1982 Volume 31 Issue 6 Pages 355-362
The site of airway obstruction in exercise-induced asthma (EIA) was determined from He flow-volume curve, and the inhibitory effect of an alpha-adrenoreceptor blocker (thymoxamine) on EIA was studied. Thirteen asthmatic children with EIA were studied, and these subjects were asked to exercise on a treadmill. A seres of pulmonary function tests was carried out before the exercise, and the results were not signifficantly different according to whether thymoxamine had been administered or not. 13subjects were divided into 8 responders and 5 non -responders according to the classification of Despas et al. (ΔV^^・_<50>≧120%, responder, central airway obstruction; ΔV^^・_<50><120%, non-responder, peripheral airway obstruction). The inhibitory effect of thymoxamin on EIA was studied in 12 of 13 subjects, and inhibition of EIA was observed in all of them. In 5 of them, the ingibition was complete. In relation to the site of airway obstruction, complete or partial inhibition of EIA was observed in 6 of 8 responders ond all of 4 non-responders. These findings indicate that aplha adrenoreceptor blocking agent (thymoxamine) has an inhibitory effect on EIA and acts on effectively both types in which central and peripheral airway obstruction occur in EIA.
