Renin, sodium, and vasodepressor response to saralasin in renovascular and essential hypertension.

Saralasin (1-sar-8-ala-angiotensin II), a competitive inhibitor of angiotensin II, was administered to 32 patients with renovascular or essential hypertension before (Day 1) and after (Day 2) they were mildly sodium depleted by furosemide (1 mg/kg body weight). A blood pressure lowering effect of saralasin was observed in 16 of 17 patients with renovascular hypertension on Day 2, but in only 10 of the 17 on Day 1. Of the 15 patients with essential hypertension, only the four with high renin levels exhibited a vasodepressor response on Day 2; three responded similarly on Day 1. The Average net sodium loss between the 2 days was greater for patients who responded to the drug on Day 2 (170 meq) than those who did not (129 meq) (P less than 0.05); however, there was no correlation between blood pressure response and either net sodium loss or urinary sodium excretion at the time of testing. Plasma renin activity correlated with saralasin responses (r=-0.74, P less than 0.01). Saralasin testing during a state of modest sodium depletion compares favorably with renin measurements in the detection of renin-mediated hypertension.