EFFECT OF DEXAMETHASONE ON A23187-INDUCED AIRWAY RESPONSES IN THE GUINEA-PIG

We examined the effect of dexamethasone on A23187-induced bronchospasm , pulmonary inflammation and airway responses to substance P. Guinea p igs, dosed orally once a day for 4 days with dexamethasone (3.0, 10.0 or 30.0 mg/kg) or saline, were exposed to an aerosol of A23187 for 12 min or until labored breathing began. Postmortem pulmonary gas trappin g was used as an indicator of in vivo airway obstruction and changes i n bronchial responses. Dexamethasone did not alter airway obstruction or inflammation 1 h after A23187 exposure. However, dexamethasone redu ced the enhanced airway responses to substance P and bronchiolar/perib ronchiolar inflammation 24 h post-A23187. It is possible that glucocor ticosteroid suppression of A23187-induced pulmonary inflammation was i mportant in reducing the increased airway responses to substance P.