The influence of subchronic application of the β-adrenergic agonist clenbuterol on plasma norepinephrine (NE), epinephrine (E) and β-receptors on lymphocytes was investigated in 8 male, healthy volunteers. Treatment with clenbuterol (0.04 mg/day) for 6 days induced significant reduction of β-receptor specific binding in 7 of the 8 subjects with a mean decrease of 40% (p < 0.01) with no changes in affinity. Concomitantly an increase in the plasma NE concentration was observed (mean 50%, p < 0.01), but no significant overall alteration of E concentration. Our results suggest that β-adrenergic agonists exercise a similar effect on the peripheral adrenergic system and on the adrenergic system in the brain.
