title: Relative distribution of estrone, estradiol and estriol between fetal and maternal perfusates during perfusions of human term placentas with labelled C19 precursors.
abstract: Published results from in vivo experiments carried out in Rhesus monkeys and from in vitro perfusions of human term placentas have indicated that placental estradiol (E2) is preferentially released towards the mother whereas estrone (E1) is about evenly distributed between fetal and maternal circulation. In order to examine the distribution of estriol, relative to that of E1 and E2, we have now prepared [3H]16-hydroxyandrostenedione by incubation of [6,7-3H]androstenedione with Streptomyces roseochromogenus and perfused placental cotyledons with mixtures of these two labeled precursors. Measurement of the concentrations of tritiated E1, E2 and E3 in the maternal and fetal perfusates, flowing at approx 10 and 5 ml/min, respectively, indicated that the distribution of E3 is different from that of E2 and resembles the distribution of E1. The simple perfusion system being used shows differences in the distribution of various estrogens between fetal and maternal perfusates which may reflect the in vivo situation and offers the opportunity for experimental examination of various explanations for these differences, e.g. existence of specific carrier systems in the syncytial membranes, specific binding of the estrogens to secreted placental proteins, and actions of placental and decidual 17 beta-hydroxysteroid dehydrogenases.
mesh_terms: D000735:Androstenedione / Q000031:analogs & derivatives / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D004964:Estriol / Q000378:metabolism*; D004970:Estrone / Q000378:metabolism*; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D010477:Perfusion; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D004970:Estrone; D000735:Androstenedione; D004997:Ethinyl Estradiol; D004958:Estradiol; C018202:16-hydroxyandrost-4-en-3,17-dione; D004964:Estriol