Inhibition of SLC26A4 regulated by electroacupuncture suppresses the progression of myocardial ischemia-reperfusion injury

Introduction:Myocardial ischemia-reperfusion(IR)injury has received widespread attention due to its damaging effects.Electroacupuncture(EA)pretreatment has preventive effects on myocardial IR injury.SLC26A4 is a Na+independent anion reverse transporter and has not been reported in myocardial IR injury.Objectives:Tofind potential genes that may be regulated by EA and explore the role of this gene in myocardial IR injury.Methods:RNA sequencing and bioinformatics analysis were performed to obtain the differentially expressed genes in the myocardial tissue of IR rats with EA pretreatment.Myocardial infarction size was detected by TTC staining.Serum CK,creatinine kinase-myocardial band,Cardiac troponin I,and lactate dehydrogenase levels were determined by ELISA.The effect of SLC26A4 on cardiomyocyte apoptosis was explored by TUNEL staining and western blotting.The effects of SLC26A4 on inflammation were determined by HE staining,ELISA,and real-time PCR.The effect of SLC26A4 on the NF-κB pathway was determined by western blotting.Results:SLC26A4 was up-regulated in IR rats but downregulated in IR rats with EA pretreatment.Compared with IR rats,those with SLC26A4 knockdown exhibited improved cardiac function according to decreased myocardial infarction size,reduced serum LDH/CK/CK-MB/cTnI levels,and elevated left ventricular ejection fraction and fractional shortening.SLC26A4 silencing inhibited myocardial inflammation,cell apoptosis,phosphorylation,and nuclear translocation of NF-κB p65.Conclusion:SLC26A4 exhibited promoting effects on myocardial IR injury,while the SLC26A4 knockdown had an inhibitory effect on the NF-κB pathway.These results further unveil the role of SLC26A4 in IR injury.

Long non-coding RNA-AK138945 regulates myocardial ischemia-reperfusion injury via the miR-1-GRP94 signaling pathway

Objective:Myocardial ischemia-reperfusion injury(MIRI)is one of the leading causes of death from cardiovascular disease in humans,especially in individuals exposed to cold environments.Long non-coding RNAs(lncRNAs)regulate MIRI through multiple mechanisms.This study explored the regulatory effect of lncRNA-AK138945 on myocardial ischemia-reperfusion injury and its mechanism.Methods:In vivo,8-to 12-weeks-old C57BL/6 male mice underwent ligation of the left anterior descending coronary artery for 50 minutes followed by reperfusion for 48 hours.In vitro,the primary cultured neonatal mouse ventricular cardiomyocytes(NMVCs)were treated with 100μmol/L hydrogen peroxide(H_(2)O_(2)).The knockdown of lncRNA-AK138945 was evaluated to detect cardiomyocyte apoptosis,and a glucose-regulated,endoplasmic reticulum stress-related protein 94(GRP94)inhibitor was used to detect myocardial injury.Results:We found that the expression level of lncRNA-AK138945 was reduced in MIRI mouse heart tissue and H2O2-treated cardiomyocytes.Moreover,the proportion of apoptosis in cardiomyocytes increased after lncRNA-AK138945 was silenced.The expression level of Bcl2 protein was decreased,and the expression level of Bad,Caspase 9 and Caspase 3 protein was increased.Our further study found that miR-1a-3p is a direct target of lncRNA-AK138945,after lncRNA-AK138945 was silenced in cardiomyocytes,the expression level of miR-1a-3p was increased while the expression level of its downstream protein GRP94 was decreased.Interestingly,treatment with a GRP94 inhibitor(PU-WS13)intensified H2O2-induced cardiomyocyte apoptosis.After overexpression of FOXO3,the expression levels of lncRNA-AK138945 and GRP94 were increased,while the expression levels of miR-1a-3p were decreased.Conclusion:LncRNA-AK138945 inhibits GRP94 expression by regulating miR-1a-3p,leading to cardiomyocyte apoptosis.The transcription factor Forkhead Box Protein O3(FOXO3)participates in cardiomyocyte apoptosis induced by endoplasmic reticulum stress through up-regulation of lncRNA-AK138945.

