Evaluation of free radical and lipid peroxide formation during global ischemia and reperfusion in isolated perfused rat heart.

Free radical species have been implicated as important agents involved in myocardial ischemic and reperfusion injuries. In our study, formation of free radicals was measured directly with electron paramagnetic resonance spectroscopy before ischemia, during 10 minutes of global ischemia, and 20 seconds after reperfusion in the rat heart. We also investigated the formation of thiobarbituric acid-reactive material as index of lipoperoxidation induced by free radicals and measured arrhythmias. Production of free radicals takes place during ischemia since the signal intensity with a g value of 2.004 attributed to free radical species was increased by 50% after 10 minutes of global ischemia. In hearts reperfused with oxygenated perfusate for 20 seconds, the signal doubled. These experiments supply evidence that free radicals are generated in isolated rat heart during a short period of global ischemia and reperfusion. However, this increase was not associated with a concomitant increase of lipid peroxides in the myocardium nor with the development of reperfusion arrhythmias.