Serum dopamineβ-hydroxylase activity, which is thought to reflect noradrenaline secretion, and free fatty acid level were measured in twenty atopic asthmatic children, of whom ten had exercise-induced asthma (EIA), after exercise on the treadmill.
There was a significant decrease in the level of serum dopamine β-hydroxylase activity in the asthmatics who developed EIA and this closely accompanied the onset of airflow obstruction. There was no change in the free fatty acid levels. In contrast, the asthmatics, who did not have EIA showed a significant rise in the levels of dopamine β-hydroxylase activity and free fatty acids after the same exercise task.
Our results suggest that the atopic children studied, who developed EIA, may have had an impaired noradrenaline response to exercise. It is further suggested that this impaired noradrenaline secretion may facilitate mediator release and contribute to the airflow obstruction in EIA.