Intraluminal ileal recovery of pancreatic polypeptide.

Pancreatic polypeptide (PP) is a normal constituent of pancreatic islet cells. Enterocytes containing PP have been identified but incompletely characterized. We previously demonstrated independent intravascular and intraluminal release of two related peptides, peptide YY and neuropeptide Y. In this study, using ileal segments in conscious dogs, we evaluated the intravascular and ileal intraluminal presence of PP to test meals. Fasted plasma and recoverable ileal PP concentrations averaged 139 +/- 2 and 65 +/- 4 pg/mL, respectively. A mixed protein meal resulted in a sustained rise of circulating PP levels associated with a brief evaluation of ileal luminal PP levels. Fat meals were followed by elevations in plasma PP levels without luminal changes. Glucose ingestion altered neither plasma nor luminal PP levels. Our data support the existence of ileal PP-containing cells that respond independently of circulatory PP-releasing cells to different ingested stimuli.