Effect of sodium taurocholate on the hepatic transport of bromsulphthalein in rats.

In anaesthetized, bile duct-cannulated rats the hepatic transport of bromsulphthalein (BSP) showed a dose-dependent increase in response to simultaneous administration of taurocholate (TC). The excretion rates of both free (BSP) and conjugated bromsulphthalein (BSP-GSH) were significantly elevated by TC. The simultaneously given TC decreased the hepatic uptake of BSP and BSP-GSH, but did not influence the conjugation of BSP with glutathione (GSH) or the biliary excretion rate of exogenous BSP-GSH. When the liver was depleted of GSH by pretreatment with diethyl-maleate (DEM), TC increased the excretion of free BSP. In DEM-treated rats free BSP markedly depressed the biliary excretion of exogenous BSP-GSH. When TC was given simultaneously with BSP, the inhibitory effect of BSP on the excretion of exogenous BSP-GSH was significantly reduced. TC also diminished the depressing effect of BSP on state III respiration of liver mitochondria in vitro. It is concluded that this effect of TC may play a role also in the increased biliary excretion of intraphepatic conjugated BSP.