Effects of Nifedipine on Isolated Arteries and Placental Perfusion in the Human Uteroplacental Unit

Abstract

The effects of nifedipine were tested in isolated maternal intramyo-metrial and fetal placental chorionic and stem villous arteries mounted as ring preparations in organ baths. Furthermore, the effects of a single oral dose of nifedipine 20 mg on feto-placental haemodynamics were evaluated by Doppler technique in 14 women with pregnancy-induced hypertension. In maternal intramyometrial arteries, nifedipine inhibited the contractile effects of vasopressin and noradrenaline, and the compound also decreased responses to prostaglandin F_2α in fetal chorionic and stem villous arteries. In patients with pregnancy-induced hypertension, blood pressure was reduced without significant changes in heart rate or in arcuate artery pulsatility index (PI). Fetal heart rate remained unchanged and no significant changes were seen in fetal aortic rising slope, PI and blood flow, or in umbilical artery PI and venous blood flow. The results do not suggest significant negative effects on uteroplacental haemodynamics during treatment of pregnancy-induced hypertension with calcium antagonists like nifedipine.