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内容記述 |
The objective of this study is to elucidate the specifically induced elevation of ATP in senescent cells after X-ray exposure. Immortalized normal human fibroblasts (BJ-5ta) were X-irradiated and cultured for 7 days. The senescence-related cell cycle regulators, p53, p21 and p16, were detected using western blotting at specific days after irradiation. The amount of intracellular ATP and extracellular lactate were quantified using commercial kits. As reported in previous articles, the expression levels of p53 and p21 increased from day 1 post-irradiation, whereas p16 increased from day 3, confirming a similar trend to gene expression in irreversible cell cycle arrest. ATP levels increased up to day 2 after irradiation, then decreased on day 4, and increased again on day 7. Extracellular lactate levels also increased with incubation following irradiation and were approximately six times higher than those of non-irradiated cells on 8 days. These results suggest that the glycolytic system is significantly enhanced in senescent cells compared to non-irradiated cells. In addition, measurements of intracellular NAD+/NADH ratio have been made to investigate changes in the activity of the mitochondrial TCA cycle and electron transfer system, and these results will also be presented. |
