Fasting canine biliary secretion and the sphincter of Oddi

This study correlates duodenal bile acid delivery with motility of the sphincter of Oddi during the fasting state. Dogs were prepared with a functional cholecystectomy, a duodenal cannula for direct vision cannulation of the common bile duct, and 12 bipolar electrodes serosally implanted from stomach to terminal ileum. In one set of experiments, the bile acid pool was depleted, and during a continuous i.v. infusion of sodium taurocholate (20 mumol/min), duodenal bile acid delivery was assessed over 6 h by a marker perfusion technique. In other experiments, a double-lumen continuously perfused manometry catheter was placed to record motility in the bile duct and sphincter of Oddi for a period of 6 h. Station pull-throughs of the sphincter of Oddi were performed in each phase of the migrating motor complex. Bile acid secretion rates fluctuated about the i.v. infusion rate during duodenal phase I and II, peaked in late phase II, and then fell to barely detectable levels during duodenal phase III. There was no peristaltic contractile activity in the common bile duct in any phase of the migrating motor complex. The sphincter of Oddi maintained a baseline pressure above common bile duct pressure. It was highest during phase III. Phasic contractions of the sphincter of Oddi were intermittent during phase I, increasingly frequent during phase II, and continuous during duodenal phase III of the migrating motor complex. Contractions were frequently peristaltic. We concluded that the occurrence and amplitude of phasic peristaltic contractions of the sphincter of Oddi are cyclically coordinated with the fasting intestinal motor pattern (migrating motor complex), and with cyclical variations in the delivery of bile acids into the duodenum. Both resting pressure and phasic contractions of the sphincter appear to play a role in coordinating the cyclic delivery of bile acids into the duodenum with the migrating motor complex. Intense phasic motor activity appears to impede bile flow, and less intense activity allows or facilitates flow.