title: Comparison of the hydroxylation of zoxazolamine and benzo[a]pyrene in human placenta: effect of cigarette smoking.
abstract: The in vitro hydroxylation of zoxazolamine was compared with the hydroxylation of benzo[a]pyrene (BP) in full-term placentas from 11 nonsmokers and from 13 women who smoked cigarettes during pregnancy. Cigarette smoking increased the average zoxazolamine and benzo[a]pyrene hydroxylase activities 13- and 39-fold, respectively. A 59-fold range in benzo[a]pyrene hydroxylase activity and a 28-fold range in zoxazolamine hydroxylase activity were found in the placentas of cigarette smokers. A plot of these two enzyme activities showed that zoxazolamine hydroxylase activity was highly correlated, with benzo[a]pyrene hydroxylase activity in the 24 placentas studied (r = 0.98; p less than 0.001). A strong correlation between the above enzymatic activities was also found in 8 placentas which had been stored for 2 yr at -20 degrees C (r = 0.95; p less than 0.001). The results suggest that benzo[a]pyrene and zoxazolamine are metabolized in the human placenta by the same enzyme or by different systems that are under the same regulatory control.
mesh_terms: D001579:Benzopyrene Hydroxylase / Q000378:metabolism; D001580:Benzopyrenes / Q000378:metabolism*; D005260:Female; D005615:Freezing; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D007700:Kinetics; D006899:Mixed Function Oxygenases / Q000378:metabolism; D009926:Organ Preservation; D010920:Placenta / Q000201:enzymology / Q000378:metabolism*; D011247:Pregnancy; D012907:Smoking / Q000503:physiopathology*; D015049:Zoxazolamine / Q000378:metabolism*
chemical_list: D001580:Benzopyrenes; D015049:Zoxazolamine; D006899:Mixed Function Oxygenases; D001579:Benzopyrene Hydroxylase