CONTRACTION BAND NECROSIS - ITS MODIFICATION BY THE FREE-RADICAL SCAVENGER N-2-MERCAPTOPROPIONYL GLYCINE

Contraction band necrosis (CBN) may represent infarct extension from f ree radical generation during reperfusion. We sought to limit CBN with the free radical scavenger N-2-mercaptopropionyl glycine (MPG, 20 mg/ kg). Sixteen chronically instrumented Beagles (8 control, and 8 MPG tr eated) underwent 90-min left anterior descending coronary artery (LAD) occlusion followed by 6-h reperfusion. Coronary blood flow (CBF) was measured by the radioactive microsphere technique. The dogs were kille d, and the hearts were perfused with red and blue dyes to determine ar ea at risk (AAR), stained with nitroblue tetrazolium for infarct local ization, and sectioned for histologic analysis and BF measurements. In controls and MPG-treated animals, infarct/risk ratios were 40 +/- 5 a nd 38 +/- 6%, and epicardial collateral BFs were 0.21 +/- 0.037 and 0. 15 +/- 0.034 ml/g/min, respectively (p = NS). Hemodynamic measurements did not differ between the two groups. However, CBN as a percentage o f total infarct was reduced in controls (22 +/- 3%) as compared with M PG-treated animals (35 +/- 2%, p = 0.002). Thus, MPG altered the histo logic composition of infarcts in this model, surprisingly increasing t he amount of CBN without altering overall infarct size (IS). These res ults raise questions about the role of free radical scavengers in gene ration of CBN and suggest that a population of cells exists in which t reatment with MPG may alter the mechanism of cell death.