Electron paramagnetic resonance measurements of free radicals in the intact beating heart: A technique for detection and characterization of free radicals in whole biological tissues

J. L. Zweier, P. Kuppusamy

Research output: Contribution to journalArticle

Abstract

Free radicals have been hypothesized to be important mediators of disease in a variety of organs and tissues. Electron paramagnetic resonance (EPR) spectroscopy can be applied to directly measure free radicals; however, it has not been possible to measure important biological radicals in situ because conventional spectrometer designs are not suitable for the performance of measurements on whole organs or tissues. We report the development of an EPR spectrometer designed for optimum performance in measuring free radicals in intact biological organs or tissues. This spectrometer consists of a 1- to 2-GHz microwave bridge with the source locked to the resonant frequency of a recessed gap loop-gap resonator. With this spectrometer, radical concentrations as low as 0.4 μM can be measured. Isolated beating hearts were studied in which simultaneous real time measurements of free radicals and cardiac contractile function were performed. This in vivo EPR technique was applied to study the kinetics of free radical uptake and metabolism in normally perfused and globally ischemic hearts. In addition, we show that this technique can be used to noninvasively measure tissue oxygen consumption. Thus, it is demonstrated that EPR spectroscopy can be applied to directly measure in vivo free radical metabolism and tissue oxygen consumption. This technique offers great promise in the study of in vivo free radical generation and the effects of this radical generation on whole biological tissues.

Original languageEnglish (US)
Pages (from-to)5703-5707
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume85
Issue number15
StatePublished - 1988

ASJC Scopus subject areas

  • General
  • Genetics

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