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.

Gamma-aminobutyric acid enhances miR-21-5p loading into adipose-derived stem cell extracellular vesicles to alleviate myocardial ischemia-reperfusion injury via TXNIP regulation

BACKGROUND Myocardial ischemia-reperfusion injury(MIRI)poses a prevalent challenge in current reperfusion therapies,with an absence of efficacious interventions to address the underlying causes.AIM To investigate whether the extracellular vesicles(EVs)secreted by adipose mesenchymal stem cells(ADSCs)derived from subcutaneous inguinal adipose tissue(IAT)underγ-aminobutyric acid(GABA)induction(GABA-EVs^(IAT))demonstrate a more pronounced inhibitory effect on mitochondrial oxidative stress and elucidate the underlying mechanisms.METHODS We investigated the potential protective effects of EVs derived from mouse ADSCs pretreated with GABA.We assessed cardiomyocyte injury using terminal deoxynucleotidyl transferase dUTP nick end-labeling and Annexin V/propidium iodide assays.The integrity of cardiomyocyte mitochondria morphology was assessed using electron microscopy across various intervention backgrounds.To explore the functional RNA diversity between EVs^(IAT)and GABA-EVs^(IAT),we employed microRNA(miR)sequencing.Through a dual-luciferase reporter assay,we confirmed the molecular mechanism by which EVs mediate thioredoxin-interacting protein(TXNIP).Western blotting and immunofluorescence were conducted to determine how TXNIP is involved in mediation of oxidative stress and mitochondrial dysfunction.RESULTS Our study demonstrates that,under the influence of GABA,ADSCs exhibit an increased capacity to encapsulate a higher abundance of miR-21-5p within EVs.Consequently,this leads to a more pronounced inhibitory effect on mitochondrial oxidative stress compared to EVs from ADSCs without GABA intervention,ultimately resulting in myocardial protection.On a molecular mechanism level,EVs regulate the expression of TXNIP and mitigating excessive oxidative stress in mitochondria during MIRI process to rescue cardiomyocytes.CONCLUSION Administration of GABA leads to the specific loading of miR-21-5p into EVs by ADSCs,thereby regulating the expression of TXNIP.The EVs derived from ADSCs treated with GABA effectively ameliorates mitochondrial oxidative stress and mitigates cardiomyocytes damage in the pathological process of MIRI.

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.

Preliminary study on the protective effect of electroacupuncture Neiguan acupoint pretreatment on rats with myocardial ischemia-reperfusion injury:role of the miR-214-3p/NCX1 axis

Background:Ischemia-reperfusion can worsen myocardial damage and increase the risk of death.Studies have revealed that ischemic preconditioning provides the best endogenous protection against myocardial ischemia-reperfusion injury(MIRI),and the principle of electroacupuncture(EA)preconditioning is comparable to that of myocardial ischemic preconditioning adaption.Our earlier research demonstrated that EA pretreatment inhibits the expression of calmodulin-dependent protein kinase IIδ(CaMKIIδ),sodium/calcium exchanger 1(NCX1),and cyclophilin D,hence providing protection against MIRI.However,the exact mechanism is still unknown.The expression of NCX1 mRNA is directly regulated by microRNA-214(miR-214).Moreover,it suppresses the levels of CaMKIIδand cyclophilin D.Whether these variables contribute to EA preconditioning to improve MIRI needs to be investigated,though.This study aimed to preliminarily determine whether EA pretreatment ameliorates MIRI by modulating the miR-214-3p/NCX1 axis.Methods:We used a rat MIRI model to investigate the effect of EA pretreatment on MIRI and the expression of miR-214-3p.In addition,adenovirus injection inhibited miR-214-3p expression in the rat MIRI model,and the influence of EA pretreatment towards MIRI was observed in the context of blocked miR-214-3p expression.Both the myocardial histological abnormalities and the alterations in the ST segment of the rat electrocardiogram were analyzed.NCX1 mRNA,cyclophilin D,and CaMKIIδexpression levels were also analyzed.Results:EA pretreatment improved MIRI.In rats with MIRI,EA administration increased miR-214-3p expression while decreasing NCX1 mRNA,cyclophilin D,and CaMKIIδproteins in cardiac tissues.The beneficial effect of EA pretreatment against MIRI was reversed,coupled with elevated levels of NCX1 mRNA,cyclophilin D,and CaMKIIδprotein expression,when an adenovirus injection disrupted the expression of miR-214-3p.Conclusions:Our findings preliminarily show that EA pretreatment inhibits the expression of NCX1 mRNA,cyclophilin D,and CaMKIIδproteins via miR-214-3p,hence exerting MIRI protection.

