Liraglutide restores late cardioprotective effects of remote preconditioning in diabetic rats via activation of hydrogen sulfide and nuclear factor erythroid 2-related factor 2 signaling pathway

ABSTRACT Purpose The present study explored the influence of liraglutide on remote preconditioning-mediated cardioprotection in diabetes mellitus along with the role of nuclear factor erythroid 2-related factor 2 (Nrf2), hypoxia inducible factor (HIF-1α) and hydrogen sulfide (H2S). Methods Streptozotocin was given to rats to induce diabetes mellitus and rats were kept for eight weeks. Four cycles of ischemia and reperfusion were given to hind limb to induce remote preconditioning. After 24 h, hearts were isolated and subjected to 30 min of ischemia and 120 min of reperfusion on Langendorff system. Liraglutide was administered along with remote preconditioning. Cardiac injury was assessed by measuring the release of creatine kinase (CK-MB), cardiac troponin (cTnT) and development of left ventricular developed pressure. After ischemia-reperfusion, hearts were homogenized to measure the nuclear cytoplasmic ratio of Nrf2, H2S and HIF-1α levels. Results In diabetic rats, there was more pronounced injury and the cardioprotective effects of remote preconditioning were not observed. Administration of liraglutide restored the cardioprotective effects of remote preconditioning in a dose-dependent manner. Moreover, liraglutide increased the Nrf2, H2S and HIF-1α levels in remote preconditioning-subjected diabetic rats. Conclusions Liraglutide restores the lost cardioprotective effects of remote preconditioning in diabetes by increasing the expression of Nrf2, H2S and HIF-1α.

Exploring the role of neurogenic pathway-linked cholecystokinin release in remote preconditioning-induced cardioprotection

Abstract Purpose: The current study explored the involvement of neurogenic pathway-linked cholecystokinin (CCK) release in RIP-induced cardioprotection in rats. Methods: Male Wistar rats were subjected to four cycles of alternate episodes of ischemia and reperfusion (five min each) to induce RIP. Thereafter, the hearts were subjected to global ischemia and reperfusion ex vivo. The myocardial damage was assessed by quantifying the levels of heartspecific biochemicals i.e. LDH-1, CK-MB and cTnT. Apoptotic cell injury was assessed by measuring the levels of caspase-3 and Bcl-2. The levels of CCK were measured in the plasma following RIP. Results: Exposure to RIP significantly increased the plasma levels of CCK and attenuated IR-induced myocardial injury. Administration of CCK antagonist, proglumide significantly attenuated RIP-induced cardioprotection. Administration of hexamethonium, a ganglion blocker, abolished RIP-induced increase in plasma CCK levels and cardioprotective effects. Exogenous delivery of CCK-8 restored the effects of RIP in hexamethonium treated animals. Conclusion: RIP activates the neurogenic pathway that may increase the plasma levels of CCK, which may act on the heart-localized CCK receptors to produce cardioprotection against I/R injury.

Acute Physical Stress Preconditions the Heart Against Ischemia/Reperfusion Injury Through Activation of Sympathetic Nervous System / Estresse Físico Agudo Precondiciona o Coração Contra a Injúria por Isquemia/Reperfusão Através da Ativação do Sistema Nervoso Simpático

Abstract Background: Stress is defined as a complicated state that related to homeostasis disturbances, over-activity of the sympathetic nervous system and hypothalamus-pituitary-adrenal axis responses. Cardiac preconditioning reduces myocardial damages. Objective: This study was designed to assess the cardioprotective effects of acute physical stress against ischemia/reperfusion (I/R) injury through the activation of the sympathetic nervous system. Methods: Thirty-two male Wistar rats were divided into four groups; (1) IR (n = 8): rats underwent I/R, (2) Acute stress (St+IR) (n = 8): physical stress induced 1-hour before I/R, (3) Sympathectomy (Symp+IR) (n = 8): chemical sympathectomy was done 24-hours before I/R and (4) Sympathectomy- physical stress (Symp+St+IR) (n = 8): chemical sympathectomy induced before physical stress and I/R. Chemical sympathectomy was performed using 6-hydroxydopamine (100 mg/kg, sc). Then, the hearts isolated and located in the Langendorff apparatus to induce 30 minutes ischemia followed by 120 minutes reperfusion. The coronary flows, hemodynamic parameters, infarct size, corticosterone level in serum were investigated. P < 0.05 demonstrated significance. Results: Physical stress prior to I/R could improve left ventricular developed pressure (LVDP) and rate product pressure (RPP) of the heart respectively, (63 ± 2 versus 42 ± 1.2, p < 0.05, 70 ± 2 versus 43 ± 2.6, p < 0.05) and reduces infarct size (22.16 ± 1.3 versus 32 ± 1.4, p < 0.05) when compared with the I/R alone. Chemical sympathectomy before physical stress eliminated the protective effect of physical stress on I/R-induced cardiac damages (RPP: 21 ± 6.6 versus 63 ± 2, p < 0.01) (LVDP: 38 ± 4.5 versus 43 ± 2.6, p < 0.01) (infarct size: 35 ± 3.1 versus 22.16 ± 1.3, p < 0.01). Conclusion: Findings indicate that acute physical stress can act as a preconditional stimulator and probably, the presence of sympathetic nervous system is necessary.

