Effects of intravenous infusions of cholecystokinin-8 and pentagastrin on plasma concentrations of insulin and glucagon in sheep.

The effects of cholecystokinin-8 (CCK-8) and pentagastrin on insulin and glucagon secretion were studied in conscious sheep. Intravenous infusions of CCK-8 (3 to 1000 pmol kg-1 min-1 for 30 minutes) induced a dose-dependent increase in plasma insulin, but did not alter plasma glucagon concentration. The threshold dose of CCK-8 for stimulation of insulin secretion was 10 to 30 pmol kg-1 min-1. Pentagastrin was infused intravenously at doses of 10 to 3000 pmol kg-1 min-1. The maximal dose of pentagastrin slightly stimulated insulin, but not glucagon, secretion. The insulin secretory activity of pentagastrin was only 1/300 that of CCK-8 on a molar basis. The threshold dose of CCK-8 for stimulation of insulin secretion was similar to that for exocrine pancreatic secretion obtained in earlier studies. In conclusion, CCK is a potential candidate as a physiological factor regulating insulin secretion in sheep.