Endoplasmic reticulum stress and autophagy in cerebral ischemia/reperfusion injury:PERK as a potential target for intervention

Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases.However,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in vivo.Therefore,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke.Matrix metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ischemia.Herein,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel PA-TIMP-QK.PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro.The results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor function.These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

Protective Effects of Zingiberis and Acniti Praeparatae Decoction on Myocardial IschemiaReperfusion Injury in Rats

This study aimed to investigate the protective effects of zin-giberis and acniti praeparatae decoction on oxidative stress injury induced by my-ocardial ischemia reperfusion in rats. [Method] Myocardial ischemia-reperfusion was performed by ligation of the left anterior descending coronary artery for 30 min, fol-lowed by reperfusion for 60 min. The effects of zingiberis and acniti praeparatae decoction on ECG ST segment, myocardial infarction percentage, malondialdehyde （MDA） content in the serum, superoxide dismutase （SOD） activity and other indica-tors were observed. [Result] Zingiberis and acniti praeparatae decoction could effec-tively inhibit ECG ST segment elevation caused by myocardial ischemia-reperfusion injuries, reduce the percentage of myocardial infarction, decline the content of MDA in the serum, and increase the activity of SOD. [Conclusion] Zingiberis and acniti praeparatae decoction exhibits protective effects on oxidative injuries caused by my-ocardial ischemia-reperfusion injuries in rats, which may be involved in reducing the formation of myocardial free radicals and enhancing antioxidant capacity of my-ocardium.

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.

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.

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.

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.

Myocardial reperfusion injury and oxidative stress: Therapeutic opportunities

Acute myocardial infarction(AMI) is the leading cause of death worldwide. Its associated mortality, morbidity and complications have significantly decreased with the development of interventional cardiology and percutaneous coronary angioplasty(PCA) treatment, which quick-ly and effectively restore the blood flow to the area previously subjected to ischemia. Paradoxi-cally, the restoration of blood flow to the ischemic zone leads to a massive production of reactive oxygen species(ROS) which generate rapid and severe damage to biomolecules, generating a phenomenon called myocardial reperfusion injury(MRI). In the clinical setting, MRI is associated with multiple complications such as lethal reperfusion, no-reflow, myocardial stunning, and reperfusion arrhythmias. Despite significant advances in the understanding of the mechanisms accounting for the myocardial ischemia reperfusion injury, it remains an unsolved problem. Although promising results have been obtained in experimental studies(mainly in animal models), these benefits have not been translated into clinical settings. Thus, clinical trials have failed to find benefits from any therapy to prevent MRI. There is major evidence with respect to the contribution of oxidative stress to MRI in cardiovascular diseases. The lack- of consistency between basic studies and clinical trials is not solely based on the diversity inherent in epidemiology but is also a result of the methodological weak-nesses of some studies. It is quite possible that pharmacological issues, such as doses, active ingredients, bioavailability, routes of administration, co-therapies, startup time of the drug intervention,and its continuity may also have some responsibility for the lack- of consistency between different studies. Furthermore, the administration of high ascorbate doses prior to reperfusion appears to be a safe and rational therapy against the development of oxidative damage associated with myocardial reperfusion. In addition, the association with N-acetylcysteine(a glutathione donor) and deferoxamine(an iron chelator) could improve the antioxidant cardioprotection by ascorbate, mak-ing it even more effective in preventing myocardial reperfusion damage associated with PCA following AMI.

Effect of peroxisome proliferator-activated receptor gamma agonist on heart of rabbits with acute myocardial ischemia/reperfusion injury

