Nitroxide free radical clearance in the live rat monitored by radio-frequency CW-EPR and PEDRI

• Published in: Physics in medicine & biology 1998-07, Vol.43 (7), p.1899-1905
• Main Authors: Alecci, Marcello, Seimenis, Ioannis, McCallum, Stephen J, Lurie, David J, Foster, Margaret A
• Format: Article
• Language: English
• Subjects: Animals; Biophysical Phenomena; Biophysics; Cyclic N-Oxides - pharmacokinetics; Electron Spin Resonance Spectroscopy - methods; Evaluation Studies as Topic; Female; Free Radicals - metabolism; Magnetic Resonance Spectroscopy - methods; Nitrogen Oxides - metabolism; Rabbits; Radio Waves; Rats; Rats, Sprague-Dawley; Spin Labels
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/43/7/011

The use of RF (100 to 300 MHz) PEDRI and CW-EPR techniques allows the in vivo study of large animals such as whole rats and rabbits. Recently a PEDRI instrument was modified to also allow CW-EPR spectroscopy with samples of similar size and under the same experimental conditions. In the present study, this CW-EPR and PEDRI apparatus was used to assess the feasibility of the detection of a pyrrolidine nitroxide free radical (2,2,5,5,-tetramethylpyrrolidine-1-oxyl-3-carboxylic acid, PCA) in the abdomen of rats. In particular, we have shown that after the PCA administration (4 mmol kg(-1) b.w.): (i) the PCA EPR linewidth does not show line broadening due to concentration effects; (ii) a similar PCA up-take phase is observed by EPR and PEDRI; and (iii) the PCA half-lives in the whole abdomen of rats measured with the CW-EPR (T1/2=26+/-4 min, mean+/-sd, n=10) and PEDRI (T1/2=29+/-4 min, mean+/-sd, n=4) techniques were not significantly different (p > 0.05). These results show, for the first time, that information about PCA pharmacokinetics obtained by CW-EPR is the same as that from PEDRI under the same experimental conditions.