Protective effect of monoclonal antibodies against LFA-1 and ICAM-1 on myocardial reperfusion injury following global ischemia in rat hearts

The effects of anti-LFA-1 and anti-ICAM-1 monoclonal antibodies (MAbs) on the reperfusion injury of rat cardiac tissues after global ischemia were studied. Studies were performed using an isolated blood perfused heart preparation in which hearts were subjected to 30 min of global ischemia followed by 40 min of reperfusion. Isolated rat hearts were perfused with blood from an anesthetized support rat with or without anti-LFA-1 or anti-ICAM-1 monoclonal antibody administration (n = 10 in each group). Ventricular function, myocardial tissue water content and myocardial energy status were evaluated in this model. In the control group, ischemia and reperfusion of isolated hearts resulted in a 63.6 ± 2.7% recovery of left ventricular developed pressure (LVDP) and a 44 ± 7 % increase in coronary vascular resistance compared with pre-ischemic baseline values. Treatment with anti-LFA-1 MAb or anti-ICAM-1 MAb resulted in a 77.2 ± 1.5% and a 80.4 ± 3.0% recovery of LVDP, respectively. In addition, increase in coronary vascular resistance was only 23 ± 7% and 13 ± 6% in anti-LFA-1 and anti-ICAM-1-treated groups, respectively. Values are significantly different between the control group and MAb-treated groups. Ischemia and reperfusion resulted in a 16% increase of myocardial tissue water content (3.71 ± 0.03 in pre-ischemic baseline versus 4.29 ± 0.08 ml/g dry weight) in the control group, whereas that resulted in only 3.0 and 5.7 % increase in anti-LFA and anti-ICAM-1-treated groups, respectively. The difference between the control group and MAb-treated groups was significant. Cardiac energy status as assessed by adenosine triphosphate (ATP) concentration was markedly reduced in the control group at 40 min of reperfusion compared with pre-ischemic baseline values (5.70 ± 0.27 vs. 14.92 ± 0.48 μmol/g dry weight). In contrast, the reduction of myocardial ATP concentration at 40 min of reperfusion was significantly inhibited by anti-LFA-1 and anti-ICAM-1 monoclonal antibody treatment (5.70 ± 0.27 vs. 8.96 ± 0.52 and 8.10 ± 0.47 μmol/g dry weight, respectively). These results suggest that a LFA-1/ICAM-1 pathway plays a critical role in the pathogenesis of postischemic myocardial injury during early reperfusion period.     

Cytochrome p450 2C inhibition reduces post-ischemic vascular dysfunction

Cytochrome p450 (CYP) inhibitors provide protection against myocardial infarction following both global and focal cardiac ischemia and reperfusion (I/R). We hypothesized that sulfaphenazole, an inhibitor of CYP2C6 and 9, also attenuates post-ischemic endothelial dysfunction by reducing CYP-mediated superoxide generation (which scavenges nitric oxide (NO)), thereby restoring NO bioavailability and vascular tone. Rat hearts were perfused in the Langendorff mode for 20 min in the presence, or absence, of sulfaphenazole and then subjected to 30 min global no-flow ischemia followed by 15 min reperfusion. Septal coronary resistance arteries were isolated and mounted on glass cannulae for measurements of luminal diameter. Preconstricted arteries were exposed to acetylcholine to elicit endothelium-dependent, NO-mediated vasodilation. Acetylcholine caused near maximal dilation in control tissues not subjected to I/R. Following I/R, endothelium-dependent vasodilation was reduced. Pretreatment with sulfaphenazole restored endothelial sensitivity to acetylcholine. Vasoresponsiveness to endothelium-independent vasodilators, sodium nitroprusside and isoproterenol, were also reduced following I/R. However, sensitivity to endothelium-independent vasodilators was not restored by pretreatment with sulfaphenazole. I/R-induced superoxide production was assessed by dihydroethidium staining of flash frozen hearts. Sulfaphenazole treatment significantly reduced superoxide production in arterial walls following I/R injury. We conclude that sulfaphenazole restores post-ischemic endothelium-dependent, NO-mediated vasodilation by reducing superoxide production, suggesting that CYP2C9 plays a key role in post-ischemic vascular dysfunction.     