Objective:To explore protective effect of rosiglitazone on myocardial ischemia reperfusion injury.Methods:A total of 48 male SD rats were randomly divided into control group(A),I/R group(B),high dose of rosiglitazone(C),low dose of rosiglitazone(D).Plasm concentration of creatine kinase(CK),CK-MB,hsCRP,Superoxide dismutase(SOD),malondialdehyde(MDA),glutathione peroxidase(GSH-Px),nitric oxide(NO)and endothelin(ET)were measured 1 h later after I/R.24 h after I/R hearts were harvested to observe pathological and ultrastructural changes.Immunohistochemistry and western blotting was used to test CD40 expression in myocardial tissue.Area of myocardial infarction were tested,arrhythmia rate during I/R was recorded.Results:Plasm concentration of creatine kinase(CK),CK-MB,hsCRP,NO,MDA and ET were decreased in group C,D compared with group B.Plasm concentration of T-SOD and GSHPx was increased significantly in group C,D compared with group B.Compared with group B,pathological and ultrastructural changes in group C,D were slightly.Myocardial infarction area and arrhythmia rate were lower in group C,D compare with group B.Conclusions:Rosiglitazone can protect myocardium from I/R injury by enhancing T-SOD and GSH-Px concentration,inhibit inflammatory reaction,improve endothelial function,reduce oxidative stress and calcium overload.

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.

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

Objective Several studies have indicated that miR-15a,miR-15b and miR-16 may be the important regulators of apoptosis.Since attenuate apoptosis could protect myocardium and reduce infarction size,the present study was aimed to find out whether these miRNAs participate in regulating myocardial ischemia reperfusion （I/R） injury.Methods Apoptosis in mice hearts subjected to I/R was detected by TUNEL assay in vivo,while flow cytometry analysis followed by Annexin V/PI double stain in vitro was used to detect apoptosis in cultured cardiomyocytes which were subjected to hypoxia/reoxygenation （H/R）.Taqman real-time quantitative PCR was used to confirm whether miR-15a/15b/16 were involved in the regulation of cardiac I/R and H/R.Results Compared to those of the controls,I/R or H/R induced apoptosis of cardiomyocytes was significantly iucreased both in vivo （24.4％ ± 9.4％ vs.2.2％ ± 1.9％,P ＜ 0.01,n =5） and in vitro （14.12％ ±0.92％ vs.2.22％ ± 0.08％）.The expression of miR-15a and miR-15b,but not miR-16,was increased in the mice I/R model,and the results were consistent in the H/R model.Conclusions Our data indicate miR-15 and miR-15b are up-regulated in response to cardiac I/R injury,therefore,down-regulation of miR- 15a/b may be a promising strategy to reduce myocardial apoptosis induced by cardiac I/R injury.

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 shenfu injection on gastrointestinal microcirculation in rabbits after myocardial ischemia-reperfusion injury

AIM： To investigate the effect of shenfu injection on gastrointestinal microcirculation after myocardial ischemic-reperfusion （IR） injury in rabbits and probe into the mechanism. METHODS： Forty healthy flap-eared white rabbits were randomly divided into 4 groups： IR injury control group （group Ⅰ ）, shenfu injection 5 mL/kg per h group （group Ⅱ）, shenfu injection 10 mL/kg per h group （group Ⅲ） and shenfu injection 20 mL/kg per h group （group Ⅳ）. The four groups were treated with Lactated Ringer＇s solution, shenfu injection 5, 10, and 20 mL/ kg per h were infused intravenously 30 min before experiment respectively. The values of hemodynamics [mean arterial pressure （MAP）, heart rate （HR）, gastric intramucosal partial pressure of carbon dioxide （PCO2）, blood gas analysis and pH] were measured and compared with those before myocardial ischemia, 60 min after myocardial ischemia and 60, 90, and 180 rain after reperfusion. RESULTS： The MAP, HR and gastric intramucosal pH were （70.50 ± 4.50） kPa, （165 ± 14） beats per rain, 7.032 ± 0.024 in group Ⅰ 60 min after myocardial ischemia, which were significantly decreased compared with those before myocardial ischemia （88.50 ± 9.75 kPa, 217 ± 18 beats per rain, 7.112 ± 0.035, P 〈 0.05）. The MAP, HR and gastric intramucosal pH were significantly decreased in group Ⅰ 60, 90, and 180 min after reperfusion （61.50 ± 5.25 kPa, 133 ± 31 beats per rain, 6.997 ± 0.025） compared with those before reperfusion respectively （P 〈 0.05）, whereas the values were insignificantly different in groups Ⅱ, Ⅲ or Ⅳ after reperfusion, compared with those before reperfusion, and there were no significant differences between groups Ⅱ, Ⅲ, and Ⅳ after reperfusion. CONCLUSION： Pre-infusion of shenfu injection has a protective effect on gastrointestinal microcirculation after myocardial IR injury in rabbits, in a dose independent manner.

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.