PANCREATIC-POLYPEPTIDE INHIBITS EXOCRINE PANCREATIC RESPONSES TO 6 STIMULANTS

The effects of 3 different doses of pancreatic polypeptide (50, 200 and 800 pmol .cntdot. kg-1 .cntdot. h-1) on pancreatic responses to graded doses of i.v. secretin, caerulein, bethanechol, intraduodenal HCl, L-phenylalanine and Na oleate was studied in dogs. The 2 lowest doses of pancreatic polypeptide (PP), which produced blood levels lower than measured after a meal, significantly inhibited the pancreatic responses to secretin, caerulein, HCl and L-phenylalanine. The highest dose of PP inhibited the responses to bethanechol and Na oleate. There was no difference in the degree of inhibition of bicarbonate or protein secretion caused by pancreatic polypeptide. With secretin, caerulein, bethanechol and Na oleate, inhibition was most pronounced against lower doses and was surmountable with higher doses of these stimulants. Inhibition of responses to HCl and L-phenylalanine was observed at all doses of these stimulants. Inhibition of the exocrine pancreatic secretory responses to these stimuli by PP suggests that this hormone may play an important role in regulation of postprandial pancreatic secretion.