Biliary excretion of fluorescent cholephiles in hepatocyte couplets: An in vitro model for hepatobiliary and hepatotoxicity studies.

Hepatocyte couplets (26.8% of cell preparation with >85% viability) were prepared from rat livers. The preparation maintained the activity of 7-ethoxycoumarin-O-deethylase throughout an 8-hr incubation. Couplets extensively secreted the fluorescent cholephiles, fluorescein and cholyl-lysyl-fluorescein isothiocyanate, into sealed canalicular spaces within 2 hr and 15-30 min, respectively, which is indicative of functional tight junctions. The time scale for biliary secretion of the cholephiles correlated well with the relative kinetics of biliary excretion reported in vivo. Hepatocyte couplets may prove useful for studies on toxicity directed towards the hepatobiliary system.