Effect of insulin on membrane potential and potassium content of rat muscle

Abstract

Insulin increased resting membrane potential of excised rat muscle, extensor digitorum longus, by about 5 mv in less than 1 hour. In 1 hour insulin caused no increase in the ratio of intra- to extracellular potassium, but in 2–3 hours intracellular K increased by about 10%. It is concluded that the increase in intracellular K is probably too small and too late to account for the hyperpolarization on the basis of conventional theory and it is suggested that the hyperpolarization produced by insulin is the cause of the potassium shift.