Skeletal Muscle Resting Membrane Potential in Potassium Deficiency

Gordon L. Bilbrey; Luis Herbin; Norman W. Carter; James P. Knochel

doi:10.1172/JCI107499

Skeletal Muscle Resting Membrane Potential in Potassium Deficiency

Gordon L. Bilbrey, Luis Herbin, Norman W. Carter, and James P. Knochel

Published December 1, 1973 - More info

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Abstract

The resting transmembrane potential of skeletal muscle (E_m) is thought to be a function of the ratio of intracellular to extracellular potassium concentration ([K_i]/[K_o]). In potassium deficiency, the fall of [K_i] is proportionately less than the fall of [K_o], thus theoretically predicting a rise of E_m. To examine this theory and to characterize E_m in kaliopenic myopathy, muscle composition and E_m were measured during moderate (n = 5) and severe (n = 11) K deficiency in the dog and compared with measurements in the severely K-deficient rat (n = 10). Mean measured E_m rose during moderate K deficiency in four of five dogs (-85.4 to -94.6 mV) and during severe K deficiency in the rat (-89.1 to -94.9 mV). Both values closely approximated the increase in E_m predicted by the Goldman equation. In contrast, during severe K deficiency in the dog, a significant decline (P < 0.001) of mean E_m to -55 mV was observed.

Since skeletal myopathy and paralysis do not occur in the rat as a consequence of K deficiency, the observation that E_m falls as paralysis occurs in the unexercised dog suggests that alteration of muscle membrane function may play a role in kaliopenic myopathy. Such an event could explain the ease with which frank muscle necrosis may be induced by exercise in the K-deficient dog.