Studies on the mechanism of somatostatin action on insulin release in man. II. Comparison of the effects of somatostatin on insulin release induced by glucose, glucagon and tolbutamide.

Abstract

Somatostatin in as small a dose as 70 mug given over a period of 90 min to seven healthy subjects inhibited insulin release induced by glucose (500 mg/kg as a bolus + 20 mg/kg/min). This inhibition seemed to be of competitive nature since the effect was nearly overcome when the glucose dose was raised considerably. Somatostatin in nine subjects also inhibited insulin release induced by glucagon and tolbutamide, and this inhibition was of the same order of magnitude as that of glucose induced insulin release. Since all these insulinogogues enhance of the accumulation of cyclic AMP in the beta-cells, it is suggested that the edenylate cyclase-cylic AMP system might be involved in the action of somatostatin. Somatostatin did not seem to interfere with the glycogenolytic effect of glucagon on the liver.