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目的:研究外源性一氧化氮(NO)对鼻咽癌5-8F放疗抵抗细胞株(5-8FRs)放射效应的影响，为寻找合适的鼻咽癌放射增敏剂提供实验依据。方法:体外培养5-8FRs细胞株，使用不同浓度NO供体药物硝普钠(SNP)干预5-8FRs细胞，CCK-8法检测细胞增殖抑制率筛选出一个对5-8FRs细胞增殖无明显影响的ICn 01 SNP浓度(细胞增殖抑制率为1%的SNP浓度)；使用1、2、4、6 Gy和8 Gy放射线干预5-8FRs细胞，确定ICn 15放射剂量(细胞增殖抑制率为15%的放射剂量)。用ICn 01SNP浓度、ICn 15放射剂量放疗单独干预及二者联合干预5-8FRs细胞，高倍镜下观察细胞形态学变化，CCK-8法检测各分组细胞增殖抑制率，流式细胞仪检测细胞凋亡情况，硝酸还原法检测细胞上清液中NO浓度。n 结果:⑴SNP以浓度依赖方式、放射线以剂量依赖方式抑制5-8FRs细胞的增殖，其中SNP ICn 01为(513.89±14.69)μmol/L(SNP组)；放射剂量ICn 15为(3.96±0.33)Gy(放疗组)；⑵联合组(SNP＋放疗)与单独SNP组和放疗组相比，5-8FRs细胞形态学差异显著，漂浮细胞显著增多，贴壁细胞数量逐渐减少并失去原有形态；⑶ICn 01的SNP浓度对5-8FRs细胞增殖无明显影响，然而联合组较单独放疗组细胞抑制率显著提高(n t＝7.708，n P<0.01)；并且联合组中NO浓度显著高于单组放疗组[(310.03±5.76)μmol/L vs (77.34±2.60)μmol/L，n P<0.05]；⑷5-8FRs自发凋亡率为(1.35±0.06)%，SNP组凋亡率为(2.22±0.37)%，SNP组细胞凋亡无明显变化，放疗组凋亡率为(15.37±0.65)%，联合组为(50.27±2.24)%，联合组较放疗组促凋亡能力显著增强(n t＝-21.459，n P＝0.001)。n 结论:合适浓度的外源性NO可在对细胞本身不产生明显毒性的情况下可显著增加5-8FRs细胞株放射敏感性。“,”Objective:To investigate the effects of exogenous nitric oxide (NO) on radiation response of nasopharyngeal carcinoma 5-8F radiotherapy resistant cell line (5-8FRs) and to provide experimental basis for finding suitable radiosensitizer on nasopharyngeal carcinoma.Methods:5-8FRs cells were cultured in n vivo and treated with sodium nitroprusside (SNP) of different concentrations. The inhibition rate of cell proliferation was detected by cell counting kit-8 (CCK8) method. A concentration of ICn 01 SNP (1% SNP) which had no obvious effect on the proliferation of 5-8FRs cells was screened out. The 5-8FRs cells were intervened with 1, 2, 4, 6 Gy and 8 Gy radiation to determine the radiation dose of ICn 15 (15% radiation dose). 5-8FRs cells were treated with ICn 01 SNP concentration, ICn 15 radiation dose and radiotherapy alone or in combination. The morphological changes of 5-8FRs cells were observed under microscope. The proliferation inhibition rate of each group was detected by CCK-8 method, the apoptosis was detected by flow cytometry, and the concentration of NO in cell supernatant was detected by nitrate reduction method.n Results:⑴ The proliferation of 5-8FRs had been inhibited in a concentration-dependent manner by SNP and a dose-dependent manner by radiation. The SNP concentration of ICn 01 was (513.89±14.69)μmol/L (SNP group). The radiation dose of ICn 15 was (3.96±0.33)Gy (radiotherapy group); ⑵ Compared with single SNP group and radiotherapy group, the morphology of 5-8FRs cells in combination group (SNP+ radiotherapy) was significantly different, floating cells increased significantly, the number of adherent cells gradually decreased and lost their original morphology; ⑶ SNP concentration of ICn 01 had no significant effect on the proliferation of 5-8FRs cells, but the inhibition rate of combined group was significantly higher than that of radiotherapy group (n t=7.708, n P<0.01); The concentration of NO in the combined group was significantly higher than that in the single radiotherapy group [(310.03±5.76)μmol/L vs (77.34±2.60)μmol/L,n P<0.05]; ⑷ The spontaneous apoptosis rate of 5-8FRs was (1.35±0.06)%, while the apoptosis rate in the group of ICn 01SNP was (2.22±0.37)%, with no significant difference. The apoptosis rate of 5-8FRs in the combined group (50.27±2.24)% was significantly higher than that of the group of ICn 15 radiation dose(15.37±0.65)%.n Conclusions:Under no obvious toxicity to cells themselves circumstances, exogenous nitric oxide with appropriate concentration could significantly enhance the radiosensitivity on 5-8FRs.