Gastroduodenal regulation of common duct bile flow in the dog

We investigated the relationship between the entry of individual drops of bile into the duodenum and gastroduodenal motor activity in the fasted state in 10 conscious dogs. The common bile duct was transected and a catheter was inserted through each end. The exteriorized catheters were connected to a photometric drop-flow meter. During phase III activity, bile entered the duodenum in single drops, only in between two consecutive contractions, or as a series of drops during transient inhibition of duodenal contractions by antral phase III contractions. During phase II activity bile also entered the duodenum, usually in between contractions or when the duodenum was intermittently quiescent. Bile entered the duodenum during a duodenal contraction only when the contraction amplitude was < 15% ± 1% (mean ± SE) of the maximal amplitude during phase III contractions. Bile flow into the duodenum showed a cyclic pattern with a peak during late duodenal phase II activity and a trough during duodenal phase I activity only when phase III activity originated in the duodenum and migrated caudad. There was no cyclic pattern of bile flow when phase III activity originated in the proximal jejunum and migrated caudad. The total volume of bile flow in a migrating motor complex cycle and bile flow rate were greater when phase III activity started in the proximal jejunum than when it started in the duodenum. We conclude that gastroduodenal contractions play an important role in the regulation of bile flow into the duodenum. The cyclic pattern of bile flow is altered when phase III activity starts ectopically in the jejunum.