Detection of myocardial ischemia before infarction, based on accumulation of labeled pyruvate

To determine whether ischemic, but not irreversibly injured myocardium, can be differentiated from normal tissue based on accumulation of labeled pyruvate, isolated hearts were perfused with buffer containing [14C]pyruvate under conditions of normal or low flow. Fifteen minutes after the hearts were exposed to labeled material, myocardial radioactivity was fourfold greater in ischemic compared to control hearts, due to accumulation of label in sequestered lactate produced from the pyruvate. Open-chest rabbits subjected to coronary occlusion exhibited a 1.73:1 ratio of radioactivity in ischemic compared with normal myocardium 15 min after systemic injection of [14C]pyruvate. The results obtained suggest that zones of myocardial ischemia should be detectable in vivo by positron tomography after systemic administration of [11C]pyruvate as well.