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The effect of meal stimulation, with and without the intraduodenal presence of pancreatic enzymes, on plasma cholecystokinin (CCK) release was studied in order to investigate the role of CCK in the putative feedback mechanism between intraduodenal pancreatic proteases and pancreatic enzyme secretion. Plasma CCK concentrations in response to a semiliquid meal, with and without the supplementation of exocrine pancreatic enzymes, were measured in 8 dogs after duodenum preserving pancreatectomy. With a well-balanced endocrine and exocrine substitution regimen all dogs were kept in good clinical condition, without steatorrhea or significant weight loss, and fasting plasma glucose levels within the normal range. Exocrine supplementation was stopped at least 3 days prior to tests. Basal plasma CCK levels after 3 days without exocrine supplementation (2.5 +/- 0.3 pM) did not significantly differ from the results with supplementation (3.0 +/- 0.5 pM) nor from the preoperative levels (2.3 +/- 0.3 pM). In addition, integrated plasma CCK responses to the meal without exocrine supplementation (330 +/- 37 pM.90 min) were not significantly different from the responses to the meal with exocrine supplementation (303 +/- 49 pM.90 min), or from the postprandial CCK response in the dogs with an intact pancreas preoperatively (390 +/- 100 pM.90 min). It is concluded that the release of CCK in dogs after total pancreatectomy is independent of intraluminal protease activity. It is therefore not likely that CCK mediates the putative feedback mechanism between intraluminal protease activity and pancreatic enzyme secretion in dogs.