Bevantolol attenuates thiazide stimulated renin secretion and catecholamine release in diuretic resistant...

An attempt was made to establish whether cardioselective beta-blockade could counteract the stimulation by hydrochlorothiazide of the renin-angiotensin and sympathetic nervous systems and to what extent such actions contributed to the antihypertensive effect of bevantolol. The hemodynamic and neurohumoral responses of 21 thiazide resistant hypertensives who had received sequential chronic therapy with hydrochlorothiazide, hydrochlorothiazide combined with bevantolol and bevantolol monotherapy were compared. In these patients, bevantolol had a negative chronotropic effect and appeared, when administered alone, to induce an overall lowering of sympathetic nervous system activity without inhibiting the reflex responses of peripheral vascular resistance to postural change or lowered heart rate. When bevantolol and hydrochlorothiazide were administered together, sympathetic activity appeared to be maintained, possibly as a reflex response to volume depletion but vascular resistance did not appear to be responsive to baroreceptor stimulation. Diminished vascular reactivity induced by the hydrochlorothiazide is suspected to be a contributory factor. Inhibition of thiazide stimulated renin release by bevantolol may contribute to the antihypertensive effect of the combined therapy.