Studies on the response of isolated human chorionic plate artery strips to angiotensin II in normal pregnancy and in pregnancy induced hypertension.

A six point concentration: response curves for the contractile effect of angiotensin II (AII) on helically-cut strips of human chorionic plate arteries were established at final concentration of between 10(-14) M to 10(-9) M. The tissues were obtained from the placentae of women who had normotensive pregnancy and from those who had pregnancy-induced hypertension (PIH). A total of 24 chorionic plate artery strips were studied. The responses of the tissues from the normotensive and hypertensive pregnant subjects to physiological concentrations of AII (10(-14)-10(-13)M) were very similar. The overall EC50s were 8.0 x 10(-13) and 4.5 x 10(-13)M for the normotensive and the hypertensive tissues respectively. However, at higher concentrations of AII (10(-12) M and above) the artery strips from the PIH subjects were significantly more sensitive to AII than the tissues from the normotensive subjects (P less than or equal to 0.05). It is suggested that vasospasm and hypersensitivity characteristic of maternal vascular response to angiotensin II, in pregnancy induced hypertension, also occur in the placental vascular system.