Nitroxides
have unique biochemical properties, and thus they have been used for many biomedical
applications. However, although piperidine nitroxide (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl: Tempol) has been presently
tested in clinical trials, details concerning the distribution and kinetics of
Tempol in vivo have not been thoroughly
studied. In particular, it is not clear whether Tempol enters the brain as
paramagnetic materials with an unpaired electron. To examine this matter, electron
paramagnetic resonance (EPR) imaging study of mouse brains was conducted using
a modified EPR imager. The obtained EPR images clearly showed that Tempol could
enter the brain with an unpaired electron.
