PANCREATIC ENDOCRINE RESPONSES TO THE PEPTIDES VIP AND PACAP IN THE CONSCIOUS CALF

Pancreatic endocrine responses to vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP) and acetylchol ine have been investigated in conscious calves, while continuously mon itoring aortic blood pressure and heart rate, in order to assess the e ffects of these neuropeptides under normal physiological conditions. V IP was found to modulate the release of pancreatic polypeptide (PP) in response to acetylcholine at a dose which had no significant effect o n the release of either pancreatic glucagon or insulin. PACAP stimulat ed the release of insulin and the effect was potentiated during infusi ons of exogenous glucose. PACAP, when infused together with acetylchol ine, also stimulated the release of pancreatic glucagon in the absence of exogenous glucose but not in its presence. Release of PP was stimu lated during infusions of PACAP, whether or not exogenous glucose was given, and this effect was found to be additive with that of acetylcho line.