Canonical transient receptor potential channel 1 aggravates myocardial ischemia-and-reperfusion injury by upregulating reactive oxygen species

The canonical transient receptor potential channel(TRPC)proteins form Ca^(2+)-permeable cation channels that are involved in various heart diseases.However,the roles of specific TRPC proteins in myocardial ischemia/reperfusion(I/R)injury remain poorly understood.We observed that TRPC1 and TRPC6 were highly expressed in the area at risk(AAR)in a coronary artery ligation induced I/R model.Trpc1/mice exhibited improved cardiac function,lower serum Troponin T and serum creatine kinase level,smaller infarct volume,less fibrotic scars,and fewer apoptotic cells after myocardial-I/R than wild-type or Trpc6/mice.Cardiomyocyte-specific knockdown of Trpc1 using adeno-associated virus 9 mitigated myocardial I/R injury.Furthermore,Trpc1 deficiency protected adult mouse ventricular myocytes(AMVMs)and HL-1 cells from death during hypoxia/reoxygenation(H/R)injury.RNA-sequencing-based transcriptome analysis revealed differential expression of genes related to reactive oxygen species(ROS)generation in Trpc1/cardiomyocytes.Among these genes,oxoglutarate dehydrogenase-like(Ogdhl)was markedly downregulated.Moreover,Trpc1 deficiency impaired the calcineurin(CaN)/nuclear factorkappa B(NF-kB)signaling pathway in AMVMs.Suppression of this pathway inhibited Ogdhl upregulation and ROS generation in HL-1 cells under H/R conditions.Chromatin immunoprecipitation assays confirmed NF-kB binding to the Ogdhl promoter.The cardioprotective effect of Trpc1 deficiency was canceled out by overexpression of NF-kB and Ogdhl in cardiomyocytes.In conclusion,our findings reveal that TRPC1 is upregulated in the AAR following myocardial I/R,leading to increased Ca^(2+) influx into associated cardiomyocytes.Subsequently,this upregulates Ogdhl expression through the CaN/NF-kB signaling pathway,ultimately exacerbating ROS production and aggravating myocardial I/R injury.

Atorvastatin Alleviates Myocardial Ischemia-Reperfusion Injury via miR-26a-5p/FOXO1

Purpose: Ischemia-reperfusion (I/R) injury exacerbates myocardial cell death (including apoptosis and necrosis), leading to complications such as arrhythmias, myocardial stenosis, microvascular obstruction and heart failure, and it is particularly important to seek new strategies to mitigate reperfusion injury. In this paper, we will investigate whether atorvastatin can alleviate myocardial ischemia-reperfusion injury and verify its molecular mechanism. Methods: We successfully constructed a hypoxia-reperfusion (H/R) H9c2 cell model and transfected miR-26a-5p mimic, miR-26a-5p inhibitor and its negative control NC-mimic or NC-inhibitor into H9c2 cells using a transfection kit. The expression of miR-26a-5p and FOXO1 were detected by RT-qPCR assay, the expression of related proteins by Western blot assay, the cell viability of H9c2 cells by CCK-8 assay, the apoptosis rate of H9c2 cells by flow cytometry, the CK and LDH activity in cells by CK and LDH assay kits. The targeting relationship between miR-26a-5p and FOXO1 was verified by dual luciferase reporter gene assay. Results: MiR-26a-5p expression was decreased in H/R-induced cells and FOXO1 expression was increased in H/R-induced cells. Atorvastatin alleviated H/R injury in cardiomyocytes and was most effective at a concentration of 1 μM. Atorvastatin alleviated H/R injury in cardiomyocytes by upregulating miR-26a-5p expression, miR-26a-5p and FOXO1 were negatively regulated by targeting. Conclusion: Atorvastatin can alleviate H/R injury in cardiomyocytes by regulating miR-26a-5p/FOXO1.

