title: Effect of smoking on benzo(a)pyrene metabolism by human placental microsomes.
abstract: Placentas were collected at term from a series of 21 women. Thirteen were smokers, and eight were nonsmokers. Microsomes were prepared and used in the following studies of benzo(a)pyrene metabolism: aryl hydrocarbon, hydroxylase, epoxide hydrase, high-pressure liquid chromatographic analysis of benzo(a)pyrene metabolites, and DNA binding. DNA-binding adducts were further characterized by Sephadex LH-20 chromatography. Aryl hydrocarbon hydroxylase activity was much higher in smokers than in nonsmokers. Epoxide hydrase activity with styrene oxide as the substrate showed no difference between smokers and nonsmokers. High-pressure liquid chromatographic analysis showed much greater formation of dihydrodiols, quinones, and phenols by microsomes from smokers. The amount of benzo(a)pyrene-7,8-dihydrodiol was almost equal to the amount of phenols produced by the microsomes of the smokers. Sephadex LH-20 analysis of DNA binding resulted in only one major benzo(a)pyrene-DNA adduct when microsomes from smokers were used; this peak corresponds to benzo(a)pyrene 7,8-diol-9, 10-oxide bound to DNA nucleoside(s).
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001580:Benzopyrenes / Q000378:metabolism*; D001711:Biotransformation; D004247:DNA / Q000378:metabolism; D004851:Epoxide Hydrolases / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008861:Microsomes / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000378:metabolism*; D012907:Smoking / Q000150:complications / Q000503:physiopathology*
chemical_list: D001580:Benzopyrenes; D004247:DNA; D001189:Aryl Hydrocarbon Hydroxylases; D004851:Epoxide Hydrolases