PLASMA CYCLIC-GMP CONCENTRATIONS AND THEIR RELATIONSHIP WITH CHANGES OF BLOOD-PRESSURE LEVELS IN PREECLAMPSIA

Background. One of the possible mechanisms responsible for pre-eclamps ia is a loss of efficiency of the L-arginine-nitric oxide pathway with subsequent inactivation of the guanylyl cyclases of the vascular smoo th muscle cells. As a result there should be a decrease in plasma cycl ic 3'-5' guanosine monophosphate (cGMP) concentrations in pre-eclampsi a. We assessed the behavior of this nucleotid in the plasma of pre-ecl amptic women. Subjects and methods. Sixteen pre-eclamptic women, 16 no rmotensive pregnant women matched for gestational age and six nonpregn ant controls were investigated. Arterial blood pressure was recorded a t inclusion time and then once a-day until the fourth day after delive ry concomitantly with the collection of blood samples for determining plasma cGMP, atrial natriuretic peptides (ANP), creatinine, uric acid and platelet counts. Also 24 h urines were simultaneously collected to calculate renal clearance of cGMP. Results. Before the initiation of antihypertensive treatment, plasma cGMP levels were significantly high er (p<0.01) in pre-eclampsia women as compared both to pregnant normot ensive controls and nonpregnant women (7.02+/-0.9 versus 4.8+/-0.76 ve rsus 1.93+/-0.15 pmol . ml(-1), p<0.01). Under antihypertensive treatm ent, cGMP levels decreased significantly (p<0.05) to 5.48+/-0.9 pmol . ml(-1). The increase of plasma cGMP was associated with high ANP leve ls; the likelihood that a renal impairment could account for an increa se in plasma cGMP was ruled out because the clearance of creatinine wa s not impaired. Similarly the possibility of a significant linear corr elation between cGMP levels and blood pressure values or biological da ta was excluded in these women. Conclusion. Plasma cGMP concentrations are increased in pre-eclampsia. They decrease to control values when blood pressure returns to normal values; they indicate enhanced guanyl yl cyclase activation by ANP and additional factors, but cannot be con sidered as a direct index of the severity of pre-eclampsia.