Examination of two small-molecule antiperoxidative agents in a rabbit model of postischemic myocardial infarction

Peroxidation of membrane phospholipid may be a causal contributor to the development of irreversible postischemic myocardial injury. In this study, two small-molecule antiperoxidative agents were tested for their ability to salvage reperfused rabbit myocardium and reduce infarct size as assessed by direct histological evaluation of hearts following a 30-min occlusion of a coronary arterial branch and a 72-h reperfusion period. The compounds tested are novel analogs of alpha-tocopherol (vitamin E), and share with the parent compound an ability to scavenge the peroxyl radicals that propagate and amplify lipid peroxidation initiated by partially reduced oxygen; however, the new analogs are significantly more potent peroxyl-radical scavengers that alpha-tocopherol. Each antiperoxidant (3 mg/kg) was administered by intravenous bolus injection in two stages: 20% of the total dose was given 15 min before occlusion, and the remaining 80% was given 5 min before reperfusion. The results revealed that neither antiperoxidant offered a sustained reduction in infarct size (expressed as a percentage of the region at risk) as compared to a nontreated vehicle control. The implications of the present study with respect to the purported cardioprotective effects of antiperoxidants in the setting of ischemia reperfusion and the pathogenic role of lipid peroxidation in the postischemic heart are discussed.