To study the changes of excitatory amino acids (EAAs) and intracellular calcium ([Ca2+]i), and the protective effect of EAAs receptor antagonists in the tissues of rabbit lumbar spinal cord after 40-minues ischemia and 4-hours reperfusion. Methods: Thirty healthy rabbits were divided into six groups: sham-operation, 40-minues ischemia,4-hour reperfusion, ketamine and MgSO4 treatment, ketamine treatment, and saline treatment groups. The contents of EAAs (glutamate and aspartate) and [Ca2+] i were measured. Results: The contents of glutamate and aspartate were decreased to 15.18 μmol/g±2.33 μmol/g and 9.99 μmol/g±0.69 μmol/g, respectively; 13.75 μmol/g±2.58 μmol/g and 6.49 μmol/g±1.39 umol/g after reperfusion. In the ischemia group, the [Ca2+]i was elevated to 221.2 μg/g±4.27 μg/g, and elevated further to 298.3 μg/g±9.26 μg/g after reperfusion, being significantly higher than that of ischemia and control groups. Ketamine could obviously increase the level of glutamate and aspartate and decrease the level of [Ca2+]i during the ischemia and reperfusion injury. Conclusions: The excitotoxicity of EAAs and the overload of calcium induced by EAAs play a harmful role in ischemia and reperfusion injury. Ketamine has an effective inhibitory effect.
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