The release of pancreatic polypeptide by intraduodenal l-phenylalanine in the dog.

In four dogs with chronic gastric and pancreatic fistulas 100 mM L-phenylalanine was delivered to the duodenum at a rate of 25 ml/15 minutes. Pancreatic secretion and plasma pancreatic polypeptide (PP) concentration were monitored. Phenylalanine induced a slight rise in pancreatic volume output and a considerable increase in protein secretion in the pancreatic juice as well as a significant (p less than 0.01) increment of plasma PP over basal levels. Administration of atropine sulfate (0.1 mg/kg i.v.) inhibited the PP release and reduced the pancreatic protein output (p less than 0.05). It is concluded that the release of PP following intraduodenal phenylalanine involves a cholinergic mechanism and may be mediated by an enteropancreatic reflex and/or endogenous CCK peptides.