Oxidative stress status in rats after intermittent exposure to hypobaric hypoxia

Programs of intermittent hypobaric hypoxia (IHH) exposure are used to raise hemoglobin concentration and erythrocyte mass. Although acclimation response increases blood oxygen transport capacity leading to a VO(2max) increase, the effects of reactive oxygen species (ROS) might determine the behavior of erythrocytes and plasma, thus causing a worse peripheral blood flow. The goals of the study were to establish the hematological changes and to discern whether an IHH protocol modifies the antioxidant/pro-oxidant balance in laboratory rats.

Male rats were subjected to an IHH program consisting of a daily 4-hour session for 5 days/week until completing 22 days of hypoxia exposure in a hypobaric chamber at a simulated altitude of 5000 m. Blood samples were taken at the end of the exposure period (H) and at 20 (P20) and 40 (P40) days after the end of the program, and compared to control (C), maintained at sea-level pressure. Hematological parameters were measured together with several oxidative stress indicators: plasma thiobarbituric acid reactive substances (TBARS) and erythrocyte catalase (CAT) and superoxide dismutase (SOD).

Red blood cell (RBC) count, hemoglobin concentration and hematocrit were higher in H group as compared to all the other groups (p < 0.001). However, there were no significant differences between the 4 groups in any of the oxidative stress-related parameters.

The absence of significant differences between groups indicates that our IHH program has little impact on the general redox status, even in the laboratory rat, which is more sensitive to hypoxia than humans. We conclude that IHH does not increase oxidative stress.