Relationship between vasopressin and the renin-angiotensin-aldosterone system in essential hypertension: effect of converting enzyme inhibitor on plasma vasopressin.

: The effect of the chronic administration of captopril on plasma levels of vasopressin (PVP) were studied in 14 patients with moderate essential hypertension and 10 normal volunteers. All patients were studied after 10 days without drugs and under a constant diet (120 mmol sodium and 80 mmol potassium/day). Plasma levels of renin activity (PRA), aldosterone (PA) and PVP were assayed before and after captopril treatment (50-100 mg/day for 1 month). In addition to the well-known effect of captopril treatment on PRA and PA, a statistically significant reduction of PVP was observed. This finding suggests that the renin-angiotensin-aldosterone system influences vasopressin release, and its inhibitors may contribute to the absence of water retention during captopril treatment compared with the effect of other vasodilatory drugs.