Effect of smoke inhalation on immediate changes in lung chemical mediators

We studied the effects of acute smoke exposure on lung and alveolar macrophage (AM) function in New Zealand white rabbits. Six rabbits were exposed to smoke (SE, N = 6) and a control group of rabbits (SS, N = 6) were exposed to sham smoke. The smoke exposure consisted of 60 tidal volume breaths of air and smoke which were aspirated by syringe from a sampling port of a smoke chamber. The smoke was generated by the combustion of 20 ml diesel fuel and 0.2 g polycarbonate plastic shavings. The smoke was administered in 8-9 min. The rabbits were then killed and the lungs were removed for lavage. Acute smoke exposure caused a significant (p = 0.037) increase in bronchoalveolar lavage fluid levels of leukotriene B₄ in the SE rabbits; 643 (± 30, SEM) pg/ml compared to 539 (± 43, SEM) pg/ml for SS rabbits at 3-4 min post-exposure. Lung surfactant, measured as μmoles/kg phosphatidylcholine, was decreased (p = 0.039) in SE rabbits' bronchoalveolar lavage fluid, 1.07 (± 0.12, SEM) -vs- 1.45 (± 0.15, SEM) for SS. Furthermore, cultured SE alveolar macrophage superoxide secretion after stimulation with phorbol myristate acetate was significantly decreased versus SS alveolar macrophage superoxide values at 40 min in culture. We conclude that acute smoke exposure causes immediate increases in bronchoalveolar lavage fluid levels of LTB₄, and decreases in alveolar macrophage superoxide production and lung surfactant. These changes in chemical mediators may contribute to the lung injury caused by the smoke insult.