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.

Network-pharmacology-based research on protective effects and underlying mechanism of Shuxin decoction against myocardial ischemia/reperfusion injury with diabetes

BACKGROUND Patients with diabetes mellitus are at higher risk of myocardial ischemia/reperfusion injury(MI/RI).Shuxin decoction(SXT)is a proven recipe modification from the classic herbal formula"Wu-tou-chi-shi-zhi-wan"according to the traditional Chinese medicine theory.It has been successfully used to alleviate secondary MI/RI in patients with diabetes mellitus in the clinical setting.However,the underlying mechanism is still unclear.AIM To further determine the mechanism of SXT in attenuating MI/RI associated with diabetes.METHODS This paper presents an ensemble model combining network pharmacology and biology.The Traditional Chinese Medicine System Pharmacology Database was accessed to select key components and potential targets of the SXT.In parallel,therapeutic targets associated with MI/RI in patients with diabetes were screened from various databases including Gene Expression Omnibus,DisGeNet,Genecards,Drugbank,OMIM,and PharmGKB.The potential targets of SXT and the therapeutic targets related to MI/RI in patients with diabetes were intersected and subjected to bioinformatics analysis using the Database for Annotation,Visualization and Integrated Discovery.The major results of bioinformatics analysis were subsequently validated by animal experiments.RESULTS According to the hypothesis derived from bioinformatics analysis,SXT could possibly ameliorate lipid metabolism disorders and exert anti-apoptotic effects in MI/RI associated with diabetes by reducing oxidized low density lipoprotein(LDL)and inhibiting the advanced glycation end products(AGE)-receptor for AGE(RAGE)signaling pathway.Subsequent animal experiments confirmed the hypothesis.The treatment with a dose of SXT(2.8 g/kg/d)resulted in a reduction in oxidized LDL,AGEs,and RAGE,and regulated the level of blood lipids.Besides,the expression of apoptosis-related proteins such as Bax and cleaved caspase 3 was down-regulated,whereas Bcl-2 expression was up-regulated.The findings indicated that SXT could inhibit myocardial apoptosis and improve cardiac function in MI/RI in diabetic rats.CONCLUSION This study indicated the active components and underlying molecular therapeutic mechanisms of SXT in MI/RI with diabetes.Moreover,animal experiments verified that SXT could regulate the level of blood lipids,alleviate cardiomyocyte apoptosis,and improve cardiac function through the AGE-RAGE signaling pathway.

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.

Effects of Ethyl Pyruvate on Myocardial Apoptosis and Expression of Bcl-2 and Bax Proteins after Ischemia-reperfusion in Rats

In order to study the effects of ethyl pyruvate on cardiomyocyte apoptosis following ischemia/reperfusion （I/R） in vitro and the expression of Bcl-2 and Bax proteins, isolated rat hearts were perfused in a Langendorff model. Twenty-four rats were randomly divided into 3 groups （n=8 in each group）： control group was perfused for 120 min. In the I/R group, after 30 min stabilization the injury was induced by 30 min global ischemia followed by 60 min reperfusion. Ethyl pyruvate （EP） group was set up with the same protocol as I/R group except that it was supplied with 2 mmol/L EP 15 rain before ischemia and throughout reperfusion. Myocardial malonaldehyde （MDA） content was measured. Myocardial apoptotic index （AI） was tested by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling （TUNEL） method. The expression of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax in cardiac myocytes was detected by immunohistochemistry. As compared with control group, the content of MDA, myocardial AI and the expression of Bcl-2, Bax proteins were increased significantly in I/R group, but the content of MDA, myocardial AI and the expression of Bax protein were decreased obviously and the expression of Bcl-2 protein was up-regulated in EP group （P〈0.05）. These results demonstrate that EP could inhibit apoptosis of cardiac myocytes possibly via alleviating oxidative stress, up-regulating Bcl-2 and down-regulating Bax proteins.

