Propranolol Inhibition of Renin Secretion

The antihypertensive effect and mechanism of propranolol were studied in 47 hypertensive patients classified according to high, normal, or low plasma renin activity. The drug was uniformly effective in 13 patients with high renin activity and malignant, renovascular, or essential hypertension, producing a mean fall in diastolic pressure of 30 mm of mercury. In 22 with normal renin, propranolol reduced mean diastolic pressure by 20 mm of mercury, but individual responses were less consistent. In contrast, the drug was uniformly ineffective in the 12 patients with low-renin essential hypertension. In all three groups, the action of propranolol closely correlated with both the control renin levels and the degree of renin suppression produced. Propranolol usually suppressed aldosterone secretion but to a lesser extent than it did renin, perhaps because of a hyperkalemic effect of the drug. These special effects of propranolol in renin-dependent hypertensions point to the possibility of an associated neurogenic mechanism in these patients.