Studies of small intestinal and pancreatic function following experimental exocrine pancreatic insufficiency in the dog.

The pathogenesis of pancreatic dysfunction and intestinal changes commonly observed in dogs with chronic diarrhoeal disorders is incompletely understood. the present study was therefore undertaken to examine the effects of experimentally induced exocrine pancreatic insufficiency (EPI) on small intestinal and pancreatic function. Four models of EPI were created surgically to assess the effects of EPI on the structure and biochemistry of the jejunal mucosa, the small intestinal bacterial flora, the absorption of cobalamin, folate and xylose, and their reversibility by canine pancreatic secretion or exogenous pancreatic enzymes. The effects of the surgical procedures on pancreatic exocrine and endocrine function were also monitored and a comparison made of two indirect tests of pancreatic function. EPI was followed by an increase in the proportion of microvillar proteins of high molecular weight, a reduction in the specific activities of lactase, catalase and Tris-resistant a-glucosidase, alterations in bacterial flora, a decrease in cobalamin absorption and an increase in folate absorption. Treatment with pancreatic enzymes, largely reversed the biochemical and bacterial changes but did not reverse structural changes or affect cobalamin and folate absorption. Intraduodenal and oral administration of canine pancreatic secretion (shown to contain cobalamin) partially restored cobalamin absorption. Pancreatic duct ligation was followed by parallel increases in plasma amylase, lipase and trypsin-like immunoreactivity (TLI). Pancreatectomy reduced circulating TLI but not amylase and lipase. Significant relations between TLI and pancreatic mass, and between TLI and peak plasma PABA were observed. Pancreatic endocrine function was similarly reduced by partial-pancreatectomy and pancreatic duct ligation. These studies confirm that EPI affects intestinal function and suggest that mucosal changes are due to the absence of pancreatic secretion and to an increase in intestinal bacteria. The pancreas may also have an important role in the turnover and absorption of cobalamin. Finally TLI is a precise indicator of exocrine pancreatic function.