Plasma Angiotensin-(1-7) Is Decreased in Preeclampsia
Angiotensin-(1-7)[Ang-(1-7)] is a bioactive component of the renin-angiotensin system (RAS), which has depressor, vasodilatory, and antihypertensive actions. In normal pregnancy we questioned whether the known rise in plasma Ang II is counterbalanced by an increase in plasma Ang-(1-7) and whether plasma Ang-(1-7)levels are decreased in preeclampsia and may thus be a factor involved in the development of hypertension. Nulliparous preeclamptic patients (PREE) and third trimester normotensive pregnant contols (NPC)(matched for parity, race, and gestational age) were enrolled (n=15/group). A nonpregnant group (CON)(n=15) was also included for comparison. PREE had no previous history of hypertension. Mean gestational age of preeclamptic subjects was 33.9±1.2 vs 33.7±1.2 weeks for normotensive pregnant subjects (n.s.,p=0.9). PREE subjects had significant hypertension (159±3/98±2 mmHg) and all had ≥3† proteinuria. Plasma Ang I, Ang II, and renin activity (PRA) were significantly elevated in normal pregnancy as compared to nonpregnant CON subjects; plasma Ang-(1-7) was increased by 51%(p<0.05). In PREE subjects all components of the RAS were reduced as compared to NPC; however, plasma Ang II remained elevated as compared to nonpregnant CON subjects. These studies confirm that the RAS is activated in the third trimester of normal pregnancy,including an increase in plasma Ang-(1-7)levels. In preeclampsia, the decreased levels of plasma Ang-(1-7)in the presence of persistent elevated plasma Ang II are consistent with the development of hypertension.