Fundamental Study about Radical Scavenger as Prevention from Radiation Injury using Electron Spin Resonance (ESR)

采用l波段电子自旋共振（ESR）谱仪研究了x射线照射后小鼠肺内一氧化氮自由基还原能力的变化。将羟基- 2,2,6,6 -四甲基哌啶- n -氧（hydroxy-TEMPO）水溶液经导管注入颈椎脱位致死小鼠肺内。在1.0 ~ 5.0 Gy辐照范围内，硝自由基的还原速率随辐照剂量的增加呈线性下降，而在7.5和10.0 Gy辐照剂量下，硝自由基的还原速率没有进一步下降。因此，我们认为小鼠肺具有两种或两种以上的氮氧化物自由基还原机制。一种受辐射影响，另一种不受影响。抗坏血酸对小鼠肺一氧化氮自由基还原能力的影响与抗坏血酸浓度的增加成正比，且在750 mg/kg以上时，其还原能力高于未给药小鼠。结果提示抗坏血酸对放射治疗后肺部的辐射损伤有一定的预防作用。

The change of nitroxide radical reduction capacity in the mouse lung after X-ray irradiation was investigated using a L-band electron spin resonance (ESR) spectrometer. An aqueous solution of hydroxy-2, 2, 6, 6-tetramethylpipeidine-N-oxyl (hydroxy-TEMPO) was injected through the catheter into lung of the mouse that was sacrificed by cervical spine dislocation.Rate of the nirtoxide radical reduction lineally decreased as the irradiation dose increased from 1.0 to 5.0 Gy, but no further decrease was observed at higher doses of 7.5 and 10.0 Gy. Thus it is thought that the mouse lung has two or more mechanisms of nitroxide radical reduction. One is affected by irradiation, and the other is not.Ascorbic acid administration to the mice prevented, in proportion as it's concentration increased, the decrease of nitroxide radical reduction capacity in the irradiated mouse lung, and that at 750 mg/kg or more, the capacity was higher than that of the mice which were not administered. The result suggests that ascorbic acid is effective in preventing from the radiation injury of the lung after radiation therapy.