Studies on the Secretion of Pancreatic Glucagon

Glucagon secretion was studied in isolated pancreatic islets, thus avoiding interference from immunologically cross-reactive polypeptides of gut origin. Glucagon release was measured by radioimmunoassay. High concentrations of glucose were shown to inhibit glucagon release. Certain amino acids and ouabain were found to stimulate glucagon release, but adrenergic agents and tolbutamide were without effect. Theophylline was found to be a potent in vitro stimulus to glucagon release, suggesting that the intracellular concentration of cyclic adenosine 3′,5′-monophosphate may play a role in the regulation of glucagon secretion.