Hamster hepatocytes in culture as a model for acetaminophen toxicity studies with inhibitors of drug metabolism.

A hamster hepatocyte system was developed for use in studying the toxicity of acetaminophen (APAP). The cells were isolated and placed in culture conditions in petri dishes containing a film of collagen. Hepatocytes, after attachment to collagen, were exposed for various periods of time to different concentrations of APAP. Hepatocytes exposed to APAP exhibited concentration- and time-dependent GSH depletion followed by cytoplasmic enzyme leakage and an increase in malondialdehyde content (TBA-reactive material). These effects were reduced by the drug metabolism inhibitors metyrapone, piperonyl butoxide, and dithiocarb. Removal of APAP and its unbound metabolites from cells prior to 1.5 hr followed by culture in drug-free medium resulted in no observable damage to the cells over a 24-hr period. Removal of drug after longer exposure times followed by culture in fresh medium resulted in eventual cell damage. This finding showed that deleterious changes caused by APAP occurred over a 1.5-hr period after which eventual hepatocyte damage could not be reversed by removal of the drug. Further experiments showed that metyrapone and dithiocarb had some protective effect when added after APAP had been completely removed from damaged cells. This result indicates that these agents have a protective action separate from, and in addition to, their ability to inhibit APAP oxidation via cytochromes P-450.