In vivo rat liver studies

In vivo biliary efflux experiments are performed on male Wistar rats (250 - 300 g) kept under standard laboratory conditions. All procedures are approved by the Institutional Animal Care and Use Committee. Before starting the experiments, the animals are fasted overnight, but are allowed free access to water. Under urethane anesthesia (1 g/kg i.p.) the common bile duct is cannulated with PE-10 tubing after laparotomy. 2 ml of saline solution is administered sc. in every hour to maintain liquid equilibrium of rats. Treatment of rats is started after 30 min of surgery. Tracer doses of ³H-Estradiol-17-b-D-glucuronide, ³H-Taurocholate, ³H-Estrone-3-sulfate, probe substrates for Mrp2, Bsep and Bcrp, respectively are coadministered with the test compounds i.p. Control rats receive the probe substrates and the vehicle only. Bile samples are collected, weighted and analyzed by liquid scintillation. Interactions with the transport proteins are determined from the altered biliary elimination of the probe substrates.