Aldose reductase inhibitors improve myocardial reperfusion injury in mice by a dual mechanism

Aldose reductase (AR) has been implicated in the pathogenesis of diabetic complications, although the clinical efficacy of AR inhibitors has not been clearly proven. To clarify the pathophysiological role of AR in the heart, we investigated effects of AR inhibitors applied either during the pre-ischemic phase, or during the post-ischemic reperfusion phase on ischemia-reperfusion injury in isolated heart from transgenic mice overexpressing human AR. On reperfusion following global ischemia, transgenic mouse hearts exhibited lower left developed pressure, increased release of creatine kinase, and lower ATP content compared with their littermates. When inhibitors of AR were applied during the pre-ischemic phase, they significantly improved deranged cardiac function, creatine kinase release, and ATP content. On the other hand, inhibition of AR during the post-ischemic reperfusion phase did not affect cardiac performance and ATP content, but it significantly attenuated creatine kinase release and the level of thiobarbiturate-reactive substances in transgenic mouse hearts. These results suggest a dual role of AR in ischemia-reperfusion injury. Inhibition of AR during ischemia preserved generation of ATP via glycolysis, whereas inhibition during the reperfusion phase reduced myocardial injury by attenuating oxidative stress elicited by ischemic insult and reoxygenation.     

Vitexin protects against myocardial ischemia/reperfusion injury in Langendorff-perfused rat hearts by attenuating inflammatory response and apoptosis

The aim of the present study is to investigate the effects and its possible underlying mechanisms of vitexin on myocardial ischemia/reperfusion (I/R) injury in isolated rat hearts. Isolated rat hearts were perfused with Langendorff apparatus, which subjected to 30 min ischemia and then followed by 60 min reperfusion. In the isolated rat heart subjected to I/R injury, treatment of vitexin (50, 100, 200 μmol/L) significantly enhanced coronary flow, and decreased the pathological scores of myocardium. 50, 100, 200 μmol/L vitexin significantly attenuated I/R-induced increases of myocardial TNF-α and IL-1β, and 25, 50, 100, 200 μmol/L vitexin significantly reduced apoptosis index of cardiac muscle cell of rat isolated heart subjected to I/R injury. Vitexin significantly inhibited I/R-induced increase of myocardial Bax protein expression; however, 100, 200 μmol/L vitexin markedly increased myocardial Bcl-2 protein expression. Furthermore, vitexin at concentrations of 50, 100, 200 μmol/L significantly reduced expression of myocardial NF-κBp65 protein. Therefore, these results demonstrate that vitexin exhibits significant protective effect against myocardial I/R injury in isolated rat heart, which is related to inhibition of the release of inflammatory cytokines and the apoptosis of cardiac muscle cell via up-regulating protein expression of Bcl-2 as well as down-regulating Bax and NF-κBp65.     

ATP敏感性钾通道和线粒体通透转换孔参与白藜芦醇苷的心肌保护作用(英文)

