Myocardial Ischemia-reperfusion Group Research Articles

Ischemic Postconditioning Attenuates Myocardial Ischemia-Reperfusion-Induced Acute Lung Injury by Regulating Endoplasmic Reticulum Stress-Mediated Apoptosis.

To explore the effect of ischemic postconditioning on myocardial ischemia-reperfusion-induced acute lung injury (ALI). Forty adult male C57BL/6 mice were randomly divided into sham operation group (SO group), myocardial ischemia-reperfusion group (IR group), ischemic preconditioning group (IPRE group) and ischemic postconditioning group (IPOST group) (10 mice in each group). Anterior descending coronary artery was blocked for 60 min and then reperfused for 15 min to induce myocardial IR. For the IPRE group, 3 consecutive cycles of 5 min of occlusion and 5 minutes of reperfusion of the coronary arteries were performed before ischemia. For the IPOST group, 3 consecutive cycles of 5 min reperfusion and 5 minutes of occlusion of the coronary arteries were performed before reperfusion. Pathological changes of lung tissue, lung wet-to-dry (W/D) weight ratio, inflammatory factors, oxidative stress indicators, apoptosis of lung cells and endoplasmic reticulum stress (ERS) protein were used to evaluate lung injury. After myocardial IR, lung injury worsened significantly, manifested by alveolar congestion, hemorrhage, structural destruction of alveolar septal thickening, and interstitial neutrophil infiltration. In addition, lung W/D ratio was increased, plasma inflammatory factors, including interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-17A, were increased, malondialdehyde (MDA) activity of lung tissue was increased, and superoxide dismutase (SOD) activity was decreased after myocardial IR. It was accompanied by the increased protein expression levels of ERS-related protein glucose regulatory protein 78 (GRP78), CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), and caspase-12, and the increased apoptotic indices of lung tissues. IPOST can effectively improve myocardial IR-induced ALI by inhibiting ERS-induced apoptosis of alveolar epithelial cells.

PI3K/Akt signaling pathway mediates the protective effect of endomorphin-1 postconditioning against myocardial ischemia-reperfusion injury in rats

To investigate the role of PI3K/Akt signaling pathway in mediating the protective effect of endomorphin-1 against myocardial ischemia-reperfusion (IR) injury. Fifty SD male rats were randomly divided into sham operation group, myocardial IR group, endomorphin-1 post-treatment group (EM50 group), endomorphin-1+wortmannin (a PI3K/Akt signaling pathway inhibitor) treatment group (EM50+Wort group), and wortmannin treatment group (Wort group). Rat models of myocardial IR injury were established by ligation of the left anterior descending coronary artery for 30 min followed by reperfusion for 120 min. The heart rate and mean arterial pressure were monitored during the experiment. Plasma levels of LDH, CK-MB, cTnI, IL-6, TNF-α, SOD and MDA were measured after reperfusion. The mRNA expression of Bax and Bcl-2 was detected using RT-PCR, and the expression of apoptosis-related protein cleaved caspase-3, phosphorylated Akt protein and total Akt protein in myocardial tissue was detected using Western blotting. Myocardial IR injury significantly decreased heart rate and blood pressure of the rats in comparison with the sham operation (P < 0.05). Compared with those in the IR group, the rats in EM50 group showed significantly increased heart rate and blood pressure (P < 0.05) with decreased plasma LDH, CK-MB, cTnI, IL-6, TNF-α and MDA levels (P < 0.05), increased SOD activity (P < 0.05), increased expression of p-Akt protein and Bcl-2 mRNA (P < 0.05), and decreased expression of Bax mRNA and cleaved caspase-3 protein (P < 0.05). In EM50+Wort group, the heart rate and blood pressure were significantly lowered (P < 0.05), plasma LDH, CK-MB, cTnI, IL-6, TNF-α and MDA levels increased (P < 0.05), SOD activity decreased (P < 0.05), the expression of p-Akt protein and Bcl-2 mRNA was reduced (P < 0.05), and the expression of Bax mRNA and cleaved caspase-3 protein increased (P < 0.05) as compared with those in EM50 group. EM-1 postconditioning can regulate cardiac myocyte apoptosis and reduce myocardial IR injury in rats. The PI3K/Akt signaling pathway may play a role in mediating the myocardial protective effects of EM-1 postconditioning.

