| ObjectiveModel of neonate rat cardiomyocyte H/R injury was established to explore the protective effects of erythropoietin(EPO). The apoptosis and oxdizing reaction of cardiomyocyte and ERK1/2- related protein was observed to reveal the mechanism and signal path of EPO against H/R injury.MethodsNeonate rat cardiomyocyte was isolated and cultured to establish model of H/R. Cardiomyocytes were randomly divided into following groups: sham group, H/R group, EPOL group, EPOM group, EPOH and U0126 group. Viability of cardiomyocytes was measured by MTT, the concentration of LDH, and CK-MB of culture medium was detected by colorimetric method. Ratio of aptosis was determined by TUNEL technology and Annexin-V-FITC with FCM. Content of MDA and activity of SOD were measured by TBA and xanthine oxidase methods. Level of ERK1/2 and phospho-ERK1/2 were measured by Western-blot analysis.ResultsMembrane permeability of cardiomyocytes injuried by H/R raised, survival cardiomyocytes decreased, and EPO reduces the release of myocardium enzyme, vibility of cardiomyocytes enhanced significantly. H/R injury aggravate the apoptosis of cardiomyocytes and after treatment of EPO, apoptosis index and ratio lowered. H/R caused MDA content heightened and SOD vibility lowered, however EPO at a certain concentration could reduce the release of free radical and analosis of SOD. There were no difference in total amount of ERK1/2 protein among groups, but with effect of H/R injury and exogenous EPO, phosphorylated ERK1/2 protein increased, and ERK1/2 path was activated. However, these effects were blocked by U0126, an inhibitor of MAPK.ConclusionEPO has the protective effects on cardiomyocytes against HR injury possibly via the mechanism of inhibition of apoptosis, reduction of free radical and activation of ERK1/2.ObjectiveWe explore the protective effects of EPO on myocardium against IRI by establishing Langendorff model of isolated rat heart and observing the changes of hemodynamic parameters and myocardial zymogram. In addition, the content of myocardial NF—κB and proinflammatory factors : TNF—α, IL-1βand ICAM-1 were measured to investigate the possible mechanism.MethodsThe Langendorff model of isolated rat heart was set up. SD rats were randomly divided into sham group, I/R group, EPOL group, EPOM group, EPOH group. HR, LVSP,±dp/dtmax and CF were recorded. LDH and CK in the coronary effluent were tested. At the end of reperfusion, the levels of myocardial Bax, Bc1-2, NF—κB were measured by immunohistochemistry and the mRNA of myocardial content of TNF—α, IL-1β, ICAM-1 were also examed by real-time PCR.ResultsMIRI had negative effects on heart function which increasing the membrane permeability of cardiomyocytes. EPO improved myocardial contraction and diastole function, dilated coronary artery. MIRI induced the apoptosis of cardiomyocytes and EPO inhibitts the apoptosis by accommodating the expression of Bax, Bc1-2 genes. NF-κB of myocardium was activated and expression of inflammatory reaction factors raised after MIRI, however EPO could inhibit the over-activation of NF-κB and expression of inflammatory reaction factors.ConclusionEPO at a certain dose has protective effects on myocardium of isolated heart against IRI possibly through the mechanism of relieving the myocardial inflammatory reaction by regulating the activation of NF-κB and then decreasing the expression of inflammatory reaction factors.ObjectiveWe set up rat I/R heart model in vivo and monitor hemodynamics, measured myocardium zymogram, recorded arrhythmia, and observed ultramicro-structure of cardiomyocardium to explore the protective effects of EPO.MethodsI/R rat heart models in vivo were set up and randomly divided into following groups: sham group, I/R group, and EPO group. Continuous electrocardio-monitoring and electrocardiogram were employed to trace arrhythmia. HR, LVSP,±dp/dtmax were recorded by bio-system. AST, CK-MB, LDH in serum were examed and ultra-microstructure of myocardium of left ventricle were observed with electron microscope.ResultsI/R made incidnece of serious arrhythmias elevated, however EPO lowered it. Parameters of haemodynamics showed that I/R damaged the contraction and diastole function of myocardium, and EPO improved it. Measurement of myocardium zymogram and observation of cadiocyte ultra-microstructure showed that I/R caused cardiomyocytes membrane permeability increased and destroyed ultra-microstructure, however EPO could lessen the injury.ConclusionEPO has protective effects on myocardium against IRI in vivo. |
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