Effect of gut peptides on glucose-stimulated insulin release by monolayer cultures of neonatal rat islet cells.

Gastric inhibitory polypeptide (GIP), pancreatic polypeptide (PP), glucagon, vasoactive intestinal polypeptide (VIP), bombesin, neurotensin, substance P, and cholecystokinin octapeptide (CCK-OP) were examined for their effects upon glucose-stimulated insulin secretion in denervated and isolated islet cells, namely, monolayer cultures of dispersed neonatal rat pancreatic islet cells. Only glucagon (14 nM), GIP (10 and 20 nM), and CCK-OP (20 nM) enhanced glucose-stimulated insulin release during a 60-min incubation period. None of the others altered insulin secretion under the conditions employed, although reported to influence insulin release in other systems.