The Circadian Clock Regulates the Expression of the Nuclear Factor Erythroid 2-Related Factor 2 in Acute Kidney Injury following Myocardial Ischemia-Reperfusion in Diabetic Rat

Cardiac surgery-associated acute kidney injury (AKI) is a serious and frequent complication with poor prognosis, and disruption in circadian rhythm shall adversely influence cardiovascular and renal functions via oxidative stress mechanisms. However, the role of circadian clock genes (circadian locomotor output cycle kaput (CLOCK) and brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1)) and its interaction with nuclear factor erythroid 2-related factor 2 (Nrf2) in AKI following myocardial ischemia-reperfusion (MIR) in the diabetic rat has not yet been explored. In this study, rats were divided into the sham (S) group, MIR (M) group, diabetic (D) group, and diabetic+MIR (DM) group. At light (zeitgeber time (ZT) 0) and dark time points (ZT12), rat MIR model was established by occlusion of the left anterior descending coronary artery for 30 min followed by 2 -hour reperfusion, and then renal injury was evaluated. The renal histological changes in the DM group were significantly high compared to other groups; serum creatinine, blood urea nitrogen, and neutrophil gelatinase-associated lipocalin levels, as well as malondialdehyde and 8-iso-prostaglandin-F2α levels in renal tissues of M ZT12 and DM ZT12 subgroups, were significantly higher than those of M ZT0 and DM ZT0 subgroups, individually indicating increased oxidative stress at a dark cycle. Further, Nrf2 protein accumulated in a circadian manner with decreasing levels at night in the DM and M groups. In conclusion, renal injury following MIR was exacerbated in the diabetic rat at night through molecular mechanisms involving transcriptional control of the circadian clock on light-dark activation of Nrf2.

Effects of Myocardial Ischemia-Reperfusion on Autophagy of Brain Cells and the Intervention Effect of Propofol in Type 2 Diabetic Rats

To investigate the expression of autophagy markers of brain cells and the effect of propofol on autophagy during myocardial ischemia-reperfusion in type 2 diabetic rats. 36 healthy male Sprague Dawley rats were randomly divided into 6 groups, 6 in each group, fed with high-sugar and high-fat diet for 8 w and intraperitoneal injection of streptozotocin to prepare the rat model of type 2 diabetes. The 6 groups are: diabetic rat with sham operation group, diabetic rat with myocardial ischemia reperfusion group, diabetic rat with myocardial ischemia reperfusion+propofol group, normal rat with sham operation, normal rat with myocardial ischemia reperfusion group, normal rat with myocardial ischemia reperfusion+propofol group[1]. In the normal rat with myocardial ischemia reperfusion+propofol group and diabetic rat with myocardial ischemia reperfusion+ propofol group, the left anterior descending coronary artery was ligated for 30 min and reperfused for 2 h after the propofol was injected with 6 mg•kg-1•h-1 for 10 min. Normal rat with myocardial ischemia reperfusion group and diabetic rat with myocardial ischemia reperfusion groups were pumped with 3 ml•kg-1•h-1 normal saline for 10 min, followed by ligation of the left anterior descending coronary artery for 30 min and reperfusion for 2 h. Arterial ligation was not performed in the normal rat with sham operation group and diabetic rat with sham operation groups. Brain tissue was taken to detect its levels of mechanistic target of rapamycin, phosphorylated mammalian target of rapamycin and Beclin-1 by Western blot. Compared with normal rat with sham operation group, phosphorylated mammalian target of rapamycin level was significantly decreased, and mechanistic target of rapamycin beclin-1 expression level was significantly increased in the other 5 groups (p<0.05). Compared with diabetic rat with myocardial ischemia reperfusion group, the expression level of phosphorylated mammalian target of rapamycin in diabetic rat with myocardial ischemia reperfusion+propofol group was increased, while beclin-1 and mechanistic target of rapamycin expression levels were significantly decreased (p<0.05). Compared with normal rat with myocardial ischemia reperfusion group, the level of mechanistic target of rapamycin in normal rat with myocardial ischemia reperfusion+propofol group was significantly increased, while the beclin-1 and mechanistic target of rapamycin expression levels were significantly decreased (p<0.05). Diabetes can promote the autophagy of brain cells during myocardial ischemia-reperfusion and aggravate the brain injury. Propofol can up-regulate the level of Phosphorylated mammalian target of rapamycin and down-regulate the expression of mechanistic target of rapamycin to alleviate the damage of brain cells after myocardial ischemia and reperfusion in normal rats and type 2 diabetic rats.

