The effect of complete biliary obstruction on bile flow and bile acid excretion: postcholestatic choleresis in the rat

Bile secretory function was studied in rats subjected to a 7-day obstructive cholestasis induced by complete common duct obstruction. Bile flow and bile acid excretion were examined during bile depletion, following the release of the biliary obstruction, and during the infusion of sodium taurocholate at submaximal and saturating rates. A highly significant increase, greater than 100%, in bile flow was evident in cholestatic rats at any bile acid excretory rate, when compared to control sham-operated rats. 14C-erythritol clearance measurements performed during bile depletion and during the infusion of taurocholate suggest that bile flow was mainly of canalicular origin in cholestatic rats. Estimated taurocholate transport maximum (mumol/min per rat) was not statistically different between cholestatic and control rats. However, significantly greater taurocholate plasma levels at Tm in cholestatic rats suggest a decreased efficiency of the bile acid transport process. In addition, the relationship between bile flow and bile acid excretion was found to be nonlinear at low bile acid excretory rates in cholestatic rats. Thus important changes in bile formation occurred in rats subjected to temporary obstructive cholestatis, which differ from those observed in other models of cholestasis that are associated to a reduction in bile flow and bile acid transport capacity.