[Identification and evaluation of free radicals in the sequence cardiac ischemia-reperfusion]

The role of free radicals (FR) has been suggested in the development of ischaemia-induced myocardial reperfusion. When the equilibrium between the cellular sources and defense system is disturbed, FR may react with cellular components and produce a number of lesions. In general, the action of FR is shown indirectly by studying the effects of substances interfering with the production or the elimination of FR or of systems which produce FR on the physiopathological consequences of ischaemia and reperfusion. A physico-chemical technique, Electronic Paramagnetic Resonance (EPR) has been used in biology. The high reactivity and the very short life span of several types of FR pose methodological problems. A "stabilisation" of FR may be obtained by spin-trapping, a technique which consists of adding a diamagnetic substance to the reaction which forms covalent bonds with FR and forms a stable, detectable radical product. This technique has enabled identification and evaluation of FR liberated in the perfusion fluid of isolated perfused rat hearts and to determine the importance of the different mechanisms of production.