Cardiac and skeletal muscle adaptations to training in systemic hypertension and effect of beta blockade (metoprolol or propranolol)

TABULAR DATA OMITTED Cardiovascular and peripheral adaptations to an aerobic conditioning program were studied in 30 hypertensive adults taking either Placebo',[beta][.sub.1]-selective [beta]-adrenergic blocker (metoprdol) or [beta][.sub.1]-nonselective [beta]-adrenergic blocker (propranoid). The placebo group increased aerobic capacity (V0[.sub.2]max) 24% (p (Am J Cardiol 1990;66:591-596)
Beta-adrenergic blocking agents prevent the activation of beta-adrenergic receptors, which are specialized cell membrane proteins that trigger specific cell processes such as heart rate and contraction. However, these drugs have been shown to decrease the capacity for exercise and to diminish conditioning response to aerobic exercise in healthy individuals. Studies have also shown that exercise conditioning normally increases aerobic capacity and decreases resting blood pressure in patients with high blood pressure (hypertension). Although beta-adrenergic blocking agents are commonly used to treat hypertension, the effects of these drugs on exercise conditioning in hypertensive patients are not known. However, a drug that selectively blocks the beta-1-type receptors may not affect the beta-2 receptor-mediated dilation of blood vessels during exercise. Hence, the effects of the beta-1 receptor blocking agent metoprolol and the nonspecific beta receptor blocker propranolol on exercise conditioning response were assessed in 30 patients with hypertension. Aerobic conditioning resulted in a 24 percent increase in aerobic capacity, reduced blood pressure, and decreased systemic resistance (the force against which blood flows in the peripheral circulation), in patients who were not treated with beta blocking agents. Aerobic capacity was increased by 8 percent and blood pressure decreased in patients treated with metoprolol. Patients treated with propranolol had no increase in aerobic capacity, no reduction in blood pressure, and no adaptation of the heart and blood vessels to exercise training. These findings show that selective beta-1 blocking agents such as metoprolol and nonspecific beta blocking agents such as propranolol can diminish the exercise conditioning effects in hypertensive patients to varying degrees. (Consumer Summary produced by Reliance Medical Information, Inc.)