Objective:To investigate the occurrence and pathological changes of the limb ischemia-reperfusion injury of different phases and the combined effects of hyperbaric oxygen and mannitol on the apoptosis and ultramicrostructure changes of rats.Methods:204 SD rats were randomly divided into various groups

underwent different phases of reperfusion after 8 hours of sustained ischemia

and treated with hyperbaric oxygen and/or mannitol for five days.The expression of cell poptosis-related gene Bax

and Bcl-2 was detected through the paraffin sections of rat skeletal muscle.Electron microscope was used to observe the ultramicrostructure changes of the gastrocnemius muscle under the effects of different interventions.Results:In all the intervention groups the Bax levels at 4 h

24 h

72 h after reperfusion were significantly less than in the control groups.In HBO and mannitol-HBO groups the Bcl-2 levels at 4 h

24 h were significantly higher than in the control groups.And in mannitol groups the Bcl-2 levels at 4h were significantly higher.In hyperbaric oxygen groups

the cellular swelling of skeletal muscle and the local cytokine response were significantly lower

almost without microvascular thrombosis in capillary vessel.The sarcomere was rarely collapsed

little plasma membrane was shattered

little mitochondrial swelled or changed into the myelinfigure.The combined effects of hyperbaric oxygen and mannitol were significantly better than single-use of hyperbaric oxygen or mannitol(P <0.01).The role of hyperbaric oxygen was significantly better than mannitol(P<0.05).Conclusion:The combined effects of hyperbaric oxygen and mannitol has a more significant role in the protection against the limb ischemia and reperfusion of different phases.