Fasting and postprandial hepatic bile flow in unanesthetized opossums

In conscious opossums, we evaluated the relationship between hepatic bile flow and the intestinal motor function during fasting as well as after feeding. In six opossums, bipolar electrodes were implanted from the gastric antrum to the terminal ileum. After cholecystectomy, the common duct was ligated, and a catheter was tied into the proximal common duct for collecting hepatic bile. During subsequent studies, hepatic bile flow was measured, and bile was returned to the duodenum through an externalized duodenal catheter. Cyclic increases in bile flow during fasting did not show a close correlate with the duodenal migratory motor complex (MMC) cycle. Rather, bile flow showed peak values [0.11 +/- 0.02 (SE) ml/min] when phase III MMC activity reached the midileum. Hepatic bile flow correlated closely with the amount of bile acid secreted by the liver. When the bile acid pool was depleted by diverting bile from the intestine, hepatic secretion of bile fell to uniformly low values of approximately 0.04 ml/min that did not show cyclic variation. Hepatic bile flow after feeding increased to a maximal value of 0.12 +/- 0.01 ml/min at 90 min. We conclude that increases in hepatic bile flow during fasting and after meals are determined mainly by variations in intestinal motor activity that alter small bowel transit and thereby affect the enterohepatic circulation of bile acids.