Resumo Fundamento: O estresse é definido como um estado complicado de distúrbios da homeostase, hiperatividade do sistema nervoso simpático e das respostas do eixo hipotálamo-hipófise-adrenal. O pré-condicionamento cardíaco diminui os danos do miocárdio. Objetivo: Esse estudo avaliou os efeitos cardioprotetores do estresse físico agudo contra a lesão por isquemia-reperfusão (I/R) através da ativação do sistema nervoso simpático. Métodos: Trinta e dois ratos machos Wistar foram divididos em quatro grupos; (1) IR (n = 8): ratos submetidos a I/R, (2) Estresse agudo (St+IR) (n = 8): estresse físico induzido 1 hora antes da I/R, (3) Simpatectomia (Symp+IR) (n = 8): a simpatectomia química foi realizada 24 horas antes da I/R e (4) Simpatectomia-estresse físico (Symp+St+IR) (n = 8): simpatectomia induzida antes do estresse físico e da I/R. A simpatectomia química foi realizada com 6-hidroxidopamina (100 mg/kg, SC). Em seguida, os corações foram isolados e colocados em aparato de Lagendorff por 30 minutos para induzir isquemia, seguida de reperfusão por 120 minutos. Os fluxos coronarianos, os parâmetros hemodinâmicos, o tamanho do infarto e os níveis de corticosterona plasmática foram investigados. Valores de p < 0,05 foram considerados significativos. Resultados: O estresse físico anterior à I/R pode melhorar a pressão desenvolvida no ventrículo esquerdo (PDVE) e duplo produto (DP), respectivamente, (63 ± 2 versus 42 ± 1,2, p < 0,05, 70 ± 2 versus 43 ± 2,6, p < 0,05) e reduzir o tamanho do infarto (22,16 ± 1,3 versus 32±1,4, p < 0,05) quando comparado com a I/R isoladamente. A simpatectomia química antes do estresse físico eliminou o efeito protetor do estresse físico sobre os danos cardíacos induzidos pela I/R (DP: 21 ± 6,6 versus 63 ± 2, p < 0,01) (PDVE: 38 ± 4,5 versus 43 ± 2,6, p < 0,01) (tamanho do infarto: 35 ± 3,1 versus 22,16 ± 1,3, p < 0,01). Conclusão: Os achados indicam que o estresse físico agudo pode funcionar como um estimulador pré-condicional e, provavelmente, a presença do sistema nervoso simpático é necessária.

Cardioprotective effect of preconditioning is more efficient than postconditioning in rats submitted to cardiac ischemia and reperfusion

Abstract Purpose: To investigate the cardioprotective effects of ischemic preconditioning (preIC) and postconditioning (postIC) in animal model of cardiac ischemia/reperfusion. Methods: Adult rats were submitted to protocol of cardiac ischemia/reperfusion (I/R) and randomized into three experimental groups: cardiac I/R (n=33), preCI + cardiac I/R (n=7) and postCI + cardiac I/R (n=8). After this I/R protocol, the incidence of ventricular arrhythmia (VA), atrioventricular block (AVB) and lethality (LET) was evaluated using the electrocardiogram (ECG) analysis. Results: After reestablishment of coronary blood flow, we observed variations of the ECG trace with increased incidence of ventricular arrhythmia (VA) (85%), atrioventricular block (AVB) (79%), and increase of lethality (70%) in cardiac I/R group. The comparison between I/R + preIC group with I/R group demonstrated significant reduction in VA incidence to 28%, AVB to 0% and lethality to 14%. The comparison of I/R + postIC group with I/R group was observed significance reduction in AVB incidence to 25% and lethality to 25%. Conclusion: The preconditioning strategies produce cardioprotection more efficient that postconditioning against myocardial dysfunctions and lethality by cardiac ischemia and reperfusion.

Transfusion of Plasma Collected at Late Phase after Preconditioning Reduces Myocardial Infarct Size Induced by Ischemia-reperfusion in Rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Plasma transfusion is a common clinical practice. Remote ischemic preconditioning (RIPC) protects organs against ischemia-reperfusion (IR) injury. Whether preconditioned plasma (PP), collected at late phase after RIPC, could protect organs against IR injury in vivo is unknown. This study explored whether transfusion of PP could reduce myocardial infarct size (IS) after IR in rat in vivo.</p><p><b>METHODS</b>Eighty Lewis rats were randomized to eight groups (n = 10 for each group). Two groups of plasma donor rats donated plasma at 48 h after transient limb ischemia (PP) or control protocol (nonpreconditioned plasma [NPP]). Six groups of recipient rats received normal saline (NS; NS-IR 1, and NS-IR 24 groups), NPP (NPP-IR 1 and NPP-IR 24 groups), or PP (PP-IR 1 and PP-IR 24 groups) at one or 24 h before myocardial IR. Myocardial IR consisted of 30-min left anterior descending (LAD) coronary artery occlusion and 180-min reperfusion. The area at risk (AAR) and infarct area were determined by double-staining with Evans blue and triphenyltetrazolium chloride. IS was calculated by infarct area divided by AAR. This was a 3 × 2 factorial design study, and factorial analysis was used to evaluate the data. If an interaction between the fluid and transfusion time existed, one-way analysis of variance with Bonferroni correction for multiple comparisons was used to analyze the single effects of fluid type when the transfusion time was fixed.</p><p><b>RESULTS</b>IS in the NPP-IR 1 and PP-IR 1 groups was smaller than in the NS-IR 1 group (F = 6.838, P = 0.005; NPP-IR 1: 57 ± 8% vs. NS-IR1: 68 ± 6%, t = 2.843, P = 0.020; PP-IR 1: 56 ± 8% vs. NS-IR 1: 68 ± 6%, t = 3.102, P = 0.009), but no significant difference was detected between the NPP-IR 1 and PP-IR 1 groups (57 ± 8% vs. 56 ± 8%, t = 0.069, P = 1.000). IS in the NPP-IR 24 and PP-IR 24 groups was smaller than in the NS-IR 24 group (F = 24.796, P< 0.001; NPP-IR 24: 56% ± 7% vs. NS-IR 24: 68 ± 7%, t = 3.102, P = 0.026; PP-IR 24: 40 ± 9% vs. NS-IR 24: 68 ± 7%, t = 7.237, P< 0.001); IS in the PP-IR 24 group was smaller than in the NPP-IR 24 group (40 ± 9% vs. 56 ± 7%, t = 4.135, P = 0.002).</p><p><b>CONCLUSION</b>Transfusion of PP collected at late phase after remote ischemic preconditioning could reduce IS, suggesting that late-phase cardioprotection was transferable in vivo.</p>

