Kwok T T, Sutherland R M
Laboratory of Cell and Molecular Biology, SRI International, Menlo Park, CA 94025.
Int J Radiat Oncol Biol Phys. 1992;22(3):411-4. doi: 10.1016/0360-3016(92)90843-7.
A431 human squamous carcinoma cells reoxygenated after 12 hr hypoxia were found to be more radiosensitive than aerobic cells not previously exposed to hypoxia. Experiments were carried out to investigate the effect of temperature and oxygen tension during the hypoxia and the reoxygenation periods on the sensitization effect. Incubation at 0 degrees C during 12 hr of hypoxia inhibited the sensitization seen after reoxygenation. During the reoxygenation period, reduced temperature did not modify the levels of enhancement but suppressed the decay of the sensitization. If oxygen tension during 12 hr of hypoxia was less than 10 ppm, maximal enhancement by reoxygenation was seen, but there was no enhancement if the oxygen concentration was greater than 1%. In cells subjected to less than 10 ppm oxygen for 12 hr, the level of sensitization by reoxygenation in 2 to 20% oxygen concentration was similar. The results indicate that radiosensitization by reoxygenation may require metabolic change(s) of cells during both the hypoxia and reoxygenation periods. The sensitization may also involve oxygen dependent species of reactions.
研究发现，经历12小时缺氧后再复氧的A431人鳞状癌细胞比未经历过缺氧的需氧细胞对辐射更敏感。开展实验以研究缺氧和复氧期间温度和氧分压对致敏效应的影响。在缺氧12小时期间于0摄氏度孵育会抑制复氧后出现的致敏现象。在复氧期间，降低温度不会改变增强水平，但会抑制致敏作用的衰减。如果缺氧12小时期间的氧分压低于10 ppm，则会出现复氧引起的最大增强效应，但如果氧浓度高于1%，则不会有增强效应。在氧含量低于10 ppm的环境中处理12小时的细胞，在2%至20%的氧浓度下复氧引起的致敏水平相似。结果表明，复氧引起的辐射致敏可能在缺氧和复氧期间都需要细胞发生代谢变化。这种致敏作用也可能涉及氧依赖性反应类型。
