Saralasin infusion in renovascular hypertension: increased response rate in seated patients.

Most series report a significant percentage of nondepressor (negative) responses to saralasin infusions in patients with surgically curable renovascular hypertension. Usually the infusions have been performed with the supine position. In the present study saralasin infusions were done in 33 acutely sodium-depleted hypertensive patients--17 with renovascular and 16 with the essential variety. Most patients were infused in the seated and supine positions to test the hypothesis that there might be a higher incidence of positive (vasodepressor) responses to the saralasin infusion when patients are in a sitting position. The results did, in fact, show a larger number of positive responses to saralasin in the seated patients with renovascular hypertension than in those in the supine position (88% versus 71%). There was a modest increase in the rate of false-positive responses in the patients with essential hypertension who were infused in the seated position (31% versus 23%). However, inasmuch as the saralasin infusion test is proposed as a screening procedure for renovascular hypertension, some false-positive responses are acceptable.