High molecular weight angiotensinogen levels in hypertensive pregnant women.

An apparent high molecular weight angiotensinogen (H-Aogen) can be separated from the usually predominant low molecular weight angiotensinogen (L-Aogen) by gel filtration of plasma. H-Aogen has been quantitated in plasma from normotensive menstruating women, estrogen treated women, normotensive pregnant women, women with pregnancy-induced hypertension (PIH), and women whose preexisting hypertension was exacerbated during pregnancy. When expressed as a percent of the total angiotensinogen, the H-Aogen levels were: menstruating women 4%, estrogen-treated women 10%, normotensive pregnant women 16%, women with PIH 25%, and pregnant women with exacerbated hypertension 28%. A significant difference (p less than 0.01) was found between H-Aogen concentration in normotensive pregnant women and women with PIH (1.10 +/- 0.12 and 1.73 +/- 0.16 micrograms angiotensin I/ml plasma respectively). In some hypertensive pregnant women, H-Aogen is the predominant form of angiotensinogen. Thus, H-Aogen should be recognized as a component of the renin-angiotensin system.