Effect of sulfobromophthalein on biliary excretion of taurocholate and pravastatin in bile duct-ligated rat

Recent studies indicated that bile duct ligation down-regulates the expression of Na⁺/taurocholate cotransporting polypeptide and Na⁺-dependent taurocholate uptake by basolateral membrane vesicles in the rat. These findings suggest that hepatic taurocholate uptake in bile duct-ligated rats is mediated by the organic anion transporting polypeptide, a Na⁺-independent taurocholate uptake system which is common for sulfobromophthalein uptake. Therefore, the effect of sulfobromophthalein on biliary excretion of taurocholate and pravastatin in bile ductligated rats was studied. Although biliary excretion of pravastatin was markedly inhibited by sulfobromophthalein, biliary taurocholate excretion was not affected by sulfobromophthalein in bile duct-ligated rats. The excretory maximum of sulfobromophthalein in bile duct-ligated rats was reduced to one-fifth of control rats. These findings indicate that, in the bile duct-ligated rats, taurocholate uptake is mediated not by the multispecific organic anion transporter, but by other uptake system(s).