Relative sensitivity of 32P-postlabelling of DNA and the autoradiographic UDS assay in the liver of mice exposed to 2-acetylaminofluorene (2AAF).

In contrast to earlier studies conducted at lower dose levels, 2AAF is shown to induce a positive UDS response in the liver of mice dosed orally at dose levels between 500 and 1000 mg/kg. Similarly exposed mice had low levels of 2AAF-related hepatic DNA adducts at dose levels in the range 10-1000 mg/kg 2AAF, as determined by 32P-postlabelling analysis. It is concluded that the attenuated UDS response observed in the mouse liver, as compared to the rat liver, is due primarily to metabolic differences between these two species, coupled to a reduced capacity for UDS in the mouse liver for a given level of total 2AAF-related adducts per unit of DNA. These observations are compared and contrasted with identical studies conducted in the rat and reported in the preceding paper (Gallagher et al., 1991).