1. Renin responses to different types of beta-adrenergic blocking agents were compared in eight normal volunteers at supine rest and during moderate upright exercise.
2. Comparable beta-adrenergic blockade was achieved with equipotent cardiodeceleratory doses of 100 mg of propranolol, 400 mg of practolol, 100 mg of oxprenolol, 10 mg of timolol, 5 mg of pindolol or 100 mg of ICI 66082.
3. All beta-blocking agents tested significantly and markedly reduced plasma renin activity during upright exercise. Renin suppression was not related to either β1- or β2-type receptor blocking action.
4. Renin levels at rest were generally reduced by the blocking drugs, but these responses did not reach significance for oxprenolol and pindolol. With both these drugs, lesser suppressibility of basal renin may be due to their inherent sympathomimetic activity.
5. The results suggest that different types of beta-blocking agents suppress plasma renin activity and therefore that they all may lower blood pressure through reduction of angiotensin vasoconstriction.