Abstract: Objective To investigate the effect of various concentration of inhaled oxygen during exercise on reactive oxygen species (ROS) production in chronic obstructive pulmonary disease (COPD) rats and the possible mechanism. Methods Eighty COPD Wistar rats were divided into low oxygen (LO, n=20), normal oxygen (NO, n=20) and inhaled oxygen (IO, n=20) exercising groups, which ran on treadmill in the conditions of 13.6%, 21%, 25% oxygen, respectively, and non-exercising normal oxygen group (C, n=20), which stood on still treadmill in the condition of 21% oxygen. Their apoptosis percentage of neutrophils and ROS content were measured with flow cytometry, glutathione (GSH) in lung with immunohistochemistry and cytochrome C oxidase IV (COXIV) in skeletal muscle with Western blotting, as one and four weeks of exercising. Results For one week of exercise, the ROS was more in LO and NO groups than in C group (P<0.05), while the neutrophils apoptosis percentage was less (P<0.05); and there was no difference among C, LO, NO, IO groups in expression of GSH and COXIV (P>0.05). For four weeks of exercise, the ROS was more in LO group but less in NO and IO groups than in C group (P< 0.05); while the expression of GSH and COXIV increased in NO and IO groups compared with those in C group (P<0.05). Conclusion A long term exercise in non-hypoxic state may inhibit ROS production for COPD patients, by promoting neutrophils apoptosis and antioxidant expression.

Key words: chronic obstructive pulmonary disease, exercise, oxygen concentration, inhaled oxygen, reactive oxygen species, rats