Is Local Nitric Oxide Availability Responsible for Myocardial Salvage after Remote Preconditioning? / A Disponibilidade de Óxido Nítrico Local é Responsável por Resgate Miocárdio após Pré-Condicionamento Remoto?

Abstract Background: Remote ischemic preconditioning (RIPC) represents an attractive therapy for myocardial protection, particularly when ischemic events can be anticipated. Although several hypothetic mechanisms have been proposed, no definite molecular pathways have been elucidated. Objective: We evaluated the effect of brachial circulation cuff occlusion on myocardial ischemic tolerance, necrosis, and nitric oxide (NO) in patients with ischemic heart disease undergoing elective percutaneous coronary interventions (PCI). Methods: 46 patients were randomly allocated into two groups: control and RIPC before PCI procedures. Electrocardiographic analysis, serum concentrations of troponin I (cTn-I) were measured at baseline and 24 hours after PCI. A blood sample from the atherosclerotic plaque was drawn to determine nitrate and nitrites. Results: RIPC increased the availability of NO in the stented coronary artery. Control patients presented a small but significant increase in cTn-I, whilst it remained unchanged in preconditioned group. The preconditioning maneuver not only preserved but also enhanced the sum of R waves. Conclusions: RIPC induced an intracoronary increase of NO levels associated with a decrease in myocardial damage (measured as no increase in cTn-I) with electrocardiographic increases in the sum of R waves, suggesting an improved myocardium after elective PCI.

Resumo Fundamento: Pré-condicionamento isquêmico remoto (PCIR) é uma terapia para proteção miocárdica, em particular quando é possível prever eventos isquêmicos. Embora vários mecanismos hipotéticos tenham sido propostos, nenhuma via molecular definitiva foi elucidada. Objetivo: Avaliar o efeito da oclusão da circulação braquial com manguito sobre a tolerância à isquemia miocárdica, a necrose miocárdica e a biodisponibilidade de óxido nítrico (NO) em pacientes com cardiopatia isquêmica submetidos a intervenção coronariana percutânea (ICP) eletiva. Métodos: 46 pacientes foram alocados aleatoriamente em dois grupos: controle e PCIR antes da ICP. Análise eletrocardiográfica e medidas da concentração sérica de troponina I (cTn-I) foram realizadas na condição basal e 24 horas após ICP. Coletou-se amostra de sangue da placa aterosclerótica para determinar os níveis de nitratos e nitritos. Resultados: O PCIR aumentou a disponibilidade de NO na artéria coronária que recebeu o stent. O grupo controle apresentou um aumento pequeno, mas significativo, da cTn-I, que permaneceu inalterada no grupo pré-condicionado. O pré-condicionamento não só preservou, como melhorou o somatório de ondas R no eletrocardiograma. Conclusões: O PCIR induziu aumento intracoronariano dos níveis de NO associado com redução do dano miocárdico (medido como aumento da cTn-I) e com aumento do somatório de ondas R, sugerindo melhora miocárdica após ICP eletiva.

Sevoflurane preconditioning during myocardial ischemia-reperfusion reduces infarct size and preserves autonomic control of circulation in rats

ABSTRACT PURPOSE: To investigate the myocardial ischemia-reperfusion with sevoflurane anesthetic preconditioning (APC) would present beneficial effects on autonomic and cardiac function indexes after the acute phase of a myocardial ischemia-reperfusion. METHODS: Twenty Wistar rats were allocated in three groups: control (CON, n=10), myocardial infarction with sevoflurane (SEV, n=5) and infarcted without sevoflurane (INF, n=5). Myocardial ischemia (60 min) and reperfusion were performed by temporary coronary occlusion. Twenty-one days later, the systolic and diastolic function were evaluated by echocardiography; spectral analysis of the systolic arterial pressure (SAPV) and heart rate variability (HRV) were assessed. After the recording period, the infarct size (IS) was evaluated. RESULTS: The INF group presented greater cardiac dysfunction and increased sympathetic modulation of the SAPV, as well as decreased alpha index and worse vagal modulation of the HRV. The SEV group exhibited attenuation of the systolic and diastolic dysfunction and preserved vagal modulation (square root of the mean squared differences of successive R-R intervals and high frequency) of HRV, as well as a smaller IS. CONCLUSION: Sevoflurane preconditioning better preserved the cardiac function and autonomic modulation of the heart in post-acute myocardial infarction period.

