The in vitro metabolic activation of dibenz[a,h]anthracene, catalyzed by rat liver microsomes and examined by 32P-postlabelling

DNA has been incubated in vitro with dibenz[a,h]anthracene (DB[a,h]A) and the related 5,6-diol and 3,4-diol in the presence of 3-methylcholanthrene- or Aroclor 1254-induced rat liver microsomes. After incubation, the DNA was extracted and examined for the presence of aromatic adducts using the nuclease P1 modification of the P-32-postlabelling technique. The maps of PEI-cellulose plates and autoradiography showed that 92 % of the radioactivity contained in DB[a,h]A-DNA adduct spots is derived from the related 3,4-diol and that about 50 % of the adducts may be formed following the conversion of this diol to the bay-region anti- and syn-3,4-diol 1,2-oxides.