Protective Effects of API_（0134） on Myocardial Ischemia and Reperfusion Injury

Previous studies have demonstrated that a crude extract from Chinese medicinal herb Andrographis Paniculata Nees (APN) could prevent myocardial ischemia and reperfusion injury. A refined extract API0134 was studied further. LAD was ligated for 90 min in 20 dogs and then reperfused for 120 min. The animals were randomly divided into 2 groups, API0134 treated group( n=10), 45 min after ischemia receiving a slow i. v. bolus of 1 mg/kg and then an infusion of 80 μg.kg-1/min for 60 min and control group (n=10) which was given only 5% glucose in saline. Result showed that the hemodynamics in API0134 treated group showed better effects of preventing the increase of the LVEDP and maintaining relatively normal CO as compared with control group. Ischemic ECGs were significantly milder. Malignant arrhythmia did not appear in API0134 treated group. After reperfusion, the infarct size was smaller ( 5. 06±2. 67 % vs 10. 45±3. 11 %, P < 0. 01 ), the damages found in myocardial ultrastructure were significantly milder. It is concluded that API0134 may protect the myocardium from ischemic reperfusion injury.

Studies on the Role of Sodium／Hydrogen Exchange System in Myocardial Ischemia－Reperfusion Injury

This study aimed at the exploration of the relationship between Na+-H+ exchange system and myocardial ischemia-reperfusion injury(MRI)in an attempt to provide a theoretic basis for the prevention and treatment of MRI.We used the isolated working guinea pig hearts as the experimental model to mimick cardiopulmonary bypass,which included 120 min hypothermic ischemic cardioplegic arrest followed by 60 min normothermic reperfusion.The hearts were divided into 2 groups:the control group receiving St.Thomas'Hospital Solution(STS)and the treated group receiving STS+ amiloride,a Na+-H+ exchangeblocker.The results showed that during reperfusion,[Na+]i and [Ca2+]i overloads,poor recovery of cardiac function,increases in CPK release and OFR generation,reduction of ATP content and serious damage of ultrastructure were seen in group 1;whereas there were no [Na+]i and [Ca2+]i overloads and better recovery of cardiac function accompanied by improved results of biochemical assay and less damage of ultrastructure was found in group 2.Our study indicates that amiloride can inhibit Na+-H+ exchange system in cardiac cells during early reperfusion period,which prevents [Na+]i overload produced by Na+-H+ exchange,and stops Na+-Ca2+ exchange activated by high level of [Na+]i,thus attenuating [Ca2+]ioverload caused by Na+-Ca2+ exchange and myocardial injury.Therefore,we conclude that Na+-H+ exchange blocker,amiloride,can exert significant protective effects on MRI and its use may prove to be a new clinical approach to prevention and cure of MRI.

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.

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.

Research progress of TRP channel's protective effect on myocardial ischemia-reperfusion injury

Transient receptor potential(TRP)channels are a type of cation channel located on the cell membrane.TRP channels are divided into 7 subfamilies(TRPC,TRPA,TRPM,TRPV,TRPN,TRPP and TRPML)and widely expressed in myocardial tissue.In recent years,with the application of gene knockout and transgenic model animals,it has been found that members of the TRP channel subfamilies TRPM,TRPC and TRPV are closely related to myocardial ischemia-reperfusion injury.The activation or inhibition of TRP channels participates in the regulation of myocardial ischemia-reperfusion injury,reduces the infarct area of the myocardium,and exerts a protective effect.Therefore,this paper first summarizes the structural characteristics of TRPM,TRPC,and TRPV and their distribution in the cardiovascular system,and then summarizes the mechanisms of TRPM,TRPC,and TRPV that regulate myocardial ischemia and reperfusion,which will provide a certain theoretical basis for treatment of myocardial ischemia-reperfusion injury.