Dexmedetomidina genera óxido nítrico mediante un mecanismo independiente de la óxido nítrico sintasa inducible / Dexmedetomidine protects the heart against ischemia-reperfusion injury by an endothelial eNOS/NO dependent mechanism

El infarto del miocardio es una de las principales causas de muerte a nivel mundial y se produce a consecuencia de procesos de isquemia-reperfusión (IR). El daño miocárdico generado por IR puede ser atenuado a través del pre-condicionamiento isquémico (PI) temprano, mediado por la vía RISK o PI tardío, que se asocia a una respuesta genómica en la que se activan proteínas como óxido nítrico sintasa inducible (iNOS). Las vías de señalización que median el PI también pueden ser activadas farmacológicamente. Dexmedetomi-dina (Dex) es un agonista alfa2-adrenérgico, que se ha descrito como un potente agente cardioprotector frente a IR. Recientemente, nuestro grupo describió que Dex requiere el endotelio y la activación de la vía óxido nítrico sintasa endotelial (eNOS)-óxido nítrico (NO) para pre-condicionar el miocardio. Sin embargo, no existen estudios que muestren la posible participación de iNOS en la protección conferida por Dex. La presente adenda tiene por objetivo evaluar si Dex activa iNOS en el corazón y en cardiomiocitos. Para esto, corazones de rata adulta fueron estimulados con Dex 10 nM y se observó que el fármaco aumentó la producción de NO medida por cuantificación de nitritos, mas no estimuló la activación de iNOS medida por Western blot. Además, Dex tampoco indujo el aumento de mRNA de iNOS en cardiomiocitos adultos. Por lo tanto, Dex genera NO independiente a iNOS durante su efecto pre-condicionante agudo. Sin embargo, se requieren más estudios que clarifiquen su papel en una posible protección a largo plazo frente a IR generada por Dex.

Myocardial infarction is one of the leading causes of death worldwide and is generated as a consequence of ischemia-reperfusion (IR). Myocardial damage inflicted by IR can be attenuate by early ische-mic pre-conditioning (IP), which is mediated by the RISK pathway or late IP, which is associated to a genomic response involving the activation of proteins such as inducible nitric oxide synthase (iNOS). The signaling pathways mediating IP can also be pharmacologically activated. Dexmedetomidine (Dex) is an alpha2-adrenergic receptor agonist, which has been described as a strong cardio protective agent against IR. Recently, our group reported that Dex requires the endothelium and the activation of the endothelial nitric oxide synthase (eNOS)-ni-tric oxide (NO) pathway to precondition the myocardium. However, there are no studies showing the involvement of iNOS in the protection elicited by Dex. The aim of this Addendum is to evaluate if Dex activates iNOS in the heart and cardiomyocytes. To test this, adult rat hearts were stimulated with Dex 10 nM and we observed that NO production measured by quantification of nitrites was increased, but Dex did not activate iNOS measured by Western blot. Moreover, Dex did not induce an increase in the mRNA levels of iNOS in adult cardiomyocytes. Therefore, Dex generates NO independent of iNOS during its early pre-conditioning effect. Nevertheless, more studies are required to clarify its role in a possible long term protection against IR generated by Dex.

Protective effect of right coronary artery ischemic preconditioning on myocardial ischemia reperfusion injury in rabbit heart / 中南大学学报(医学版)

To explore the protective effects of right coronary artery ischemic preconditioning and post-conditioning on myocardial ischemia reperfusion injury in rabbit heart.
 Methods: A total of 30 rabbits were randomly divided into 4 groups: a control group (n=7), an ischemia reperfusion group (IR group, n=8), an ischemic preconditioning group (IPC group, n=8) and an ischemic post-conditioning group (IPO group, n=7). Venous blood samples were taken at pre-operation, 1 and 6 h post-operation, and the concentration of serum creatine kinase isoenzyme (CK-MB) and cardiac troponin-T (cTn-T) were measured. The infarct area of cardiac muscle was calculated.
 Results: Compared with the IR group, the levels of CK-MB and cTn-T at 1 and 6 h post-operation in the IPC group and the IPO group were reduced (all P<0.05). Compared with the IR group, the infarct size in the IPC group and the IPO group was significantly decreased, with significant difference (both P<0.05) .
 Conclusion: Right coronary artery ischemic preconditioning and post-conditioning exert significant protective effects on the myocardial ischemia reperfusion injury in New Zealand rabbits.

