[Effect of insulin of frog skeletal muscle respiration]

The respiration of the isolated frog sartorius muscle was measured polarographically. The endogenous respiration was seen to increase by 8 and 6 times in 20 mM KCL and 0.05 mM 2,4-DNP, resp., and by 40 percent in 10mM pyruvate or lactate. Insulin stimulated the endogemous respiration from 27 to 38 mm-3 O2/hr. per gramm of wet weight. In the excess of exogenous lactate and pyruvate, the degree of the insulin stimulated respiration did not change. It is suggested that the increase of the endogenous respiration by insulin cannot be accounted for by the mobilization of the substrate of glycolysis.