The Effect of Adding β-2 Agonism to improve β -1 Blockade Exercise Responses on Hypertensive Patients

Abstract

This study assesses the Effect of adding β-2 Agonism to improve β -1
Blockade Exercise Responses on Hypertensive Patients. The ultimate
aim is to test the hypothesis that celiprolol, a β -1 adrenoceptor
antagonist with the ancillary property of β -2 mediated vasodilation,
would increase blood flow to active muscles during exercise and result
in less impairment of exercise performance compared with the β -1
antagonist atenolol. After an initial 3 week 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
ergometry 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 b-blocker significantly affected submaximal exercise oxygen
uptake, rate of perceived exertion, minute ventilation, or respiratory
exchange ratio. Both β -blockers significantly and similarly decreased
peak oxygen uptake; celoprolol 23.9 ± 1.7, atenolol 24.9 ± 1.7, placebo
27.3 ± 1.3 ml.kg-1 min-1. My findings suggest that during exercise while
on b-blockade, other factors such as sympathetic vasoconstriction or
local metabolic vasodilation may override β -2-mediated vasodilation.
Thus the addition of β -2 agonism to β -1 antagonism decreases resting
vascular resistance but offers no advantage over conventional β -1
blockade therapy during exercise.