Response to airway phagocytes to lung damage before and after strenuous physical exercise

Quantitative ratios between alveolar polymorphonuclear leukocytes (PML) and macrophages and the ingesting and reducing potentials of these phagocytic cells were studied after lung damage in unstressed mice and mice that had just been stressed by strenuous physical exercise (swimming for 60 min). Three days after the lung damage induced in unstressed mice by AgNO3 (0.1 ml instilled intratracheally), PML numbers in the airway lumens were significantly increased, while the bronchoalveolar lavage fluid samples taken on day 14 after lung damage indicated intensified macrophage activity. In the mice instilled with AgNO3 immediately after being stressed, the recruitment of PML and macrophages to the lungs was markedly decreased, although the percentage of macrophages reducing nitro blue tetrazolium had significantly increased. That the lungs of stressed mice sustained less injury than those of unstressed animals was indicated by the finding that lactate dehydrogenase activity in the cell-free fraction of bronchoalveolar lavage fluid was less damaged in response to intratracheal instillation of the destructive agent.