Olmesartan restores the protective effect of remote ischemic perconditioning against myocardial ischemia/reperfusion injury in spontaneously hypertensive rats

OBJECTIVES: Remote ischemic perconditioning is the newest technique used to lessen ischemia/reperfusion injury. However, its effect in hypertensive animals has not been investigated. This study aimed to examine the effect of remote ischemic perconditioning in spontaneously hypertensive rats and determine whether chronic treatment with Olmesartan could influence the effect of remote ischemic perconditioning. METHODS: Sixty rats were randomly divided into six groups: vehicle-sham, vehicle-ischemia/reperfusion injury, vehicle-remote ischemic perconditioning, olmesartan-sham, olmesartan-ischemia/reperfusion and olmesartan-remote ischemic perconditioning. The left ventricular mass index, creatine kinase concentration, infarct size, arrhythmia scores, HIF-1α mRNA expression, miR-21 expression and miR-210 expression were measured. RESULTS: Olmesartan significantly reduced the left ventricular mass index, decreased the creatine kinase concentration, limited the infarct size and reduced the arrhythmia score. The infarct size, creatine kinase concentration and arrhythmia score during reperfusion were similar for the vehicle-ischemia/reperfusion group and vehicle-remote ischemic perconditioning group. However, these values were significantly decreased in the olmesartan-remote ischemic perconditioning group compared to the olmesartan-ischemia/reperfusion injury group. HIF-1α, miR-21 and miR-210 expression were markedly down-regulated in the Olmesartan-sham group compared to the vehicle-sham group and significantly up-regulated in the olmesartan-remote ischemic perconditioning group compared to the olmesartan-ischemia/reperfusion injury group. CONCLUSION: The results indicate that (1) the protective effect of remote ischemic perconditioning is lost in vehicle-treated rats and that chronic treatment with Olmesartan restores the protective effect of remote ischemic perconditioning; (2) chronic treatment with Olmesartan down-regulates HIF-1α, ...

Role of mitochondrial ATP-sensitive potassium channel-mediated PKC-ε in delayed protection against myocardial ischemia/reperfusion injury in isolated hearts of sevoflurane-preconditioned rats

This study aimed to determine the role of mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels and protein kinase C (PKC)-ε in the delayed protective effects of sevoflurane preconditioning using Langendorff isolated heart perfusion models. Fifty-four isolated perfused rat hearts were randomly divided into 6 groups (n=9). The rats were exposed for 60 min to 2.5% sevoflurane (the second window of protection group, SWOP group) or 33% oxygen inhalation (I/R group) 24 h before coronary occlusion. The control group (CON) and the sevoflurane group (SEVO) group were exposed to 33% oxygen and 2.5% sevoflurane for 60 min, respectively, without coronary occlusion. The mitoKATP channel inhibitor 5-hydroxydecanoate (5-HD) was given 30 min before sevoflurane preconditioning (5-HD+SWOP group). Cardiac function indices, infarct sizes, serum cardiac troponin I (cTnI) concentrations, and the expression levels of phosphorylated PKC-ε (p-PKC-ε) and caspase-8 were measured. Cardiac function was unchanged, p-PKC-ε expression was upregulated, caspase-8 expression was downregulated, cTnI concentrations were decreased, and the infarcts were significantly smaller (P<0.05) in the SWOP group compared with the I/R group. Cardiac function was worse, p-PKC-ε expression was downregulated, caspase-8 expression was upregulated, cTnI concentration was increased and infarcts were larger in the 5-HD+SWOP group (P<0.05) compared with the SWOP group. The results suggest that mitoKATP channels are involved in the myocardial protective effects of sevoflurane in preconditioning against I/R injury, by regulating PKC-ε phosphorylation before ischemia, and by downregulating caspase-8 during reperfusion.

Long-term, regular remote ischemic preconditioning improves endothelial function in patients with coronary heart disease

Remote ischemic preconditioning (RIPre) can prevent myocardial injury. The purpose of this study was to assess the beneficial effects of long-term regular RIPre on human arteries. Forty patients scheduled for coronary artery bypass graft (CABG) surgery were assigned randomly to a RIPre group (n=20) or coronary heart disease (CHD) group (n=20). Twenty patients scheduled for mastectomy were enrolled as a control group. RIPre was achieved by occluding arterial blood flow 5 min with a mercury sphygmomanometer followed by a 5-min reperfusion period, and this was repeated 4 times. The RIPre procedure was repeated 3 times a day for 20 days. In all patients, arterial fragments discarded during surgery were collected to evaluate endothelial function by flow-mediated dilation (FMD), CD34+ monocyte count, and endothelial nitric oxide synthase (eNOS expression). Phosphorylation levels of STAT-3 and Akt were also assayed to explore the underlying mechanisms. Compared with the CHD group, long-term regular RIPre significantly improved FMD after 20 days (8.5±2.4 vs 4.9±4.2%, P<0.05) and significantly reduced troponin after CABG surgery (0.72±0.31 and 1.64±0.19, P<0.05). RIPre activated STAT-3 and increased CD34+ endothelial progenitor cell counts found in arteries. Long-term, regular RIPre improved endothelial function in patients with CHD, possibly due to STAT-3 activation, and this may have led to an increase in endothelial progenitor cells.

Effects of ischemia and omeprazole preconditioning on functional recovery of isolated rat heart / Efeitos da isquemia e pré-condicionamento com omeprazol na recuperação funcional do coração isolado de rato

Abstract Objective: The aim of this study was to compare protective effects of ischemic and potential protective effects of pharmacological preconditioning with omeprazole on isolated rat heart subjected to ischemia/reperfusion. Methods: The hearts of male Wistar albino rats were excised and perfused on a Langendorff apparatus. In control group (CG) after stabilization period, hearts were subjected to global ischemia (perfusion was totally stopped) for 20 minutes and 30 minutes of reperfusion. Hearts of group II (IPC) were submitted to ischemic preconditioning lasting 5 minutes before 20 minutes of ischemia and 30 minutes of reperfusion. In third group (OPC) hearts first underwent preconditioning lasting 5 minutes with 100μM omeprazole, and then submitted 20 minutes of ischemia and 30 minutes of reperfusion. Results: Administration of omeprazole before ischemia induction had protective effect on myocardium function recovery especially regarding to values of systolic left ventricular pressure and dp/dt max. Also our findings are that values of coronary flow did not change between OPC and IPC groups in last point of reperfusion. Conclusion: Based on our results it seems that ischemic preconditioning could be used as first window of protection after ischemic injury especially because all investigated parameters showed continuous trend of recovery of myocardial function. On the other hand, preconditioning with omeprazole induced sudden trend of recovery with positive myocardium protection, although less effective than results obtained with ischemic preconditioning not withstand, we must consider that omeprazole may be used in many clinical circumstances where direct coronary clamping for ischemic preconditioning is not possible. .

