Abstract: Objective: To explore the effect of different doses of magnesium sulfate(MgSO₄) on reperfusion injury of mice with general cerebral ischemia.Methods: The mice were randomly divided into control group,ischemia reperfusion(I/R) group,MgSO₄ 90 mg/kg group,MgSO₄ 180 mg/kg group and MgSO₄ 360 mg/kg group.General cerebral ischemia model was established by blocking the bilateral common carotid arteries and pressing the soft tissues in carotid.The mice were reperfused for 60 min after 30 min ischemia.The change of EEG was monitored and the pathological change in morphology was observed.The content of nitric oxidel(NO) and the activity of nitric oxide synthase(NOS) and inducible NOS(iNOS) were also detected.Results: Compared with MgSO₄ groups,the content of NO(P<0.01),the activities of NOS and iNOS in the I/R group were decreased(P<0.01),and the pathologic damage in brain tissues relieved.Conclusions: The curative effect of MgSO₄ on cerebral ischemia-reperfusion injury might be associated to the decrease of the NO contents and the lowering of the activities of NOS and iNOS.