Calcitonin inhibition of insulin release from isolated rat pancreatic islets.

Calcitonin is known to inhibit secretion of gastrin and insulin in vivo. The objective of this study was to determine whether calcitonin can act directly on pancreatic islets in vitro to inhibit insulin release. Isolated islets were obtained from collagenase-treated rat pancreas, and three peptides (gastrin-releasing peptide, cholecystokinin-8, bombesin) and glucose were used to stimulate insulin release. All agents caused a significant increase in insulin secretion and calcitonin inhibited these responses, but had no consistent effect on basal release. This study provides evidence that calcitonin is an effective inhibitor of insulin secretion and acts directly on islet tissue.