本研究以3H－TdR掺入14C－TdR预标记的经同步化培养的BALB／3T3细胞，测定DNA非程序合成（UDS）的变化。结果发现一定浓度的硒、维生素A和视黄酸都对1μg／ml苯并（α）芘（BαP）诱发的UDS有显著的抑制作用（P<0．05－0．001）。这揭示它们均能阻止化学致癌物BαP对DNA的攻击，并存在剂量一效应关系。加致癌物前24小时加入硒、维生素A或视黄酸，则抑制作用更强（P<0．01－0．001）。当硒、维生素A和视黄酸两两联合作用时，抑制效果均比单独使用时明显增强（P<0．05－0．001），表明它们两两之间有协同保护DNA的作用。 In this study, 3H-TdR was incorporated into 14C-TdR pre-labeled synchronized cultured BALB/3T3 cells to determine changes in DNA non-programming (UDS). The results showed that certain concentrations of selenium, vitamin A, and retinoic acid all had a significant inhibitory effect on 1 μg/ml benzo(a)pyrene (BαP)-induced UDS (P<0.05-0.001). This reveals that they all can prevent the attack of chemical carcinogen BαP on DNA and have a dose-effect relationship. Adding selenium, vitamin A, or retinoic acid 24 hours before adding carcinogens had stronger inhibition (P<0.01-0.001). When selenium, vitamin A, and retinoic acid were combined, the inhibitory effects were significantly greater than when they were used alone (P<0.05-0.001), suggesting that they have a synergistic protective effect on DNA.