SENSITIVE HEPATOCYTE-MEDIATED ASSAY FOR THE METABOLISM OF NITROSAMINES TO MUTAGENS FOR MAMMALIAN-CELLS

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 40  (2) , 406-411
Abstract
A sensitive cell-mediated assay was developed for testing mutagenesis in Chinese hamster V79 cells by carcinogenic nitrosamines. Mutations were characterized by resistance to ouabain and 6-thioguanine. Since V79 cells do not metabolize nitrosamines, mutagenesis in the V79 cells was tested in the presence of primary hepatocytes capable of metabolizing nitrosamines. The hepatocytes were isolated after collagenase and hyaluronidase digestion of liver slices. All 7 liver carcinogens of the 9 tested nitrosamines exhibited a mutagenic response in this cell-mediated assay. The potent liver carcinogens nitrosodimethylamine, nitrosodiethylamine, nitrosoethylmethylamine and nitrosodipropylamine could be detected with doses as low as 1 .mu.M. The noncarcinogenic nitrosodiphenylamine was not mutagenic. Nitrosomethoxymethylamine was the only nitrosamine that exhibited mutagenic activity in the absence of hepatocytes and this activity was diminished in the presence of hepatocytes. The use of hepatocytes prepared by the slicing method for carcinogen metabolism and mutable V79 cells offers a highly sensitive assay for determining the mutagenic potential of carcinogenic nitrosamines and probably of other classes of hazardous chemicals occurring in the environment.

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