Enhanced bronchoconstriction responses to prostaglandin F2 alpha following inhalation of sulfur dioxide

The effect of chronic sulfur dioxide (SO2) inhalation was investigated in pharmacologic-induced bronchoconstriction in beagle dogs. Increases in pulmonary resistance (RL) and decreases in dynamic lung compliance (CDYN) were observed with i.v. and aerosol administration of prostaglandin F2 alpha (PGF2 alpha). After control historical data were accumulated, the animals received exposures of 500 ppm of SO2 for two hours twice a week. After six months of chronic SO2 exposure, a significant enhancement in the RL response to i.v. and aerosolized PGF2 alpha was observed as compared to pre-SO2 data. Tracheobronchial inflammation, as observed by fiberoptic bronchoscopy, occurred as a result of the chronic inhalation of SO2; however, only a small increase in mucous production was observed visually. In addition, hypercapnic and acidotic changes in blood gas profiles were found. Therefore, beagle dogs chronically exposed to SO2, developed hyperactive airways as seen by increased sensitivity to PGF2 alpha. This model appears to reflect many of those changes observed in clinical bronchial hyperreactivity and may provide an additional insight into obstructive airways disease.