Effect of captopril and propranolol, alone and in combination, on the responses to isometric and dynamic exercise in normotensive and hypertensive men.

This study evaluated the effects of single doses of the angiotensin converting enzyme inhibitor captopril and the beta-adrenergic blocking agent propranolol, alone or in combination, on the blood pressure, heart rate and humoral responses to both isometric (handgrip) and dynamic (ergometric) exercise in normotensive and hypertensive men. Single oral doses of either placebo, captopril 50 mg, propranolol 80 mg, or the latter two in combination were administered to age-matched groups (n = 5) of normotensive and hypertensive men in a random, double-blind manner. Captopril alone was indistinguishable from placebo after both isometric and ergometric exercise. Propranolol suppressed heart rate after both types of exercise and tended to decrease systolic blood pressure only in the hypertensive group; combination with captopril did not alter these responses. These data suggest that in sodium-replete subjects undergoing short-term vigorous exercise, the renin-angiotensin system, as measured by captopril inhibition, is less important than the sympathoadrenal system, as measured by propranolol inhibition, in the reflex cardiovascular adjustments accompanying acute isometric and dynamic exercise in both normotensive and hypertensive men.