BETA-ADRENERGIC RESPONSIVENESS IS REGULATED SELECTIVELY IN HYPERTENSION

Veta-adrenergic receptor responsiveness is impaired in hypertension. A low-sodium diet both corrects this defect and lowers blood pressure. To determine whether upregulation of beta-adrenergic receptor function in hypertension might be related nonspecifically to lowering of blood pressure, vascular beta-adrenergic response was assessed after pharma cologic antihypertensive treatment by use of dorsal hand vein linear d ifferential transformer techniques in patients with hypertension. Subj ects were studied after randomized treatments with placebo and verapam il and after randomized treatments with verapamil and hydrochlorothiaz ide. After 2 weeks of treatment, verapamil lowered blood pressure in t he subjects with hypertension but did not significantly upregulate vas cular beta-adrenergic response (58% +/- 8% to 68% +/- 8%; p > 0.2 vers us placebo). Further vascular beta-adrenergic responsiveness after tre atment with hydrochlorothiazide did not significantly differ from that with verapamil (hydrochlorothiazide, 68% +/- 9%; verapamil, 53% +/- 7 %; n = 8, p > 0.3). Thus, reduction of blood pressure with either vera pamil or hydrochlorothiazide did not correct the defect in beta-adrene rgic responsiveness in hypertension. Vascular beta-adrenergic response appears to be regulated selectively in hypertension, not simply by lo wering of blood pressure.