Cardiac proteomic responses to ischemia-reperfusion injury and ischemic preconditioning.
ABSTRACT Cardiac ischemia and ischemia-reperfusion (I/R) injury are major contributors to morbidity and mortality worldwide. Pathological mechanisms of I/R and the physiological mechanisms of ischemic preconditioning (IPC), which is an effective cardiac protective response, have been widely investigated in the last decade to search for means to prevent or treat this disease. Proteomics is a powerful analytical tool that has provided important information to identify target proteins and understand the underlying mechanisms of I/R and IPC. Here, we review the application of proteomics to I/R injury and IPC to discover target proteins. We analyze the functional meaning of the accumulated data on hundreds of proteins using various bioinformatics applications. In addition, we review exercise-induced proteomic alterations in the heart to understand the potential cardioprotective role of exercise against I/R injury. Further developments in the proteomic field that target specialized proteins will yield new insights for optimizing therapeutic targets and developing a wide range of therapeutic agents against ischemic heart disease.
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ABSTRACT: It is now appreciated that mitochondrial creatine kinase (CKm) may play an important role in heart high-energy phosphate metabolism and that this isozyme is solubilized in vitro by dilute solutions of Pi. Since an increase in cellular Pi is known to occur with even brief periods of myocardial ischemia, we investigated the relationship between CKm activity and myocardial performance in rabbit hearts subjected to total global ischemia. CKm activity is expressed as a ratio to mitochondrial malate dehydrogenase (MDHm), a stable marker enzyme. A significant decline in this ratio was observed after only 10 min of ischemia, a time prior to changes in total homogenate creatine kinase activity. After 60 min of ischemia, the CKm/MDHm ratio was depressed by more than 70%. Since there was no restoration of activity following 30 min of reperfusion, we correlated changes in enzyme activity to contractile dysfunction following variable periods of total ischemia. The data showed a close correlation between the decline in the CKm/MDHm ratio and the reduction in performance, measured as left ventricular developed pressure. No correlation was observed between State 3 respiratory rates and performance. Using KCl arrest at 27 degrees C or hyperthermic ischemia at 40 degrees C, the CKm/MDHm ratio consistently correlated to the degree of postischemic functional depression, independent of the duration of ischemia. Isoenzyme electrophoresis failed to detect soluble CKm activity in the postischemic supernatant. Therefore, CKm activity appears to be altered rapidly and irreversibly by ischemia. The implications of these observations on the integration of myocardial high-energy phosphate metabolism are discussed.Journal of Biological Chemistry 02/1985; 260(1):208-14. · 4.65 Impact Factor
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ABSTRACT: Acute myocardial ischemia induced by coronary occlusion in dogs is most severe in the subendocardial region, whereas more collateral blood flow is often present in the subepicardial region. Initially, all ischemic myocytes are reversibly injured, but beginning at 15 to 20 minutes after the onset, and continuing for 3 to 6 hours, there is a wave front of cell death from the subendocardial region to the less ischemic subepicardial region, such that by 6 hours, the final transmural extent of the infarct is established. Thus, ischemic myocardium cannot be salvaged by reperfusion after greater than or equal to 6 hours of coronary occlusion in open-chest anesthetized dogs. In the severely ischemic subendocardial region, most of the creatine phosphate is lost within the first 3 minutes of ischemia in vivo, and adenosine triphosphate (ATP) is depleted to 35% of control by 15 minutes (when cellular injury is still reversible), and to less than 10% of control at 40 minutes (when injury is irreversible). Tissue ATP content and other indexes of subcellular damage have also been compared after different periods of ischemia using a model of total myocardial ischemia in vitro. As long as the ATP of the tissue was not depleted below 5 mumols/g dry weight, incubated slices of injured myocardium resynthesized high-energy phosphates and excluded inulin. However, lower tissue ATP was associated with depressed high-energy phosphate resynthesis and failure of cell volume regulation. Overt membrane damage, as measured by an increased inulin-diffusible space, was detected only after the tissue ATP decreased to less than 2.0 mumols/g of dry weight. Thus, marked ATP depletion is associated with the onset of structural and functional indexes of irreversible injury. However, whether irreversibility is caused by the marked ATP depletion or by other concomitant metabolic consequences of ischemia is not known. Myocardial ischemic cellular injury is reversible despite depletion of 70% of the control ATP. Nevertheless, when myocyte injury is reversible, there is slow repletion of adenine nucleotides. This slow metabolic recovery may explain the delayed recovery of contractile function observed after reperfusion of ischemic myocardium.The American Journal of Cardiology 08/1983; 52(2):72A-81A. · 3.21 Impact Factor
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ABSTRACT: The effects of myocardial ischemia and reperfusion on pyruvate dehydrogenase (PDH) activity were studied in isolated rat hearts. PDH remained largely (80%) in the active form during 10 min of whole heart ischemia in hearts receiving 11 mM glucose as substrate. With reperfusion, PDH was converted to the inactive form (45% by 2 min) and then returned slowly to control levels. Addition of pyruvate (10 mM) to the glucose containing perfusate during reperfusion prevent the reperfusion inactivation of PDH (96% active). The maintenance of a high percent of PDH in the active form during ischemia occurred in spite of high mitochondrial ratios of NADH/NAD and acetyl CoA/CoA and was related to a very low mitochondrial ATP/ADP ratio. The low ATP and high ADP would restrict PDH kinase phosphorylation and inactivation of PDH during ischemia. Reperfusion resulted in a rapid increase in mitochondrial ATP/ADP ratio and the increased availability of ATP as substrate for the kinase coupled with continued high levels of NADH and acetyl CoA which stimulate kinase activity may have accounted for the early inactivation of PDH with reperfusion. Addition of pyruvate to the perfusate probably inhibited the PDH kinase and prevent the reperfusion inactivation of PDH.Journal of Molecular and Cellular Cardiology 07/1983; 15(6):359-67. · 5.15 Impact Factor