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Long‐term effect of ouabain and sodium pump inhibition on a neuronal membrane
Author(s) -
Gorman A. L. F.,
Marmor M. F.
Publication year - 1974
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1974.sp010693
Subject(s) - ouabain , chemistry , hyperpolarization (physics) , membrane potential , sodium , biophysics , membrane , sodium pump , conductance , endocrinology , medicine , biochemistry , biology , stereochemistry , mathematics , organic chemistry , combinatorics , nuclear magnetic resonance spectroscopy
1. The long‐term effects of ouabain on the membrane potential of the Anisodoris giant neurone (G cell) were examined in cells maintained for periods of up to 15 hr at 11–13° C. 2. In the presence of ouabain (5 × 10 −4 M ), the membrane potential depolarized to a constant level for 1‐4 hr, then hyperpolarized for 5‐7 hr after which it gradually depolarized again. 3. During the hyperpolarizing phase, after 6–8 hr in ouabain, [K] 1 fell approximately 50%, [Na] 1 increased 50–100% and the P Na / P K ratio decreased to 25% of its initial value. 4. After 8 hr in ouabain the membrane conductance increased two‐ to fourfold. This increase was independent of temperature and membrane rectification. 5. The K permeability ( P K ) was calculated from the constant field equation, and showed a fourfold increase after long‐term treatment with ouabain. This rise in P K probably underlies the membrane hyperpolarization and the decrease in the P Na / P K ratio. 6. It is suggested that inhibition of the Na + pump with ouabain causes a gradual rise in [Na] 1 which secondarily leads to Ca 2+ uptake, an increase in [Ca] 1 , and thereby an increase in P K .