Mechanism of TLR-4/NF-κB pathway in myocardial ischemia reperfusion injury of mouse

Objective: To detect the expression of Toll-like receptor 4(TLR-4) and NF-κB and to discuss the mechanism of TLR-4/NF-κB pathway in the myocardial ischemia reperfusion injury of mouse. Methods: TLR-4 mutant mice and wild homozygous mice were divided into the model group and sham group. Mice in the model group were given the ligation of left anterior descending coronary artery for the modeling, while mice in the sham group were not given the ligation after threading. The cardiac muscle tissues were collected for the morphological observation. The immuno histochemistry was employed to detect the expression of NF-κB, Western blot was used to detect the expression of TLR-4 and ELISA to detect the expression of serum inflammatory factors. Results: The expression of NF-κB in TLR-4 null mice after the myocardial ischemia reperfusion was significantly lower than that in wild homozygous mice. For the model group and sham group, the expression of TLR-4 in wild homozygous mice was all significantly higher than that in TLR-4 null mice, while the expression of TLR-4 in TLR-4 null mice in the model group was significantly higher than that in sham group, with the statistical difference(P<0.05). The expression of inflammatory factors in TLR-4 null mice and wild homozygous mice in the model group was significantly higher than that in sham group. The expression of all factors in group A with TLR-4 null was significantly lower than that in group B with wild homozygous type, with the statistical difference(P<0.05). Conclusions: TLR-4/NF-κB pathway is closely related to the myocardial ischemia reperfusion injury, which plays its role through the release of inflammatory cytokines.

Calpain system and its involvement in myocardial ischemia and reperfusion injury

Calpains are ubiquitous non-lysosomal Ca2+-dependent cysteine proteases also present in myocardial cytosol and mitochondria.Numerous experimental studies reveal an essential role of the calpain system in myocardial injury during ischemia,reperfusion and postischemic structural remodelling.The increasing Ca2+-content and Ca2+-overload in myocardial cytosol and mitochondria during ischemia and reperfusion causes an activation of calpains.Upon activation they are able to injure the contractile apparatus and impair the energy production by cleaving structural and functional proteins of myocytes and mitochondria.Besides their causal involvement in acute myocardial dysfunction they are also involved in structural remodelling after myocardial infarction by the generation and release of proapoptotic factors from mitochondria.Calpain inhibition can prevent or attenuate myocardial injury during ischemia,reperfusion,and in later stages of myocardial infarction.

GYY4137 protects against myocardial ischemia and reperfusion injury by attenuating oxidative stress and apoptosis in rats

Hydrogen sulfide （H2S） is a gasotransmitter that regulates cardiovascular functions. The present study aimed to determine the protective effect of slow-releasing H2S donor GYY4137 on myocardial ischemia and reperfusion （I/R） injury and to investigate the possible signaling mechanisms involved. Male Sprague-Dawley rats were treated with GYY4137 at 12.5 mg/（kg.day）, 25 mg/（kg.day） or 50 mg/（kg.day） intraperitoneally for 7 days. Then, rats were subjected to 30 minutes of left anterior descending coronary artery occlusion followed by reperfusion for 24 hours. We found that GYY4137 increased the cardiac ejection fraction and fractional shortening, reduced the ischemia area, alleviated histological injury and decreased plasma creatine kinase after myocardial I/R. Both H2S concentration in plasma and cystathionine-γ-lyase （CSE） activity in the myocardium were enhanced in the GYY4137 treated groups. GYY4137 also decreased malondialdehyde and myeloperoxidase levels in serum, attenuated superoxide anion level and suppressed phosphorylation of mitogen activated protein kinases in the myocardium after I/R. Meanwhile, GYY4137 increased the expression of Bcl-2 but decreased the expression of Bax, caspase-3 activity and apoptosis in the myocardium. The data suggest that GYY4137 protects against myocardial ischemia and reperfusion injury by attenuating oxidative stress and apoptosis.

Comparative analysis of different cyclosporine A doses on protection after myocardial ischemia/reperfusion injury in rat

