Effect of Insulin on Free Glucose Content of Rat Diaphragm in Vitro

Abstract

Insulin increases the free glucose content of the isolated rat diaphragm when the muscle is incubated in a very high concentration of glucose or at low temperature. Studies with C14 labeled glucose indicate that insulin does not increase glucose production by the diaphragm. Increase in the glucose content of the tissue in the presence of insulin therefore arises from glucose which has penetrated from the external medium. It is concluded that an action of insulin on glucose uptake is to accelerate a step concerned with the transfer of glucose into the tissue. This step antecedes and is distinct from glucose phosphorylation by the hexokinase reaction.