Utsumi H, Elkind M M
Radiation Biology Center, Kyoto University, Japan.
Int J Radiat Biol. 1991 Oct;60(4):647-55. doi: 10.1080/09553009114552471.
Earlier work (Ben-Hur et al. 1980) has been extended to compare the killing of log-phase V79 Chinese hamster cells by ionizing radiation when they are treated immediately after irradiation with medium containing either caffeine or 90% D2O. The object was to determine if the enhanced killing due to post-treatment with caffeine, or D2O, resulted from action on the same sector of potentially lethal damage as appeared to be the case for hypertonic shock and D2O medium. The treatments by themselves were not toxic to unirradiated cells. We found that the enhanced expression of potentially lethal damage by post-treatment with caffeine or D2O medium is similar. For example, the kinetics of the repair of the potentially lethal damage expressible by either post-treatment was similar, and an additive enhancement of potentially lethal damage occurred when the two treatments were administered sequentially. These findings suggest that caffeine and D2O medium affect the same sector of potentially lethal damage. When the two treatments were combined, however, they competed with each other. That is, exposures to caffeine, which by themselves did not enhance killing (up to 1 mM for 2 h), decreased the enhanced killing due to D2O medium, Reciprocally, D2O medium reduced the enhanced killing due to high concentrations of caffeine (greater than 1 mM). Thus, although caffeine and D2O medium act on the same sector of potentially lethal damage they do so differently, suggesting that more than one pathway of the expression of radiation damage can result in the same phenotypic effect.
早期的研究工作（本 - 胡尔等人，1980年）已得到拓展，用于比较对数期V79中国仓鼠细胞在接受电离辐射后，立即用含有咖啡因或90%重水的培养基处理时的杀伤情况。目的是确定咖啡因或重水处理后增强的杀伤作用，是否与高渗休克和重水培养基的情况一样，是由于作用于潜在致死损伤的同一部分。这些处理本身对未受辐射的细胞无毒。我们发现，咖啡因或重水培养基处理后潜在致死损伤的增强表达是相似的。例如，两种处理方式所表达的潜在致死损伤的修复动力学相似，并且当两种处理依次进行时，潜在致死损伤会有累加增强。这些发现表明咖啡因和重水培养基影响潜在致死损伤的同一部分。然而，当两种处理结合时，它们会相互竞争。也就是说，单独使用时不会增强杀伤作用（2小时内浓度高达1 mM）的咖啡因处理，会降低重水培养基导致的增强杀伤作用，反之，重水培养基会降低高浓度咖啡因（大于1 mM）导致的增强杀伤作用。因此，尽管咖啡因和重水培养基作用于潜在致死损伤的同一部分，但方式不同，这表明辐射损伤表达的多条途径可导致相同的表型效应。
