Short-term hyperoxia induced mitochondrial respiratory chain complexes dysfunction and oxidative stress in lung of rats

Background: Oxygen therapy is an alternative for many patients with hypoxemia. However, this practice can be dangerous as oxygen is closely associated with the development of oxidative stress. Methods: Male Wistar rats were exposed to hyperoxia with a 40% fraction of inspired oxygen (FIO₂) and hyperoxia (FIO₂ = 60%) for 120 min. Blood and lung tissue samples were collected for gas, oxidative stress, and inflammatory analyses. Results: Hyperoxia (FIO₂ = 60%) increased PaCO₂ and PaO₂, decreased blood pH and caused thrombocytopenia and lymphocytosis. In lung tissue, neutrophil infiltration, nitric oxide concentration, carbonyl protein formation and the activity of complexes I and II of the mitochondrial respiratory chain increased. FIO₂ = 60% decreased SOD activity and caused several histologic changes. Conclusion: In conclusion, we have experimentally demonstrated that short-term exposure to high FIO₂ can cause oxidative stress in the lung.