Objectives: We aimed to compare placental small artery function from women with pre-eclampsia and normal pregnancy. In particular, we wished to test the hypothesis that these arteries respond differently to an endothelium-dependent vasodilator, to the presence of nitric oxide, and to the presence of cyclic monophosphate nucleotides.
Methods: A small vessel wire myograph was used to study placental arteries (200 to 550 microm). Contractile function was assessed with vasopressin. Relaxation was assessed with the endothelium-dependent vasodilator, bradykinin, and the endothelium-independent vasodilators sodium nitroprusside (a nitric oxide donor) and papaverine (a phosphodiesterase inhibitor).
Results: The constrictor response to vasopressin did not differ between patient groups (p=0.79; repeated measures ANOVA). For both normal pregnancy and pre-eclampsia, the response of pre-constricted arteries to the endothelium-dependent vasodilator, bradykinin, was minimal. Vasorelaxation to sodium nitroprusside and papaverine was attenuated in pre-eclampsia compared to normal pregnancy (p=0.03 and p<0.001, respectively; repeated measures ANOVA).
Conclusions: In pre-eclampsia, placental arteries exhibit an attenuated vasodilatory response to nitric oxide.