The effects of exposure to NO or NO2 and an antigen on the breathing curve pattern in guinea pigs

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 pigs (3 groups of 12 animals each) were sensitized with intraperitoneal injection of 10 mg of C. albicans, given twice. Two groups of animals were exposed to about 5 ppm of NO2 or SO2 for 4 h/d, 5 d/wk; this exposure was conducted a total of 30 times during the study. The third group served as the control and was not exposed to these pollutants. Two weeks after the second sensitization, all the animals were subjected to inhalation exposure to C. albicans. For 42 h after the antigen challenge, the respiratory rates and expiration/inspiration ratios of the animals were automatically monitored. The number of animals showing tachypnea was significantly higher in the NO2 exposure group than in the control from 15 h after antigen challenge. In the SO2 exposure group, the number of animals showing prolonged expiration or prolonged inspiration, 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.

Procedure for evaluating changes in respiratory symptoms of experimentally asthma-induced guinea pigs by a personal computer

An automated system was developed for evaluating changes in respiratory symptoms in guinea pigs over a long period with a personal computer. The data on breathing curves obtained with a body plethysmograph were analyzed to determine respiratory rate, expiration/inspiration ratio, ventilation ratio, and other parameters. With this system, respiratory changes in guinea pigs, such as increase or decrease of respiratory rate, expiration/inspiration ratio, and ventilation ratio, and death of animals could be easily observed. Investigation of delayed respiratory response to Candida albicans in sensitized guinea pigs and of the effects of SO2 or NO2 exposures on its response was carried out using this system. Respiratory changes in delayed respiratory response were mostly increased respiration rate and succeeding expiratory prolongation being noted just before death. In the influences of SO2 or NO2 exposure on delayed respiratory response, increase of respiratory rate in NO2 and expiratory and inspiratory prolongation in SO2 were found. This system should prove useful for evaluating changes in respiratory symptoms due to toxic agents, medicines, and air pollutants in small animals.

Effects of exposure to sulfate aerosols and antigen on breathing curve patterns of guinea pigs

We investigated the effects of ammonium sulfate aerosols on asthmatic dyspnea (immediate type) induced by repeated inhalation of a mixture of bovine serum and egg albumin and on the nonspecific responsiveness of the airway tract to acetylcholine. Guinea pigs were exposed to sulfate aerosol in concentrations of 0.2, 0.4, and 2.0 mg/m3 and to 0.2 mg/m3 sulfate aerosol combined with 0.1 ppm of SO2. The exposure time was 2 h/d, 5 d/wk, 38 times in all. The animals were successively exposed to aerosol (for 2 h) and, after 30 min, to the spraying of albumin solution 3 times per week, 7 or 9 times in all. Breathing curves were continuously recorded by a body plethysmograph system during the sensitization periods. The experiments showed that the degree of asthmatic dyspnea in guinea pigs was increased by the exposure to aerosol, and that there is a quantitative relation between the severity of the dyspnea and extent of the exposure. Exposure in the combination with SO2 showed no effect at the concentration studied. Following the exposure experiment, each group of animals was exposed to the spraying of acetylcholine. The sensitivity to acetylcholine increased at aerosol concentrations of 0.4 and 2.0 mg/m3.