Resumo Objetivo: O objetivo deste estudo foi comparar os efeitos protetores de efeitos protetores isquêmicos e potenciais de précondicionamento farmacológico com omeprazol no coração isolado de rato submetido à isquemia/reperfusão. Métodos: Os corações de ratos albinos Wistar machos foram excisados e perfundidos em um aparelho de Langendorff. No grupo controle (grupo I), após o período de estabilização, os corações foram submetidos à isquemia global (a perfusão foi totalmente interrompida) por 20 minutos e 30 minutos de reperfusão. Corações do grupo II (IPC) foram submetidos a précondicionamento isquêmico com duração de 5 minutos antes de 20 minutos de isquemia e 30 minutos de reperfusão. No terceiro grupo (OPC), corações foram submetidos a pré-condicionamento com duração de 5 minutos com 100 μM de omeprazol, e, então, submetidos a 20 minutos de isquemia e 30 minutos de reperfusão. Resultados: A administração de omeprazol antes da indução da isquemia teve efeito protetor sobre a recuperação funcional do miocárdio especialmente em relação aos valores de pressão sistólica ventricular esquerda e dp/dt max. Também os nossos achados são de que os valores de fluxo coronário não se alteraram entre os grupos OPC e IPC no último ponto de reperfusão. Conclusão: Com base nos nossos resultados, o pré-condicionamento isquêmico poderia ser usado como primeira janela de proteção após a lesão isquêmica, especialmente porque todos os parâmetros analisados apresentam tendência contínua de recuperação da função do miocárdio. Por outro lado, o pré-condicionamento induzido com omeprazol apresenta tendência repentina de recuperação com proteção miocárdio positiva, embora menos efetiva da obtida com o pré-condicionamento isquêmico. Devemos considerar que o omeprazol pode ser usado em muitas circunstâncias clínicas em que o pinçamento coronariano direto para pré-condicionamento isquêmico não é possível. .

Flow cytometric analysis of circulating microvesicles derived from myocardial Ischemic preconditioning and cardioprotection of Ischemia/reperfusion Injury in rats / 中国应用生理学杂志

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

Protective effect against myocardial ischemia reperfusion injuries induced by hyperoside preconditioning and its relationship with PI3K/Akt signaling pathway in rats / 中国中药杂志

To investigate the protective effect of preconditioning with hyperoside ( Hyp) against myocardial ischemia-reperfusion injury (MIRI) in rats and the role of PI3K/Akt signaling pathway. MIRI was established by ligation of left anterior descending coronary artery for 30 min followed by reperfusion for 120 min in rats. Male SD rats were randomly divided into five groups: sham group,model group (MIRI),Hyp preconditioning group(Hyp), Hyp preconditioning + LY294002 (a PI3K/Akt signaling pathway inhibitor) group (Hyp + LY), and LY294002 group (LY). At the end of reperfusion, hemodynamic parameters were recorded as left ventricular systolic pressure (LVSP) , left ventricular end-diastolic pressure ( LVEDP) and maximal rate of increase and decrease of left ventricular pressure (± dP/dt(max)). Myocardial infaret size, the oxidative stress markers, myocardial enzymes indicators and inflammatory factors were also analyzed. The expressions of Akt, p-Akt, Bax and Bcl-2 proteins was detected by using Western blot method. The results showed that Hyp preconditioning remarkably improved cardiac constriction and relaxation function, reduced myocardial infarct size and enhanced the activities of oxidative stress markers about correlated to MIRI, such as superoxide dismutase (SOD), catalase (CAT) and glutathione-peroxidase (GSH-Px) and decreased the contents of malondialdehyde (MDA) as compared with MIRI group. Simultaneouly, the levels of myocardial enzymes, i. e. creatine kinase ( CK) and creatine kinase MB isoenzyme (CK-MB), and inflammatory factors, for instance tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were decreased. Hyp pretreatment apparently restrained myocardial apoptosis as evidenced by decreasing the level of Bax expression, increasing the levels of phosphorylation of Akt and Bcl-2 expression. These effects were inhibited by LY294002, a blocker of PI3K/Akt signaling pathway. These findings indicated that the cardioprotection of Hyp preconditioning against MIRI may be related to activating PI3K/Akt signaling pathway, upregulating the expression of BCL-2 protein and down-regulating the expression of Bax protein.

