Sympathetic nerve hyperactivity in high-renin hypertension effects of saralasin infusion

We found increased levels of catecholamines in some patients who had high-renin hypertension. To study relations between angiotensin and the sympathetic nerves further, we infused saralasin, a blocker of angiotensin II, into 11 hypertensive patients being evaluated for renovascular hypertension. There were variable responses of mean arterial pressure, plasma renin activity, and norepinephrine levels. When high-renin hypertensive patients with increased levels of norepinephrine were compared with those having high renin and normal levels of norepinephrine, they showed a lesser decrease in mean arterial pressure--5 +/- 5% versus 14 +/- 4%, P less than 0.05--a decrease in plasma renin activity of 20 +/- 17% versus an increase of 77 +/- 24% (P less than 0.01), and a decrease in norepinephrine levels of 42 +/- 7% versus an increase of 10 +/- 23% (P less than 0.05) (means +/- SE). The evidence suggests that patients with high-renin levels are heterogeneous and that the primary mediator of the hypertension is sympathetic tone hyperactivity in those with increased levels of norepinephrine and angiotensin excess in those with normal levels of norepinephrine.