Plasma hemopexin activity in pregnancy and preeclampsia

Objective: Plasma hemopexin activity, associated with increased vascular permeability, was evaluated in healthy pregnant and non-pregnant women and in pre-eclamptic women. Methods: Hemopexin activity and the hemopexin inhibitor, extracellular ATP, were assayed in plasma from pregnant (n=10), preeclamptic (n=9), and non-pregnant women (n=10) using standard methods. Abdominal fascia tissue fragments from preeclamptic and pregnant women were immunohistochemically stained for vascular ectoapyrase or ecto-5'nucleotidase. Results: The data show significantly enhanced Hx activity exclusively in plasma from pregnant women and significantly enhanced plasma ATP in pre-eclamptic women compared with the other groups. Dephosphorylation of preeclamptic plasma resulted in reactivation of Hx activity. Fascia tissue-samples from preeclamptic women showed reduced ecto-apyrase activity and enhanced ecto-5'nucleotidase activity compared to pregnant women. Conclusion: Enhanced hemopexin activity may be associated with normal pregnancy, but not with preeclampsia. Decreased hemopexin in pre-eclamptic patients may be due to enhanced plasma ATP, which is possibly promoted by diminished activity of vascular ecto-apyrase.