NONSPECIFIC AIRWAY HYPERRESPONSIVENESS INDUCED BY INHALATION EXPOSURETO SULFURIC-ACID AEROSOL - AN IN-VITRO ASSESSMENT

Air pollution may be a factor in the recent increase in severity and p revalence of asthma, but the specific chemical components within the a mbient pollutant mix which may be responsible have not been delineated . Acid sulfate aerosols, such as sulfuric acid, have been associated w ith exacerbation of symptoms in asthmatics and induction of nonspecifi c airway hyperresponsiveness in normal laboratory animals. This study examined the ability of single (3 hr) inhalation exposures to sulfuric acid to induce nonspecific airway hyperresponsiveness in healthy rabb its. Responsiveness was assessed using an in vitro assay involving adm inistration of increasing doses of acetylcholine or histamine to bronc hial and tracheal rings obtained from animals exposed to 50-500 mu g/m (3) sulfuric acid aerosol. Bronchial hyperresponsiveness to both agoni sts was noted following exposures at greater than or equal to 75 mu g/ m(3). In addition, sulfuric acid altered the normal response pattern o f trachea to histamine. The results provide further support for a role of acid sulfates in the induction of airway hyperresponsiveness, and suggest that effects may be due to modulation of pharmacological recep tors involved in maintaining airway tone. (C) 1994 Academic Press, Inc .