Objective:To investigate the protective effect of different cyclosporin A(CsA)doses on myocardial ischemia/reperfusion injury in rat models.Methods:A rat model of myocardial ischemia/reperfusion injury was established in vivo and the rats were randomly divided into four groups:placebo(PBS;T1),low-dose(CsA dose:1.0 mg/kg:T2),medium-dose(CsA dose:2.5 mg/kg:T3),and high-dose(CsA dose:5.0 mg/kg;T4)groups.Heart function indexes were monitored at different time points,the extent of myocardial infarction was assessed by Evans Blue-TTC staining,and creatine kinase MB mass and cardiac troponin 1 values were measured by biochemical assays.Results:Compared with the T1 and T2 groups,both the creatine kinase MB mass and cardiac troponin 1 were significantly lower in the T3 and T4 groups(P<0.05).The mean arterial pressure(MAP)and left ventricular systolic pressure(LVSP)decreased sequentially in each group,with the extending reperfusion time.Significant decreases in LVSP and MAP were observed in the T3 and T4 groups as compared to the T1 and T2 group(P<0.05)and the T2 group showed a significantly lower LVSP and MAP decline than the T1 group(P<0.05).Compared with the Tl group,the rats from the T2.T3,and T4 groups suffered from a significantly lower extent of myocardial infarction(P<0.05).Also,the a animals in the T3 and T4 groups had a significantly smaller extent of myocardial infarction than those in the T2 group(P<0.05).Conclusions:Various CsA doses exert different degrees of protection against ischemia/reperfusion injury,and this protective effect peaks at approximately 2.5 mg/kg in rat models.

Effect of rosiglitazone on rabbit model of myocardial ischemia-reperfusion injury

To explore mechanism and protective effect of rosiglitazone on myocardial ischemia reperfusion(I/R) injury.Methods:A total of 48 male Japanese white big-ear rabbits were randomly divided into control group(A),I/R group(B),low dose of rosiglitazone group(C),high dose of rosiglitazone group(D).Plasma concentration of and also reduced the concentration of plasma serum creatine kinase(CK),CK-MB.high-sensitivity C-reactive protein(hsCRP).ultrasuperoxide dismutase(SOD),malondialdehyde(MD.A).lactic acid glutathione skin peroxidase (C-SH-PX).nitric oxide(NO)and endothelin(ET) were measured 1 h later after I/R.Twenty-four hours after I/R the hearts were harvested for pathological and ultrastructural analysis.Area of myocardial infarction were tested.Results:Plasma concentration of CK,Ck-MB.hsCRP,NO. MDA and ET were decreased in C,D group compared with group B.Plasma concentration of T-SOD and GSH-Px were increased significantly in C.D group compared with group B.Compared with group B.pathological and ullraslructural changes in C and D group were slightly.There was significant difference in myocardial infarction area between group C.D and group B(P【0.05). Myocardial infarction area and arrhythmia rate were lower in group C,D compare with group B. Rosiglitazone may protect myocardium from I/R injury by enhancing T-SOD and GSH-Px concentration,inhibit inflammatory reaction,and improve endothelial function.

Effects of Ang Ⅱ perfusion on transmural heterogeneous of Cx43 in acute myocardial ischemia reperfusion

Objective:To observe the effects of angiotensin Ⅱ(Ang Ⅱ) pefusion on transmural heterogeneity of Cx43 expression in the rabbit model with acute myocardial ischemia reperfusion(MIR),and investigate the role of rennin-angiotensin system in malignant ventricular arrhythmia induced by MIR.Methods:Twenty rabbits were randomly divided into MIR group(n=10) and Ang Ⅱ group(n=10).MIR model was produced with traditional ligation and opening of the anterior descending coronary artery in all animal.The hearts in vitro in the MIR group and the Ang Ⅱ group were perfused with simply improved Tyrode's solution and containing Ang Ⅱ Tyrode's solution respectively.90%monophasic action potential repolarization duration,transmural dispersion of repolarization.Cx43 protein(Cx43-pro) and mRNA(Cx43-Cq) expression in subepicardial,midmyocardial and subendocardial myocardium were measured in both groups.The greatest differences of Cx43-pro and Cx43-Cq among three myocardial layers were calculated and shown with △Cx43-pro and △Cx43-Cq respectively.Results:After Ang Ⅱ perfusion,90%monophasic action potential repolarization duration among three myocardial layer were significantly prolonged(P < 0.05 and P < 0.01),and transmural dispersion of repolarization also significantly increased compared with the MIR group(P < 0.05).Compare with the MIR group,three myocardial Cx43-pro and Cx43-Cq expression in the Ang Ⅱ group were significantly decreased(P < 0.05 and P < 0.01).but△Cx43-pro and △Cx43-Cq were significant increased.Conclusions:Renin-angiotensin system increases transmural heterogeneity of Cx43 expression in the rabbit model with MIR by Ang Ⅱ,and enlarge transmural dispersion of repolarization among three myocardial layers of left ventricular which induces malignant ventricular arrhythmia.

