Cytotoxicity of xenobiotics in adult rat hepatocytes in primary culture.

Primary cultures of hepatocytes isolated by collangenase perfusion of adult rats were used as an in vitro system for assessing cytotoxicity of xenobiotics. The leakage of two intracellular enzymes, lactate dehydrogenase (LDH) and glutamic oxaloacetic transaminase (GOT) were compared as indicators of cell damage. Although some differences in sensitivity were detected, either enzyme could be used to evaluate the cytotoxic potential of a chemical. Release of LDH was also compared with determination of cell viability by trypan blue uptake. For cultures exposed to 2-aminofluorene or alpha-naphthylisothiocyanate both endpoints gave comparable results. The cytotoxicities of benzo(a)pyrene, 2-aminofluorene, 3,2'-dimethyl-4-aminobiphenyl, methylene-bis-2-chloroaniline, aflatoxin B1, pyrene, aflatoxin G2, fluorene, methapyrilene, and alpha-naphthylisothiocyanate were monitored by the release of LDH and were found to be related to the length of exposure and concentration of the chemical. For chemicals that elicited DNA repair, little or no cytoxicity was observed at genotoxic concentrations in the hepatocyte primary culture/DNA repair test. Thus, measurement of enzyme release provides a means of quantifying cytotoxicity. Moreover, the use of hepatocyte primary cultures permits identification of genotoxic effects versus general cytotoxic effects of chemicals.