RESUMEN
Fischer 344 rats were injected with the spin traps C-phenyl N-tert-butyl nitrone (PBN, 150 mg/kg bw, ip) or 4-pyridine-N-oxide N-tert-butyl nitrone (POBN, 775 mg/kg bw, ip), and exposed to clean air or 2 ppm ozone for two hours. The presence of spin adducts was determined by electron paramagnetic resonance (EPR) spectroscopy of chloroform extracts of lung and liver homogenates. No significant levels of adducts were detected in the lungs of air control animals. Benzoyl N-tert-butyl aminoxyl, attributed to direct reaction of ozone with PBN, and tert-butyl hydroaminoxyl, the scission product of the hydroxyl adduct of PBN, were detected in the lungs of ozone exposed rats. EPR signals for carbon-centred alkoxyl and alkyl adducts were also detected with PBN in the lungs and liver of animals exposed to ozone. With POBN, only carbon-centred alkyl radicals were detected. Senescent, 24 months old rats were found to retain about twice more 14C-PBN in blood, heart and lungs by comparison to juvenile, 2 months old animals. Accordingly, the EPR signals were generally stronger in the lungs of the senescent rats by comparison to juvenile rats. Together, the observations were consistent with the previously proposed notion that a significant flux of hydrogen peroxide produced from the reaction of ozone with lipids of the extracellular lining, or from activated macrophages in the lungs could be a source of biologically relevant amounts of hydroxyl radical.
Asunto(s)
Hígado/efectos de los fármacos , Pulmón/efectos de los fármacos , Oxidantes Fotoquímicos/toxicidad , Ozono/toxicidad , Detección de Spin , Animales , Óxidos N-Cíclicos , Espectroscopía de Resonancia por Spin del Electrón , Hígado/química , Pulmón/química , Masculino , Óxidos de Nitrógeno/química , Ratas , Ratas Endogámicas F344 , Marcadores de SpinRESUMEN
Free radicals were detected from the in vitro metabolism of halothane (rat liver microsomes) by the PBN spin trapping method. The detected radical species include the 1-chloro-2,2,2-trifluoro-1-ethyl radical (I), as determined by mass spectral analysis, and lipid-type radicals assigned by high resolution ESR spectroscopy with the use of d14-deuterated PBN. The lipid-derived radicals are a carbon-centred radical with the partially assigned structure CH2R and an oxygen-centred radical of the OR' type. From the mass spectral analysis of the spin adduct mixture there is also evidence for a halocarbon double adduct of PBN of the type I-PBN-I.
Asunto(s)
Radicales Libres , Halotano/metabolismo , Microsomas Hepáticos/metabolismo , Óxidos de Nitrógeno , Marcadores de Spin , Animales , Óxidos N-Cíclicos , Espectroscopía de Resonancia por Spin del Electrón , Cromatografía de Gases y Espectrometría de Masas , Técnicas In Vitro , Masculino , Ratas , Ratas EndogámicasRESUMEN
General procedures for the synthesis and purification of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and its synthetic intermediates for electron paramagnetic resonance (EPR) spin trapping is described. The synthetic methods are not new per se and are based on Todd's original scheme (1959). In contrast to his account, however, we provide a detailed description of the numerous procedures and precautions necessary to obtain DMPO of very high 'chemical' and (most importantly) 'EPR' purity for use in biological spin trapping.
Asunto(s)
Óxidos N-Cíclicos/síntesis química , Marcadores de Spin/síntesis química , Óxidos N-Cíclicos/aislamiento & purificación , Espectroscopía de Resonancia por Spin del ElectrónRESUMEN
The spin trapping chemistry of carbon tetrachloride has been previously investigated in rat liver, both in vitro and in vivo. In addition to the trichloromethyl radical, both a 'carbon-centered' and an 'oxygen-centered' radical have been detected in vitro. These spin adducts have been assigned to 'lipid' and 'lipid oxyl' radicals. However, no specific structural characterization has been provided to date. The spin trapping chemistry of this system was reinvestigated with the use of deuterated alpha-phenyl N-tert-butyl nitrones to obtain better spectral resolution. Results indicate that the PBN trapped carbon-centered lipid radical is of a primary alkyl type.