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The circulatory effects of blocking the beta adrenergic receptors with Nethalide were studied in 10 patients with hypertrophic subaortic stenosis and in five postoperative subjects undergoing right heart catheterization. In the resting state, the heart rate and the rate of pressure development in the right ventricle diminished slightly, but cardiac index was not altered by the administration of Nethalide. These observations suggest that tonic sympathetic activity is not of major importance in basal subjects in the supine position. Nethalide attenuated the increase in heart rate and right ventricular dp/dt associated with exercise, and abolished the response of these two variables to the administration of isoproterenol. In the patients with hypertrophic subaortic stenosis Nethalide had little effect on the severity of the obstruction at rest, but reduced the intensification of the obstruction produced by exercise or isoproterenol. The possible clinical benefits of blocking the beta adrenergic receptors in these patients were discussed.

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SUMMARYThe hypotensive efficacies of two vasodilators, hydralazine and minoxidil, were assessed as these drugs were used individually in combination with beta-adrenergic blockade and diuretics in 11 hypertensive patients in whom elevated blood pressure had not been adequately controlled previously by other antihypertensive therapy.Control supine blood pressure fell from 191/128 mm Hg on propranolol and hydrochlorothiazide to 169/108 mm Hg on hydralazine, with a significantly greater reduction to 142/92 mm Hg on minoxidil. Although sodium retention and tachycardia were controlled by the use of concomitant diuretics and beta-blockade, an increment in each of these drugs was occasionally required to prevent these complications. Renal function was changed little with the decrease in blood pressure. Plasma renin increased from a standing control of 14.5 mgg/ml/hr to 35.9 and 31.1 m,gg/ml/hr, respectively, on hydralazine and minoxidil. These data suggest the role of vasodilators used in combination with beta-blockers and diuretics and indicate the greater therapeutic efficacy of minoxidil. previous study minoxidil, a new vasodilator, was shown to lower blood pressure effectively in hypertensive patients and to have a significantly greater effect when combined with beta-adrenergic blockade with propranolol.2 Beta-blockade itself has recently received considerable attention in the treatment of hypertension.3 4 However, the magnitude of the antihypertensive response with beta-blockade alone has been variable, with some investigators reporting effective control of hypertension using propranolol,5 while others have found minimal reductions using either propranolol6 or newer beta-blocking drugs, alprenolol7 and practolol.8 In addition, propranolol has been found not to lower vascular resistance, and the observed hypotensive response appears to be the consequence of a reduction in cardiac output.6