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Transfusion of fresh but not old stored blood reduces infarct size and improves cardiac function after acute myocardial infarction in anemic rats*

Objectives:We recently demonstrated that transfusion of fresh blood to 100 g/L hemoglobin in anemic animals offers cardioprotection after acute myocardial infarction. The objective of this study was to compare the cardioprotective effects of fresh vs. stored blood when transfused in anemic rats after acute myocardial infarction. Study Design:Randomized animal study. Setting:University laboratory. Subjects:Male Sprague-Dawley rats weighing 200–300 g. Intervention:Myocardial infarction was induced by coronary artery ligation in 49 male Sprague-Dawley rats weighing 200–300 g, 38 of which were anemic (80–90 g/L) and 11 with normal hemoglobin levels. Anemic animals were randomized to receive fresh blood (within 4 hrs), stored blood (7 days), or no transfusion immediately after myocardial infarction. Measurements and Main Results:At 24 hrs after myocardial infarction, cardiac function, infarct size, and apoptosis were determined. Erythrocyte ATP, 2,3-DPG, hemoglobin, and free hemoglobin levels in the supernatant were determined. Transfusion with fresh but not stored blood significantly decreased infarct size and myocardial apoptosis in anemic rats when compared to anemic animals not undergoing transfusion. Cardiac function and survival were significantly improved in the anemic animals undergoing fresh blood transfusion compared to control anemic animals. Analysis of stored red blood cells showed reductions of intracellular ATP and 2,3-DPG levels and free hemoglobin was increased in the supernatant. Conclusions:The prolonged storage of blood negates the beneficial effects of fresh blood transfusion, which include reductions in infarct size and myocardial apoptosis, and improvements in cardiac function and short-term survival after acute myocardial infarction in this animal model.