BACKGROUND: Energy depletion, induced by ischemia or hypoxia, is one of the first events in neuronal injury. OBJECTIVE: To investigate the dynamic changes of Na+-K+-ATPase and Ca2+-ATPase activity in the rat brain following transient global cerebral ischemia-reperfusion (IR), as well as the effects of hyperbaric oxygen (HBO) treatment. DESIGN, TIME AND SETTING: A randomized and controlled animal study was performed in the Department of Biochemistry and Molecular Biology, Capital Medical University between February and December 2006. MATERIALS: Clean-grade, female, Sprague Dawley rats were provided by the Animal Research Department of Capital Medical University (License number: SYXK11-00-0047). Na+-K+-ATPase and Ca2+-ATPase kits were provided by Nanjing Jiancheng Bioengineering Institute (Nanjing, China). A hyperbaric oxygen chamber (DWC150-300) was supplied by Shanghai 701 Medical Oxygen Chamber Factory (Shanghai, China). METHODS: Sixty-three rats were randomly divided into nine groups: sham operated group (sham-O) as control, groups of IR, and groups treated with hyperbaric oxygen (HBO) after IR. Animal from the IR and HBO groups were sacrificed after four different survival intervals of 6, 24, 48 and 96 hours, respectively. Each group consisted of seven rats. The rats of HBO groups were placed into the hyperbaric chamber. The HBO chamber was flushed with pure oxygen for 5 minutes, followed by a gradual rise in pressure over 5 minutes and stabilization at 0.2 MPa. Then, pure oxygen was supplied for 45 minutes in stabilized pressure, followed by gradually reduced pressure over 15 minutes. The rats of the 6-h HBO group were placed into the HBO chamber following reperfusion for 3 hours on the first day, which was repeated on three consecutive days, always at the same time. Rats in the sham-O group and IR group remained under normal atmospheric pressure. MAIN OUTCOME MEASURES: The Na+-K+-ATPase and Ca2+-ATPase activity in rat brain homogenate was detected by the ammonium molybdate assay method. RESULTS: All 63 rats were included in the final analysis. After 6 hours, Na+-K+-ATPase activity was significantly greater in HBO animals, compared with IR animals (P< 0.05) and sham-O controls (P< 0.01). In both, the HBO group and IR group, Na+-K+-ATPase activity returned to normal levels after 24 hours (P> 0.05). At 48 and 96 hours, Na+-K+-ATPase activity was significantly greater in HBO and IR animals, compared with sham-O animals (P < 0.05). Ca2+-ATPase activity was significantly greater in the HBO group after 6 hours, compared with the sham-O group (P < 0.01), and returned to normal levels at 24 and 96 hours (P > 0.05). In the IR group, Ca2+-ATPase activity was significantly higher after 6 hours than in the sham-O group (P< 0.01 ), and returned to normal levels after 24 hours (P > 0.05). CONCLUSION: The Na+-K+-ATPase and Ca2+-ATPase activity in LR groups increased during the acute and the delayed phase following transient global cerebral IR. HBO treatment not only increased Na+-K+-ATPase activity at the acute stage, but also induced a faster recovery of Ca2+-ATPase activity.