Action of pancreatic polypeptide on exocrine pancreas and on release of cholecystokinin and secretin.
We have studied the effect of exogenous porcine pancreatic polypeptide (PP; 0.8 and 2.1 microgram/kg . h, iv) on endogenously stimulated pancreatic exocrine secretion in five pancreatic-fistula dogs. Plasma levels of cholecystokinin (CCK), secretin, and PP were measured in addition to pancreatic secretion of water, bicarbonate, and protein. Intraduodenal infusions of acid and a mixture of phenylalanine and tryptophan were used to stimulate hormone release. PP caused a dose-dependent inhibition of endogenously stimulated pancreatic secretion, whereas the release of CCK and secretin was not affected. Duodenal acidification and intraduodenal infusion of phenylalanine and tryptophan caused a significant release of PP. This study shows that: 1) PP suppresses pancreatic secretion by means of a mechanism that is probably direct; this effect is not mediated through inhibition of release of CCK or secretin, and 2) phenylalanine and tryptophan, both strong stimulants of CCK release, cause a substantial rise in PP in peripheral blood. The mechanism of PP release may involve CCK (in previous studies, we have shown a rise in circulating PP levels after iv CCK infusion).
D000818:Animals; D002766:Cholecystokinin / Q000097:blood / Q000378:metabolism*; D004285:Dogs; D004386:Duodenum / Q000502:physiology; D007700:Kinetics; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D010189:Pancreatic Juice / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000494:pharmacology*; D012633:Secretin / Q000097:blood / Q000378:metabolism*; D013552:Swine
D012633:Secretin; D010191:Pancreatic Polypeptide; D002766:Cholecystokinin