Deficiency of c-Gmrp Level in Placental Circulation in Pregnancy-Induced Hypertensive Disorders: Possibility of Decreased Endothelium-Derived Relaxing Factor Activity

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Abstract
Objective: To investigate the hypothesis that a decrease in the synthesis of endothelium-derived relaxing factor (EDRF) is involved in the pathophysiology of pregnancy-induced hypertensive disorders. Methods: Levels of cyclic nucleotides and prostacyclin were measured by RIA methods in umbilical venous plasma, obtained from 28 women with normotensive pregnancy, 8 with pregnancy-induced hypertension and 8 with preeclampsia. The sampling was done at the time of delivery. The criterion for hypertension was a diastolic blood pressure of 90 mm Hg or more; preeclampsia was defined as hypertensive pressure with proteinuria (≥ 1 g/L). Statistical analysis was done by the Student t test. Main Outcome Measures: Umbilical venous plasma concentrations of c-GMP, 6-keto-PGF1α and c-AMP. Results: A significantly lower level of c-GMP was found in hypertensive pregnant patients compared with normotensive women (P < 0.01), but there was no difference between groups with pregnancy-induced hypertension and preeclampsia. The level of 6-keto-PGFlα in umbilical venous plasma in hypertensive patients was also significantly reduced (P < 0.05). Conclusions: The reduced c-GMP activity in umbilical venous plasma in patients with pregnancy-induced hypertensive disorders may support the hypothesis that a reduced production of endothelium-derived relaxing factor in the placental circulation may be involved in the pathophysiology of pregnancy-induced hypertension and preeclampsia.