目的探讨白藜芦醇苷(Poly)对大鼠缺血再灌注(I-R)心肌损伤的保护作用及其机制。方法应用Langendorff室技术制备离体大鼠心脏I-R损伤模型。雄性SD大鼠随机分为对照组、模型组、Poly(25, 50和75μmol.L-1)组、格列本脲(Gli) +Poly组、5-羟基癸酸(5-HD) +Poly组和苍术苷(Atr) +Poly组。对照组心脏由K-H液灌流110 min;模型组由K-H液灌流20 min后,停灌30 min,复灌60min;Poly组在I-R处理前用含不同浓度Poly的K-H液灌流10 min;Gli +Poly和5-HD+Poly组在I-R前分别用含Gli (10μmol.L-1)和5-HD(100μmol.L-1)的K-H液灌流5 min,再加入Poly (50μmol.L-1)灌流10 min;Atr +Poly组用含Poly(50μmol.L-1)K-H液灌流10 min及停灌30 min后,先用含Atr(20μmol.L-1)的K-H液灌流15 min,然后改用K-H液灌流。分别记录各组停灌前、停灌30 min和复灌60 min内的左心室舒张末压(LVEDP)、左心室舒张压(LVDP)、左心室等容期压力最大变化速率(±dp/dtmax)和冠脉流量(CF)等心功能指标。心脏复灌60 min后,用氯化三苯基四氮唑染色法测定心肌梗死面积,透射电镜下检测心肌超微结构变化。结果缺血前各组心功能参数无明显变化。与模型组相比,Poly可浓度依赖性地促进大鼠I-R后心功能的恢复,预防I-R损伤。复灌60 min后,Poly组大鼠心脏LVDP,±dp/dtmax和CF明显高于模型组;LVEDP则低于模型组;缺血前给予Poly(50μmol.L-1)10 min可明显减小I-R后心肌梗死面积,并改善心肌超微结构。Gli, 5-HD和Atr可阻断Poly对I-R心脏心功能参数和心肌梗死面积等的保护作用。结论 Poly具有明显的抗心肌I-R损伤作用,其心脏保护作用可能与其增加细胞膜和线粒体膜ATP敏感性钾通道开放和抑制线粒体通透转换孔开放有关。     

Targeted inhibition of calpain in mitochondria alleviates oxidative stress-induced myocardial injury

The protein levels and activities of calpain-1 and calpain-2 are increased in cardiac mitochondria under pathological conditions including ischemia, diabetes, and sepsis, and transgenic overexpression of mitochondrial-targeted calpain-1 induces dilated heart failure, which underscores an important role of increased calpain in mitochondria in mediating myocardial injury. However, it remains to be determined whether selective inhibition of calpain in mitochondria protects the heart under pathological conditions. In this study, we generated transgenic mice overexpressing mitochondrial-targeted calpastatin in cardiomyocytes. Their hearts were isolated and subjected to global ischemia/reperfusion. Hyperglycemia was induced in the transgenic mice by injections of STZ. We showed that transgenic calpastatin was expressed exclusively in mitochondria isolated from their hearts but not from other organs including skeletal muscle and lung tissues. Transgenic overexpression of mitochondrial-targeted calpastatin significantly attenuated mitochondrial oxidative stress and cell death induced by global ischemia/reperfusion in isolated hearts, and ameliorated mitochondrial oxidative stress, cell death, myocardial remodeling and dysfunction in STZ-treated transgenic mice. The protective effects of mitochondrial-targeted calpastatin were correlated with increased ATP5A1 protein expression and ATP synthase activity in isolated hearts subjected to global ischemia/reperfusion and hearts of STZ-treated transgenic mice. In cultured rat myoblast H9c2 cells, overexpression of mitochondrial-targeted calpastatin maintained the protein levels of ATP5A1 and ATP synthase activity, prevented mitochondrial ROS production and decreased cell death following hypoxia/reoxygenation, whereas upregulation of ATP5A1 or scavenging of mitochondrial ROS by mito-TEMPO abrogated mitochondrial ROS production and decreased cell death. These results confirm the role of calpain in myocardial injury, suggesting that selective inhibition of calpain in myocardial mitochondria by mitochondrial-targeted calpastatin is an effective strategy for alleviating myocardial injury and dysfunction in cardiac pathologies.     