Protective action of the ginsenoside Rh3 in a rat myocardial ischemia-reperfusion injury model by inhibition of apoptosis induced via p38 mitogen-activated protein kinase/caspase-3 signaling.

ObjectiveTo investigate the protective effects of the ginsenoside Rh3 on rats subjected to myocardial ischemia-reperfusion (MIR) via its impact on caspase-3 and the p38 mitogen-activated protein kinase (MAPK) pathway.MethodsFifteen male Sprague-Dawley rats were randomly categorized into the MIR group (MY group, n = 5), sham surgery group (SS group, n = 5), and ginsenoside Rh3 group (GR group, n = 5).ResultsThe MY group exhibited the largest myocardial infarctions compared with the GR and SS groups. The GR group exhibited significantly higher cell viability of cardiomyocytes and significantly decreased apoptosis compared with the MY group. Fibrils of infarcted tissue in the GR group were disordered but less swollen, with a more organized fibril orientation than those in the MY group. The GR group showed reduced p-p38 MAPK protein and caspase-3 mRNA expression levels compared with the MY and SS groups.ConclusionsRh3 significantly improved myocardial necrosis and caspase-3 levels in myocardial tissues by suppressing the p38 MAPK pathway, thereby inhibiting caspase-3 involvement in apoptosis. Thus, Rh3 was effective in inhibiting the escalated apoptotic pathway in myocardial infarction and can potentially serve as a useful therapeutic agent to rescue myocardial infarction.

Effects on cardiac function, remodeling and inflammation following myocardial ischemia\u2013reperfusion injury or unreperfused myocardial infarction in hypercholesterolemic APOE*3-Leiden mice

Many novel therapies to treat myocardial infarction (MI), yielding promising results in animal models, nowadays failed in clinical trials for several reasons. The most used animal MI model is based on permanent ligation of the left anterior descending (LAD) coronary artery in healthy mice resulting in transmural MI, while in clinical practice reperfusion is usually accomplished by primary percutaneous coronary interventions (PCI) limiting myocardial damage and inducing myocardial ischemia–reperfusion (MI-R) injury. To evaluate a more similar murine MI model we compared MI-R injury to unreperfused MI in hypercholesterolemic apolipoprotein (APO)E*3-Leiden mice regarding effects on cardiac function, left ventricular (LV) remodeling and inflammation. Both MI-R and MI resulted in significant LV dilation and impaired cardiac function after 3 weeks. Although LV dilation, displayed by end-diastolic (EDV) and end-systolic volumes (ESV), and infarct size (IS) were restricted following MI-R compared to MI (respectively by 27.6% for EDV, 39.5% ESV, 36.0% IS), cardiac function was not preserved. LV-wall thinning was limited with non-transmural LV fibrosis in the MI-R group (66.7%). Two days after inducing myocardial ischemia, local leucocyte infiltration in the infarct area was decreased following MI-R compared to MI (36.6%), whereas systemic circulating monocytes were increased in both groups compared to sham (130.0% following MI-R and 120.0% after MI). Both MI-R and MI models against the background of a hypercholesterolemic phenotype appear validated experimental models, however reduced infarct size, restricted LV remodeling as well as a different distributed inflammatory response following MI-R resemble the contemporary clinical outcome regarding primary PCI more accurately which potentially provides better predictive value of experimental therapies in successive clinical trials.

