Myocardial metabolism and regional myocardial blood flow in the canine left ventricle following twenty minutes of circumflex artery occlusion and reperfusion.

The recovery of high energy phosphate stores (ATP plus phosphocreatine) was examined following various periods of reperfusion after 20 min circumflex artery occlusion in the open-chest dog. Transmural tissue samples were obtained from the posterior wall of the left ventricle of control dogs, after 20 min occlusion and after 1, 5, 10, 15 and 20 min reperfusion. Significant reductions in high energy phosphate stores were observed in the subepicardium (41.6% of control) and subendocardium (31.3% of control) after occlusion. Upon reperfusion, recovery was rapid and exceeded control by 65.4% (91.0 v. 55.0 microns/g dry wt) in the subendocardium, but only by 2.6% (72.2 v. 70.4, mumg/g dry wt) in the subepicardium and was due mainly to recovery of phosphocreatine. Regional myocardial blood flow was studied in a separate, but identical, series of experiments. During occlusion, posterior wall blood flow was reduced by 54% (0.85 +/- 0.04 to 0.37 +/- 0.04, ml/g/min) in the subepicardium and by 94.7% (1.13 +/- 0.05 to 0.06 +/- 0.005, ml/g/min) in the subendocardium. Reperfusion produced a rapid recovery including overshoot of blood flow compared to control blood flow. Peak blood flow occurred one minute after release of the occlusion becoming 3.34 +/- 0.16 ml/g/min in the subepicardium and 2.39 +/- 0.13 ml/g/min in the subendocardium. Blood flow in both levels returned to control flow after 15 min reperfusion. These results indicate that metabolic recovery of high energy phosphate stores occurred within 5 min of restoration of blood flow in this model.