Persistent changes in myocardial glucose metabolism in vivo during reperfusion of a limited-duration coronary occlusion

Background-Rapid reperfusion of an occluded coronary artery salvages region al mechanical function, but this benefit may not be realized for hours or d ays because of postischemic stunning, Recovery from stunning is incompletel y understood but may involve adaptive changes in heart glucose metabolism, Methods and Results-To examine whether reversible coronary occlusion produc es sustained changes in regional glucose metabolism in vivo, we performed a 20-minute left coronary artery occlusion followed by 24 hours of open-arte ry reperfusion in intact rats. Coronary occlusion produced stunning of the anterolateral left ventricle that resolved over 24 hours. When examined at 24 hours, reperfused regions were fully contractile and viable by vital sta ining and microscopy but demonstrated 25% reduction in blood flow and 50% i ncreased uptake of circulating glucose, as estimated by in vivo [N-13]NH3 a nd [F-18]fluorodeoxyglucose (FDG) tracer uptake. Reperfused regions had lar gely inactive glycogen synthase, low rates of glycogen synthesis, and persi stent 50% glycogen depletion but increased flux of plasma [1-C-13]glucose i nto myocardial [3-C-13]alanine, indicating preferential shunting of importe d glucose away from storage and into glycolysis, Conclusions-Sustained increases in regional glycolytic consumption of circu lating glucose occur during reperfusion of a limited-duration coronary occl usion, This suggests a role for glycolytic ATP in the recovery from postisc hemic stunning in vivo. Furthermore, [N-13]NH3/FDG regional mismatch may co nstitute a clinically accessible late metabolic signature of regional myoca rdial ischemia.