[Bile secretion and motilin and pancreatic polypeptide (PP) release in dogs during infusion of bile acids in the interdigestive period]

Abstract

In 4 dogs functional cholecystectomy was performed, 2 cannulas were inserted into the common bile duct and 9 pairs of the electrodes were implanted in the stomach and small intestine. During chronic experiments exteriorized tubes were disconnected for both monitoring of biliary secretion and intraduodenal infusions of buffer, standard bile, Na-taurocholate, Na-taurodeoxycholate and Na-taurochenodeoxycholate used in 3 various concentrations as well as mixtures of these salts. During other experiments Na-taurocholate was infused intravenously. In the control group biliary tubes were not opened. The interdigestive myoelectric activity was recorded simultaneously and blood samples were taken for motilin and PP radioimmunoassays. Biliary secretion and motilin release were the highest during phase III of the myoelectric cycle. During both bile acid depletion and intravenous infusion no clear fluctuation of biliary secretion was observed. Bile and bile acid infusions resulted in the increased motilin release about 20-50% depending on bile acid concentration and in more than 50% inhibition of PP release. Plasma level of PP fluctuated in relation to the phase of the cycle entirely during bile acid depletion. The results suggest that the regulation of myoelectric cycle by bile acid secretion can be mediated by motilin and PP as well as confirm the important role of small intestine in the modification of PP release.