Examination of 7-ethoxycoumarin deethylation and ammonia removal activities in 31 hepatocyte cell lines.

Aiming the selection of possible candidates for the reactor cells in a hybrid artificial liver, we investigated the activities of 7-ethoxycoumarin deethylation and ammonia removal in 31 hepatocytes cell lines established from the human, rat, mouse, and chicken, compared with freshly isolated rat hepatocytes. Rat liver homogenate and hepatocytes showed 7-ethoxycoumarin deethylation activity of 0.925 and 1.840 nmol/mg protein/min, respectively. Two human hepatoblastoma cell lines, Hep G2 and HuH 6, showed the activity of 0.190 and 0.027 nmol/mg protein/min, respectively. While the rat hepatocytes efficiently removed added ammonia form the culture medium, no ammonia removal activity was detectable in any cell line with the assay conditions in this study. Ammonia removal activity, possibly catalyzed by the urea cycle, is likely to be harder to restore than the drug metabolizing system in the course of cell immortalization.