In the human pregnant state a high molecular weight form of
angiotensinogen (
HMrA) is present in significant quantities in addition to the usual low molecular weight
angiotensinogen (LMrA). 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
HMrA. It has been determined that there are five
isoforms of
HMrA. 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
HMrA are elevated in PIH. Plasma LMrA and
HMrA were quantitated in 24 normotensive pregnant women and 65 women with PIH. The PIH group had higher levels of
HMrA and somewhat lower levels of LMrA than the normotensive group. The
HMrA/LMrA ratio was elevated in 47% of the PIH group. The five
isoforms of
HMrA 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
HMrA/LMrA ratio. The relative proportion of the
HMrA 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
HMrA, all five
isoforms of
HMrA are equally elevated.