The influence of bile acids on biliary excretion of indocyanine green in rats of different ages.

In rats of different ages bile flow and biliary excretion of indocyanine green (ICG) were estimated in dependence on bile acid excretion. In 20, 30, 60 and 180 day old rats bile acid excretion was diminished to a quarter of the control by pretreatment with cholestyramine (1.5 g/kg b.wt.). To enhance bile acid excretion, taurocholate sodium (TC, 50 mg/kg b.wt.) was given together with the dye. Bile acid depletion diminished the bile flow to a greater extent in young rats, which were found to have a higher bile acid dependent fraction of canalicular bile flow (60%) compared to 60 (35%) and 180 day old rats (20%). After bile acid depletion the decrease in ICG excretion was more pronounced in 30 and 60 day old rats which exhibit highest dye excretion rates. TC was able to enhance the bile flow in all age groups investigated, however, the ICG excretion was enhanced only in adult animals. Our results indicate that the bile acid dependence of the hepatobiliary transport of ICG is influenced by age.