Comparison of S9 fractions from rats, mice, and Chinese hamsters to metabolize dimethylnitrosamine and diethylnitrosamine to intermediates that induce sister-chromatid exchanges in V79 cells.

This study was designed to compare the ability of hepatic S9 preparations from rats, mice and Chinese hamsters to activate dimethylnitrosamine (DMN) and diethylnitrosamine (DEN) into intermediates capable of causing sister-chromatid exchanges (SCEs) in V79 cells. The results indicated that the hepatic preparations from the species studied differed in their ability to activate DMN while in the case of DEN no species difference in bioactivation was observed. For DMN, a dose-dependent increase of SCEs was seen in cultures treated with various concentrations plus rat, mouse or hamster S9 mix and the mouse S9 mix was the most effective activator of DMN and this was followed by the rat and Chinese hamster S9 mix with little difference noted for the latter 2 species. For DEN, an increase of SCE was seen in cultures treated with various doses plus S9 mix from any of the species studied but unlike DMN, the SCE rate did not increase in a significant dose-dependent manner and no species difference in bioactivation was observed.