A secretin releasing peptide exists in dog pancreatic juice

Abstract Canine pancreatic juice has been shown to stimulate exocrine pancreatic secretion in the dog. In the present study we investigated whether there is a secretin-releasing peptide in canine pancreatic juice. Pancreatic juice was collected from the dogs with Thomas gastric and duodenal cannulas while pancreatic secretion was stimulated by intravenous administration of secretin at 0.5 μ/gk/gh and CCK-8 at 0.2 μg/kg/h, respectively. The pancreatic juice was separated into three different molecular weight (MW) fractions (Fr) by ultrafiltration (Fr 1; MW > 10,000, Fr 2; MW = 10,000 − 4,000 and Fr 3; MW mg ml for 60 min at 37 ° C) but not by heating (100 ° C, 10 min). Intravenous injection of a rabbit anti-secretin serum, which rendered plasma secretin almost undetectable in rat plasma, also abolished Fr 3-stimulated pancreatic secretion of fluid and bicarbonate secretion. These observations suggest that a secretin-releasing peptide exists in the canine pancreatic juice. It is trypsin-sensitive and heat-resistant. This peptide may play a significant physiological role on the release of secretin and regulation of exocrine pancreatic secretion.