Effect of Glucose Concentration on Insulin and Glucagon Release from Isolated Islets of Langerhans of the Rat

The isolated islets of Langerhans of the rat have been utilized to study simultaneous insulin and glucagon release. There is very little degradation of insulin or glucagon when a proteolytic enzyme inhibitor, Trasylol, is added to the incubation vessels. Glucose exerts an opposite effect on insulin and glucagon release. As the glucose concentration in the incubation media is raised from 30 to 300 mg. per 100 ml., there is a decreased secretion of glucagon and an increased secretion of insulin. The addition of 2-deoxyglucose to the media inhibited insulin release but had no effect on glucagon. The results are discussed in reference to the role of glucagon in insulinogenesis and in regard to the possible mechanisms of insulin and glucagon release.