Reduction of plasma and urinary vasopressin during treatment of severe hypertension by captopril

Abstract

Plasma concentrations and urinary excretion rate of vasopressin (VP) were examined in ten cases of severe hypertension before and during short-term treatment by Captopril (SQ 14225). Before Captopril, plasma and urinary VP were high (respectively 5.24 pmol/l and 68 pmol/day) and positively correlated to plasma renin activity (PRA) and plasma aldosterone (PA). The decline in blood pressure (mean -15%) after Captopril was correlated not only to initial PRA and PA values, but also to plasma (r = 0.89; P less than 0.001) and urinary (r = 0.78; P less than 0.01) VP values. The initial dose of Captopril (1 mg/kg) induced a rapid decrease in blood pressure whereas plasma VP did not rise and aldosterone decreased. At the eighth day of Captopril treatment (mean daily dose 6 +/- 1.5 mg/kg) the drop in blood pressure (-12%) and in aldosterone persisted together with a significant reduction in plasma (1.18 pmol/l; P less than 0.01) and urinary (25 pmol/day; P less than 0.01) VP. It is suggested that these sustained simultaneous reductions in the rates of secretion of vasopressin and aldosterone are both elements of the antihypertensive effect of Captopril.

Role of the renin-angiotensin system in the control of vasopressin and ACTH secretion during the development of renal hypertension in dogs.

“…Indeed, in some animals, plasma vasopressin levels actually increased following captopril administration, presumably because of the large fall in arterial pressure. Thibonnier et al 22 also reported that acute administration of captopril in hypertensive patients did not decrease plasma vasopressin concentration. However, they ob- VOL 6, No 1, JANUARY-FEBRUARY 1984 served significant reductions in both plasma vasopressin concentration and urinary vasopressin excretion during chronic treatment with captopril and this agrees well with observations made in rats with spontaneous hypertension by Crofton and associates.…”

“…18 ' " It has also been reported that plasma vasopressin levels are increased in patients with malignant hypertension. 20 " 22 Indeed, Thibonnier and associates 22 reported a close correlation between plasma vasopressin concentration and PRA in a group of patients with severe hypertension. In general, the results of the present study confirm and extend these previous findings.…”

“…However, reduction in plasma vasopressin concentration may become more significant in blood pressure regulation during chronic captopril treatment. 22 There is little information concerning possible interactions between the renin-angiotensin system and the pituitary-adrenal axis in hypertension. Recently Atlas and associates 26 reported that plasma cortisol concentration at 0800 hours was higher in patients with high renin essential hypertension or renovascular hypertension than in patients with normal renin or low renin forms of hypertension.…”