Effect of beta-adrenoceptor blockade on exercise-induced plasma catecholamine concentrations and their dissipation...

The time-course of plasma noradrenaline (NA) and adrenaline (A) concentrations and their dissipation profiles were examined concomitantly with heart rate changes after strenuous exercise in eight normal subjects receiving either placebo or carteolol, a beta-adrenoceptor blocker. Post-exercise NA concentrations declined with time in a biexponential manner, while A disappearance curves were apparently monophasic. Plasma NA concentrations and their peak value attained within 3 min after exercise were higher in the carteolol than in the placebo phase, whereas there were no significant differences in the first and second disappearance t1/2 between the two trials. The monoexponential t1/2 of A in the carteolol trial was significantly longer than in the placebo trial. Our results suggest that the dissipation profiles of catecholamines released by exercise appear to be affected by beta-adrenoceptor blockade.