Role of Bile Acids in Duodenal Migrating Motor Complexes in Dogs

Previous studies have suggested thatenterohepatic circulation of bile acids is essential forregular cycling of duodenal migrating motor complexes(MMCs). The present study was an attempt to clarify the role of bile acids in the enterohepaticcirculation system in initiating duodenal MMCs. Sevendogs underwent total external biliary diversion thatresulted in the loss of MMCs originating from theduodenum. Sodium ursodeoxycholate (6 mg/kg/hr) was thengiven either through the portal vein or a peripheralvein, and motility of the gastrointestinal tract wasserially recorded. When sodium ursodeoxycholate was given either through the portal vein or aperipheral vein during external biliary diversion,duodenal MMCs restarted. The cyclic change in plasmamotilin levels during an MMC cycle as induced by sodium ursodeoxycholate was almost the same as in anormal MMC cycle. Total bile acid concentration in theportal vein changed cyclically with MMC cycles when bileflow was intact but did not change cyclically with MMC cycles restarted by intravenous bilesalt infusion. Bile acid stimulation of putativereceptors existing between the portal vein andintrahepatic bile ducts may be involved in initiatingnormal duodenal MMC cycles.