FEEDBACK-REGULATION OF PANCREATIC EXOCRINE SECRETION IN MINIPIGS

Background: The mechanism behind the possible feedback regulation of p ancreatic exocrine secretion is not well understood. Methods: Thirteen minipigs were prepared with fistulas to the pancreatic duct and the d uodenum. Peripheral venous blood was obtained for determination of sec retin and cholecystokinin (CCK) levels. Four different experiments wer e performed: 1) diversion and reinfusion of pancreatic juice; 2) intra duodenal infusion of NaHCO3 solution, with the same volume, bicarbonat e concentration, and osmolality as the collected pancreatic secretion, and reinfusion of pancreatic juice; 3) reinfusion of pancreatic secre tion for 1 h before and 2 h after a meal; and 4) diversion of pancreat ic secretion and intraduodenal infusion of NaHCO3 solutions before and after a meal. Results: Reinfusing pancreatic juice significantly decr eased pancreatic juice volume and bicarbonate output and slightly decr eased the level of secretin in plasma. Alternating infusions of substi tute NaHCO3 and pancreatic juice did not change pancreatic output of b icarbonate and protein, nor did it change the CCK and secretin levels in plasma. Replacing pancreatic juice with intraduodenal NaHCO3 infusi ons during a meal did not significantly modify the pancreatic secretio n of bicarbonate and protein or the hormonal levels in blood. Conclusi ons: A negative feedback regulation of pancreatic exocrine secretion i s present in starved minipigs. Duodenal acidity and plasma levels of s ecretin seem to be of importance, whereas duodenal enzymatic activity and the level of CCK in plasma probably are not. A postprandial negati ve feedback regulation through duodenal enzymatic activity and release of CCK into blood could not be shown.