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

Air pollution may be a factor in the recent increase in severity and prevalence of asthma, but the specific chemical components within the ambient pollutant mix which may be responsible have not been delineated. Acid sulfate aerosols, such as sulfuric acid, have been associated with exacerbation of symptoms in asthmatics and induction of nonspecific 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 rabbits. Responsiveness was assessed using an in vitro assay involving administration of increasing doses of acetylcholine or histamine to bronchial and tracheal rings obtained from animals exposed to 50-500 mu g/m(3) sulfuric acid aerosol. Bronchial hyperresponsiveness to both agonists was noted following exposures at greater than or equal to 75 mu g/m(3). In addition, sulfuric acid altered the normal response pattern of 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 receptors involved in maintaining airway tone. (C) 1994 Academic Press, Inc.