Reduced vascular responsiveness to infused angiotensin II (ANG II) has been observed during pregnancy. It has been proposed that infusions produced lower circulating concentrations of ANG II in pregnancy, due to an increase in the metabolic clearance rate of ANG II [MCR(ANG II)]. We have evaluated that MCR(ANG II) and the arterial plasma concentrations of ANG II during constant infusions of 1.15 μg ANG II/min into chronically instrumented pregnant (n = 6) and nonpregnant (n = 9) sheep. Although the pressor responses were significantly less in the pregnant than in the nonpregnant sheep (17.5 ± 0.5 vs. 34.9 ± 3.2 mmHg, P < 0.001), the values of MCR(ANG II) were not different: 56.2 ± 6.3 ml · min-1 · kg-1 in nonpregnant and 55.9 ± 4.3 ml · min-1 · kg-1 in pregnant sheep. The steady-state plasma ANG II concentrations during the infusions were slightly less in pregnant than in nonpregnant sheep (388 ± 36 vs 454 ± 36 pg/ml); however, this difference would be responsible for only a 2-mmHg reduction in the pressor response. We conclude that the reduced pressor response to infused ANG II in pregnancy is not due to an increase in MCR(ANG II) nor to lower plasma ANG II concentrations.
|Original language||English (US)|
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|State||Published - Jan 1 1985|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Physiology (medical)