Expression of xenobiotic-metabolizing enzymes in propagatable cell cultures and induction of micronuclei by 13 compounds

Activities of various xenobiotic-metabolizing enzymes were determined in 18 cell lines. Activities of cytochrome P450 reductase, microsomal epoxide hydrolase and glutathione transferase were detectable in all lines. The highest values were similar to the activities found in freshly isolated rat hepatocytes. Catalase activity was also present in all 12 investigated cell lines. Activity of UDP-glucuronosyl transferase was high in some lines, but low or undetectable in others. Activity of cytosolk epoxide hydrolase was not measurable in most lines, and was low in the others. Metabolism of benzo[a]pyrene was observed in eight out of nine examined lines, no activity being found in V79 cells. V79 and three epithelial cell lines were then used as target cells in a genotoxicity assay in which the frequency of micro-nucleated cells was determined. In V79 cells, 7,12-dimethyl-benz[a]anthracene, benzo[a]pyrene, benzo[a]pyrene-*rcins-7,8-dihydrodiol, aflatoxin Bj, iV-nitrosomorpholine and 2-acetylaminofluorene showed negative responses, wherea