Stimulation of Na,K-ATPase activity of frog skeletal muscle by insulin

Na,K-ATPase activity of a plasma membrane fraction obtained from frog skeletal muscles was increased approximately two-fold by exposing muscles to insulin, whereas the addition of insulin to a membrane preparation suspension has no effect on Na,K-ATPase activity. The effect of insulin on Na,K-ATPase activity of whole muscles was specific to insulin and insulin derivatives that had the ability of receptor-binding and was not inhibited by actinomycin D. Insulin also induced a development of Na,K-ATPase activity in muscles whose Na,K-ATPase activity had been blocked by ouabain-pretreating. Such a insulin action was inhibited by monensin. These observations suggest that insulin stimulates the monensin-sensitive intracellular transport of membrane proteins which should be responsible for the increase in Na/K pumping activity.