Effects of exposures to various air pollutants on experimental asthma induction, in particular on its late asthmatic response.

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On bronchial asthma, it is pointed out that late asthmatic response (LAR) is important and its significance is large, but its adequate identification/experimental procedure has not been developped for the difficulty of objective long-time observation (over 48 hours) on experimental animals' breathing symptoms.In the first step of our project, new procedure of long-time exact observation on breathing symptoms was planned to be developped. Animals (guinea pigs) were fixed in bodyplethsmo-boxes, and each output was amplified, converted to digital data, and stored in hard-disk. Stored data were analized numerically to obtain the following indices of respiratory frequency, ecpiration/ inspiration-ratio (expiratory/inspiratory elongation), breathing curve pattern, power spectrum of breathing curve etc.With this system, effect of nitrogen dioxide on LAR was investigated. By ovo-albumin or candidaextract spray, it was noticed that LAR was elevated siginificantly by exposure to nitrogen dioxide (0.5 ppm X 24 hours X 4 days).