Abstract: Objective To investigate the dynamic changes of the activities of Ca⁺-K⁺-ATPase and Ca²⁺-ATPase in brain of Sprague-Dawlay rats after transient global cerebral ischemia-reperfusion and the effects of HBO treatment after ischemia-reperfusion which will provide experimental evidence for clinical treatment with HBO for ischemic stroke.Methods Sixty-three Sprague-Dawlay rats were randomly divided into nine groups:the groups of ischemia-reperfusion(I/R) and the groups treated with hyperbaric oxygen(HBO) after ischemia-reperfusion in four phases at 6 h,24 h,48 h and 96 h respectively and sham operated groups(sham-O) as control.Global cerebral ischemia animal model was constructed by a modified four-vessel occlusion model originally described by Pulsinelli and Buchan.The homogenate of brain was collected respectively at each phase after ischemia-reperfusion.The activities of Ca⁺-K⁺-ATPase and Ca²⁺-ATPase in the homogenate were measured.Results The activity of Ca⁺-K⁺-ATPase in 6 h HBO group was significantly higher than that of 6 h MI/R group(P<0.05) and sham-O group(P<0.01).The activities of Ca⁺-K⁺-ATPase of HBO group and I/R group returned to their normal levels at 24 h(P>0.05).The activities of Ca⁺-K⁺-ATPase in 48 h,96 h HBO groups and I/R groups of corresponding phases were significantly higher than those of sham-O groups again(P<0.05),but there was no statistically difference between HBO groups and I/R group of corresponding phases(P>0.05).The activities of Ca²⁺-ATPase in 6 h HBO group were significantly higher than those of sham-O groups(P<0.01) and they returned to normal levels in 24 h,48 h and 96 h HBO groups(P>0.05).The activities of Ca²⁺-ATPase in 6 h I/R and 48 h I/R groups were significantly higher than those of sham-O groups(P<0.01) twice and returned to normal levels in 24 h and 96 h(P>0.05).Conclusion The results suggest that the activities of Ca⁺-K⁺-ATPase and Ca²⁺-ATPase in I/R groups both stepped up twice at acute and tardy phases after transient global cerebral ischemia-reperfusion.Not only the advancing extent of Ca⁺-K⁺-ATPase activity at acute stage by hyperbaric oxygen treatment is higher than those of the corresponding I/R groups,but also Ca²⁺-ATPase activity by hyperbaric oxygen treatment recovered faster than those of the corresponding I/R groups.These experimental results reveal the mechanism of hyperbaric oxygen treatment for ischemic stroke.

Key words: hyperbaric oxygen, cerebral ischemia-reperfusion, ATPase, Sprague-Dawlay rat