title: Placental transfer of benzo(a)pyrene and its hydrophilic metabolites in the guinea pig.
abstract: The placental transfer of benzo(a)pyrene, (BP) and its hydrophilic metabolites, (mBP) have been studied in the guinea pig by a placental perfusion technique during constant infusion of BP to the dam. In connection with stop of infusion, blood samples were withdrawn from intact foetuses remaining in utero via the umbilical vein. The placental transfer rate of BP is faster compared with that of mBP when heparinized blood from adult guinea pigs is used as perfusion media. Transfer rate was essentially the same when heparinized blood from foetuses was used instead of blood from adults. With a dextran solution as perfusion media no transfer of BP or mBP could be seen. With albumin solutions of different concentrations only negligible amounts of BP or mBP penetrated the placenta. The concentration of BP in perfusion plasma was significantly higher than that in the foetal plasma, contrary to the concentration of mBP which is significantly lower in perfusion plasma than in foetal plasma. It is concluded that in late gestation the foetal exposure for mBP is due more to the foetal metabolic conversion of BP than to the foetal exposure of mBP produced by maternal enzymatic activity.
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006168:Guinea Pigs; D008431:Maternal-Fetal Exchange; D008657:Metabolic Clearance Rate; D010477:Perfusion; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D001564:Benzo(a)pyrene