Identificación y expresión diferencial del factor de transcripción asociado a microftalmia en corazón y cardiomiocitos aislados de cobayo: su posible papel en la hipertrofia y la viabilidad / Identification and differential expression of the microphthalmia-associated transcription factor in heart and isolated cardiomyocytes from Guinea pigs: Possible role in hypertrophy and viability

Introducción. El factor de transcripción asociado a la microftalmia ( Microphtalmia-Associated Transcription Factor , MITF) regula la expresión de genes específicos, pero no se conoce su expresión y su función a nivel cardiaco. Objetivos. Identificar la expresión del MITF en corazón y en cardiomiocitos aislados de cobayo, describir los cambios morfológicos asociados con su disminución y evaluar los niveles relativos de su expresión en cardiomiocitos aislados en condiciones de preacondicionamiento isquémico. Materiales y métodos. El análisis de la expresión relativa de la isoforma específica de tejido cardiaco ( heart-type MITF, MITF-H), se determinó mediante reacción en cadena de la polimerasa (PCR) en tiempo real semicuantitativa, secuenciación y Western blot . La disminución del ARNm del MITF se indujo con un ARN pequeño de interferencia ( short hairpin RNA interference , shRNAi) específico. El tamaño, el diámetro y el número de fibras musculares se evaluaron por observación directa con microscopía de luz. Resultados. Se amplificó un fragmento de 281 pb de ADNc; el análisis de la secuencia confirmó la identidad del exón 1 y la isoforma H del MITF. La interferencia del ARNm del MITF se asoció con un mayor índice cardiaco (peso corazón/peso corporal: 5,46 x 10 -3 Vs. 4,6 x 10 -3 ) y un incremento del diámetro de las fibras cardiacas (50,2±16 µm Vs. 38,7±14,7 µm; p<0,05, n=150). En los cardiomiocitos aislados en condiciones de preacondicionamiento isquémico, se observó una expresión relativa del MITF-H mayor que en los miocitos en normoxia y expuestos a lesión por isquemia simulada (80 y 100 veces más, n=5, p<0,05, n=3). Conclusión. Los resultados sugieren que el MITF-H podría estar involucrado en la hipertrofia, la respuesta al estrés por isquemia y la supervivencia de cardiomiocitos de cobayo.

Introduction: The microphthalmia -associated transcription factor ( MITF ) regulates the expression of specific genes and its cardiac expression and function is not known. Objectives: To identify the expression of MITF in hearts and isolated cardiomyocytes from Guinea pigs, to describe morphological changes associated with mRNA interference of MITF and to evaluate their relative changes in expression in isolated cardiomyocytes under ischemic preconditioning. Materials and methods: The cardiac specific isoform, MITF-H, and relative expression level analysis, was determined by semi-quantitative real time PCR, sequencing and Western blotting. Reduction of mRNA-MITF-H was induced by transduction of specific-MITF-shRNAi interference. The cardiac morphological changes, diameter and number of cardiac fibers were evaluated by direct observation and light microscopy. Results: A cDNA fragment of 281 bp was amplified from heart and isolated ventricular cardiac myocytes. Sequence analysis confirmed the identity of the isoform MITF-H, exon 1. The MITF silencing was associated with an increase in cardiac index (heart weight/body weight vs . 5.46 x 10 -3 vs 4.6 x 10 -3 ) and higher diameter of cardiac fibers (50.2±16 µ m vs 38,7±14,7 µ m p<0.05, n=150). In isolated cardiac myocytes under ischemic preconditioning we observed a higher relative expression compared with that measured in myocytes exposed to normoxia and simulated ischemia (eighty and one hundred times, p <0.05, n = 5). Conclusion. The results suggest that MITF-H isoform may be involved in Guinea pig cardiac hypertrophy, response to stress by ischemia and cardiomyocytes survival.

Aperfeiçoamento em técnica de perfusão cardioplégica no pinçamento único de aorta - resultados iniciais / Improvement in cardioplegic perfusion technique in single aortic clamping - initial results

INTRODUÇÃO: O método mais comumente utilizado para a proteção miocárdica é o de administrar-se solução cardioplégica na circulação coronária. Entretanto, a proteção pode ser alcançada através da perfusão intermitente do sistema coronariano com sangue do próprio paciente, que é realizada por meio de múltiplas sequências de pinçamento e abertura do clamp aórtico ou por meio do pinçamento único e canulação acessória da raiz aórtica. Objetivo: Avaliar o desfecho clínico e a ocorrência de eventos neurológicos no período intra-hospitalar dos pacientes submetidos à cirurgia de revascularização do miocárdio com a técnica proposta aqui neste estudo. Métodos: Descreve-se uma técnica de proteção miocárdica no uso do pinçamento único de aorta que consiste na canulação acessória da raiz aórtica com sistema aperfeiçoado para perfusão coronária intermitente, foi realizado estudo observacional transversal prospectivo onde foram estudados 50 pacientes (idade média 58,5±7.19 anos) submetidos à cirurgia de revascularização do miocárdio sob a técnica proposta. Foram avaliadas variáveis clínicas e laboratoriais pré e pós-operatórias. Resultados: O nível médio de pico da CKMB pós-operatória foi de 51,64±27,10 U/L no segundo pós-operatório e da troponina I foi de 3,35±4,39 ng/ml no quarto pós-operatório, e estiveram dentro do limite da normalidade. Não foi observado nenhum óbito e um paciente evoluiu com alteração neurológica leve. A monitorização hemodinâmica não revelou alterações. Conclusão: A cirurgia de rev...

