Abstract: AimTo study the effects of sodium magnesium fructose diphosphate (SMFD) on free calcium concentration and nitric oxide synthase activity of ischemic synaptosome, so as to explore the protective mechanisms of SMFD on cerebral ischemia. MethodsThe synaptosomes from normal rat brain were prepared by phase partition and cultured with oxygen-glucose deprivation to establish ischemic synaptosome model. The intrasynaptosomal free calcium concentration and nitric oxide synthase activity were detected separtately after the synaptosomes were co-incubated with SMFD (1.3 mmol·L^-1) or fructose-1,6-diphosphate (FDP, 4.0 mmol·L^-1) for 60 min. ResultsSMFD decreased the free calcium concentration and reduced the activity of nitric oxide synthase (NOS) of ischemic synaptosomes. Its effects were more powerful than those of FDP. ConclusionSMFD may protect neurons from ischemic injury by preventing intracellular Ca²⁺ overload and inhibiting the activity of nitric oxide synthase.