title: Transfer and metabolism of norepinephrine studied from maternal-to-fetal and fetal-to-maternal sides in the in vitro perfused human placental lobe.
abstract: An in vitro system for the dual perfusion of an isolated lobe of human placenta was used to study transfer and metabolism of 3H-labeled norepinephrine at two different concentrations. At 39 mumol/L, the transfer of total radioactivity from the maternal to the fetal side was 11.60% +/- 0.60% and significantly higher (p less than 0.05) than that in the opposite direction (6.50% +/- 0.37%). In both directions almost 50% of tritium was transferred as norepinephrine while the rest was metabolized and appeared on the other side as normetanephrine, dihydroxymandelic acid, and vanillylmandelic acid. When a reduced concentration (870 nmol/L) was infused into either the maternal or the fetal compartment, transfer and metabolism were similar to those determined before. Analysis of the tissue showed 50% of total radioactivity as normetanephrine, dihydroxymandelic acid, and vanillylmandelic acid and 17% as conjugates. Inclusion of the monoamine oxidase inhibitor clorgyline in the perfusate significantly reduced fetal-to-maternal transfer but not transfer in the reverse direction. In addition, inhibition of placental monoamine oxidase resulted in a considerable reduction in dihydroxymandelic acid and vanillylmandelic acid while the normetanephrine fraction increased. Norepinephrine significantly increased glucose utilization and lactate production. A possible physiologic role of norepinephrine transferred from the fetal into the maternal circulation during labor is discussed.
mesh_terms: D000983:Antipyrine / Q000378:metabolism; D003010:Clorgyline / Q000494:pharmacology; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008333:Mandelic Acids / Q000378:metabolism; D008431:Maternal-Fetal Exchange; D009638:Norepinephrine / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D014642:Vanilmandelic Acid / Q000378:metabolism
chemical_list: D007773:Lactates; D008333:Mandelic Acids; D011773:Pyruvates; D019344:Lactic Acid; D014642:Vanilmandelic Acid; C000989:3,4-dihydroxymandelic acid; D019289:Pyruvic Acid; D005947:Glucose; D003010:Clorgyline; D000983:Antipyrine; D009638:Norepinephrine