Progress in protective effect and mechanism of 6-gingerol on myocardial ischemia/reperfusion injury

The morbidity and mortality of cardiovascular diseases are very high,which has attracted more and more attention all over the world.Common treatment methods for clinical treatment of acute myocardial infarction include direct percutaneous coronary intervention and coronary artery bypass grafting,which can quickly restore blocked coronary blood flow and reduce the infarct size.However,the inevitable ischemia/reperfusion injury will occur during the recovery of coronary blood flow,its pathological mechanism is complicated,and the Western medicine countermeasures are very limited.Among the current drugs for the treatment of cardiovascular diseases,traditional Chinese medicine has become a research hotspot due to its multiple targets,safety,and low side effects.Ginger is the fresh rhizome of Zingiber officinale Rosc.,a perennial herbaceous plant in the ginger family.It is a dual-purpose resource of medicine and food.Ginger has the functions of relieving the appearance and dispelling cold,warming up and relieving vomiting,resolving phlegm and relieving cough,and relieving fish and crab poison.The chemical components of ginger mainly include volatile oil,gingerol,diphenylheptane,etc..Among them,6-gingerol,as the main active component of gingerols,has obvious pharmacological effects in myocardial protection,anti-oxidation,anti-inflammatory,etc..Studies have shown that 6-gingerol protects myocardium mainly through anti-oxidative stress,anti-inflammatory,inhibiting cell apoptosis,and preventing calcium influx.①Anti-oxidative stress:oxidative stress is a state where oxidation and anti-oxidation in the body are out of balance,and it is also an important factor leading to myocardial damage.Many studies have confirmed that 6-gingerol has an antioxidant effect,and it is considered a natural antioxidant.6-gingerol can significantly reduce the degree of oxidative stress and the level of reactive oxygen species caused by cardiomyocyte damage,and has a significant cardioprotective effect.②Anti-inflammatory:inflammation can cause substantial cell damage and organ dysfunction,which is another important cause of myocardial damage.6-gingerol can reduce the levels of inflammatory factors such as interleukin-6,interleukin-1β,and tumor necrosis factor-αin cardiomyocytes,and at the same time inhibit the TLR4/NF-κB signaling pathway,an important regulatory pathway of inflammation,showing that it may improve myocardial damage through anti-inflammatory effects.③Inhibition of apoptosis:apoptosis is a complex and orderly process in the autonomous biochemical process of cells,and one of the main mechanisms of myocardial injury.This process can be roughly divided into three pathways:mitochondria,endoplasmic reticulum,and death receptors.Among them,the mitochondrial pathway plays an important role,and Bcl-2 and Bax located upstream of this pathway can regulate the entire process of cell apoptosis by regulating the permeability of the mitochondrial membrane.Studies have found that the preventive application of 6-gingerol can reduce cell damage,reduce the number of apoptotic cells,reduce the activity of Bax and caspase-3,and increase the expression of Bcl-2.Therefore,6-gingerol pretreatment can reduce the damage of cardiomyocytes,and its mechanism may be related to the inhibition of apoptosis.④Prevent calcium influx:calcium overload is involved in the pathogenesis of myocardial ischemic injury,which may be related to excessive contracture,arrhythmia,and mitochondrial Ca2+accumulation that impairs myocardial function.6-gingerol inhibits the increase of intracellular Ca2+concentration by inhibiting L-type calcium current,thereby reducing extracellular Ca2+influx,thereby avoiding calcium overload and playing a cardioprotective effect.In summary,6-gingerol can effectively treat and improve myocardial ischemia/reperfusion injury,and it has great development potential in the fields of medicine and health products.

