Induction of DNA repair in human and rat hepatocytes by 1,6-dinitropyrene.

1,6-Dinitropyrene (DNP) was found to be an extremely potent genotoxicant in metabolically competent primary cultures of human and rat hepatocytes. Dose-dependent increases in DNA repair as measured by unscheduled DNA synthesis (UDS) were observed in the range from 0.05 to 5 microM 1,6-DNP for both species, indicating that the rat-hepatocyte assay is an appropriate model for assessing genotoxic potential in human hepatocytes for this class of compound. Unlike some nitroaromatic compounds, 1,6-DNP did not require gut flora for metabolic activation. No DNA repair was observed in hepatocytes isolated from rats treated with 50 mg/kg 1,6-DNP in corn oil by gavage 2, 12 or 24 h previously. The reason for the lack of a response in vivo is not known, but may relate to detoxification or distribution of the compound in the animal.