Myocardial reperfusion injury in the canine model after 40 minutes of ischemia: effect of intracoronary adenosine.

To explore the contribution of reperfusion injury to final infarct size after a short duration of ischemia, closed-chest dogs underwent 40 minutes of proximal left anterior descending artery occlusion followed by 3 days of reperfusion. Animals randomly received intracoronary adenosine (n = 8) at 3.75 mg/min during the first hour of reperfusion or no therapy (control, n = 9). Infarct size was measured histologically. Regional ventricular function was determined with contrast ventriculography. The risk region was similar and collateral blood flow in the inner two thirds of the ischemic zone was markedly reduced in both groups (adenosine: 0.05 +/- 0.07 ml/min/gm; control: 0.02 +/- 0.07 ml/min/gm; p = NS). Infarct size as a percent of the area at risk was significantly reduced in the adenosine group (5.0 +/- 1.3% versus 13.5 +/- 3.2%; p = 0.03), associated with a trend for improved recovery of regional ventricular function. Relative endothelial preservation was seen in the adenosine group. These results suggest that reperfusion injury contributes to final myocardial cell necrosis in the closed-chest canine model subjected to 40 minutes of regional ischemia.