Mechanism of hesperidin improving myocardial ischemia/reperfusion injury in type 2 diabetic rats through SIRT1/Nrf2/HO-1 signaling pathway

Objective:To observe the protective effect of hesperidin on myocardial ischemia/reperfusion injury in type 2 diabetes mellitus and its effect on SIRT1/Nrf2/HO-1 signaling pathway.Methods:50 Sprague-Dawley(SD)rats were randomly assigned to the normal control group(NC),model group,ischemia-reperfusion group(IR),hesperidin group,SIRT1 inhibitor group and hesperidin plus SIRT1 inhibitor group.In addition to NC,the rats in the remaining groups were replicated by intraperitoneal of high-fat diet combined with injection of streptozotocin for type 2 diabetic rats.After then,the myocardial ischemia/reperfusion injury(MIRI)rat model was established by LAd for 30 minutes with 2 hours reperfusion.He staining was used to observe the pathological changes of myocardial tissue,and the levels of serum LDH,CK-MB and SOD,GSH and MDA in myocardial tissue were detected by kit methods,and the expression abundance of related proteins in 4-HNE and SIRT1/Nrf2/HO-1 signal pathway were detected by immunohistochemistry and Western blot;Results:Hesperidin could significantly inhibit cardiomyocyte necrosis and inflammatory cell infiltration,reduce LDH activity,CK-MB and MDA level,and increase SOD activity,GSH and 4-HNE level,the differences were statistically significant when compared with IR group(P<0.01).In addition,compared with the ischemia-reperfusion group,the expressions of SIRT1,Nrf2 and HO-1 proteins in hesperidin group were significantly up-regulated,the differences were statistically significant(P<0.01);Conclusion:Hesperidin inhibits oxidative stress by activating SIRT1/Nrf2/HO-1 signaling pathway,and play a protective effect of myocardial ischemia reperfusion injury in diabetic rats.

Activation of epidermal growth factor receptor mediates myocardial ischemia/reperfusion arrhythmias in anaesthetized rats

Objectives Epidermal growth factor receptor （EGFR）is a receptor protein tyrosine kinase and plays a critical role in the development and function of the heart.Previous studies have demonstrated that EGFR is involved in regulating electrical excitability of the heart.The present study was designed to investigate whether EGFR activation would mediate myocardial arrhythmias induced by ischemia/reperfu- sion in anaesthetized rats.Methods and results Myocardial ischemia/reperfusion arrhythmias were induced by 10 min ligation of the left anterior descending coronary artery,followed by a 30 min reperfusion in anaesthetized rats.Incidence and severity of cardiac arrhythmias were significantly reduced by pretreatment with the EGFR kinase inhibitor AG556.Phosphorylation level of myocardial EGFR was increased during ischemia and at early reperfusion.Intramyocardial transfection of EGFR siRNA reduced EGFR mRNA and protein,and decreased the incidence of ventricular fibrillation induced by reperfusion.Interestingly,tyrosine phosphorylation levels of cardiac Na+ channel(INa) and L-type Ca2+ channel(ICa.l) were significantly increased at corresponding time points to the alteration of phosphorylated EGFR level during reperfusion.AG556 pretreatment countered the increased tyrosine phosphorylation level of Na+ and L-type Ca2+ channels induced by reperfusion.No significant alteration was observed in tyrosine phosphorylation levels of cardiac Kv4.2 and Kir2.1 channels during the cardiac ischemia/reperfusion. Conclusions These results demonstrate for the first time that EGFR plays an important role in the genesis of myocardial ischemia/reperfusion arrhythmias,which is likely mediated at least in part by enhancing tyrosine phosphorylation of cardiac Na+ and L-type Ca2+ channels.

EFFECT OF REPERFUSION THERAPY ON SOLUBLE CELL ADHESION MOLECULES IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION

Objective To observe the changes of serum soluble intercellular adhesion moiecuie type-1(ICAM-1) and E-selectin in patients with acute myocardial inlarction (AMI) receiving reperfusiontherapy. Methods Peripheral venous blood samples were taken from 21 patients with AMI before and4,8,12,24,48,72h after thrombolytic treatment or direct percutaneous transluminal coronary angioplasty (PTCA).Blood samples from 16 control subjects were drawn for one time. Serum concentration of ICAM-1 and E-selectinwas determined by double antibodies sandwich enzyme-linked immunosorbent assay. Results Serum levels ofICAM-1 and E-selectin were higher in patients with AMI than those in controls. Sixteen patients with AMIand successful roperfusion therapy had signifcantly reduction in serum concentration of ICAM-1 and E-selectinat 24 and 48h, but had a peak at 4h. The remaining live patients who failed in mperfusion theropy didn’t show anysignificant changes in these values. Conclusion The serum concentration of ICAM-1 and E-selectin waselevated significantly in patients with AMI Successful reperfusion therapy can reduce the increased serumconcentration.

