[Distribution of nitroxide radical compounds and its reducing activity in liver, spleen and kidney of rat by electron spin resonance (ESR) spectroscopy].

The time courses of intensity changes of X-band electron spin resonance (ESR) spectra in the blood, liver, spleen, kidney and porta hepatis of rats were examined after 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxyl (carbamoyl-PROXYL) was perorally administered. The quenching activities of nitroxide radicals were determined using homogenate of the organs of individual rats. It was found that administrated nitroxide radicals were delivered to the liver, spleen, and kidney after peroral administration, where ESR signal intensities in the blood decreased gradually. The concentration of the elivered nitroxide radical varied with the individual organs. The quenching activity of the nitroxide radical for the homogenate of the porta hepatis was the highest before administration, while the concentration due to the reduced deoxidized-nitroxide radical compounds after 4 h of peroral administration was shown to be high in the kidney. It is concluded that the nitroxide radical compound is quenched in the porta hepatis of the liver, while the reduced nitroxide radical compound is delivered to the kidney.