Recently we demonstrated the principal possibility of application of F-19 NMR spin-trapping technique for in vivo (NO)-N-center dot detection [Free Radic. Biol. Med. 36 (2004) 248]. In the present Study, we employed this method to elucidate the significance of (NO)-N-center dot availability in animal models of hypertension. In vivo (NO)-N-center dot-induced conversion of the hydroxylamine of the fluorinated nitronyl nitroxide (HNN) to the hydroxylamine of the iminonitroxide (HIN) in hypertensive ISIAH and OXYS rat strains and normotensive Wistar rat strain was measured. Significantly lower HIN/HNN ratios were measured in the blood of the hypertensive rats. The NMR data were found to positively correlate with the levels of nitrite/nitrate evaluated by Griess method and negatively correlate with the blood pressure. In comparison with other traditionally used methods 19F NMR spectroscopy allows in vivo evaluation of (NO)-N-center dot production and provides the basis for in vivo (NO)-N-center dot imaging. (c) 2005 Elsevier Inc. All rights reserved.