Effect of alprenolol and hydralazine on plasma renin concentration in patients with arterial hypertension.

The effect of alprenolol alone and in combination with hydralazine on plasma renin concentration has been studied in 25 patients with arterial hypertension. Alprenolol caused a significant fall in plasma renin concentration and in BP but the two falls were not intercorrelated. Addition of hydralazine to the treatment regimen produced a further reduction of BP. Changes in plasma renin concentration varied greatly during combination therapy. A modest, non-significant increase in plasma renin concentration was measured compared with the level after treatment with alprenolol. It is concluded that mechanisms other than suppression of plasma renin concentration are important for the reduction of BP during beta-adrenergic blockade and that the plasma renin concentration probably has no clinical significance with regard to forecasting the antihypertensive effect of alprenolol. Even though a significant correlation was found between the fall in plasma renin concentration and the fall in diastolic BP during combination therapy, it is uncertain whether changes in the renin-angiotensin system are of primary importance for BP regulation during this therapy.