Vasoconstriction of small arteries isolated from the human placental chorionic plate in normal and compromised pregnancy.

Our aim was to compare placental chorionic plate small artery function in normal pregnancies and those complicated by preeclampsia and intrauterine growth restriction. In particular we wished to test the hypothesis that the constrictive potential of placental small arteries is modified in compromised pregnancy. Biopsies were obtained from term placentas from uncomplicated pregnancies and those affected by preeclampsia and intrauterine growth restriction. Small arteries from the chorionic plate were dissected free from surrounding tissue and studied using parallel wire myography. Placental small arteries developed maintained constrictions to arginine vasopressin and the thromboxane-mimetic U46619. Arterial maximal constriction was reduced in both preeclampsia and intrauterine growth restriction. This effect was agonist independent. In intrauterine growth restriction, placental small arteries showed decreased sensitivity to U46619 but not to arginine vasopressin. Human placental chorionic plate small artery vasoconstriction is significantly reduced in compromised pregnancy, a factor that may lead to altered blood flow within the fetoplacental circulation in these conditions.