Influence of treatment by betaxolol on the renal response to postural changes in moderate hypertension.

Assumption of upright posture is known to be associated with significant variations in renal function, which are thought to be mediated through the stimulation of the renin angiotensin system. The effect of an eight-week treatment with betaxolol, a selective beta-blocker, was studied in patients with moderate hypertension and normal renal function. Betaxolol induced the expected changes in systemic hemodynamics and reduced supine plasma renin activity and aldosteronemia. The glomerular filtration rate showed no variation but the tubular reabsorption of sodium increased. The renal adaptation to postural changes (decrease in glomerular filtration rate, increase in sodium reabsorption and in plasma renin activity) was unaffected by treatment. It is concluded that betaxolol does not impair the renal response to a physiological stimulus such as change in posture.