The response of forearm resistance vessels to dilator agents in patients with primary hypertension: use of nifedipine in long term therapy.

Local infusion of verapamil induced a significantly greater dilatation in the forearm resistance vessels of men with primary hypertension than that observed in a control group of men with normal arterial pressure; the response to sodium nitroprusside, however, was reduced. These findings indicate an abnormality in the mechanisms by which resistance vessel tone is maintained in patients with raised arterial pressure and they suggest that calcium channel blockers may be particularly suited for use as arteriolar dilators in hypertension. In an open trial in patients with hypertension that was inadequately controlled by the combination of a beta-adrenoceptor antagonist and a diuretic, nifedipine was shown to be effective in causing a further fall in arterial pressure; this finding was confirmed in a subsequent double-blind, placebo controlled study.