Abstract

The hypothesis that celiprolol, a -1 adrenoceptor antagonist with the ancillary property of -2 mediated vasodilation, would increase blood flow to active muscles during exercise and result in less impairment of exercise performance, compared with the -1 antagonist atenolol was tested. After an initial 3 weeks washout phase, 11 untrained hypertensive men participated in a 6 week crossover study of the two drugs. Each treatment phase was followed by a 3 week placebo phase. Resting forearm and calf vascular resistance measured by venous occlusion plethysmography and submaximal and maximal bicycle ergometer exercise responses were evaluated at the end of each treatment and placebo phase. Celiprolol significantly decreased resting forearm and calf vascular resistance whereas atenolol had no significant effect. Neither -blocker significantly affected submaximal exercise oxygen uptake, rate of perceived exertion, minute ventilation, or respiratory exchange ratio. Both -blockers significantly and similarly decreased peak oxygen uptake; celiprolol 23.9 ±1.7, atenolol 24.9 ± 1.7, placebo 27.3 ± 1.3 ml/kg/min. These findings suggest that during exercise while on -blockade, other factors such as sympathetic vasoconstriction or local metabolic vasodilation may override β-2-mediated vasodilation. Thus, the addition of β-2 agonist to β-1 antagonism decreases resting vascular resistance, but offers no advantage over conventional β-1 blockade therapy during exercise.

Key words:         Celiprolol, atenolol, oxygen uptake, venous occlusion plethysmography, bicycle ergometer, β-blocker, blood flow, vascular resistance.