Hepatic clearance and biliary secretory rate maximum of taurocholate in the recirculating and single pass isolated perfused rat liver. Effects of the cholestatic agent, estradiol-17 beta-(beta-D-glucuronide).

The ability of the cholestatic steroid glucuronide, estradiol-17 beta-(beta-D-glucuronide) (E(2)17G), to inhibit the hepatic clearance (ClH) and biliary secretory rate maximum (SRm) of taurocholate was investigated in the recirculating and single pass isolated perfused male rat liver. In the recirculating perfused liver, E(2)17G (0, 2, 4, or 6 mumol) was added as a bolus dose to the reservoir at zero time while taurocholate was infused into the portal vein in increasing amounts (15, 30, 45, or 60 mumol/mL; 1 mL/hr for 15 min each). E(2)17G (4 mumol) caused a significant (P less than 0.05) inhibition of bile flow and bile acid secretion at 10-15 min during infusion of 15 mumol/hr taurocholate but did not inhibit the SRm which occurred at 42 min, indicating that E(2)17G had not caused an irreversible inhibition of taurocholate transport. E(2)17G (6 mumol) caused a profound and irreversible inhibition of bile flow attributable to retention of E(2)17G in the liver. The noncholestatic estradiol-3-(beta-D-glucuronide) (E(2)3G; 6 mumol) had no significant effect on bile flow or the SRm. In the single pass perfused liver (10 mL/min flow rate), E(2)17G (0, 1, 2, 5, or 10 nmol/mL) or E(2)3G (2 nmol/mL) was added to the perfusate resulting in a stable infusion to the liver. [3H]Taurocholate was infused into the portal vein in increasing amounts to give inflow concentrations (Cin) of 25, 50, 75 or 100 nmol/mL. In the absence of E(2)17G, taurocholate ClH decreased from 0.92 to 0.70 mL/min/g liver with increasing taurocholate concentrations. Neither E(2)17G nor E(2)3G altered the ClH of 25 nmol/mL taurocholate. E(2)17G (10 nmol/mL) inhibited bile flow and bile acid secretion first at 20-25 min, followed by inhibition of ClH of 75 and 100 nmol/mL taurocholate (35-60 min). In contrast, E(2)3G stimulated bile acid secretion and increased the SRm by 80%. Thus, at doses that did not block its own elimination, E(2)17G did not cause an irreversible inhibition of taurocholate transport into bile. E(2)17G did not directly inhibit the uptake of taurocholate into the liver but first inhibited the biliary excretion of taurocholate, resulting in its intrahepatic accumulation and decreased clearance from the perfusate.