白介素8和兔心肌缺血/再灌注损伤研究

目的 探讨白介素8(rhIL-8)参与兔心肌缺血/再灌注损伤的机制,为减轻再灌注损伤探索新的治疗途径。方法 结扎兔冠状动脉左前降支(left anterior descending coronary artery,LAD)造成缺血1小时,再灌注3.5小时。实验分两组:缺血/再灌注组(MI/R,n=8)和假结扎组(Sham MI/R,n=8)。结果 MI/R组发生严重的心肌损伤,包括受累心肌髓过氧化物酶(myeloperoxidase,MPO)活性增大和血清肌酸磷酸激酶-MB同工酶(CPK-MB)、异构前列腺素(eoi-PGF_(2α))水平增高(均P<0.01)。血清IL-8浓度逐渐升高,免疫组化示受损心肌区血管内皮基底膜呈IL-8阳性染色。结论 血管内皮细胞释放的IL-8是吸引中性粒细胞浸润于缺血区心肌,造成缺血/再灌注损伤的因素之一。     

The potential benefits of 1.5% hetastarch as a cardioplegia additive

INTRODUCTION: Myocardial edema is a clinically relevant problem found in post-ischemic reperfused hearts. The objective of this study was to understand the effects of hetastarch-supplemented cardioplegia on post-ischemic edema and cardiac function. MATERIALS AND METHODS: Swine hearts were arrested with either St. Thomas Hospital cardioplegia with (n=6) or without (n=7) 1.5% hetastarch. Following hypothermic global ischemia, hearts were crystalloid reperfused in a four-chamber isolated working mode. RESULTS: Hetastarch decreased myocardial water content gains after three hours of reperfusion (control versus hetastarch, hour 0: 67+/-5% versus 67+/-3%, NS; hour 3: 82+/-2% versus 78+/-1%, p=0.1). Post-ischemic control group left ventricular end-diastolic pressures were elevated after 1h (in mm Hg, hour 0: 13+/-2, hour 1: 19+/-3, hour 2: 19+/-3, hour 3: 20+/-2) but remained stable (<16 mm Hg) in the hetastarch group. Post-reperfusion creatine phosphokinase perfusate levels in the hetastarch treated hearts were decreased (control: 1.6 IU/l/g versus hetastarch: 0.6 IU/l/g, p=0.15). DISCUSSION/CONCLUSIONS: Hetastarch treatment delayed myocardial edema development and attenuated myocardial creatine kinase efflux, thereby preserving diastolic function.     

Role of endogenous endothelin-1 in post-ischemic cardiac dysfunction and norepinephrine overflow in rat hearts

Endothelin-1 and norepinephrine are involved in myocardial ischemia/reperfusion injury. The aim of this study was to investigate the role of endogenously generated endothelin-1 in ischemia/reperfusion-induced norepinephrine overflow and cardiac dysfunction using a nonselective prototype of endothelin-converting enzyme (ECE) inhibitor, phosphoramidon, and a selective ECE inhibitor, SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl)amino]carbonyl]benzenesulfonamide, monosodium salt). According to the Langendorff technique, isolated Sprague-Dawley rat hearts were subjected to 40-min global ischemia followed by 30-min reperfusion. Phosphoramidon and SM-19712 were perfused 30 min before ischemia and during reperfusion. Endothelin-1 level in left ventricle was increased by ischemia/reperfusion. This increase in left ventricular endothelin-1 level was suppressed by treatment with SM-19712. SM-19712 significantly improved ischemia/reperfusion-induced cardiac dysfunction such as decreased left ventricular developed pressure and dP/dt(max) and increased left ventricular end diastolic pressure. In addition, this agent suppressed excessive norepinephrine overflow in the coronary effluent from the post-ischemic heart. In contrast, treatment with phosphoramidon further enhanced left ventricular endothelin-1 level and norepinephrine overflow, and significantly worsened cardiac dysfunction after ischemia/reperfusion. These responses such as exaggerated norepinephrine overflow and the cardiac dysfunction observed after ischemia/reperfusion were markedly suppressed in the presence of a selective endothelin ET(A) receptor antagonist, ABT-627 [2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid]. These findings indicate that cardiac endothelin-1 production is enhanced by ischemia/reperfusion, and this endogenously increased endothelin-1 is involved in post-ischemic norepinephrine overflow and cardiac dysfunction via the activation of endothelin ET(A) receptors.     

