Takeda H, Iwakura T
Division of Environmental Health, National Institute of Radiological Sciences, Chiba-shi, Japan.
Int J Radiat Biol Relat Stud Phys Chem Med. 1987 Dec;52(6):957-64. doi: 10.1080/09553008714552531.
Average doses to rat tissues from the ingestion of 2-[14C]thymidine were compared with those from methyl-[3H]thymidine or 6-[3H]thymidine. Among the three precursors, [14C]thymidine gave the highest dose to spleen and small intestine. The doses to other tissues from [14C]thymidine were almost the same or lower as compared with those from [3H]thymidine, irrespective of the 9 times higher beta-ray energy of 14C than that of 3H. In the case of [14C]thymidine, most of the dose was given by radioactivity incorporated into the organic tissue constituents (non-volatile radioactivity). In the case of [3H]thymidine, however, the dose contributions by non-volatile radioactivity were very small and the major contributions were rather from volatile radioactivity (3HHO), formed by degradation of [3H]thymidine. No significant difference in their total doses was found between the two [3H]precursors, but the dose from non-volatile radioactivity alone was 2-3 times higher with methyl-[3H]thymidine than with 6-[3H]thymidine. Estimates of the dose to cell nuclei in various tissues after the ingestion of [3H]thymidine were also made in order to predict more precisely possible radiation hazards.
将大鼠摄入2-[¹⁴C]胸苷后各组织所接受的平均剂量与摄入甲基-[³H]胸苷或6-[³H]胸苷后的平均剂量进行了比较。在这三种前体中，[¹⁴C]胸苷给予脾脏和小肠的剂量最高。与[³H]胸苷相比，[¹⁴C]胸苷给予其他组织的剂量几乎相同或更低，尽管¹⁴C的β射线能量比³H高9倍。对于[¹⁴C]胸苷，大部分剂量是由掺入有机组织成分中的放射性（非挥发性放射性）产生的。然而，对于[³H]胸苷，非挥发性放射性的剂量贡献非常小，主要贡献相当于是由[³H]胸苷降解形成的挥发性放射性（³HHO）。两种[³H]前体之间的总剂量没有显著差异，但仅非挥发性放射性产生的剂量，甲基-[³H]胸苷比6-[³H]胸苷高2至3倍。为了更精确地预测可能的辐射危害，还对摄入[³H]胸苷后各种组织中细胞核所接受的剂量进行了估算。
