Zweier J L, Kuppusamy P
Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21224.
Proc Natl Acad Sci U S A. 1988 Aug;85(15):5703-7. doi: 10.1073/pnas.85.15.5703.
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 microM 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.
自由基被认为是多种器官和组织中疾病的重要介质。电子顺磁共振（EPR）光谱可用于直接测量自由基；然而，由于传统的光谱仪设计不适合对整个器官或组织进行测量，因此无法原位测量重要的生物自由基。我们报告了一种EPR光谱仪的开发，该光谱仪设计用于在完整生物器官或组织中测量自由基时具有最佳性能。该光谱仪由一个1至2 GHz的微波桥组成，其源锁定在一个凹陷间隙环形间隙谐振器的谐振频率上。使用该光谱仪，可以测量低至0.4 microM的自由基浓度。对离体跳动心脏进行了研究，同时对自由基和心脏收缩功能进行了实时测量。这种体内EPR技术被应用于研究正常灌注和全心缺血心脏中自由基摄取和代谢的动力学。此外，我们表明该技术可用于无创测量组织氧消耗。因此，证明了EPR光谱可用于直接测量体内自由基代谢和组织氧消耗。该技术在研究体内自由基生成以及这种自由基生成对整个生物组织的影响方面具有巨大潜力。
