Inhibition of Insulin Secretion by Infused Epinephrine in Rhesus Monkeys

Abstract

The effect of infused 1-epinephrine bitartrate on plasma insulin levels has been studied in the fasted, normal, waking rhesus monkey, with chronically implanted venous catheters. It was demonstrated that sharp rises in peripheral plasma glucose levels during infusion were not accompanied by rises in plasma insulin levels but that these did rise rapidly following the end of infusion in the majority of cases. The same phenomenon was seen when large amounts of intravenous glucose were given during epinephrine infusion. Further experiments showed that portal vein plasma insulin levels were also suppressed in the same way by epinephrine. No effect of epinephrine on plasma insulin levels was seen when epinephrine was added to plasma in vitro, and no effect of infused epinephrine on disappearance of injected insulin was found. These results were interpreted to mean that infused epinephrine inhibits secretion of insulin. Further findings were presented to reject the hypothesis that this effect of epinephrine is a consequence of its psychological (anxiety-like) effects, through sensations it may arouse. A series of experiments on a single animal, with carotid artery infusion of epinephrine, suggest that the brain is not the site of action.