Insulin-induced membrane changes in K+-depleted rat skeletal muscle

Pretreatment of K+-deprived rat diaphragm with insulin caused a 38% increase in input resistance and a decline in K+ current in the skeletal muscle, resulting in membrane depolarization and deactivation. Depolarization in K+-depleted muscle is induced by insulin-associated blockage of K+ channels and is maintained by triggering noninactivating Na+ channels. Conductance in K+-depleted fibers is opposed by a large leakage current in the absence of insulin. The diminished outward current is distinct from the inward current carried by Ca2+, as demonstrated by the decline in insulin-induced current in nitrendipine.