Expression and regulation of tumor necrosis factor-α-induced protein-8-like 2 is associated with acute lung injury induced by myocardial ischemia reperfusion in diabetic rats

AimsThe purpose of the present study was to investigate the possible role of TIPE2 on acute lung injury (ALI) induced by myocardial ischemia/reperfusion (MIR) in diabetic rats. MethodsSprague-Dawley (SD) rats were randomly separated into four groups: control+sham (C + sham); control+MIR (C + MIR); diabetes+sham (D + sham); diabetes+MIR (D + MIR). Diabetes was induced using streptozotocin. Eight weeks after diabetes induction, MIR was conducted. At 2 h after MIR, myocardial injury indices were assessed; arterial blood, bronchoalveolar lavage fluid (BALF) and lung tissues were collected for corresponding detection. ResultsRats subjected to MIR showed serious ALI (estimated via pathological changes, lung injury score and Wet/Dry weight ratio), lung inflammation and pulmonary cell apoptosis compared with sham groups, especially in D + MIR group. Evaluation of protein expression in lung tissues showed that p-JNK and nuclear NF-κB p65 protein levels were higher in D + MIR group as compared with C + MIR group. Besides, either hyperglycemia or MIR can significantly upregulate TIPE2 protein levels. ConclusionsIn conclusion, diabetic lungs are more susceptible to MIR. TIPE2 may involve in this pathological process, possibly through regulation of inflammation, oxidative stress and apoptosis.

MiR-19a suppress apoptosis of myocardial cells in rats with myocardial ischemia/reperfusion through PTEN/Akt/P-Akt signaling pathway.

To detect differentially expressed micro ribonucleic acids (miRNAs) in rats with myocardial ischemia/reperfusion (MIR), and to explore the influence of miR-19a on MIR rats and its mechanism. Firstly, the Sprague-Dawley (SD) rats were used to prepare MIR models, RNAs were extracted, and miRNA sequencing analysis was carried out to determine differentially expressed miRNAs related to MIR. Secondly, the predicted target genes of miR-19a were collected, and WebGestalt was applied to analyze gene ontology (GO) and pathway enrichment. Thirdly, the expression of the related proteins and the apoptosis of myocardial cells in MIR rats were detected via Western blotting. Fourthly, the interaction between miR-19a and the target gene phosphatase and tensin homolog (PTEN) was examined through Luciferase reporter assay. Compared with that in the Sham operation (Sham) group, the miR-19a expression in rat myocardial tissues in the MIR group was significantly increased (p<0.05). Compared with those in the miR-negative control (miR-NC) group, the messenger RNA (mRNA) and protein expressions of PTEN in the miR-19a group were notably decreased (p<0.05). In comparison with the miR-NC group, miR-19a group had elevated expression of phosphorylated protein kinase B (p-Akt) (p<0.05). The Luciferase reporter gene assay manifested the direct binding of miR-19a to PTEN mRNA. MiR-19a inhibits the PTEN expression by directly binding to the 3'-UTR of PTEN mRNA, thus activating the Akt/p-Akt signaling pathway to suppress the apoptosis of myocardial cells in MIR injury.

Resveratrol increase myocardial Nrf2 expression in type 2 diabetic rats and alleviate myocardial ischemia/reperfusion injury (MIRI).

