Hypotensive effects of sodium volume depletion and 1-sar-8-ala-angiotensin II in relation to plasma renin in hypertensive patients

Abstract

The hypotensive effect of acute sodium volume depletion, produced by chlorthalidone and a low sodium diet, was inversely related to the plasma renin concentration (PRC) in 13 hypertensive patients of varying aetiology (r = 0.61; p less than 0.05); weight reduction induced by this therapy was not related to PRC (r = 0.12; p greater than 0.1). The angiotensin II antagonist 1-sar-8-ala-angiotensin II failed to reduce arterial pressure when the patients ingested 130 mEq sodium per day, but pressure fell when it was infused during sodium volume depletion, except when PRC remained low; the changes in pressure were related to the plasma renin level (r = 0.78; p less than o.005). The combined hypotensive response to acute sodium volume depletion and to angiotensin II blockade during sodium volume depletion was not related to PRC (r = 0.15; p greater than 0.1). The results demonstrate that acute sodium volume depletion caused similar weight loss in patients with high and low PRC values, and it would have had similar hypotensive effects but for angiotensin-induced vasoconstriction in the high renin patients. Since 1-sar-8-ala-angiotensin II also reduced arterial pressure in 6 patients during chronic diuretic therapy, angiotensin II must still induce vasoconstriction in these circumstances.