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内容記述 |
Effects of X-ray irradiation on the redox status in colorectum tissues were investigated by the magnetic resonance redox imaging.
A pyrrolidine-ring nitroxyl contrast agent, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP), was selected and used as the suitable redox-sensitive contrast agent for colorectum tissues. The lower abdomen of the 8-week-old female C3H/He Slc mouse was irradiated by X-ray with 10 Gy single dose under anesthesia. X-ray was collimated through a 19 mm slit made by a pair of 5 cm thick lead blocks. The MRI experiments using CmP as the contrast agent were conducted on mice irradiated by X-ray at different times, i.e., 2?8 hours, 1, 2, 4, 8, 12, and 16 day(s) after irradiation. Dynamic data sets of multi-slice T1-weighted images were obtained by repeating scans every 20 sec for 22 min. Time course of CmP-induced T1-weighted signal in the colorectum tissue were analyzed. The relation between mitochondrial damages and the redox responses was examined.
The k1 decay rate of CmP, that mainly reflects biological reduction of nitroxyl radical in the tissue, was significantly suppressed on day 2, increased on day 8, and then recovered to the control level. The decreasing k1 value observed on day 2 are probably reflecting suppression of biological activity of injured tissue. The increasing k1 value on day 8 may be due to generation of reactive oxygen species from injured mitochondria, although the index of mitochondrial damages was not significantly varied. The magnetic resonance redox imaging technique can potentially visualize radio-biological response in the tissue of a living animal. |
Ueno.M.2023.Adv.Redox.Res.8.100067.pdf (1.9 MB)
