Metabolic responses to varying restrictions of coronary blood flow in swine.

An in situ working swine heart preparation is described in which total coronary perfusion was controlled. At normal rates of coronary flow, oxygen, glucose, and fatty acid utilization were stable for at least a 60-min perfusion period. With a 50% reduction in coronary flow, oxygen and glucose consumption were reduced during 30 min of perfusion and fatty acid extraction was lower at the end of 30 min. Glycogen utilization was increased, but tissue levels of creatine phosphate, ATP, and lactate were similar to those in hearts receiving normal flow. With a 60% reduction in coronary flow, uptake of oxygen, glucose, and fatty acids were further decreased. Tissue levels of high-energy phosphates and glycogen were decreased and ADP, AMP, and lactate increased. Mechanical performance progressively deteriorated in these hearts, and ventricular fibrillation developed after about 20 min (19.8 plus or minus 3.0 min). The data indicate that this preparation is suitable for the study of myocardial metabolism during mild and severe ischemia and may be useful for the evaluation of pharmacological interventions designed for the treatment of myocardial ischemia.