[Exercise-induced asthma].
Exercise-induced asthma (EIA) is common in children. In our experience, the incidence of EIA in adults with asthma was 54.4% (37 of 68), and those with and without EIA similar in many ways. Anti-cholinergic drugs were effective in patients with central airway obstruction during episodes of EIA, but disodium cromoglycate protected 80% of EIA patients regardless of the site of airway obstruction. The relationship between chemical mediators and EIA remains controversial but our data show a close relationship between the production of neutrophil chemotactic factor and the severity of EIA. To investigate the mechanism of EIA, we used hyperpnea-induced bronchoconstriction in sensitized rabbits. In this model, bronchoconstriction followed inhalation of dry air regardless of temperature; there was a refractory period, and the bronchoconstriction was completely blocked by an anti-cholinergic drug. The results of studies of inhalation of hypertonic saline, hyperosomolar solutions and amiloride suggest that hyperpnea-induced bronchoconstriction is caused by degranulation of mast cells or by vagal stimulation secondary to changes in osmolarity and in sodium concentration in the airway surface, which result from water loss induced by inhalation of dry air. Vascular phenomena are probably not involved in EIA.
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First Department of Internal Medicine, Nihon University School of Medicine.
D000328:Adult; D000818:Animals; D001250:Asthma, Exercise-Induced / Q000209:etiology* / Q000503:physiopathology; D016084:Bronchoconstriction; D015550:Cell Degranulation; D002648:Child; D004195:Disease Models, Animal; D006801:Humans; D016209:Interleukin-8 / Q000502:physiology; D009994:Osmolar Concentration; D011817:Rabbits
D016209:Interleukin-8