FEEDBACK-REGULATION OF EXOCRINE PANCREATIC-SECRETION IN DOGS

Important basic physiological mechanisms of exocrine pancreas secretio n were delineated in a canine model. However, dogs have been considere d unsuitable for the study of the controversial feedback regulation of exocrine pancreas secretion. The present study reveals a marked modif ication of pancreas secretion following the intraduodenal instillation of lipase: The postprandial lipase secretion decreases from 2,421 U x 180 min-1 to 1,490 U x 180 min-1, but simultaneously determined chole cystokinin (CCK) concentrations in plasma do not increase under these circumstances. The intraduodenal application of a protease inhibitor ( 800 mg camostate) significantly stimulates the secretion of the exocri ne pancreas in the fasting dog: After 15 min the protein release incre ased to 133 +/- 30 mg. Intravenous atropine blocks this increase. The plasma concentrations of CCK are not significantly influenced. These r esults in our canine model show that the secretory activity of the exo crine pancreas depends on the intraduodenal enzyme content. CCK is irr elevant in this context.