ANGIOTENSIN-II HAS DEPRESSOR EFFECTS IN PREGNANT AND NONPREGNANT WOMEN

Studies in anesthetized animals suggest that angiotensin II evokes a d epressor as well as a presser effect, which becomes evident on cessati on of infusion. We have studied 18 nonpregnant and 8, 23, and 22 women in the first, second, and third trimesters of pregnancy to determine whether such an effect is present in conscious women, whether it is do se dependent, and whether it is influenced by pregnancy. Angiotensin I I was infused intravenously in doubling concentrations at 10-minute in tervals until a presser effect of approximate to 20 mm Hg was observed . The infusion was stopped, and blood pressure was monitored at 2-minu te intervals for 30 minutes. There was a significant diastolic depress or effect after stopping angiotensin II in the nonpregnant women and t hose in the second and third trimesters of pregnancy. Individual women required differing doses of angiotensin II to evoke the standardized presser response. It was thus possible to examine the depressor respon se in each group in relation to infused doses of angiotensin II. In no npregnant women and in those in the second and third trimesters of pre gnancy, the depressor response was dose dependent (P<.001). At any giv en dose, the depressor response deepened as pregnancy progressed (P<.0 01). Basal plasma prostacyclin concentrations rise in pregnancy, and a ngiotensin II can stimulate prostacyclin synthesis. This might mediate the depressor effect. In conclusion, the diminished presser response to angiotensin II in normal pregnancy may be partly due to an increasi ng depressor effect of the hormone.