Comparison of effects of in vivo nitrogen dioxide exposure starting from different periods on alveolar macrophage activity, assessed by a chemiluminescence technique in Brown-Norway rats.

Nitrogen dioxide (NO2) has been extensively studied for its immune modulating effects on pulmonary cells. Alveolar macrophages (AMs) play an important role in pulmonary immunity. The Brown-Norway (BN) rat has been studied as a high-risk model of allergic diseases. In this study, BN rats were exposed to NO2 from the embryonic or weanling period (EP or WP, respectively). To evaluate the effects of NO2 exposure on pulmonary immunity, the activity levels of rat AMs were assessed as reactive oxygen species-generating capacity, measured by a chemiluminescence (CL) technique, and as cytokine-producing ability. Except for 0.2 ppm of NO2 exposure, the CL responses of AMs obtained from the WP group at 12 weeks old were suppressed significantly. Changes of the cytokine-producing levels suggest that inflammatory reactions are terminated at 12 weeks in the EP group. Correlations between the CL responses and the cytokine levels reveal that NO2 exposure may modulate the direction of AM activation. The CL technique is thought to be useful to evaluate changes in AM activity. In this study, the results suggest that, using the high-risk model of allergic diseases, NO2 exposure from the weanling period has stronger effects on AM activity.

Assessment of training effects on activity levels of alveolar macrophage in matured rats using chemiluminescent technique.

Chemiluminescence responses have been used for the evaluation of phagocyte function. In this study, to evaluate effects of training started after maturation on pulmonary immunity, the activity levels of rat alveolar macrophages (AMs) were assessed as reactive oxygen species (ROS) generating capacity, measured by lucigenin- and luminol-dependent chemiluminescence, using a parallel luminometer. One group of male Wistar rats started training at 11 weeks old and another group at 17 weeks old. The experimental period was 12 weeks, and about half of the rats were sacrificed after 6 weeks. The forced and voluntary exercises affect the mean levels of body weights and cell populations in the bronchoalveolar lavage fluid in younger animals; however, the voluntary exercise group in younger animals seemed to adapt after 12 weeks. By contrast, chemiluminescence responses in older rats observed after 6 weeks suggest that AMs are primed, and the maximum releasing activities of ROS are reduced. These changes in AM activity may be caused by the exercise and separation stresses and the rats may adapt to those stressors after 12 weeks. The chemiluminescent technique is thought to be useful to evaluate the changes of AM activity.