Secretory effects of VIP on isolated perfused porcine pancreas

We studied the secretion of insulin, glucagon, and the exocrine secretion of the isolated perfused porcine pancreas in response to vasoactive intestinal polypeptide (VIP) in concentrations ranging from 30 to 18,750 pmol/liter at various concentrations of glucose in the perfusion medium. VIP stimulated the insulin and glucagon secretion in a dose-dependent manner. The response pattern was critically dependent on the glucose concentration. In the presence of a glucose concentration of 7.5 mmol/liter, VIP enhanced insulin release without affecting glucagon release. Maximal insulin release was obtained at a VIP concentration of 3,750 pmol/liter. At a glucose concentration of 5.0 or 3.5 mmol/liter, VIP enhanced glucagon release but not insulin release. VIP stimulated the exocrine secretion in a secretin-like manner. The lowest concentration of VIP observed to increase pancreatic exocrine secretion was 30 pmol/liter, whereas the maximal pancreatic exocrine responses were not obtained.