Atrial natriuretic peptide and arginine vasopressin in pregnancy and pregnancy-induced hypertension.

Atrial natriuretic peptide (ANP) and arginine vasopressin concentrations were measured in 9 patients with pregnancy-induced hypertension. The results were compared to those found in 7 normal pregnant women matched for age, duration of pregnancy, and parity. Plasma ANP levels were significantly higher in the pregnancy-induced hypertension patients than in the control group. Plasma arginine vasopressin concentrations, however, were not significantly different in the two populations. The mechanism of the observed rise in ANP concentrations in the patients with pregnancy-induced hypertension is not known. However, it may be related to a rise in intra-atrial pressures secondary to hypertension, an increase in baroreceptor discharge as a result of hypertension, or, less likely, the ANP may be released from extracardiac sites.