title: Importance of volume limitation for tissue redox status measurements using nitroxyl contrast agents: a comparison of X-band EPR bile flow monitoring (BFM) method and 300 MHz in vivo EPR measurement.
abstract: Methods proposed for in vivo redox status estimation, X-band (9.4 GHz) electron paramagnetic resonance (EPR) bile flow monitoring (BFM) and 300 MHz in vivo EPR measurement, were compared. The spin probe 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) was utilized for both methods, due to its suitable lipophilicity. EPR signal decay of a nitroxyl spin probe in the bile flow and in the liver region (upper abdomen) of several rat groups with different selenium status were measured by both the BFM and the in vivo EPR method, respectively. The nitroxyl radical clearance measured with in vivo EPR method may be affected not only by the redox status in the liver but also by information from other tissues in the measured region of the rat. On the other hand, the time course of nitroxyl radical level in the bile flow of rats was found to be a reliable index of redox status. Measurement site and/or volume limitation, which was achieved by the BFM method in this paper, is quite important in estimating reasonable EPR signal decay information as an index of tissue/organ redox status.
authors.affiliation: Department of Physical Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan.
authors.forename: Iori
authors.initials: I
authors.lastname: Ui
authors.forename: Aya
authors.initials: A
authors.lastname: Okajo
authors.forename: Kazutoyo
authors.initials: K
authors.lastname: Endo
authors.forename: Hideo
authors.initials: H
authors.lastname: Utsumi
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism*; D003287:Contrast Media / Q000493:pharmacokinetics*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009589:Nitrogen Oxides / Q000493:pharmacokinetics*; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D012643:Selenium / Q000378:metabolism; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D009589:Nitrogen Oxides; D013113:Spin Labels; C039900:nitroxyl; D012643:Selenium