The expression of oxidative stress genes related to myocardial ischemia reperfusion injury in patients with ST-elevation myocardial infarction

BACKGROUND:We aimed to investigate the gene expression of myocardial ischemia/reperfusion injury(MIRI)in patients with acute ST-elevation myocardial infarction(STEMI)using stress and toxicity pathway gene chip technology and try to determine the underlying mechanism.METHODS:The mononuclear cells were separated by ficoll centrifugation,and plasma total antioxidant capacity(T-AOC)was determined by the ferric reducing ability of plasma(FRAP)assay.The expression of toxic oxidative stress genes was determined and verified by oligo gene chip and quantitative real-time polymerase chain reaction(qRT-PCR).Additionally,gene ontology(GO)enrichment analysis was performed on DAVID website to analyze the potential mechanism further.RESULTS:The total numbers of white blood cells(WBC)and neutrophils(N)in the peripheral blood of STEMI patients(the AMI group)were significantly higher than those in the control group(WBC:11.67±4.85×10^(9)/L vs.6.41±0.72×10^(9)/L,P<0.05;N:9.27±4.75×10^(9)/L vs.3.89±0.81×10^(9)/L,P<0.05),and WBCs were significantly associated with creatine kinase-myocardial band(CK-MB)on the first day(Y=8.945+0.018X,P<0.05).In addition,the T-AOC was significantly lower in the AMI group comparing to the control group(12.80±1.79 U/mL vs.20.48±2.55 U/mL,P<0.05).According to the gene analysis,eight up-regulated differentially expressed genes(DEGs)included GADD45A,PRDX2,HSPD1,DNAJB1,DNAJB2,RAD50,TNFSF6,and TRADD.Four down-regulated DEGs contained CCNG1,CAT,CYP1A1,and ATM.TNFSF6 and CYP1A1 were detected by polymerase chain reaction(PCR)to verify the expression at different time points,and the results showed that TNFSF6 was up-regulated and CYP1A1 was down-regulated as the total expression.GO and kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis suggested that the oxidative stress genes mediate MIRI via various ways such as unfolded protein response(UPR)and apoptosis.CONCLUSIONS:WBCs,especially neutrophils,were the critical cells that mediating reperfusion injury.MIRI was regulated by various genes,including oxidative metabolic stress,heat shock,DNA damage and repair,and apoptosis-related genes.The underlying pathway may be associated with UPR and apoptosis,which may be the novel therapeutic target.

Caffeoylquinic acid derivatives extract of Erigeron multiradiatus alleviated acute myocardial ischemia reperfusion injury in rats through inhibiting NF-kappaB and JNK activations

Erigeron multiradiatus(Lindl.)Benth.,has been used in Tibet folk medicine to treat various inflammatory diseases.The aim of this study was to investigate anti-myocardial ischemia and reperfusion(I/R)injury effect of caffeoylquinic acids derivatives of E.multiradiatus(AE)in vivo and to explain underling mechanism.AE was prepared using the whole plant of E.multiradiatus and contents of 6 caffeoylquinic acid determined through HPLC analysis.Myocardial I/R were induced by left anterior descending coronary artery occlusion for 30 min followed by 24 h of reperfusion in rats.AE administration(10,20 and 40 mg·kg-1)inhibited I/R-induced injury as indicated by decreasing myocardial infarct size,reducing of CK and LDH activities and preventing ST-segment depression in dose-dependent manner.AE decreased cardiac tissue levels of pro-inflammatory factors TNF-αand IL-6 and attenuated leukocytes infiltration.AE was further demonstrated to significantly inhibit I-κB degradation,nuclear translocation of p-65 and phosphorylation of JNK.Our results suggested that cardioprotective effect of AE could be due to suppressing myocardial inflammatory response and blocking NF-κB and JNK activation pathway.Thus,caffeoylquinic acids might be the active compounds in E.multiradiatus on myocardial ischemia and be a potential natural drug for treating myocardial I/R injury.

