, S. N. (1969) Metabolically dependent fraction of membrane potential and electrode properties of the membrane of giant neurons in mollusks. Biofizika 14, 1027–1031.
Carpenter, D. O. (1973) Electrogenic sodium pump and high specific resistance in nerve cell bodies of the squid. Science 179, 1336–1338.
Carpenter, D. O. (1970) Membrane potential produced directly by the Na+ pump in Aplysia neurons. Comp. Biochem. Physiol. 35, 371–385.
Cole, K. S. (1972) Membranes, Ions and Impulses. University of California Press, Los Angeles.
Skou, J. C. (1960) Further investigation on a Mg++ and Na+ across the nerve membrane. Biochem. Biophys. Acta 42, 6.
Skou, J. C. (1992) The Na-K pump. NIPS 7, 95–100.
Salánki, J., Evans, M. L., Carpenter, D. O. (1989) Desensitization kinetics of a K+ acetylcholine response in Aplysia. Brain Res. 495, 298–308.
Slater, N. T., Hall, A. F., Carpenter, D. O. (1984) Kinetic properties of cholinergic desensitization in Aplysia neurons. Proc. R. Soc. Lond. B 223, 63–78.
Slater, N. T., Carpenter, D. O. (1984) A study of the cholinolytic actions of strychnine using the technique of concentration jump relaxation analysis. Cell. Molec. Neurobiol. 4, 263–271.
Author information
Authors and Affiliations
Corresponding author
Additional information
Dedicated to Professor János Salánki for his 70th birthday.
Rights and permissions
About this article
Cite this article
Ayrapetyan, S.N., Ayrapetyan, G. & Carpenter, D.O. The electrogenic sodium pump activity in Aplysia neurons is not potential dependent. BIOLOGIA FUTURA 50, 27–34 (1999). https://doi.org/10.1007/BF03543028
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03543028