Changes of cTnI in myocardial ischemic and reperfusion injury during correction of cardiac defects in children

Objective The purpose of this study is to investgate changes of cTnI in myocardial ischemic and reperfusion injury during correction of cardiac defects in children. Methods From June, 1999 to May,2000,45 children (30 male, 15 female) undergoing correction of cardiac defects were divided into three groups randomly: group Ⅰ no myocardial ischemia,group Ⅱ myocardial ischemia less than 60 minutes, group Ⅲmyocardial ischemia 】 60 minutes. There were no significant differences in the three groups in age, sex ratio, C/T ratio, or left ventricular function. Blood samples for analysis were collected before skin incision and at time intervals up to 6 days postoperatively. Analysis of creatine kinase MB.LDH and cardiac-specific troponin I was used for the detection of myocardial damage. Meantime, the ECG was checked for myocardial infarction. After the reperfusion, myocardial tissue was obtained from the free wall of right ventricle myocardial structure studies. Results The level of cTnI was increased

Effect of electroacupuncture at Neiguan(PC6)at different time points on myocardial ischemia reperfusion arrhythmia in rats

OBJECTIVE:To observe the effects of electroacupuncture at Neiguan(PC6)at different time points on reperfusion arrhythmia(RA)after myocardial ischemia and reperfusion in rats,and to investigate the correlation of this protective effect with nerve growth factor(NGF),tyrosine kinase A(Trk A),tyrosine hydroxylase(TH),and norepinephrine(NE).METHODS:A total of 72 Sprague-Dawley male rats were randomly divided into six groups(n=12 rats/group):normal group(Norm),sham operation group(Sham),ischemia reperfusion group(I/R),pre-ischemic electroacupuncture group(EAI),pre-reperfusion electroacupuncture group(EAII),post-reperfusion electroacupuncture group(EAIII).The myocardial ischemia-reperfusion injury(MIRI)model was induced by occlusion of left anterior descending coronary artery for 20 min followed by reperfusion for 40 min in rats.With no intervention in the Norm group and only threading without ligation in the Sham group.Electroacupuncture pretreatment at 20 min/d for 7 d before ligation in the EAⅠgroup,20 min of electroacupuncture before reperfusion in the EAII group and 20 min of electroacupuncture after reperfusion in the EAIII group.The electrocardiogram(ECG)of each group was recorded throughout the whole process,and the success of the MIRI model was determined based on the changs of J-point and T-wave in the ECG.The arrhythmia score was used to record premature ventricular contractions,ventricular tachycardia and ventricular fibrillation during the reperfusion period to assess the reperfusion induced arrhythmias.The expression levels of NGF,Trk A,TH protein were measured by Western blot.Moreover,the expression levels of plasma and myocardial NE levels were detected by enzyme linked immunosorbent assay.RESULTS:The differences between Norm group and Sham group were not statistically significant in all indexes.Arrhythmia score,myocardial NGF,Trk A,TH,and NE expression were significantly higher in the I/R group compared with the Sham group.Arrhythmia score,myocardial NGF,Trk A,TH,and NE expression were significantly lower in each EA group compared with the I/R group.CONCLUSION:Electroacupuncture at Neiguan(PC6)at different time points can reduce the incidence and severity of reperfusion arrhythmias in rats.This protective effect is related to electroacupuncture regulating NGF,Trk A,TH,NE expression and reducing sympathetic hyperactivation.

