Nitroxide free radical clearance in the live rat monitored by radio-frequency CW-EPR and PEDRI.
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.
Department of Biomedical Physics and Bioengineering, University of Aberdeen, Foresterhill, UK.
M
M
Alecci
I
I
Seimenis
S J
SJ
McCallum
D J
DJ
Lurie
M A
MA
Foster
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D003497:Cyclic N-Oxides / Q000493:pharmacokinetics; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005069:Evaluation Studies as Topic; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009589:Nitrogen Oxides / Q000378:metabolism*; D011817:Rabbits; D011846:Radio Waves; D051381:Rats; D017207:Rats, Sprague-Dawley; D013113:Spin Labels
D003497:Cyclic N-Oxides; D005609:Free Radicals; D009589:Nitrogen Oxides; D013113:Spin Labels; C032289:2,2,5,5-tetramethyl-1-pyrrolidinyloxy-3-carboxylic acid