In Vivo Imaging of Free Radicals and Oxygen
Free radicals are highly reactive compounds that play an essential role in many biological processes, both beneficial and deleterious. Detection and quantification of these species is critical to develop a better understanding of normal and pathophysiological functions at the cellular and tissue levels. Electron paramagnetic resonance (EPR) spectroscopy is the technique most commonly used for this purpose through the detection of exogenous probes or spin traps that interact with the free radical species of interest. Over the past several years, the spatial and temporal distribution of free radicals within cells and tissues has been of particular interest. This chapter briefly explains the principles and challenges in the use of EPR for biological samples and introduces the concept of EPR for free radical imaging purposes. In addition, specific examples are given for the use of EPR imaging in four principal areas: free radical probes, nitric oxide (•NO), redox state, and oxygen (O2) concentration.
Key wordsFree radicals EPR spectroscopy imaging nitric oxide nitroxyl redox state metabolism oximetry
The EPR imaging results illustrated in the review were composed from several publications from our laboratory. We gratefully acknowledge the publishers of the respective journals for permitting us to reproduce the figures used in this article. The work was supported by the NIH grants CA102264, EB004031, and EB005004.
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