Oxidative stress is one of the main factors that increases reperfusion injury in the diabetic heart. Resveratrol could decrease oxidation and promote antioxidant factor expression. Nrf2 is an important endogenous antioxidant. making the heart more resistant to ischemic injury. As Nrf2 expression is considered to be reduced in diabetic heart, we therefore hypothesized that up-regulation of Nrf2 in the diabetic heart may overcome its increased susceptibility to ischemic injury. A total of 50 diabetic rats were randomly divided into five groups: the sham operation group (DM + sham), the MIRI group (DM + MI/R), the resveratrol treatment group (DM + MI/R + RSV), the resveratrol + ex527 (SIRT1 inhibitor) group (DM + MI/R + RSV + ex527), and the resveratrol + LY294002 (Akt inhibitor) group (MD + MI/R + RSV + LY294002). Another 20 normal rats were randomly divided into two groups: the sham-operated group (CON + sham) and the myocardial ischemia-reperfusion group (CON + MI/R). A type 2 diabetes model was induced by a high-fat diet-fed and intraperitoneal injection of streptozotocin (STZ). All rats were subjected to 30 min myocardial ischemia followed by 120 min reperfusion except sham groups. Plasma were collected to measure the creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), malondialdehyde (MDA) level, glutathione (GSH) level, and superoxide dismutase (SOD) activity. Pathologic changes in myocardial tissues were observed by Hematoxylin and eosin (HE) straining. SIRT1, p-GSK3β, Nrf2, HO-1 protein expressions were measured by western blot. Compared with the control (CON) group, the diabetic (DM) group had more severe myocardial injury, higher oxidative stress index increase, and a more reduced expression of Nrf2 in the myocardium. After supplementing with resveratrol, the myocardial damage was reduced and the oxidative stress index decreased in the DM group, while the Nrf2 in the myocardium was increased. It also was found that inhibition of SIRT1 also partially inhibited the expression of Nrf2 and the corresponding antioxidant factor HO-1. Decreased expression of p-GSK3β by Akt inhibitors also partially inhibited Nrf2 and HO-1 expression. Resveratrol can enhance the expression of Nrf2 in a diabetic heart by stimulating SIRT1 or inhibiting GSK3β, alleviating myocardial oxidative stress, and improving ischemia-reperfusion injury.

Renal Damage Induced by Myocardial Ischemia Reperfusion in Mouse: Role of Oxidative Stress

The aim of this study was to investigate whether oxidative stress has a role in myocardial ischemia reperfusion induced renal damage. The 30 male C57 mice were divided into control group, myocardial ischemia reperfusion (MIR) group and MnTBAP treatment group. In MIR group, the left coronary artery was occluded for 45minutes and reperfusion for 4 weeks. The same procedure was used for the MnTBAP group, with the additional step of MnTBAP (10mg/kg) administered intraperitoneally for 28 days. Before surgery and 4 weeks later, transthoracic echocardiography was performed and urine protein and albumin were measured. At the end of the time, mice were sacrified and kidneys collected for ROS and fibrosis analysis. The plasma was collected for BUN and SCR determination. It was observed that MIR decreased renal function and increased production of ROS, compelled with renal fibrosis. Administration of MnTBAP reduced production of ROS and renal fibrosis and increased renal function. These findings suggest that the MIR plays a causal role in causing renal injury and the MnTBAP exerts renal-protective effects, probably by its antioxidant activities.

Mechanism of myocardial ischemia/reperfusion-induced acute kidney injury through DJ-1/Nrf2 pathway in diabetic rats.

The objective of the present study was to investigate acute kidney injury (AKI) induced by myocardial ischemia/reperfusion (MIR) in diabetic rats and elucidate its underlying mechanism. A rat model of MIR was established by left anterior descending coronary artery occlusion for 30 min, followed by reperfusion for 2 h. Rats were randomly divided into four groups: i) Sham group, ii) sham + MIR group, iii) diabetic group and iv) diabetes + MIR group. Myocardial injury was detected by plasma creatine kinase isoenzyme MB and lactate dehydrogenase assays. AKI induced by MIR in diabetic rats was characterized by increases in cystatin C and β2-microglobulin levels. Oxidative stress injury was accompanied by an increase of malondialdehyde levels and a decrease of total antioxidative capacity in the renal tissues. Immunohistochemistry and western blot analysis demonstrated that the expression of DJ-1 and nuclear factor erythroid 2-related factor 2 (Nrf2) were significantly increased in the diabetes + MIR group compared with that in the sham + MIR and diabetic groups. Taken together, these results suggested that AKI induced by MIR in diabetic rats may be associated with activation of the DJ-1/Nrf2 pathway.

