The role of the vascular endothelium in the contractile responses of human chorionic plate artery in pre-eclampsia to prostaglandin F_2alpha, 5-hydroxytryptamine, and potassium chloride

This study characterises the reactivity of chorionic plate artery in preeclampsia to prostaglandin F_2alpha (PGF_2alpha), 5-hydroxytryptamine (5-HT), and potassium chloride (KCl) and examines the role of the vascular endothelium in these responses. Ring segments of the chorionic plate arteries of women after normal and pre-eclamptic pregnancies were contracted by PGF_2alpha, 5-HT, and KCl. The experiments were carried out in the presence and absence of endothelium, and on intact rings treated with 10^-6M indomethacin. The maximal contractile responses of rings from pre-eclamptic women to 5-HT, PGF_2alpha, or KCl were significantly greater than those of rings from normotensive pregnant women. The EC₅₀ values of responses were significantly lower in rings from pre-eclamptic subjects. Endothelium removal and treatment of the rings with indomethacin had no effect on the contractile responses of rings from normotensive pregnant women to all the agents, but significantly increased the EC₅₀ value and decreased the maximal contractile responses of rings from pre-eclamptic women to 5-HT and PGF_2alpha. While de-endothelialisation increased the EC₅₀ value for responses of the rings from pre-eclamptic women to KCl, pretreatment with indomethacin did not significantly affect the KCl-induced responses. The results of the study suggest that pre-eclampsia enhanced the reactivity of human chorionic plate artery to 5-HT, PGF_2alpha, and KCl through the involvement of endothelial derived contracting factors. The increased responses to 5-HT and PGF_2alpha were inhibited by indomethacin, but those to KCl were not.