Increased plasma catecholamines in high renin hypertension.
Plasma catecholamines, indexes of sympathetic nervous tonicity, were measured simultaneously with renin both supine and after standing plus furosemide in patients with primary hypertension and normotensive volunteers. Seventy percent of hypertensive patients with high renin levels had increased catecholamines compared with a 14% incidence in the combined group with low and normal renin (P less than 0.001). Basal catecholamines were related directly to renin in the hypertensive patients and to blood pressure in the normal (P less than 0.05), but not in the high and low renin subgroups, and inversely to percent increase of catecholamines after standing plus furosemide in hypertensive and normotensive patients (P less than 0.01). Sympathetic nervous hypertonicity may be responsible for the elevation of blood pressure and for the activation of the renin-angiotensin system in patients with high renin hypertension.