The occurrence of oxidative stress during reperfusion in experimental animals and men.

Reperfusion is the prerequisite for the ischemic myocardium to recover its metabolic and mechanical function. However, reperfusion after a prolonged period of ischemia in the experimental animal may exacerbate, or at least accelerate, the occurrence of ischemic injury, whilst in humans at the least it is not beneficial. This entity has been called reperfusion damage, since much of the damage is believed to be caused by events occurring at the moment of reperfusion rather than by changes occurring during ischemia. The existence of reperfusion damage, however, has been questioned, and evidence in favour of the concept is sparse. At the moment the molecular events occurring at the time of reperfusion are not completely understood, and the relative importance of several proposed deleterious mechanisms is not yet established. One of the most fashionable ideas for the cause of reperfusion damage is that the function of cell membrane is modified by oxygen radicals generated at the moment of reperfusion. Evidence in favour of and against this hypothesis is described in detail in the present article.