Effect of microRNA-10a on expression of brain natriuretic peptide after myocardial ischemia reperfusion in rats

Objective To investigate the effect of microRNA (miRNA, miR)-10a on the expression of brain natriuretic peptide (BNP) in ventricular remodeling after myocardial ischemia reperfusion injury in rats. Methods Forty-five male Wistar rats were randomly divided into sham operation group A (sham operation group, n=15) and myocardial ischemia reperfusion group (n=30). Rats in myocardial ischemia reperfusion group were inflicted by ligating the left anterior descending coronary of rats. After 24 h, 30 survived rats were randomly divided into group B (myocardial ischemia reperfusion group, n=15) and group C (miR-10a group, n=15). Rats in group C were treated with miR-10a agomirs (80 mg/kg body weight) by tail intravenous injection for 4 weeks, and those in group A and group B were treated with negative control reagents. The expression of histone deacetylase 2 (HDAC2) mRNA was detected by Real-time PCR method respectively. The content of BNP was examined by Western blotting. Results After 4 weeks, the relative expression of HDAC2 mRNA in groups A, B and C was 6.58±0.23×10-5, 14.29±2.16×10-5, and 10.11±1.55×10-5 respectively. Left ventricular mass index was 2.10±0.26, 2.61±0.11, and 2.41±0.12 respectively in groups A, B and C. As compared with group B and group C, the expression of HDAC2 mRNA and BNP in the myocardial ischemia reperfusion zone and left ventricular mass index in group A were significantly increased (P< 0.05). The expression of HDAC2 mRNA and BNP in the myocardial ischemia reperfusion zone and left ventricular mass index in group C were significantly higher than those in group B (P< 0.05). Conclusion miR-10a may improve ventricular remodeling after myocardial ischemia reperfusion in rats via inhibiting the expression of HDAC2 mRNA. Key words: MicroRNA-10a; Histone deacetylase 2; Brain natriuretic peptide; Myocardial ischemia; Reperfusion injury; Myocardial remodeling

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

To observe the effects of angiotensin Ⅱ(Ang Ⅱ) perfusion 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. 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 invitro 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 ΔCx43-pro and ΔCx43-Cq respectively. 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 ΔCx43-pro and ΔCx43-Cq were significant increased. 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.

Relationship between mitofusin-2 and diabetes mellitus-caused influence on cardioprotection induced by sevoflurane postconditioning in rats

Objective To evaluate the relationship between mitofusin-2 (Mfn-2)expression and diabetes mellitus (DM)-caused influence on cardioprotection induced by sevoflurane postconditioning in rats. Methods Healthy male Sprague-Dawley rats, weighing 210-260 g, were studied.DM was induced by intraperitoneal 1% streptozotocin 60 mg/kg, and confirmed by blood glucose ≥16.7 mmol/L 72 h later.Thirty-six rats with DM were randomly divided into 3 groups (n=12 each) using a random number table: sham operation group (group DMS), myocardial ischemia-reperfusion group (group DMIR), and sevoflurane postconditioning group (group DMSP). Another 36 normal rats were selected, and were also randomly divided into 3 groups (n=12 each) using a random number table: sham operation group (group NS), myocardial ischemia-reperfusion group (group NIR), and sevoflurane postconditioning group (group NSP). Myocardial ischemia was induced by 30 min occlusion of the left anterior descending branch of the coronary artery, followed by 120 min reperfusion.In NSP and DMSP groups, sevoflurane was inhaled for 5 min after the end-tidal concentration reached 2.5% starting from 1 min before reperfusion.The rats were sacrificed at 120 min of reperfusion, and their hearts were removed for measurement of myocardial infarct size (IS) (by TTC), cell apoptosis and Mfn2 expression, and for examination of pathological changes (with light microscope) and ultra-structure (with electron microscope). Apoptosis index (AI) was calculated. Results Compared with group NS, the myocardial IS was significantly enlarged, AI was increased, and the expression of Mfn-2 was down-regulated in NIR and NSP groups (P 0.05). Compared with group NSP, the myocardial IS was significantly enlarged, AI was increased, and the expression of Mfn-2 was down-regulated in group DMSR (P<0.05). The pathological changes were significantly attenuated in group NSP compared with group NIR.No significant difference was found in pathological changes between group DMSP and group DMIR. Conclusion The mechanism by which DM abolishes cardioprotection induced by sevoflurane postconditioning may be related to inhibited up-regulation of Mfn-2 expression in rats. Key words: Diabetes mellitus; Anesthetics, inhalation; Ischemic postconditioning; Myocardial reperfusion injury; Fusion proteins, bcr-abl

