The interaction of rifamycin SV with hepatic transport of taurocholic acid in the isolated perfused rat liver.

The effect of rifamycin SV on hepatic transport of taurocholic acid was investigated using isolated perfused rat liver technique. In all experiments, the perfused liver was maintained at taurocholic acid steady state by infusing constant amount of taurocholic acid. Infusion of rifamycin SV at various rates decreased biliary secretion of bile acids in a dose-dependent manner. Replacement of rifamycin SV by perfusion medium reversed this effect. To determine the site of action of rifamycin SV, kinetic experiments with 14C-taurocholic acid were undertaken. Rifamycin SV elevated the half-life of the medium disappearance of 14C-taurocholic acid. Furthermore, the antibiotic delayed the biliary appearance of 14C-taurocholic acid. The analysis of the results gave indications that the antibiotic interferred with hepatic uptake as well as biliary secretion of taurocholic acid.