Effects of Lipoteichoic Acid induced Delayed Preconditioning on Ischemia-reperfusion Injury in Isolated Rat Hearts

To explore the potential of lipoteichoic acid (LTA) induced cardioprotection against ischemia-reperfusion (I/R) injury in isolated rat hearts and whether endogenous nitric oxide (NO) participates in the protection, the rats were pretreated with LTA (1 mg/kg, i p ) 24 h before the experiment, and the isolated hearts were subjected to 30 min no-flow normothermic global ischemia and 60 min reperfusion after a 20-min stabilization period by the langendorff method Cardiac functions were evaluated at the end of stabilization, and at 30 min, 60 min of reperfusion The amounts of MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase(LDH) and total NO oxidation products in the coronary effluent were measured spectrophotometrically at the end of reperfusion It was revealed that pretreatment with LTA could significantly improve the recovery of cardiac function, reduce the release of CK-MB and LDH, and increase the concentrations of NO in coronary effluent The protective effects were abrogated by pretreatment of the rats with L-NAME It was concluded that LTA could induce the delayed cardioprotection against I/R injury, and endogenous NO may be involved in the mechanisms

Shuxuening Injection Inhibits Apoptosis and Reduces Myocardial Ischemia-Reperfusion Injury in Rats through PI3K/AKT Pathway

Objective: To investigate the main components and potential mechanism of Shuxuening Injection(SXNI) in the treatment of myocardial ischemia-reperfusion injury(MIRI) through network pharmacology and in vivo research. Methods: The Traditional Chinese Medicine Systems Pharmacology(TCMSP) and Pharm Mapper databases were used to extract and evaluate the effective components of Ginkgo biloba leaves, the main component of SXNI. The Online Mendelian Inheritance in Man(OMIM) and Gene Cards databases were searched for disease targets and obtain the drug target and disease target intersections. The active ingredient-target network was built using Cytoscape 3.9.1 software. The STRING database, Metascape online platform, and R language were used to obtain the key targets and signaling pathways of the anti-MIRI effects of SXNI. In order to verify the therapeutic effect of different concentrations of SXNI on MIRI in rats, 60 rats were first divided into 5 groups according to random number table method: the sham operation group, the model group, SXNI low-dose(3.68 mg/kg), medium-dose(7.35 mg/kg), and high-dose(14.7 mg/kg) groups, with 12 rats in each group. Then, another 60 rats were randomly divided into 5 groups: the sham operation group, the model group, SXNI group(14.7 mg/kg), SXNI+LY294002 group,and LY294002 group, with 12 rats in each group. The drug was then administered intraperitoneally at body weight for 14 days. The main biological processes were validated using in vivo testing. Evans blue/triphenyltetrazolium chloride(TTC) double staining, hematoxylin-eosin(HE) staining, terminal deoxynucleotidyl transferase d UTP nick end labeling(TUNEL) assay, enzyme-linked immunosorbent assay(ELISA), and Western blot analysis were used to investigate the efficacy and mechanism of SXNI in MIRI rats. Results: Eleven core targets and 30 Kyoto Encyclopedia of Genes and Genomes(KEGG) pathways were selected. Among these, the phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT) pathway was closely related to SXNI treatment of MIRI. In vivo experiments showed that SXNI reduced the myocardial infarction area in the model group, improved rat heart pathological damage, and reduced the cardiomyocyte apoptosis rate(all P<0.01). After SXNI treatment, the p-PI3K/PI3K and p-AKT/AKT ratios as well as B-cell lymphoma-2(Bcl-2) protein expression in cardiomyocytes were increased, while the Bax and cleaved caspase 3 protein expression levels were decreased(all P<0.05). LY294002 partially reversed the protective effect of SXNI on MIRI. Conclusion: SXNI protects against MIRI by activating the PI3K/AKT signaling pathway.