Effects of apocynin, an NADPH oxidase inhibitor, on levels of ADMA, MPO, iNOS and TLR4 induced by myocardial ischemia reperfusion.

In this study, the effects of apocynin, an NADPH oxidase inhibitor, on the levels of inducible nitric oxide synthase (iNOS) and the toll-like receptor 4 (TLR4), which are inflammatory mediators in myocardial ischemia-reperfusion (MIR) injury, and myeloperoxidase (MPO), which is the indicator of neutrophil infiltration and the endogenous nitric oxide synthase inhibitor asymmetric dimethyl arginine (ADMA) increasing with oxidative stress were investigated. MIR injury was accomplished by the application of occlusion for 30 minutes and reperfusion for 120 minutes in the left anterior descending artery (LAD). In the study, 21 Sprague-Dawley male rats were divided into three groups: a sham group (n = 7); a MIR group (n = 7); and a MIR + apocynin treatment group (n = 7, before the procedure, an intraperitoneal administration of 10 mg/kg of apocynin for 15 days). After reperfusion, iNOS, TLR4, MPO and ADMA levels in myocardial tissue were measured by ELISA. While myocardial TLR4, MPO and ADMA levels increased in the MIR group, these parameters were found to be decreased significantly in the group treated with apocynin. Although iNOS levels showed an increase in the MIR group compared to the sham group and a reduction in the MIR+apocynin group, there was no statistically significant difference between the groups. In our study, the effect of the treatment of apocynin in MIR on ADMA, MPO, iNOS and TLR4 levels in myocardial tissue was shown for the first time. It is thought that apocynin treatment may show a protective effect in MIR injury by affecting oxidative stress (ADMA) and inflammatory parameters (iNOS, MPO).

Effect of L-arginine on Function of Mitochondria in Ischemia – Reperfusion Myocardial Cell in Rabbits

Objective: To investigate the effect of the L-arginine (L-Arg) on function of the myocardial mitochondrial during myocardial ischemia - reperfusion (MIR). Methods: Thirty rabbits were randomly divided into three groups (n =10 per group), namely control group, myocardial ischemia-reperfusion group (MIR) and L-Arginine pre-treated group (L-Arg +MIR). The relevant parameters, including myocardial mitochondrial respiratory function, Ca 2 + concentration ((Ca 2 + ) m ), malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, myocardial adenosine triphosphate (ATP), Adenosine diphosphate (ADP), adenosine monophosphate (AMP) content, the total amount of AMP (TAN), and energy charge (EC), were respectively determined. Results: The mitochondrial respiratory control rate (RCR), Ⅲ state respiration rate (V3), and SOD in L-Arg +MIR group were significantly higher than those of MIR group, while Ⅳ state respiration rate (V4), ((Ca 2+ )m, and MDA were significantly lower than those of MIR group, myocardial ATP, ADP, TNA and the EC were significantly higher than those of group MIR; when compared with the group C, there was no significant difference in terms of V3, V4, SOD, MDA, and AMP, TAN between the L-Arg +MIR group and control group (group C). Conclusion: It is indicated that L-arginine can reduce the level of the oxygen free radicals and attenuate calcium overload to improve the function of myocardial mitochondria during myocardial ischemia reperfusion injury.