Introduction: The most common method used for myocardial protection is administering cardioplegic solution in the coronary circulation. Nevertheless, protection may be achieved by intermittent perfusion of the coronary system with patient's own blood. The intermittent perfusion may be performed by multiple sequences of clamping and opening of the aortic clamp or due single clamping and accessory cannulation of the aortic root as in the improved technique proposed in this study, reperfusion without the need for multiple clamping of the aorta. Objective: To evaluate the clinical outcome and the occurrence of neurological events in in-hospital patients submitted to myocardial revascularization surgery with the "improved technique" of intermittent perfusion of the aortic root with single clamping. Methods: This is a prospective, cross-sectional, observational study that describes a myocardial management technique that consists of intermittent perfusion of the aortic root with single clamping in which 50 patients (mean age 58.5±7.19 years old) have been submitted to the myocardial revasculrization surgery under the proposed technique. Clinical and laboratory variables, pre- and post-surgery, have been assessed. Results: The mean peak level of post-surgery CKMB was 51.64±27.10 U/L in the second post-surgery and of troponin I was 3.35±4.39 ng/ml in the fourth post-surgery, within normal limits. No deaths have occurred and one patient presented mild neurological disorder. Hemodynamic monitoring has not indicated any changes. Conclusion: The myocardial revascularization surgery by perfusion with the improved technique with intermittent aortic root with single clamping proved to be safe, enabling satisfactory clinical results. .

Role of Notch signaling in the mammalian heart

Notch signaling is an evolutionarily ancient, highly conserved pathway important for deciding cell fate, cellular development, differentiation, proliferation, apoptosis, adhesion, and epithelial-to-mesenchymal transition. Notch signaling is also critical in mammalian cardiogenesis, as mutations in this signaling pathway are linked to human congenital heart disease. Furthermore, Notch signaling can repair myocardial injury by promoting myocardial regeneration, protecting ischemic myocardium, inducing angiogenesis, and negatively regulating cardiac fibroblast-myofibroblast transformation. This review provides an update on the known roles of Notch signaling in the mammalian heart. The goal is to assist in developing strategies to influence Notch signaling and optimize myocardial injury repair.

Effect of stress on myocardial apoptosis in ischemic preconditioning in rabbit hearts / 中南大学学报(医学版)

OBJECTIVE@#To determine the influence of stress on myocardial apoptosis in ischemic preconditioning group (IPC).@*METHODS@#Twenty-four Japanese white rabbits were randomly divided into 4 groups (n=6): an etomidate group (the Etom group) of depressed stress established by intravenous etomidate, an IPC group, an ischemic reperfusion group (the IR group) and a methylprednisolone group (the MP group). Myocardial apoptosis was examined by DNA-laddering, in situ nick-end labeling (TUNEL) and Hoechst dyeing.@*RESULTS@#The DNA ladder increased in the Etom group. The percentage of apoptosis by TUNEL method was 1.7%±0.2% in the IPC group, 2.3%±0.8% in the MP group, 3.8%±1.3% in the IR group and 3.0%±0.4% in the Etom group. Hoechst dying was 4.1%±0.9% in the IPC group, 3.5%±0.4% in the MP group, 6.2%±1.6% in the IR group and 7.6%±0.4% in the Etom group. There was significant difference between the IPC group and the Etom group or IR group, and also between the MP group and the IR group.@*CONCLUSION@#A depressed stress response impairs the inhibition on myocardial apoptosis in ischemic preconditioning. Methylprednisolone may inhibit myocardial apoptosis.

Effect of sufentanil preconditioning on myocardial P-Akt expression in rats during myocardial ischemia-reperfusion / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the protective effect of sufentanil preconditioning against myocardial ischemia-reperfusion (I/R) injury and the role of PI3K/Akt signaling pathway.</p><p><b>METHODS</b>Sixty male SD rats weighing 250-350 g were randomly divided into 5 equal groups, namely the sham-operated group, I/R group, sufentanil preconditioning group (Spc group), sufentanil preconditioning +PI3K inhibitor group (Spc+W group), and PI3K inhibitor group (W group). Myocardial I/R model was established by ligation of the anterior descending branch of the left coronary artery for 30 min followed by reperfusion for 120 min. Sufentanil was administered in 3 doses via the femoral vein before the occlusion, each at 1 µg/kg infused within 5 min at a 5-min interval. In Spc+W and W groups, PI3K inhibitor wortmannin (15 µg/kg) was given intravenously 5 min before sufentanil preconditioning and 35 min before ischemia, respectively. Heart rate and mean arterial pressure (MAP) were continuously monitored during I/R. At the end of reperfusion, blood samples were obtained to determine plasma activation of CK-MB and LDH. Acute infarct size was measured by triphenyltetrazolium chloride staining, and the myocardial tissues were obtained to detect the expression of phosphorylated Akt using Western blotting.</p><p><b>RESULTS</b>Phosphorylated Akt expression was significantly up-regulated in I/R and Spc groups as compared with the sham group, and was significantly higher in Spc group than in I/R group. After reperfusion, sufentanil preconditioning significantly decreased myocardial infarct size (P<0.01) and lowered the levels of CK-MB (P<0.01) and LDH (P<0.01) compared with those in the I/R group. The I/R , Spc+W and W groups showed no significant differences in myocardial infarct size or the levels of CK-MB and LDH.</p><p><b>CONCLUSION</b>The protective effect of sufentanil preconditioning against myocardium against I/R injury in rats may involve PI3K/Akt signaling pathway activation.</p>