Abstract: Nitronyl nitroxides, NN*, have been increasingly used in the field of NO-related studies as specific antagonists of NO*. We employed a combination of EPR and NMR spin trapping to study the mechanisms of the reaction of NN* with NO* in reducing environments. EPR allowed observation of NO-induced transformation of the paramagnetic trap, NN*, to the corresponding iminonitroxide, IN*. In a complementary way, corresponding EPR-invisible diamagnetic products (the hydroxylamines NN-H and IN-H) were detected by F-19-NMR using newly synthesized fluorinated traps. Addition of reducing agents to a solution of NN* resulted in fast disappearance of its EPR spectra and appearance of a F-19-NMR peak of the corresponding hydroxylamine, NN-H. Addition of NO* as a bolus, or NO* generated on sodium nitroprusside photolysis, resulted in F-19-NMR-detectable accumulation of the hydroxylamine, IN-H. Upon high rates of NO* generation in ascorbate-containing solutions, partial recovery of NN* was observed, which undergoes further reactions with NO* and ascorbate in a competitive manner. Using 19F-NMR and a fluorinated trap, NO-induced conversion of NN-H into IN-H was also observed in vivo in hypertensive ISIAH rats compared with normotensive WAG rats. The results provide insight into a new potential redox-sensitive mechanism of the antagonistic action of NN* against NO*, which may provide insight into previously unexplained behavior of this category of NO-reacting compounds. (C) 2003 Elsevier Inc. All rights reserved.

Cite: Bobko A. , Bagryanskaya E. , Reznikov V. , Kolosova N. , Clanton T. , Khramtsov V.
Redox-sensitive mechanism of no scavenging by nitronyl nitroxides
Free Radical Biology and Medicine. 2004. V.36. N2. P.248-258. DOI: 10.1016/j.freeradbiomed.2003.10.022 WOS Scopus РИНЦ

Dates:

Published print:

Jan 15, 2004

Identifiers:

Web of science	WOS:000188817700012
Scopus	2-s2.0-1642505507
Elibrary	13466944
OpenAlex	W2052724241

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