Regulation of porcine biliary secretion by secretin

Physiological parameters governing the action of pancreatic lipase

The most widely used pharmacological therapies for obesity and weight management are based on inhibition of gastrointestinal lipases, resulting in a reduced energy yield of ingested foods by reducing dietary lipid absorption. Colipase-dependent pancreatic lipase is believed to be the major gastrointestinal enzyme involved in catalysis of lipid ester bonds. There is scant literature on the action of pancreatic lipase under the range of physiological conditions that occur within the human small intestine, and the literature that does exist is often contradictory. Due to the importance of pancreatic lipase activity to nutrition and weight management, the present review aims to assess the current body of knowledge with regards to the physiology behind the action of this unique gastrointestinal enzyme system. Existing data would suggest that pancreatic lipase activity is affected by intestinal pH, the presence of colipase and bile salts, but not by the physiological range of Ca ion concentration (as is commonly assumed). The control of secretion of pancreatic lipase and its associated factors appears to be driven by gastrointestinal luminal content, particularly the presence of acid or digested proteins and fats in the duodenal lumen. Secretion of colipase, bile acids and pancreatic lipase is driven by cholecystokinin and secretin release.

Long-term bile diversion enhances basal and duodenal oleate-stimulated pancreatic exocrine secretion in dogs

There have been no previous reports whether long-term bile diversion enhances pancreatic exocrine secretion. The aim of this study was to elucidate the effect of long-term bile diversion on pancreatic exocrine secretion. Four mongrel dogs were prepared for chronic gastric and pancreatic fistulas and received intraduodenal sodium oleate infusion (controls). These dogs, then underwent diversion of bile from the intestines by ligating the common bile duct and interposing a segment of jejunum between the gallbladder and the urinary bladder (total biliary diversion [TBD]). After three weeks, the dogs received an identical sodium oleate infusion. TBD augmented basal pancreatic exocrine secretion compared with controls (4.4-fold increase in basal flow volume; 9.0-fold increase in bicarbonate output; and 3.3-fold increase in protein output). Likewise, TBD augmented oleate-stimulated exocrine secretion (2.0-fold increase in cumulative flow volume; 2.6-fold increase in bicarbonate output; and 1.4-fold increase in protein output). TBD also augmented basal and oleate-stimulated plasma cholecystokinin levels. Administration of a Cholecystokinin-A receptor antagonist (loxiglumide) after TBD reduced the flow volume and bicarbonate output to the control levels, and the protein output to less than a half of the control level. Long-term bile diversion enhances basal and oleate-stimulated pancreatic exocrine secretion, at least partly via increased cholecystokinin secretion.