钌红与三磷酸腺苷前体对再灌注损伤大鼠心脏的快速恢复作用(英文)

急性缺血后心力衰竭可能与高能化合物的合成障碍有关.用?Wistar大鼠进行离体心脏实验,30min全心缺血和30 min再灌注导致心肌收缩力显著下降,三磷酸腺苷含量不足和线粒体内钙含量升高 用钌红(1μmol·L~(-1))进行再灌注,线粒体内钙超负荷减轻,同时心肌收缩力增加,但三磷酸腺苷含量不变 用钌红,核糖(1mmol·L~(-1))和腺嘌吟(1mmol·L~(-1))同时进行再灌注,不但心肌收缩力显著升高,而且三磷酸腺苷含量显著恢复。实验表明,急性缺血后的心肌受线粒体内钙含量升高的影响,合成高能化合物的能力减低.钌红,核糖和腺嘌吟可协同性地提高心肌肉三磷酸腺苷含量和恢复心肌收缩力。     

Relationship between myocardial cation content and injury in reperfused rat hearts treated with cation channel blockers.

A role for K+ and Ca2+ channel blockers in cardiac contractile dysfunction and myocardial ionic imbalance was examined in isolated rat hearts with 35-min ischemia and 60-min reperfusion. The K+ channel blockers glibenclamide (1-30 microM) and sematilide (1-30 microM), Ca2+ channel blockers diltiazem (0.1-3 microM) and nicardipine (0.03-1 microM) and fast Na+ channel blocker tetrodotoxin (0.01-0.3 microM) were delivered for the last 3-min pre-ischemia. Ischemia-induced increase in Na+ content was attenuated by diltiazem and tetrodotoxin at all concentrations employed and by nicardipine at 0.3 microM, whereas the ischemia-induced loss of K+ was suppressed partially by glibenclamide and sematilide and almost completely by the two drugs in combination. Left ventricular developed pressure of untreated hearts did not recover upon reperfusion, which was associated with increases in myocardial Na+ and Ca2+ contents and decreases in K+ and Mg2+ contents. Glibenclamide and sematilide neither enhanced the post-ischemic recovery of left ventricular developed pressure nor affected cation changes during reperfusion. Diltiazem enhanced the recovery of left ventricular developed pressure and attenuated imbalance of the myocardial Na+ during ischemia and of all myocardial cations examined during reperfusion. The effects of nicardipine on these parameters were small. Tetrodotoxin enhanced the recovery of left ventricular developed pressure and reversed the imbalance of all myocardial cations examined during reperfusion in a concentration-dependent manner. The results suggest that blockade of transmembrane flux of K+ during ischemia plays a minor role in the improvement of post-ischemic contractile recovery, rather blockade of transmembrane flux of Na+ attenuates the ischemia and reperfusion injury.     

ERK1/2参与丙泊酚预处理对肾性高血压大鼠离体心肌缺血再灌注损伤的作用

目的探讨丙泊酚预处理对肾性高血压大鼠离体缺血再灌注心肌的作用及细胞外信号调节激酶(ERK1/2)活化在其中的可能机制。方法在Langendorff离体心脏灌注模型上,64只肾性高血压大鼠随机分为8组(n=8):对照组(CTRL组),缺血再灌注组(ISCH组),DMSO组,30、100和300μmol.L-1丙泊酚预处理组(P30、P100和P300组),ERK1/2激酶抑制剂PD98059组(PD组)及PD98059+100μmol.L-1丙泊酚预处理组(PD+P100组)。持续监测心功能指标,实验末生化比色法检测心肌细胞超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,W estern B lotting方法半定量测定p-ERK1/2蛋白表达水平。结果再灌注60 m in末,ISCH组心功能较CTRL组恶化(P<0.01),DMSO组、P30组、P300组和PD组心功能指标与ISCH组相比未见差异,P100组心功能恢复程度高于ISCH组(P<0.01),PD98059能拮抗100μmol.L-1丙泊酚预处理引起的心功能改善。P100组MDA含量低于ISCH组和PD+P100组,SOD活性高于ISCH组和PD+P100组。P100组胞浆p-ERK1、胞核p-ERK1/2活性较ISCH组升高,PD+P100组较P100组胞核p-ERK1/2活性明显降低(P<0.01)。结论100μmol.L-1丙泊酚预处理减轻了肾性高血压大鼠离体心肌缺血再灌注损伤,其机制可能涉及心肌细胞p-ERK1/2,尤其是细胞核p-ERK1/2活性的增加。     

