[Oxidative damage of gasoline engine exhausts to rat lung tissues].

Objective: To study the effects of extracts of condensate, particulates and semivolatile organic compounds from gasoline engine exhaust on DNA damage, 8-oxoguanine DNA glycosylase-1 (OGG1) expression, and changes of ultra-structures in lungs of rats.

Methods: Organic extracts of gasoline engine exhaust (GEE) was intratrachealy instilled into rat lungs at 0, 5.6, 16.7, and 50.0 L/kg body weight, respectively, once a week for a month. The single DNA strand break was measured by comet assay. The OGG1 was determined using immunohistochemistry method. The ultrastructure of lung cells was observed with electronic microscope.

Results: The rates of tailed cells detected by the comet assay increased significantly when the rats were exposed to 16.7 and 50.0 L/kg of GEE compared with those exposed to solvent only (P < 0.05). However, the tail length did not differ significantly between the groups. Similarly, exposure to 16.7 and 50.0 L/kg of GEE led to increased OGG1 significantly. Significant changes of mitochondria in type I and II alveolar cells as well as respiratory bronchiole epithelial cells were observed, which included decrease of numbers, pyknosis and swelling.

Conclusion: Gasoline engine exhausts induce single DNA strand break, increase OGG1 expression, decrease numbers of mitochondria, and destroy ultrastructures of mitochondria in various lung cells of rats.