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. 1974 Oct;242(1):35–48. doi: 10.1113/jphysiol.1974.sp010692

Steady-state contribution of the sodium pump to the resting potential of a molluscan neurone

A L F Gorman, M F Marmor
PMCID: PMC1330598  PMID: 4436827

Abstract

1. The electrogenic contribution of the Na+-K+ exchange pump to the membrane potential of the Anisodoris giant neurone (G cell) was examined under steady-state and Na+ loaded conditions.

2. The membrane potential was variable for the first 1-4 hr after impalement, but, in the absence of experimental manipulation, remained constant thereafter. The average membrane potential for ten cells maintained at 11-13 °C and measured 5-36 hr after impalement was 55·8 ± 1·0 mV (S.E. of mean).

3. Low concentrations of external ACh caused a reversible increase in membrane Na+ conductance. Brief exposure to ACh proved a fast and reversible technique to load the cell with Na+ ions, and transiently stimulate the electrogenic Na+ pump.

4. In ten cells maintained from 5 to 36 hr at 11-13° C the reduction in membrane potential produced by inhibition of the Na+ pump with ouabain was remarkably constant between cells and averaged + 9·7 mV.

5. Cells maintained under steady-state conditions (at 11-13° C) for extended periods of time were shown to be relatively insensitive to changes in temperature and to small changes in external K+.

6. It is estimated that the Na+-K+ exchange pump contributes approximately - 10 mV to the steady-state resting potential of the G cell, and that two Na+ ions are extruded for every K+ ion transported into the cell per pump cycle.

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Selected References

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

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