Intestinal phase of pancreatic polypeptide release: The effect of segmental perfusion of the small intestine with various secretagogues

The purpose of this study was to examine the effect of various nutrients perfused selectively into isolated sections of the small intestine on the release of pancreatic polypeptide (PP). Six dogs were prepared with chronic gastric, duodenal, and three permanent intestinal fistulas (one distal to the ligament of Treitz, one in the terminal ileum, and one halfway between). After a 24-h fast, the duodenum was perfused for 45 min (200 ml/h) via the duodenal limb with HC1 (30 mM), an amino acid solution (50 vaM), or sodium oleate (NaO, 40 mM). In separate studies, the jejunal and ileal segments were isolated by inflating two balloon catheters via the intestinal fistula, and these segments were perfused as described earlier. Plasma PP, cholecystokinin (CCK)-33, and secretin levels were measured. Results of this study showed that the perfusion of all segments of the small intestine with amino acid caused a significant elevation of plasma PP levels. Perfusion of the duodenum and jejunum but not the ileum with a fatty acid resulted in a significant elevation of plasma levels of PP. Perfusion of HC1 into any segment did not affect plasma levels of PP. This study shows that PP is released by the presence of nutrients in all segments of the small intestine, and that a PP elevation was always accompanied with a rise in plasma levels of CCK-33.