甲基黄酮醇胺对家兔离体工作心脏缺血再灌注损伤的保护作用

在家兔离体工作心脏模型上,观察MFA对心脏的直接作用及对心肌缺血再灌注损伤的保护作用。结果发现MFA 2.5,5,10和20μmol/L灌注心脏10min,剂量依赖性地抑制心功能参数并增加冠脉流量;MFA 2.5,5和10μmol/L对60min缺血30min再灌注所致的心肌损伤有保护作用,增加心功能参数的恢复并降低细胞内CPK外漏。     

Cardioprotective effects of abciximab (ReoPro) in an isolated perfused rat heart model of ischemia and reperfusion

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in cardiac contractile dysfunction as well as myocardial injury, due in large part to endothelial dysfunction, upregulation of cell adhesion molecules and subsequent neutrophil induced cardiac injury. We studied the effects of abciximab (ReoPro), an anti-IIb/IIIa antibody, which has been shown to attenuate platelet interactions, in a neutrophil-platelet mediated isolated perfused rat heart model of ischemia (I) (20 min) and reperfusion (R) (45 min). Administration of abciximab (6.5 micrograms/kg) 10 min prior to the perfusion of the PMN + platelet perfused I/R heart improved post-reperfusion coronary flow and preserved post-reperfusion left ventricular developed pressure (LVDP) and +dP/dt max as indices of cardiac contractile function. Abciximab-treated hearts reperfused in the presence of PMNs and platelets preserved all indices of cardiac contractile function. I/R heart perfused with PMNs and platelets produced a profound injury to the hearts which was attenuated with the treatment of abciximab. In addition, abciximab significantly reduced PMN accumulation in the ischemic myocardium from 38 +/- 1 PMNs/mm2 in untreated hearts to 7 +/- 1 in rats given abciximab. Similar results were obtained with PMN perfused I/R rat hearts without platelets. These results provide evidence that abciximab is a potent and effective cardioprotective agent that inhibits leukocyte-endothelial cell interactions as well as platelet-endothelial cell interaction and preserves cardiac contractile function and coronary perfusion following myocardial ischemia and reperfusion. Therefore, IIb/IIIa may be important in attenuating both platelet and neutrophil-mediated myocardial dysfunction.     

银杏内酯A对缺血/再灌注损伤的大鼠心功能的影响

目的探讨银杏内酯A(Ginkgolide A,GA)对离体大鼠心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤的心功能的影响。方法 Langendorff灌注离体大鼠心脏,用停灌复灌的方式制备心肌缺血/再灌注损伤模型,记录左心室收缩峰压(LVSP)、左心室舒张末压(LVEDP)、收缩压和舒张压最大变化速率(±LVdp/dtmax)和心率(HR)的变化,并测定复灌后冠状动脉流出液中LDH和SOD的含量及心肌梗死面积。分离单个细胞进行GA预处理,模拟缺血/再灌注培养后检测心肌细胞存活率和单个心肌细胞的收缩幅度。结果 GA预处理以后,LVSP、-dp/dtmax和HR在复灌10 min时较缺血/再灌注组具有明显的改善(P<0.05),并增加心率,减少LDH的生成,增加SOD的活性,降低心肌梗死面积。经GA预处理的心肌细胞存活率明显提高,10μmol.L-1GA能够明显提高缺血后单个心肌细胞的收缩幅度。结论 GA对缺血/再灌注损伤的心肌具有一定的改善作用。     

