Levels of Plasma Atrial Natriuretic Peptide in Normal and Preeclamptic Pregnancies

Our aims were to clarify the possible role of atrial natriuretic peptide (ANP) in the pathophysiology of preeclampsia, to study the relationship between ANP levels and gestational age, and to evaluate the correlation between ANP and blood pressure findings in preeclamptic pregnancies. Plasma ANP levels were measured by RIA in normotensive (n=10) and preeclamptic (n=13) pregnant women in their third trimesters. The mean (± SE) plasma ANP levels in the normal and preeclamptic pregnant women were 33.33 ± 8.75 and 44.62 ± 7.02 pg/ml, respectively, the higher level in the hypertensive group being statistically non-significant. Despite plasma volume reduction in preeclampsia, elevated plasma ANP levels suggest that ANP may be released in response to a rise in intra-atrial pressures secondary to hypertension in this state. It is also concluded that ANP, which is also a potent vasorelaxant, can induce compensatory mechanisms following the increased responsiveness of the vascular bed to angiotensin II in the preeclamptic state. What is more, higher ANP levels may also explain volume reduction characteristic of preeclampsia. Plasma ANP levels correlation with the gestational age non-significantly and negatively in the preeclamptics (r=-0.16). A nonsignificant, positive correlation existed between plasma ANP levels and mean blood pressure in the preeclamptic patients (r=0.38).