Effect of neural blockades, gastrointestinal regulatory peptides, and diversion of gastroduodenal contents on periodic pancreatic secretion in the preruminant calf

Abstract

The role of nerves, gastrointestinal peptides, and gastroduodenal contents in the regulation of pancreatic periodic function were studied in preruminant calves. Nine male, Friesian calves were surgically fitted with pancreatic and duodenal catheters, abomasal and duodenal cannulae, and duodenal electrodes. Pancreatic secretion oscillated in phase with the duodenal migrating myoelectric complex. Pancreatic secretion and duodenal motility were abolished by intravenous atropine (5 μg∙kg−1∙min−1). The frequency of pancreatic and duodenal cycles was similarly increased by motilin and decreased by pituitary adenylate cyclase activating polypeptide-27; secretin lengthened duodenal but not pancreatic cycles, resulting in loss of synchronization; cholecystokinin-8 and secretin increased pancreatic secretion (all infusions at 120 pmol∙kg−1∙h−1); intraduodenal lidocaine (2%) or diversion of gastroduodenal contents reduced pancreatic secretion without altering periodicity. In conclusion, generation of pancreatic as well as of duodenal periodicity in the calf depends upon cholinergic neural efferent input. Secretin, cholecystokinin-8, pituitary adenylate cyclase activating polypeptide, duodenal contents, and mucosal afferent receptors seem to have relatively minor regulatory roles but can modulate the level of pancreatic secretion. The importance of enteric neural influence from the duodenum and the role of motilin in the regulation of pancreatic periodicity and its synchronization with the duodenal motility cycle remain to be determined.Key words: pancreatic juice, duodenal migrating myoelectric complex, secretin, motilin, pituitary adenylate cyclase activating polypeptide, atropine, lidocaine, calf.