AIRWAY EFFECTS OF LOCAL CHALLENGE WITH HYPERTONIC SALINE IN EXERCISE-INDUCED ASTHMA

Hypertonicity of airway lining fluid has been suggested as the stimulu s for bronchoconstriction in exercise-induced asthma. We explored the airway effects of delivering a direct hypertonic stimulus to asthmatic airways via a fiberoptic bronchoscope, comparing hypertonic saline ch allenge by direct instillation with local aerosol delivery. A group of 18 asthmatic subjects responsive to inhaled hypertonic saline with a history of EIA were studied; the first 9 subjects received local chall enge with hypertonic saline by direct instillation, and the next 9 sub jects were challenged by local aerosol delivery. A control challenge w ith isotonic saline by either instillation or aerosol was performed at a same bronchoscopy. Local challenge with hypertonic saline by aeroso l delivery was found to be more effective in inducing local bronchocon striction (8 of 9 subjects) than instillation (2 of 6 subjects). Paire d BAL fluid samples and bronchial biopsies were obtained in total of 1 1 and 9 subjects, respectively. Local challenge with hypertonic saline either by instillation or aerosol produced no significant change in h istamine, tryptase, or PGD(2) levels in BAL fluid or mast cell numbers and degranulation in bronchial biopsies. A significant correlation wa s observed between histamine levels in BAL fluid and airway responsive ness to inhaled hypertonic saline (r(s) = -0.59, p < 0.05). Bronchial biopsies showed evidence of extensive epithelial damage; however, this was not related to airway responsiveness to inhaled hypertonic saline .