MicroRNA-15a/b are up-regulated in response to myocardial ischemia/reperfusion injury

ObjectiveSeveral 研究显示了 miR-15a， miR-15b 和 miR-16 可以是 apoptosis 的重要管理者。后来稀释 apoptosis 能保护心肌层和还原剂梗塞尺寸，现在的学习被瞄准发现是否这些 miRNAs 参予调整心肌的局部缺血灌注( I/R )在受到 I/R 的老鼠心的 injury.MethodsApoptosis 被 TUNEL 试金在 vivo 检测，当流动 cytometry 分析由 Annexin V/PI 列在后面时，在 vitro 的两倍污点被用来在受到 hypoxia/reoxygenation ( H/R )的有教养的 cardiomyocytes 检测 apoptosis 。Taqman 即时量的 PCR 被用来证实 miR-15a/15b/16 是否涉及心脏的 I/R 的规定，控制， I/R 或 H/R 的到那些的 H/R.ResultsCompared 导致了 cardiomyocytes 的 apoptosis 显著地在 vivo 两个都被增加(24.4%&#x000b1；9.4% 对 2.2%&#x000b1；1.9% ， P &#x0003c；0.01， n = 5 ) 并且在 vitro (14.12%&#x000b1；0.92% 对 2.22%&#x000b1；0.08%) 。 miR-15a 和 miR-15b 的表达式，然而并非 miR-16 ，在鼠标 I/R 模型，和结果被增加在 H/R model.ConclusionsOur 数据是一致的显示因此， miR-15 和 miR-15b 响应心脏的 I/R 损害是起来调整的 miR-15a/b 的下面规定可以是有希望的策略减少心脏的 I/R 损害导致的心肌的 apoptosis 。

Effect and mechanism of salvianolic acid B on the myocardial ischemiareperfusion injury in rats

Objective:To investigate the effect of salvianolic acid B on rats with myocardial ischemiareperfusion injury.Methods:SD rats were randomly divided into five groups(n=10 in each group):A sham operation group,B ischemic reperfusion group model group,C low dose salvianolic acid B group,D median dose salvianolic acid B group,E high dose salvianolic acid B group.One hour after establishment of the myocardial ischemia-reperfusion model,the concentration and the apoptotic index of the plasma level of myocardial enzymes(CTnⅠ,CKMB),SOD,MDA,NO,ET were,measured.Heart tissues were obtained and micro-structural changes were observed.Results:Compared the model group,the plasma CTnⅠ,CK-MB,MDA and ET contents were significantly increased,NO,T-SOD contents were decreased in the treatment group(group C,D,and E)(P<0.05);compared with group E,the plasma CTnⅠ,CKMB,MDA and ET levels were increased,the NO,T-SOD levels were decreased in groups C and D(P<0.05).Infarct size was significantly reduced,and the myocardial ultrastructural changes were improved significantly in treatment group.Conclusions:Salvianolic acid B has a significant protective effect on myocardial ischemia-reperfusion injury.It can alleviate oxidative stress,reduce calcium overload,improve endothelial function and so on.

Fructose 1,6-diphosphate alleviates myocardial ischemia reperfusion injury in rats through JAK2/STAT3 pathway

Objective: To study the effect of fructose 1,6-diphosphate(FDP) on myocardial ischemia reperfusion injury in rats and its molecular mechanism.Methods: Male SPF SD rats were selected as experimental animals and randomly divided into four groups.Sham group received sham operation, I/R group were made into myocardial ischemia reperfusion injury models, FDP group were made into myocardial ischemia reperfusion injury models and then were given FDP intervention, and FDP+AG490 group were made into myocardial ischemia reperfusion injury models and then were given FDP and JAK2 inhibitor AG490 intervention.Results: CK, CK-MB, c Tn I and LDH contents in serum as well as Bax and Caspase-3 protein expression in myocardial tissue of I/R group were significantly higher than those of Sham group whereas Bcl-2, p-JAK2 and p-STAT3 protein expression in myocardial tissues were significantly lower than those of Sham group; CK, CK-MB, c Tn I and LDH contents in serum as well as Bax and Caspase-3 protein expression in myocardial tissue of FDP group were significantly lower than those of I/R group whereas Bcl-2, p-JAK2 and p-STAT3 protein expression in myocardial tissue were significantly higher than those of I/R group; CK, CK-MB, c Tn I and LDH contents in serum as well as Bax and Caspase-3 protein expression in myocardial tissue of FDP+AG490 group were significantly higher than those of FDP group whereas Bcl-2 protein expression in myocardial tissue was significantly lower than that of FDP group.Conclusion: FDP could reduce the myocardial ischemia reperfusion injury in rats by activating the JAK2/STAT3 pathway.

