ABSTRACT
Objective To investigate the protective effects of erythropoietin (EPO) on myocardium injury after sepsis in rats in order to clarify the mechanisms.Methods The rat models of sepsis were produced by cecal ligation and perforation method (CLP).Ninty-six healthy SD rats were randomly (random number) divided into 3 groups:the sham operation group (Sham group,n =32),the sepsis group (CLP group,n =32),and the EPO treatment group (EPO group,n =32) treated with EPO 1000 IU/kg intraperitoneal injection after the CLP.The observation intervals were set at 3 h,6 h,12 h and 24 h after the surgery.The cardiac hemodynamics of the CLP group were measured.Plasma levels of inflammatory factors and myocardial enzyme indicators were determined by enzyme-linked immunosorbent assay (ELISA) ; Membrane potential levels of chondriosome of myocardial cells,cell apoptosis rates and expressions of nuclear factor-κB p65 of myocardium tissue were detected by flow cytometer; Then the pathological change of myocardium with HE staining was observed under light microscopy.Results (1) Compared with the CLP group,left ventricle systolic pressure (LVSP),left ventricle diastolic end pressure (LVEDP),the maximum rate of left ventricle rise and fall (+ dp/dtmax and-dp/dtmax) in the EPO group improved (P ＜0.05,P＜0.01); (2) Compared with the Sham operation group,plasma levels of tumor necrosis factoralpha (TNF-α),interleukin-6 (IL-6),C-reactive protein (CRP),cardiac troponin-I (cTNI),creatine kinase (CK),lactate dehydrogenase (LDH) and glutamine-oxaloacetic transaminase (GOT) in the CLP group increased at each interval (P ＜ 0.05),and those biomarkers in the EPO group were lower than those in the CLP group (P ＜ 0.05) ; On the contrary,plasma level of anti-inflammatory factor IL-10 in EPO group was higher than that in the CLP group (P ＜ 0.01) ; (3) Compared with the Sham operation group,the cell apoptosis rates in the CLP group increased significantly (P ＜ 0.01),and it decreased obviously in the EPO group (P ＜ 0.01); (4) Compared with the Sham group,membrane potential levels of chondriosome of myocardial cell in the CLP group decreased (P ＜0.01),while it increased in the EPO group in comparison with the CLP group (P ＜ 0.01) ; (5) Pathological changes of myocardium after the CLP could be lessened by the EPO treatment.Conclusions EPO may increase membrane potential levels of chondriosome and decrease the apoptosis rates of myocardial cell in rats after sepsis,and it may reduced the production of inflammatory factors to protect the myocardial cell by down-regulating NF-κB p65.Both increased membrane potential level of chonriosome and decreased inflammatory factor may implicate in myocardium protection thereby improving cardiac function after sepsis.
ABSTRACT
BACKGROUND:Sepsis-induced myocardial injury is one of the major predictors of morbidity and mortality of sepsis. The cytoprotective function of erythropoietin (EPO) has been discovered and extensively studied. However, the cardioprotective effects of EPO on sepsis-induced myocardial injury in the rat sepsis model has not been reported.METHODS:The rat models of sepsis were produced by cecal ligation and perforation (CLP) surgery. Rats were randomly (random number) assigned to one of three groups (n=8 for each group):sham group, CLP group and EPO group (1000 IU/kg erythropoietin). Arterial blood was withdrawn at 3, 6, 12, and 24 hours after CLP. cTnI, BNP, CK-MB, LDH, AST, TNF-α, IL-6, IL-10, and CRP were tested by the ELISA assay. Changes of hemodynamic parameters were recorded at 3, 6, 12, 24 hours after the surgery. Histological diagnosis was made by hematoxylin and eosin. Flow cytometry was performed to examine cell apoptosis, myocardium mitochondrial inner membrane potential, and NF-κB (p65). Survival rate at 7 days after CLP was recorded.RESULTS:In the CLP group, myocardial enzyme index and inflammatory index increased at 3, 6, 12 and 24 hours after CLP compared with the sham group, and EPO significantly blocked the increase. Compared with the CLP group, EPO significantly improved LVSP, LV +dp/dtmax, LV -dp/dtmin, and decreased LVEDP at different time. EPO blocked the reduction of mitochondrial transmembrane potential, suppressed the cardiomyocyte apoptosis, inhibited the activation of NF-κB, and reduced the production of proinflmmatory cytokines. No difference in the survival rate at 7 days was observed between the CLP group and the EPO group.CONCLUSION:Exogenous EPO has cardioprotective effects on sepsis-induced myocardial injury.