In addition to the well characterized predominant form of plasma
angiotensinogen, which will be termed low molecular weight
angiotensinogen (LMrA), significant quantities of a high molecular weight
angiotensinogen (
HMrA) occur in the human pregnant state.
HMrA is the predominant form of
angiotensinogen in the placenta and amniotic fluid. The ratio of
HMrA/LMrA is elevated in approximately half of the women who develop
pregnancy induced hypertension (PIH). This report documents a simple two step methodology for the separation and quantitation of different forms of
HMrA. The two steps are gel filtration and ion exchange chromatography. The application of this methodology to amniotic fluid and plasma from normotensive pregnant women and extracts of amnion, chorion, and placental tissue has shown five distinct forms in the
tissue extracts and amniotic fluid, but only three significant forms in plasma. The elution position of all forms of
HMrA are highly reproducible and are the same for each tissue or fluid studied, thus lending support to the concept that the three forms seen in plasma of normotensive pregnant women are the same as three of the forms of
HMrA seen in extracts of placental tissue.