EFFECTS OF EXPOSURE TO NO2 OR SO2 ON BRONCHOPULMONARY REACTION INDUCED BY CANDIDA-ALBICANS IN GUINEA-PIGS

The effects of NO2 or SO2 on the bronchopulmonary reactions induced by Candida albicans in guinea pigs were evaluated. Thirty-six guinea pig s (3 groups of 12 animals each) were sensitized with intraperitoneal i njection of 10 mg of C. albicans, given twice. Two groups of animals w ere exposed to about 5 ppm of NO2 or SO2 for 4 h/d, 5 d/wk; this expos ure was conducted a total of 30 times during the study. The third grou p served as the control and was not exposed to these pollutants. Two w eeks after the second sensitization, all the animals were subjected to inhalation exposure to C. albicans. For 42 h after the antigen challe nge, the respiratory rates and expiration/inspiration ratios of the an imals were automatically monitored. The number of animals showing tach ypnea was significantly higher in the NO2 exposure group than in the c ontrol from 15 h after antigen challenge. In the SO2 exposure group, t he number of animals showing prolonged expiration or prolonged inspira tion, or both, was significantly higher than that in the control group , and the symptoms were observed from approximately 15 h after antigen challenge. These findings showed that delayed-type dyspneic symptoms in guinea pigs were increased by exposure to NO2 or SO2, although the symptoms and degree of dyspnea were different for the two gases.