Quantitative assessment of free-radical generation during ischemia and reperfusion in the isolated rabbit heart

BACKGROUND: Several investigators have indirectly implicated oxygen free radicals in reperfusion injury following ischemia in the isolated rabbit heart. METHODS: A quantitative assessment of free-radical production during ischemia and reperfusion was made using electron paramagnetic resonance (EPR) spectroscopy. Serial frozen (77 degrees K) tissue biopsies of the left ventricular wall in isolated rabbit hearts were performed during perfusion, ischemia, and reperfusion. These were pulverized into a fine powder that was filled into EPR tubes. EPR spectra of the tissue were recorded at 77 degrees K. RESULTS: Three predominant signals were seen on EPR analysis: signal A, g = 2.028; signal B, g = 2.005, and signal C, g = 1.940. All three signals were present during the perfusion period and decreased in size during the period of ischemia. After reperfusion, all three signals doubled in size. CONCLUSION: This study lends direct support to the theory that free radicals are generated during myocardial reperfusion and may result in reperfusion injury.