IDENTIFICATION AND EVALUATION OF FREE-RAD ICALS IN THE SEQUENCE OF CARDIAC ISCHEMIA-REPERFUSION

The role of free radicals (FR) has been suggested in the development o f ischaemia-induced myocardial reperfusion. When the equilibrium betwe en 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 substa nces interfering with the production or the elimination of FR or of sy stems which produce FR on the physiopathological consequences of ischa emia and reperfusion. A physico-chemical technique, Electronic Paramag netic Resonance (EPR) has been used in biology. The high reactivity an d 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 re action which forms covalent bonds with FR and forms a stable, detectab le radical product. This technique has enabled identification and eval uation of FR liberated in the perfusion fluid of isolated perfused rat hearts and to determine the importance of the different mechanisms of production.