Rao D V, Narra V R, Howell R W, Sastry K S
Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark 07103.
Radiat Res. 1990 Nov;124(2):188-93.
When the radionuclide 125I is localized in mouse testis as 125I-iododeoxyuridine (an analogue of thymidine) and incorporated into the DNA of spermatogonial cells, the cytocidal effects are as severe as those due to densely ionizing alpha particles. In contrast, 125I confined to the cytoplasm of these cells is much less radiotoxic, the efficacy being the same as for selective irradiation of the testis with sparsely ionizing external X rays. The biological effects, in both cases, are strongly mitigated upon pretreatment of the testes with very small amounts (0.75 microgram) of cysteamine, a radioprotector. These findings suggest an important role for such chemical agents in radiation protection and in understanding the mechanisms of radiation damage involving radionuclides incorporated in tissue.
当放射性核素125I以125I-碘脱氧尿苷（胸腺嘧啶核苷类似物）的形式在小鼠睾丸中定位并掺入精原细胞的DNA时，其细胞杀伤作用与高电离α粒子引起的作用一样严重。相比之下，局限于这些细胞细胞质中的125I的辐射毒性要小得多，其效果与用低电离外部X射线选择性照射睾丸相同。在这两种情况下，用极少量（0.75微克）的半胱胺（一种辐射防护剂）对睾丸进行预处理后，生物学效应都会大大减轻。这些发现表明，此类化学物质在辐射防护以及理解涉及组织中掺入的放射性核素的辐射损伤机制方面具有重要作用。
