ROLE OF CCK IN THE REGULATION OF SECRETION AND ADAPTATION IN THE PIG PANCREAS

The effect of cholecystokinin (CCK) on the pancreas was investigated i n the pig in two experiments. Fifteen pigs were fed a diet containing 17 or 48% protein with or without MK329 (4.5 mg per meal). MK329 enhan ced the postprandial peak of plasma CCK during the first 30 min, but p ancreas adaptation to high protein was not affected. Sixteen pigs were divided into two groups: 12 pigs were infused with CCK-8 + secretin f or 1 h and four pigs received a standard meal. In both groups, pancrea tic secretion tests were performed under infusion of the vehicle alone or with MK329. After CCK + secretin, MK329 (65-500 CLg/kg/h) did not alter CCK plasma levels and reduced the early pancreatic protein respo nse by about 30%. Enzyme outputs in pancreatic juice were modestly aff ected by MK329. After the meal, MK329 (500 mu g/kg/h) doubled the post prandial peak of plasma CCK and lowered the pancreatic protein output by 35-40% for the first 30 min. We suggest that (a) pancreatic adaptat ion to high dietary protein is not mediated via CCK-A receptors and (b ) the stimulation of pancreatic protein secretion by a meal or by exog enous CCK-8 is mediated partly by CCK-A receptors.