Effect of hydrogen sulfide-induced delayed preconditioning on glutathione S-transferase expression during myocardial ischemia-reperfusion in rats

To investigate the effect of hydrogen sulfide-induced delayed preconditioning on glutathione S-transferase (GST) expression during myocardial ischemia-reperfusion in rats. Sprague-Dawley male rats were randomly divided into 4 groups (n= 10 in each): Group S (sham operation group), Group IR (ischemia/reperfusion group), Group H (IR+ NaHS 0.05 mg/kg iv, 24 h before ischemia) and Groups D receiving IR+NaHS 24 h before ischemia and 5-hydroxydecanoate (5-HD)15 min before ischemia. Animals in groups IR, H and D were subjected to ischemia by 30 min of coronary artery occlusion followed by 2 h of reperfusion. At the end of the reperfusion, myocardial infarct size (IS) was examined. Glutathione S-transferase (GST) was measured by Western blotting. The myocardial ultrastructures were observed under the electron microscopy. The IS was significantly smaller in Group H than that in Group IR [(25.40 ± 3.54)% compared with (38.27 ± 5.64)%, P<0.05]. The GST expression in myocardium was significantly higher in Group H than that in Group IR. Microscopic examination showed less myocardial damage in Group H than in Group IR. The protective effects of delayed preconditioning by hydrogen sulfide was prevented by 5-HD pre-treatment. The hydrogen sulfide-induced delayed preconditioning attenuates myocardial IR injury possibly through up-regulating glutathione S-transferase expression in rats.

Glycogen Synthase Kinase 3 Inhibition Protects the Heart From Acute Ischemia-Reperfusion Injury Via Inhibition of Inflammation and Apoptosis

Glycogen synthase kinase (GSK)-3beta inhibitors play an anti-inflammatory role in several inflammatory diseases. Recent studies have demonstrated that GSK-3beta inhibitors protect against myocardial ischemia-reperfusion injury. However, the precise mechanisms remain unclear. We aimed to investigate the roles of inflammation and apoptosis induced by ischemia-reperfusion in the cardioprotection by GSK-3beta inhibitor 4-benzyl-2-methyl-1, 2, 4-thiadiazolidine-3, 5-dione (TDZD-8). Anaesthetized Sprague-Dawley rats underwent an open-chest procedure involving 30 min of myocardial ischemia and 6 h of reperfusion with or without TDZD-8 given at reperfusion. TDZD-8 reduced myocardial infarct size by nearly 43% (P < 0.05 vs. myocardial ischemia-reperfusion) and attenuated myeloperoxidase activity (21.80 +/- 1.07 U/100 mg tissue. vs. myocardial ischemia-reperfusion group, P < 0.05). Administration of TDZD-8 significantly suppressed nuclear factor kappa B (NF-kappaB) and p38 MAPK activation (P < 0.05 vs. myocardial ischemia-reperfusion) and the concentrations of the myocardial-derived cytokines tumor necrosis factor-alpha (TNF-alpha, 107.40 +/- 7.34 pg/mg protein vs. myocardial ischemia-reperfusion group, P < 0.05) and interleukin-6 (IL-6, 29.28 +/- 6.3 pg/mg protein vs. myocardial ischemia-reperfusion group, P < 0.05). Treatment with TDZD-8 also inhibited myocardial cell apoptosis compared with the myocardial ischemia-reperfusion group (12 +/- 1% vs. 22 +/- 2%, P < 0.05). Therefore, blocking this protein kinase activity may be a novel approach to the treatment of this condition, which is characterized by inflammation and apoptosis.