The preliminary characterization of a vasoactive circulating factor(s) in preeclampsia.

Objective: The endothelium-dependent behavior of myometrial resistance vessels from women with preeclampsia differs dramatically from that of healthy pregnant women. Similar functional changes may be induced in vessels from healthy pregnant women by incubation with plasma from women with preeclampsia.
Study Design: Myometrial arterioles, obtained from healthy pregnant women at elective cesarean section, were incubated with plasma from women with preeclampsia or plasma from healthy pregnant women. Myographic techniques were used to study the endothelium-dependent relaxation to bradykinin. The effects of subjecting plasma from women with preeclampsia to heat treatment, charcoal stripping, protein extraction and digestion, and column fractionation on the inducible changes in endothelial function were likewise investigated.
Results: Incubation with plasma from women with preeclampsia resulted in a significant reduction in the vessel's endothelium-dependent relaxation, a change that was reversible. This effect was reduced by heat treating and charcoal stripping, maintained within a plasma protein concentrate, and completely removed by protease digestion. The vasoactive component(s) of the plasma had a molecular weight greater than 100 kd.
Conclusions: Plasma of women with preeclampsia alters the endothelium-dependent relaxation of myometrial vessels. Our findings suggest that such alterations are induced by a high-molecular-weight protein/glycoprotein, with possible contributions from a hydrophobic, lipophilic factor.