title: Importance of renal mitochondria in the reduction of TEMPOL, a nitroxide radical.
abstract: Spin probing methods using an electron spin resonance (ESR) spectrometer are used extensively and bring us a lot of information about in vivo redox mechanisms. However, the in vivo reducing mechanisms of exogenous nitroxide radicals, which serve as typical spin probing reagents are not clear. To clarify this, we examined the sequential kinetics of a spin probe, 4-hydroxy 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) in the in vivo organs, tissue homogenates and subcellular fractions of kidney and liver using an in vivo and X-band ESR spectrometers. As a parameter of reducing activity, we calculated the half-life of TEMPOL from the decay curve of ESR signal intensity. The half-life of TEMPOL in the whole organs and homogenates of the kidney was significantly shorter than that of the liver, this indicates that the kidney has more reducing activity against TEMPOL as compared to the liver. Subcellular fractional studies revealed that this reducing activity of the kidney mainly exists in the mitochondria. Contrarily, in addition to reduction in the mitochondria, TEMPOL in the liver was reduced by the microsome and cytosol.
authors.affiliation: Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ueda
authors.forename: Sohji
authors.initials: S
authors.lastname: Nagase
authors.forename: Hidekatsu
authors.initials: H
authors.lastname: Yokoyama
authors.forename: Mika
authors.initials: M
authors.lastname: Tada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noda
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kamada
authors.forename: Aki
authors.initials: A
authors.lastname: Hirayama
authors.forename: Akio
authors.initials: A
authors.lastname: Koyama
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013113:Spin Labels; D013347:Subcellular Fractions; D013997:Time Factors
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D009589:Nitrogen Oxides; D013113:Spin Labels; C039900:nitroxyl; D010100:Oxygen; C001803:tempol