Duodenal mucosal bicarbonate secretion in pigs is accompanied by compensatory changes in pancreatic and biliary HCO₃^- secretion

Background: The purpose of the study was to examine the effect of stimulation and inhibition of duodenal mucosal bicarbonate secretion on pancreatic and hepatic bicarbonate secretion in response to acid. Methods: The effect of inhibition (indomethacin) or stimulation (misoprostol) of duodenal mucosal bicarbonate secretion on pancreatic and biliary bicarbonate secretion in response to intraduodenal infusion of HCl or intravenous infusion of secretin was studied in anaesthetized pigs. Results: The hepatic and pancreatic response to exogenous secretin was not significantly altered by stimulation/ inhibition of duodenal bicarbonate secretion. However, pancreatic and biliary bicarbonate secretion in response to duodenal acidification was significantly augmented by inhibition of duodenal mucosal bicarbonate secretion; conversely, it was reduced by stimulation of duodenal bicarbonate secretion. The increase in plasma secretin levels in response to duodenal acidification was reduced by stimulation and augmented by inhibition of duodenal mucosal bicarbonate secretion. Conclusions: Duodenal mucosal bicarbonate secretion can serve as a modulator of both pancreatic and biliary bicarbonate secretion in response to luminal acidification, possibly through regulation of the release of secretin.