Effects of internal Na and external K concentrations on Na/K coupling of Na,K-pump in frog skeletal muscle |
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Authors: | Yoshinori Marunaka |
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Affiliation: | (1) Department of Physiology, Shiga University of Medical Science, 520-21 Ohtsu, Japan;(2) Present address: Department of Physiology, Emory University School of Medicine, 30322 Atlanta, Georgia |
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Abstract: | Summary To clarify the dependency of the Na/K coupling of the Na,K-pump on internal Na and external K concentrations in skeletal muscle, the ouabain-induced change in membrane potential, the ouabain-induced change in Na efflux and the membrane resistance were measured at various internal Na and external K concentrations in bullfrog sartorius muscle.Upon raising the internal Na concentration from 6 mmol/kg muscle water to 20 mmol/kg muscle water, the magnitude of the ouabain-induced change in membrane potential increased about eightfold and the magnitude of the ouabain-induced change in Na efflux increased about fivefold while the membrane resistance was not significantly changed. As the external K concentration increased from 1 to 10mm, the magnitude of the ouabain-induced change in membrane potential decreased (1/5.5 fold), while the magnitude of the ouabain-induced change in Na efflux increased (about 1.5-fold). The membrane resistance decreased upon raising the external K concentration from 1 to 10mm (1/2-fold). These observations imply that the values of the Na/K coupling of the Na,K-pump increases upon raising the internal Na concentration and decreases upon raising the external K concentration. |
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Keywords: | Na,K-pump Na/K coupling membrane potential internal Na external K skeletal muscle |
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