The effect of the co-infusion of ursodeoxycholate and its
taurine conjugate, 3-O-glucuronide and 3,7-disulfate on
estradiol-17 beta-glucuronide-induced
cholestasis was examined.
Estradiol-17 beta-glucuronide was intravenously administered to bile-drained rats at a rate of 0.075 mumol/min/100 g for 20 min. Co-infusion of ursodeoxycholate and its conjugates was simultaneously begun at a rate of 0.2 mumol/min/100 g and continued for 120 min. Ursodeoxycholate failed to improve and
tauroursodeoxycholate only partially improved
estradiol-17 beta-glucuronide-induced
cholestasis between 20 and 40 min, although both
bile acids increased bile flow after 80 min.
Tauroursodeoxycholate increased biliary
estradiol-17 beta-glucuronide excretion.
Ursodeoxycholate-3-O-glucuronide completely inhibited
cholestasis induced by
estradiol-17 beta-glucuronide without changing biliary
estradiol-17 beta-glucuronide excretion. Although ursodeoxycholate-3,7-disulfate had only a minor effect on
cholestasis, it increased biliary excretion of
estradiol-17 beta-glucuronide. In the Eizai hyperbilirubinuria rat (EHBR), a hyperbilirubinemic mutant Sprague-Dawley rat, the same dose of
estradiol-17 beta-glucuronide failed to induce
cholestasis with a marked delay in biliary excretion of
estradiol-17 beta-glucuronide. In summary,
ursodeoxycholate-3-O-glucuronide is more effective than
tauroursodeoxycholate in inhibiting
estradiol-17 beta-glucuronide-induced
cholestasis and ursodoexycholate-3,7-disulfate had little effect. However, the unexpected effects of
ursodeoxycholate-3-O-glucuronide and 3,7-disulfate on excretion of
estradiol-17 beta-glucuronide suggest that the interaction of these
anions at the canalicular membrane is complicated, with interaction occurring at more than two pathways of the biliary excretion of these
anions.