In vitro metabolic activation of chemical mutagens. I. Development of an in vitro mutagenicity assay using liver microsomal enzymes for the activation of dimethylnitrosamine to a mutagen.

Qualitative and quantitative assays were developed to study the in vitro enzymatic activation of dimethylnitrosamine (DMNA) to its mutagenic form. Three different fractions from mouse liver homogenates, including purified microsomes, were employed for the activation, and several parameters of the assays were investigated. Qualitative tests were conducted to measure the ability of hepatic enzymes obtained from six mammalian species to activate DMNA. A comparison between two inbred mouse strains using the in vitro activation assay demonstrated that this technique might be a useful tool in quantitatively measuring differences in genetically influenced levels of DMNA metabolism in individuals animals and their tissues.