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

用L波段电子自旋共振光谱仪研究了X射线照射后小鼠肺组织中氮氧自由基还原力的变化。将羟基-2，2，6，6-四甲基哌啶-N-氧基(羟基-TEMPO)的水溶液经导管注入颈椎脱位小鼠肺内，随着照射剂量的增加，氧自由基的减少量呈线性下降，但在7.5和10.0Gy时无进一步降低。因此，认为小鼠肺具有两种或两种以上的氮氧自由基还原机制。抗坏血酸对照射小鼠肺组织中氮氧自由基还原能力的降低有一定的抑制作用，且在750 mg/kg或以上剂量时，其抑制能力高于未照射组。提示抗坏血酸对放射治疗后肺的放射性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.