Clausen O P, Kirkhus B
Cell Tissue Kinet. 1985 Jan;18(1):83-9. doi: 10.1111/j.1365-2184.1985.tb00634.x.
The influence of pulse labelling with 50 microCi tritiated thymidine ( [3H]TdR) (2 microCi/g) on epidermal cell-cycle distribution in mice was investigated. Animals were injected intraperitoneally with the radioactive tracer or with saline at 08.00 hours, and groups of animals were sacrificed at intervals during the following 32 hr. Epidermal basal cells were isolated from the back skin of the animals and prepared for DNA flow cytometry, and the proportions of cells in the S and G2 phases of the cell cycle were estimated from the obtained DNA frequency distributions. The proportions of mitoses among basal cells were determined in histological sections from the same animals, as were the numbers of [3H]TdR-labelled cells per microscopic field by means of autoradiography. The results showed that the [3H]TdR activity did not affect the pattern of circadian rhythms in the proportions of cells in S, G2 and M phase during the first 32 hr after the injection. The number of labelled cells per vision field was approximately doubled between 8 and 12 hr after tracer injection, indicating an unperturbed cell-cycle progression of the labelled cohort. In agreement with previous reports, an increase in the mitotic index was seen during the first 2 hr. These data are in agreement with the assumption that 50 microCi [3H]TdR given as a pulse does not perturb cell-cycle progression in mouse epidermis in a way that invalidates percentage labelled mitosis (PLM) and double-labelling experiments.
研究了用50微居里氚标记胸腺嘧啶核苷（[3H]TdR）（2微居里/克）进行脉冲标记对小鼠表皮细胞周期分布的影响。在08:00时给动物腹腔注射放射性示踪剂或生理盐水，在接下来的32小时内每隔一段时间处死一组动物。从动物背部皮肤分离表皮基底细胞并制备用于DNA流式细胞术，根据获得的DNA频率分布估计细胞周期S期和G2期的细胞比例。在同一动物的组织切片中确定基底细胞中的有丝分裂比例，并通过放射自显影确定每个显微镜视野中[3H]TdR标记细胞的数量。结果表明，在注射后最初的32小时内，[3H]TdR活性不影响S期、G2期和M期细胞比例的昼夜节律模式。在示踪剂注射后8至12小时之间，每个视野中标记细胞的数量大约增加了一倍，表明标记群体的细胞周期进展未受干扰。与先前的报道一致，在最初的2小时内有丝分裂指数增加。这些数据与以下假设一致：以脉冲形式给予50微居里[3H]TdR不会以使标记有丝分裂百分比（PLM）和双标记实验无效的方式干扰小鼠表皮的细胞周期进展。
