LITHOCHOLATE-3-O-GLUCURONIDE-INDUCED CHOLESTASIS - A STUDY WITH CONGENITAL HYPERBILIRUBINEMIC RATS AND EFFECTS OF URSODEOXYCHOLATE CONJUGATES

The mechanism of lithocholate-3-O-glucuronide-induced cholestasis is unknown. In this study, we investigated the cholestatic effects of this agent in a congenital hyperbilirubinemic rat, EHBR. We also studied the effects of ursodeoxycholate-3-O-glucuronide and tauroursodeoxycholate on lithocholate-3-O-glucuronide-induced cholestasis ia rats. Lithocholate-3-O-glucuronide, administered at the rate of 0.1 mumol/min/100 g for 40 min, a cholestatic dose in control rats, failed to cause cholestasis in EHBR, and biliary lithocholate-3-O-glucuronide excretion was delayed. Biliary concentrations of this agent did not correlate with the severity of cholestasis. Both tauroursodeaxycholate and ursodeoxycholate-3-O-glucuronide, infused at the rate of 0.2 mumol/min/100 g for 120 min, completely inhibited cholestasis induced by lithocholate-3-O-glucuronide administered at the rate of 0.1 mumol/min/100 g for 40 min. Only tauroursodeoxycholate enhanced biliary lithocholate-3-O-glucuronide excretion. These findings indicate that lithocholate-3-O-glucuronide-induced cholestasis is induced by damage at the level of the bile canalicular membrane. Ursodeoxycholate-3-O-glucuronide inhibits this cholestasis, possibly by inhibiting the access of lithocholate-3-O-glucuronide to the bile canalicular membrane.