THE ROLE OF THE VASCULAR ENDOTHELIUM IN THE CONTRACTILE RESPONSES OF HUMAN CHORIONIC PLATE ARTERY IN PREECLAMPSIA TO PROSTAGLANDIN F-2ALPHA, 5-HYDROXYTRYPTAMINE, AND POTASSIUM-CHLORIDE

This study characterises the reactivity of chorionic plate artery in p re-eclampsia to prostaglandin F-2alpha (PGF(2alpha)), 5-hydroxytryptam ine (5-HT), and potassium chloride (KCl) and examines the role of the vascular endothelium in these responses. Ring segments of the chorioni c plate arteries of women after normal and pre-eclamptic pregnancies w ere contracted by PGF(2alpha) 5-HT, and KCl. The experiments were carr ied out in the presence and absence of endothelium, and on intact ring s treated with 10(-6) M indomethacin. The maximal contractile response s of rings from pre-eclamptic women to 5-HT, PGF(2alpha) or KCl were s ignificantly greater than those of rings from normotensive pregnant wo men. The EC(50) 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 signific antly increased the EC(50) value and decreased the maximal contractile responses of rings from pre-eclamptic women to 5-HT and PGF(2alpha). While de-endothelialisation increased the EC(50) value for responses o f the rings from pre-eclamptic women to KCl, pretreatment with indomet hacin did not significantly affect the KCl-induced responses. The resu lts of the study suggest that pre-eclampsia enhanced the reactivity of human chorionic plate artery to 5-HT, PGF(2alpha), and KCl through th e involvement of endothelial derived contracting factors. The increase d responses to 5-HT and PGF(2alpha) were inhibited by indomethacin, bu t those to KCl were not.