Vasodilators and the catecholamine content of the blood plasma in patients with the moderate form of hypertension

Vasodilators (verapamil, nifedipine, and prazosin) versus hypothiazide and clofelin were studied for their effects on resting and exercise blood levels of catecholamines in 58 patients with moderate arterial hypertension. Clofelin decreased norepinephrine levels, whereas hypothiazide increased it at rest and during exercise test. The most marked effect on norepinephrine levels was produced by nifedipine, then prazosin, particularly in patients with initially enhanced total peripheral vascular resistance. Verapamil failed to substantially affect norepinephrine levels. Due to the fact that the elevated levels of norepinephrine may have a negative action, it is suggested that antiadrenergic agents should be supplemented to a long-term therapy with nifedipine or prazosin.