Atrial Natriuretic Peptide and Vasoactive Hormones During Preeclampsia Compared to Normal Pregnancy

Objective: To determine whether serial serum sampling throughout the entire pregnancy would reveal significant differences in plasma levels of vasoactive agents in preeclampsia compared to normal pregnancy.Methods: Serial changes in plasma levels of vasoactive agents [atrial natriuretic peptide (ANP), aldosterone, angiotensin II, Cortisol, vasopressin, noradrenaline, calcitonin gene related peptide (CGRP), neuropeptide Y (NPY)] were determined in 10 normal and 12 preeclamptic pregnancies. We also examined renal (urinary sodium and potassium, osmolality in plasma and urine, creatinine clearance) and hemodynamic (peripheral resistance, blood volume, total hemoglobin) parameters.Results: Preeclamptic patients had higher plasma levels of ANP (27.2 ± 7.7 vs. 10.5 ± 4 pmol/L, P = 0.02), lower levels of the vasodilator CGRP (46.2 ± 17 vs. 80.3 ± 20 pmol/L, P = 0.05), lower levels of aldosterone, and a tendency to lower levels of angiotensin II and cortisol compared to normal pregnancies in weeks 29-38. Noradrenaline, vasopressin, and NPY were un-altered. Furthermore, peripheral resistance was increased, blood volume was decreased, and total hemoglobin was decreased in the preeclampsia group.Conclusions: High plasma levels of ANP will decrease blood volume by increasing diuresis and extravasation of fluid; low levels of CGRP will increase peripheral resistance and blood pressure. We conclude that these alterations in plasma concentrations of the two vasoactive peptides ANP and CGRP may be important in the pathophysiology of preeclampsia.