DIMETHYLNITROSAMINE GENOTOXICITY - DOES N-ACETYLTRANSFERASE ACTIVITY PLAY A ROLE

Dimethylnitrosamine (DMN) genotoxicity was evaluated in two test syste ms: induction of the umu operon (as measured by expression of a lacZ g ene fusion) and mutagenicity (as measured by the Ames assay). Three Sa lmonella typhimurium strains were used; the strains differ in the leve l of expression of the enzyme acetyl CoA:arylamine N-acetyltransferase (NAT). We did not observe increased sensitivity in a strain ,vith a p lasmid-borne copy of the nat gene, and expressing very high levels of NAT activity. In contrast to a recent report, we conclude that NAT-dep endent metabolic activation does not play a major role in the genotoxi city of this carcinogenic nitrosamine.