T-0162, A Novel Free Radical Scavenger, Reduces Myocardial Infarct Size In Rabbits

SUMMARY 1. We investigated the effects of 1-(3-tert-butyl-2-hydroxy- 5-methoxyphenyl)-3-(3-pyridylmethyl)urea hydrochloride (T-0162), a novel low-molecular weight free radical scavenger, on the generation of superoxide anions and hydroxyl radicals in vitro and in vivo and on myocardial infarct (MI) size in an in vivo model of MI in rabbits. 2. It was found that T-0162 scavenged both superoxide anions and hydroxyl radicals in a concentration-dependent manner in vitro. 3. In an in vivo rabbit model with 30 min coronary occlusion and 30 min reperfusion, T-0162 scavenged hydroxyl radicals generated in the myocardium during reperfusion. 4. Anaesthetized open-chest Japanese white male rabbits were subjected to 30 min coronary occlusion and 48 h reperfusion. The control group (n = 10) was infused with 10% lecithin solution for 220 min from 10 min before occlusion to 180 min after reperfusion. The pretreatment group (n = 10) was infused with T-0162 dissolved in 10% lecithin solution for 220 min from 10 min before occlusion to 180 min after reperfusion at a rate of 400 μg/kg per min. The post-treatment group (n = 10) was injected with an i.v. bolus of 10 mg/kg T-0162 and was then infused with 400 μg/kg per min T-0162 for 190 min from 10 min before reperfusion to 180 min after reperfusion. After 48 h reperfusion, infarct size was measured histologically and expressed as a percentage of area at risk (AAR). 5. There was no significant difference in haemodynamic parameters among the three groups throughout the experimental period. The per cent infarct size of the AAR in the T-0162 groups (24.8±4.3 and 30.5±3.9% for pre- and post- treatment groups, respectively) was significantly reduced compared with control (44.7±4.1%; P < 0.05). There was no significant difference in the AAR among the three groups. 6. In conclusion, T-0162 reduces MI size through the inhibition of reperfusion injury.