Enterohepatic circulation of bile acids in pigs: diurnal pattern and effect of a reentrant biliary fistula.

The present studies were undertaken 1) to assess the quantitative absorption of total bile acids in the portal vein of normally fed, unanesthetized pigs with an intact biliary tract and 2) to evaluate the effect of a chronic reentrant biliary fistula on absorption. In the intact biliary tract group (5 pigs), mean total bile acid concentration averaged 83.9 +/- 2.0 and 15.6 +/- 0.6 microM in portal and arterial blood, respectively, and 216.9 +/- 20.4 mmol of total bile acids were absorbed over 24 h. Time courses of blood concentration and absorption were described all along the light-dark cycle, and hepatic uptake averaged 79.3 +/- 0.5%. A reentrant choledocal fistula in the upper duodenum (5 pigs) did not affect mean daily blood concentrations (87.5 +/- 2.4 and 19.1 +/- 0.8 microM in portal and arterial blood, respectively), daily absorption (226.4 +/- 23.7 mmol, i.e., 93.5% of the daily secretion), or hepatic uptake (76.4 +/- 1.1%), but it did seem to influence the daily kinetics of blood concentration and absorption. These studies supply quantitative and kinetic data about the absorptive stage of the enterohepatic cycle in pigs and show that a bile fistula is suitable for the study of biliary dynamics.