中文摘要：

目的探讨氧化型辅酶Ⅰ（NAD^＋）抗辐射损伤作用及其量效关系。方法L02人正常肝细胞株加入含10％胎牛血清的RPMl 1640培养基中常规方法培养，X线照射后和在照射后即刻加入NAD^＋,采用MTT法检测细胞活性，TUNEL法检测细胞凋亡，观察X线照射对L02人正常肝细胞的辐射损伤，并观察NAD＋对受照射L02肝细胞辐射损伤的影响作用及其与NAD^＋浓度的关系。结果L02人正常肝细胞受X线照射后细胞损伤随照射吸收剂量的增大而加重，受照射后24h细胞抑制作用最显著，细胞损伤多表现为细胞凋亡；加入NAD^＋可提高受照射细胞存活率，其作用在NAD^＋终浓度为100-1000μg／ml范围内与浓度呈正相关，在浓度大于1000μg／ml后，加大浓度并不再显著增加受照射细胞的存活率。结论NAD^＋具有一定的抗细胞辐射损伤作用，其作用在一定范围内与其浓度呈正相关关系。

英文摘要：

Objective To explore the effect ofNAD＋ against radiation injury and its dose-effect relationship. Methods L02 liver cells cultured in RPMI 1640 medium containing 10% fetal calf serum were exposed to X-ray irradiation followed by immediate application of NAD＋. The cellular viability was analyzed by MTT assay and the apoptotic cells were detected by TUNEL methods to observe the damages of L02 liver cells induced by X-ray exposure and analyze the dose-effect relationship of NAD＋. Results The viability of L02 liver cells was decreased with increasing dose of X-ray irradiation. The most obvious growth inhibition of L02 cells occurred 24 h after the irradiation. NAD＋ significantly increased the cell survival rate alter irradiation, and this effect was gradually increased within the concentration range of 100-1000 μg/ml; at higher concentrations, the survival rate of the irradiated L02 cells showed no significant increase. Conclusion NAD＋ provides partial protection of the liver cells against radiation injury, and the effect is positively correlated to NAD＋ concentration within a certain range.