Abstract: Objective: To investigate the protective effects of hyperbaric oxygen (HBO) in the exercise-induced fatigue mice, and to elucidate its mechanism.Methods: A total of 30 healthy male Kunming mice were randomly divided into control group, fatigue group and HBO intervention group. The mice in control group accepted normal exercise and swimming training without weight-bearing everyday. The mice in fatigue group and HBO intervention group accepted weight-bearing swimming everyday; after each exhaustive training, the mice in fatigue group were placed in the cage and the mice in HBO intervention group were immediately placed into the hyperbaric chamber with fresh sodium lime. The exhaustive swimming time of the mice in various groups were detected. The levels of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione-peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) in liver tissue of the mice in various groups were measured by ELISA method. The morphology of liver tissue of the mice in various groups were observed by electron microscope. The activities of ATPase in liver tissue of the mice in various groups were detected.Results: At the last exhaustive training, the exhaustive swimming time of the mice in HBO intervention group was significantly longer than that in fatigue group (P=0.002). Compared with control group, the levels of MDA in liver tissue of the mice in fatigue group and HBO intervention group were increased (P<0.05); while the levels of CAT, SOD, GSH-Px and T-AOC were decreased (P<0.05). Compared with fatigue group, the level of MDA in liver tissue of the mice in HBO intervention group was decreased (P<0.05), while the levels of CAT, SOD, GSH-Px and T-AOC were increased (P<0.05). There were no obvious abnormal changes in liver tissue of the mice in control group; the livercells of the mice in fatigue group showed concentration and endoplasmic reticulosis, the mitochondria were swollen or concentrated, and the structure of the iliac crest was broken, deformed and fused; but in HBO intervention group, the cytomembrane of liver tissue was intact, the mitochondrial changes were less than that in fatigue group, the structure of fistula was intact, and the changes of endoplasmic reticulum were also alleviated. Compared with control group, the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase and total ATPase in liver tissue of the mice in fatigue group and HBO intervention group were decreased (P<0.05);compared with fatigue group, the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase and total ATPase in liver tissue of the mice in HBO intervention group were increased (P<0.05).Conclusion: HBO intervention could effectively prolong the exhaustive swimming time of the mice and protect the function of liver,and its mechanism may be related to improving the antioxidant capacity and ATPase activity of liver tissue.

Key words: hyperbaric oxygen, exercise fatigue, liver, antioxidant capacity, ATPase