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艾氏腹水癌小鼠腹腔内注入平阳霉素1/6半致死剂量,腹水癌细胞DNA合成受到抑制。随注入药物时间之延长,DNA合成呈直线下降。但在同一剂量和时间条件下,对腹水癌细胞RNA合成率没有影响。通过放射自显影和MPV II显微分光光度计,测定了S期细胞百分数和单个S期细胞中~3H-TdR放射自显影银粒,说明DNA合成率之抑制不是由于S期细胞百分数之降低,而是由于单个S期细胞中DNA合成强度之下降。进一步用MPV II显微分光光度计对同一S期细胞中放射自显影银粒和孚尔根萤光定量测定,发现平阳霉素能引起早S期细胞积累;同时早S期细胞DNA合成抑制也较为明显。说明早S期细胞对平阳霉素较为敏感。其机制可能与早S期细胞合成之DNA富含GC组分有关。这与博莱霉素优先和富含GC组分的多聚核苷酸结合的结果是一致的。
Ehrlich ascites carcinoma mice were injected intraperitoneally with a lethal dose of pingyangmycin 1/6, and DNA synthesis in ascites cancer cells was inhibited. With the prolonged injection of drugs, DNA synthesis declined linearly. However, there was no effect on the RNA synthesis rate of ascites cancer cells at the same dose and time. Autoradiography and MPV II spectrophotometer were used to determine the percentage of cells in S phase and ~3H-TdR autoradiograph silver particles in single S phase cells, indicating that the inhibition of DNA synthesis rate was not due to a decrease in the percentage of S phase cells. It is due to a decrease in the intensity of DNA synthesis in individual S-phase cells. Further quantification of autoradiography silver particles and fulgorine fluorescence in the same S phase cells using the MPV II microspectrophotometer revealed that Pingyangmycin can cause early S phase cell accumulation; at the same time, the early S phase cell DNA synthesis inhibition More obvious. It shows that early S phase cells are more sensitive to pingyangmycin. Its mechanism may be related to the GC-rich components of the DNA synthesised by early S-phase cells. This is consistent with the binding of bleomycin- and polynucleotides rich in GC components.