Detection of an ascorbate radical in an irradiated mice using electron spin resonance (ESR)

Ascorbate radical (Asc.-) produced by the reaction of AscH- (ascorbic acid) with HO or O2.- after irradiation in mice has been measured. It is possible to measure Asc.- easily using ESR and a dialysis method in which Asc.- is collected at room temperature in the interstitial fluid through the dialysis membrane. After irradiation, Asc.- increases in both normal muscle and tumor tissues (SCC-VII) in proportion to the radiation dose. These results suggest that the amount of HO and O2.- produced is reflected in the Asc.- production. This method has been found more useful for the following reasons, (i) no special treatment, such as freezing of the sample, and no administration of noxious agents are necessary to measure Asc.-, (ii) irradiation using a dose of only a few Gy shows an increase in production of Asc.-, and (iii) this method dose not require removal of organs. Using this method, Asc.- can serve as an indicator of the amount of HO and O2.- produced by irradiation in vivo.