Comparison of plasma concentrations of arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) in normal and preeclamptic pregnancies

The study was undertaken to measure both plasma arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) concentrations in normal and preeclamptic pregnancies to elucidate the mechanisms of plasma volume regulation during pregnancy. The mean plasma AVP concentration in healthy pregnant women was much lower than nonpregnant controls; however, the concentration in preeclamptic patients was similar to that in the comparative period of normal pregnancy. Despite volume expansion, the mean plasma concentration of ANP in normal pregnancy showed no changes compared to nonpregnant controls. The concentration of plasma ANP in patients complicated by mild preeclampsia was higher than that in normal pregnant women. The concentration of plasma ANP in those with severe preeclampsia was much higher roughly in proportion to the severity of the disease. It is inferable that the lowered concentration of plasma AVP is involved in plasma volume expansion in normal pregnancy, largely but not in a depletion of plasma volume in preeclampsia. The elevated concentration of plasma ANP appears to be closely related to impaired plasma volume expansion in preeclampsia.