THE ROLE OF CELL-FREE HEMOGLOBIN ON MYOCARDIAL ISCH-EMIC INJURY

Abstract

Background: Although cardioprotective effects of substrates such as amino acids or antioxidants have been examined, the role of cell-free hemoglobin on myocardial ischemia-reperfusion is uncertain. We evaluated its effects on myocardial functional recovery during warm ischemia and reperfusion in an isovolumic Langendorff rat heart model. Materials and Methods: Isolated hearts were perfused at 90 mmHg with Krebs-Henseleit buffer (KHB) in Group I (n = 8), KHB with cross-linked bovine hemoglobin (HC) (2.6 gm %) in Croup II (n = 8), cell culture medium (M 199) in Croup Ml (n = 8) or M199 with HG in Croup IV (n = 8). After 30 min equilibration, hearts were subjected to 15 min of normothermic no-flow ischemia followed by 60 min reperfusion. Following histopathological examinations were periormed: Masson's trichrome and apoptotic change (TUNEL assay). Results: Pre-ischemic LV performance (left ventricular developed pressure ILVDPI, and 5 LVdP/dt) and Coronary Flow (CF) were similar among groups. Compared to Group I, Groups 11, Ill and IV demonstrated improved LV performance after 15min reperfusion (p <0.05 for Group 11). Group 11, 111 and IV had similar hyperemic response of CF at initial reperfusion. After 6Omin reperfusion only Group 111 preserved both LV performance and CF equivalent to pre-ischemic level. The degree of contraction hand formation was similar and minimal among groups. TUNEL-positive endothelial cells were seen in both HC containing cells. Conclusions: Blood substitute enhanced early functional recovery but may have harmful effect (in endothelial cells.