Differential Effects of Long-Term Cardioselective and Nonselective Beta-Receptor Blockade on Plasma Catecholamines During and After Physical Exercise in Hypertensive Patients

Abstract

The effects of 4 weeks of treatment with equivalent doses of meto-prolol (200 mg daily) and pindolol (15 mg daily) on plasma noradrenaline, adrenaline, and dopamine at rest, during submaximal steady-state exercise and near-maximal exercise, and 5 min after exercise were studied in 8 moderately hypertensive men aged 27 to 51 years using a single-blind, crossover design. The two drugs had similar effects on heart rate and arterial pressure. Plasma noradrenaline level was raised by metoprolol during submaximal steady-state exercise from 5.09 ± 2.09 to 7.39 ± 3.65 pmoles/ml (p < 0.05). Noradrenaline concentration 5 min after exercise was significantly reduced by pindolol (from 4.7 ± 1.8 to 3.9 ± 1.8 pmoles/ml, p < 0.05) but increased on metoprolol (5.8 ± 3.4 pmoles/ml, p < 0.05). Plasma adrenaline concentration was significantly raised by pindolol only during maximal exercise (from 3.1 ± 1.6 to 5.6 ± 4.0 pmoles/ml, p < 0.05). Plasma dopamine level was not significantly affected either by metoprolol or by pindolol. The differential effects of the two agents on plasma catecholamines may contribute to the different hemodynamic patterns seen after long-term treatment with metoprolol and pindolol and may have clinical implications in ischemic heart disease and hypertension.