The role of glycogen synthase kinase 3 beta in brain injury induced by myocardial ischemia/reperfusion injury in a rat model of diabetes mellitus

Myocardial ischemia/reperfusion injury can lead to severe brain injury.Glycogen synthase kinase 3 beta is known to be involved in myocardial ischemia/reperfusion injury and diabetes mellitus.However,the precise role of glycogen synthase kinase 3 beta in myocardial ischemia/reperfusion injury-induced brain injury is unclear.In this study,we observed the effects of glycogen synthase kinase 3 beta on brain injury induced by myocardial ischemia/reperfusion injury in diabetic rats.Rat models of diabetes mellitus were generated via intraperitoneal injection of streptozotocin.Models of myocardial ischemia/reperfusion injury were generated by occluding the anterior descending branch of the left coronary artery.Post-conditioning comprised three cycles of ischemia/reperfusion.Immunohistochemical staining and western blot assays demonstrated that after 48 hours of reperfusion,the structure of the brain was seriously damaged in the experimental rats compared with normal controls.Expression of Bax,interleukin-6,interleukin-8,terminal deoxynucleotidyl transferase d UTP nick end labeling,and cleaved caspase-3 in the brain was significantly increased,while expression of Bcl-2,interleukin-10,and phospho-glycogen synthase kinase 3 beta was decreased.Diabetes mellitus can aggravate inflammatory reactions and apoptosis.Ischemic post-conditioning with glycogen synthase kinase 3 beta inhibitor lithium chloride can effectively reverse these changes.Our results showed that myocardial ischemic post-conditioning attenuated myocardial ischemia/reperfusion injury-induced brain injury by activating glycogen synthase kinase 3 beta.According to these results,glycogen synthase kinase 3 beta appears to be an important factor in brain injury induced by myocardial ischemia/reperfusion injury.

Flow cytometric analysis of circulating microvesicles derived from myocardial ischemic preconditioning and cardioprotection of ischemia/reperfusion injury in rats

Objective: To establish a flow cytometric method to detect the alteration of phenotypes and concentration of circulating microvesicles(MVs) from myocardial ischemic preconditioning(IPC) treated rats(IPC-MVs), and to investigate the effects of IPC-MVs on ischemia/reperfusion(I/R) injury in rats. Methods: Myocardial IPC was elicited by three cycles of 5-min ischemia and 5-min reperfusion of the left anterior descending(LAD) coronary artery. Platelet-free plasma(PFP) was isolated through two steps of centrifugation at room temperature from the peripheral blood, and IPC-MVs were isolated by ultracentrifugation from PFP. PFP was incubated with anti-CD61, anti-CD144, anti-CD45 and anti-Erythroid Cells, and added 1, 2 μm latex beads to calibrate and absolutely count by flow cytometry. For functional research, I/R injury was induced by 30-min ischemia and 120-min reperfusion of LAD. IPC-MVs 7 mg/kg were infused via the femoral vein in myocardial I/R injured rats. Mean arterial blood pressure(MAP), heart rate(HR) and ST-segment of electrocardiogram(ECG) were monitored throughout the experiment. Changes of myocardial morphology were observed after hematoxylin-eosin(HE) staining. The activity of plasma lactate dehydrogenase(LDH) was tested by Microplate Reader. Myocardial infarct size was measured by TTC staining. Results: Total IPC-MVs and different phenotypes, including platelet-derived MVs(PMVs), endothelial cell-derived MVs(EMVs), leucocyte-derived MVs(LMVs) and erythrocyte-derived MVs(RMVs) were all isolated which were identified membrane vesicles(<1 μm) with corresponding antibody positive. The numbers of PMVs, EMVs and RMVs were significantly increased in circulation of IPC treated rats(P<0.05, respectively). In addition, at the end of 120-min reperfusion in I/R injured rats, IPC-MVs markedly increased HR(P<0.01), decreased ST-segment and LDH activity(P<0.05, P<0.01). The damage of myocardium was obviously alleviated and myocardial infarct size was significantly lowered after IPC-MVs treatment(P<0.01). Conclusion: The method of flow cytometry was successfully established to detect the phenotypes and concentration alteration of IPC-MVs, including PMVs, EMVs, LMVs and RMVs. Furthermore, circulating IPC-MVs protected myocardium against I/R injury in rats.

