HUMAN PLACENTAL NOREPINEPHRINE TRANSPORTER MESSENGER-RNA - EXPRESSIONAND CORRELATION WITH FETAL CONDITION AT BIRTH

The purpose of this study was to determine the primary form of human p lacental norepinephrine transporter (hNET) mRNA expressed in the human placenta and to compare the level of expression in normal pregnancies and in pregnancies complicated by drug exposure or other forms of phy siological derangement. We used the hNET cDNA to measure RNA extracted from placenta and examined placental RNA following complicated and un complicated pregnancies. To compare transporter expression and its rel ation to fetal condition at birth, umbilical arterial plasma catechola mine levels, umbilical arterial blood gases and placental transporter mRNA level were compared by linear regression analysis. Uncomplicated pregnancies had a higher level of placental norepinephrine transporter mRNA than complicated pregnancies. An inverse relationship between um bilical cord norepinephrine level and transporter expression was demon strated. We conclude that placental transporter expression represents an important and newly described metabolic function of the placenta. P lacental catecholamine clearance mediated via the placental NET may be important in the pathophysiology of disorders associated with placent al dysfunction, impaired placental blood flow or intrauterine growth r etardation. This may also explain the adverse effects of drugs, such a s cocaine, which block catecholamine transport. (C) 1997 W. B. Saunder s Company Ltd.