Quantitation of the five forms of plasma high molecular weight angiotensinogen in women with pregnancy-induced hypertension

Abstract

In the human pregnant state a high molecular weight form of angiotensinogen (HM rA) is present in significant quantities in addition to the usual low molecular weight angiotensinogen (LM rA). In a previous study involving a small number of white women, it was found that women who had developed pregnancy-induced hypertension (PIH) had significantly higher levels of plasma HM rA. It has been determined that there are five isoforms of HM rA. The objectives of this study were to expand the previous study with the inclusion of black women and to determine which isoform(s) of plasma HM rA are elevated in PIH. Plasma LM rA and HM rA were quantitated in 24 normotensive pregnant women and 65 women with PIH. The PIH group had higher levels of HM rA and somewhat lower levels of LM rA than the normotensive group. The HM rA/LM rA ratio was elevated in 47% of the PIH group. The five isoforms of HM rA were quantitated in plasma from 10 white women with PIH, 10 black women with PIH, and 6 normotensive pregnant white women. Half of both the white and black women with PIH had an elevated HM rA/LM rA ratio. The relative proportion of the HM rA isomers was similar in all groups. These studies show that half the women with PIH have a distinct abnormality in their renin angiotensin system. Both white and black women show this abnormality. In those women who have an elevated total HM rA, all five isoforms of HM rA are equally elevated.