Non-invasive measurement of in vivo free radical reactions]

It was proven that in vivo free radicals roles in various physiological phenomena and many diseases such as inflammation, ischemic disease, digestive problems and neurodegeneration, thus making measurements of free radicals very important for determining the mechanisms of these diseases. Spin trapping method using ESR, salicylic acid methods using high performance liquid chromatography and chemiluminescent methods are reported for ex vivo and in situ measurements. And, among these techniques, in vivo ESR is the most powerful for performing non-invasive measurements in animals. In in vivo ESR, exogenous nitroxyl radicals are administered to animal and then by measuring the signal change, the radical reaction can be indirectly determined. The signal decay rate is enhanced by oxidative stress, and this enhanced signal decay is suppressed by giving radical scavengers, etc. By analyzing the enhancement of this attenuation in detail, it is possible to specify the type of radical or the location at which the free radicals are produced. Such non-invasive techniques to measure free radicals like the present in vivo ESR technique should provide considerable information for elucidating the mechanisms of diseases.