Pancreastatin inhibits insulin secretion and exocrine pancreatic secretion in the pig

Pancreastatin is a 49 amino acid peptide that occurs in pancreatic endocrine cells. Porcine pancreastatin has previously been shown to inhibit insulin secretion in vitro in the rat and in vivo in mice and dogs. However, the effects of this novel peptide in the porcine pancreas, i.e., in its species of origin, have not yet been established. Therefore, we have investigated the effects of porcine pancreastatin on the secretion of insulin and pancreatic juice (volume, protein and trypsin) from the porcine pancreas in vivo. The peptide was infused for 10 min at 74 pmol/min into the superior pancreatic artery either alone (blood glucose level 4.3 +/- 0.5 mM) or during an ongoing intravenous infusion of glucose (blood glucose level 11.0 +/- 2.2 mM). Blood was sampled from the portal vein and pancreatic juice was sampled from the cannulated pancreatic duct. We found that pancreastatin reduced the portal venous concentration of insulin, both during normoglycemia (from 28 +/- 3 to 12 +/- 4 microU/ml; p less than 0.001) and during hyperglycemia (from 53 +/- 6 to 17 +/- 5 microU/ml; p less than 0.001). Likewise, pancreastatin reduced the secretion of both protein (from 177 +/- 42 to 92 +/- 30 mg/h; p less than 0.05) and trypsin (from 93 +/- 19 to 57 +/- 17 U/h; p less than 0.05) in pancreatic juice without significantly altering the secreted volume. In conclusion, in the porcine pancreas in vivo, porcine pancreastatin (a) inhibits insulin secretion, and (b) inhibits the secretion of protein and trypsin to the pancreatic juice.(ABSTRACT TRUNCATED AT 250 WORDS)