量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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[BACKGROUND] Ultraviolet (UV) light causes various injuries such as sunburn, inflammation, aging, cancer, etc. There have been little reports about in vivo evidence of generation of free radicals including oxygen radicals during exposure to UV light, although free radicals may be involved in those injuries. In this study, induction of radical reaction was examined in skin of living mouse under UV light by using in vivo ESR spectroscopy with a nitroxyl radical, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (carbamoyl-PROXYL), as a redox probe.
[METHODS] An aqueous solution of carbamoyl-PROXYL was injected intravenously to an anesthetized mouse, and L-band ESR spectra of the probe were recorded at the dorsal region of hairless mice with a surface-coil-type resonator.
[RESULTS] The intensity of ESR signal for mouse whose skin was removed and then returned was about two-third of the intensity for intact mouse, indicating that the signal of probe in skin should be about one-third of signal observed in intact mouse. The rate of signal decay significantly increased by irradiation with UV light (UV-A+B). The increase of signal decay rate was not observed in mouse with removed, and then returned skin. The increase of signal decay rate was suppressed by pre-administration of a spin trapping reagent, N-t-butyl-alpha-phenylnitrone (PBN), while PBN did not change the decay rate for non-irradiated mouse. There was no relationship between the signal decay rate and physiological parameters (blood velocity and blood mass in skin and body surface temperature). In vitro experiment shows that PBN inhibited only signal reduction of carbamoyl-PROXYL caused by peroxyl radicals.
[CONCLUSION] Relation of enhanced signal decay of the probe to the generation of peroxyl radical in skin is suggested. The measurement of radical generation under UV light may be possible by using in vivo ESR spectroscopy with asurface-coil-type resonator and a nitroxyl redox probe.
会議概要（会議名, 開催地, 会期, 主催者等）
International Symposium on the Instrumentation of EPR Spectroscopy
Use of a surface-coil-type resonator for in vivo assessment of radical generation in mouse skin during UV irradiation
