Reduction of myocardial ischemic injury with oxygen-derived free radical scavengers.

Experimental data suggesting that oxygen-derived free radicals may play a role in the myocardial injury associated with ischemia and reperfusion are presented. In several studies of prolonged global myocardial ischemia, the administration of free radical scavenging agents, such as superoxide dismutase, catalase, and mannitol, resulted in significantly better recovery of left ventricular function following reperfusion. In a region-at-risk model of localized myocardial ischemia, both superoxide dismutase and allopurinol significantly reduced the extent of myocardial necrosis that developed following reversible coronary arterial branch occlusion. The manner in which oxygen-derived free radicals may be harmful is examined. In particular, the possibility that these toxic species are involved in the exacerbation of the ischemic injury that develops upon reflow and reoxygenation is examined.