Research Progress on Myocardial Protection Strategies

Myocaridial protection aims to salvage myocardium from ischemia and reperfusion injury and to reduce infarct size and its consequences.After more than 30 years of development,the concept of ischemic preconditioning has evolved into"ischemic conditioning",a term that encompasses a number of related endogenous cardioprotective strategies,which can be applied either directly to the heart(ischemic preconditioning or postconditioning)or from afar,for example to a limb(remote ischemic preconditioning,preconditioning,or postconditioning).A variety of cardioprotective therapies have shown promising results in reducing infarct size and improving clinical outcomes in patients with ischemic heart disease.

Myocardial ischemia-reperfusion injury:Possible role of melatonin

Our knowledge and understanding of the pathophysiology of coronary atherosclerosis has increased enormously over the last 20 years.Reperfusion through thrombolysis or percutaneous coronary angioplasty is the standard treatment for preventing acute myocardial infarction.Early reperfusion is an absolute prerequisite for survival of the ischemic myocardium,but reperfusion itself may lead to accelerated and additional myocardial injury beyond that generated by ischemia alone.These outcomes,in a range of reperfusion-associated pathologies,are collectively termed "reperfusion injuries".Reactive oxygen species are known to be produced in large quantities in the first few minutes of the post-ischemia reperfusion process.Similarly,scientific evidence from the last 15 years has suggested that melatonin has beneficial effects on the cardiovascular system.The presence of vascular melatoninergic receptor binding sites has been demonstrated;these receptors are functionally linked to vasoconstrictor or vasodilatory effects of melatonin.It has been shown that patients with coronary heart disease have a low melatonin production rate,especially those with higher risk of cardiac infarction and/or sudden death.Melatonin attenuates molecular and cellular damage resulting from cardiac ischemia-reperfusion in which destructive free radicals are involved.

Effect of Minocycline Postconditioning and Ischemic Postconditioning on Myocardial Ischemia-reperfusion Injury in Atherosclerosis Rabbits

This study examined the protective effect of ischemic postconditioning(IPoC) and minocycline postconditioning(MT) on myocardial ischemia-reperfusion(I/R) injury in atherosclerosis(AS) animals and the possible mechanism.Forty male healthy rabbits were injected with bovine serum albumin following feeding on a high fat diet for 6 weeks to establish AS model.AS rabbits were randomly divided into 3 groups:(1) I/R group,the rabbits were subjected to myocardial ischemia for 35 min and then reperfusion for 12 h;(2) IPoC group,the myocardial ischemia lasted for 35 min,and then reperfusion for 20 s and ischemia for 20 s [a total of 3 cycles(R20s/I20s×3)],and then reperfusion was sustained for 12 h;(3) MT group,minocycline was intravenously injected 10 min before reperfusion.The blood lipids,malondialdehyde(MDA),superoxide dismutase(SOD),soluble cell adhesion molecule(sICAM),myeloperoxidase(MPO),and cardiac troponin T(cTnT) were biochemically determined.The myocardial infarction size(IS) and apoptosis index(AI) were measured by pathological examination.The expression of bcl-2 and caspase-3 was detected in the myocardial tissue by using reverse transcription-polymerase chain reaction(RT-PCR).The results showed that the AS models were successfully established.The myocardial IS,the plasma levels of MDA,sICAM,MPO and cTnT,and the enzymatic activity of MPO were significantly decreased,and the plasma SOD activity was significantly increased in IPoC group and MT group as compared with I/R group(P<0.05 for all).The myocardial AI and the caspase-3 mRNA expression were lower and the bcl-2 mRNA expression was higher in IPoC and MT groups than those in I/R group(all P<0.05).It is concluded that the IPoC and MT can effectively reduce the I/R injury in the AS rabbits,and the mechanisms involved anti-oxidation,anti-inflammation,up-regulation of bcl-2 expression and down-regulation of caspase-3 expression.Minocycline can be used as an effective pharmacologic postconditioning drug to protect myocardia from I/R injury.