Reduced placental vascular reactivity to 5-hydroxytryptamine in pre-eclampsia and the status of 5HT(2A) receptors.

This study investigates the contractile response to 5 hydroxytryptamine (5HT) of chorionic artery and vein segments from normotensive (NT) and pre-eclamptic (PE) placentae. It also looked at the effectiveness of ketanserin (KET), a 5HT(2A) receptor antagonist, in reducing 5HT-mediated vasoconstriction. 5HT induced vasoconstriction in all of the vessels was studied. Compared to NT vessels, Emax (%KCl) was significantly reduced in PE arteries (p<0.05) and veins (p<0.0005). The mean Emax for NT arteries was 104.1 (±10.71) whilst PE arteries showed a mean Emax of 57.02 (±12.13). KET produced a statistically significant reduction of Emax in both vessels in NT and the arteries in PE. However the antagonistic effect of KET was not pronounced in PE veins. The EC50 values for NT and PE arteries and veins did not change significantly. There were no noticeable changes in the expression profiles of 5HT(2A) receptor mRNA and protein expressions. The data from this study suggest that in PE, the vascular reactivity of chorionic vessels to 5HT is reduced and it was not due to the altered expression of 5HT(2A) receptors.