Inhibition of NF-kappa B activation can attenuate ischemia/reperfusion-induced contractility impairment via decreasing cardiomyocytic proinflammatory gene up-regulation and matrix metalloproteinase expression

Following cardiopulmonary bypass (CPB) and cardiac global ischemia and reperfusion, proinflammatory genes are up-regulated, and nuclear factor (NF)-kappaB is involved in this regulation. We studied whether inactivation of NF-kappaB could decrease myocardial ischemia/reperfusion injury with cardioplegia during CPB, attenuate matrix metalloproteinase (MMP) activation, and prevent cardiac mechanical dysfunction. Rabbits received normal saline (group 1) or curcumin (70 and 7 micromol/kg in groups 2 and 3) injection 2 hours before CPB. Total CPB was initiated, and myocardial protection was delivered every 20 minutes for 60 minutes of cardiac arrest. Rabbits were weaned from CPB and reperfused for 4 hours before the hearts were harvested. Blood was sampled at various time points. Postoperative expression of myocardial mRNA levels of interleukin 6, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha, postreperfusion plasma level of troponin I, and cardiac mechanical dysfunction were significantly decreased in the curcumin groups. The myocardial levels of activated MMP-2 and -9 were also significantly reduced compared with the control group. In conclusion, by inhibiting NF-kappaB activation, the up-regulation of cardiac proinflammatory genes can be ameliorated, and the activation of MMPs can be decreased during CPB, thereby lessening severity of cardiac mechanical dysfunction after global cardiac ischemia/reperfusion injury.     

伴刀豆球蛋白A，核糖和腺嘌呤协同促进缺血后心功能不全的恢复

急性缺血后心功能不全可能与细胞膜损害及高能化合物的合成障碍有关。用Ｗｉｓｔａｒ大鼠进行离体心脏灌注，３０ｍｉｎ全心缺血和３０ｍｉｎ再灌注导致心肌收缩力显著下降，细胞内钙含量升高和肌酸激酶漏出。用核糖（１ｍｍｏｌ·Ｌ１）和腺嘌呤（１ｍｍｏｌ·Ｌ１）进行再灌注，上述各项指标均无改善。用伴刀豆球蛋白Ａ（４０ｍｇ·Ｌ１）进行再灌汁，细胞内钙负荷减轻，肌酸激酶漏出减少，同时心肌收缩力增加，但ＡＴＰ含量无改善，用核糖，腺嘌呤和伴刀豆球蛋白Ａ联合进行再灌注，不但心肌收缩力显著升高，细胞内钙负荷减轻，肌酸激酶漏出减少，而且高能磷酸化合物含量显著恢复。实验表明，ＡＴＰ前体不能在短时间内使急性缺血后心功能不全恢复，但在伴刀豆球蛋白Ａ的协同作用下，能快速地恢复心肌收缩力和ＡＴＰ含量。     

人参皂苷 Rg1减轻大鼠离体心脏缺血再灌注损伤的作用研究

目的：探讨人参皂苷 Rg1对大鼠离体心脏缺血再灌注损伤的减轻作用及机制。方法制备大鼠离体心脏 I/ R 模型,将18只大鼠随机分为正常对照组、I/ R 组、人参皂苷 Rg1组。100μmol/ L 人参皂苷 Rg1进行预处理10 min,观察血流动力学指标左心室内压最大上升/下降速率和心率压力乘积的变化,检测灌流液中肌酸激酶（CK）、乳酸脱氢酶（LDH）活性。Western blotting 检测心肌组织 PI3K 下游激酶 Akt、ERK1/2及其磷酸化水平的变化,磷酸化GSK-3β的蛋白表达。结果与 I/ R 组比较,人参皂苷 Rg1预处理显著改善心脏功能,降低灌流液中 CK、LDH 活性（ P ﹤0.05）;升高 p-Akt 和 p-GSK-3β的蛋白表达（ P ﹤0.05）。结论人参皂苷 Rg1对大鼠离体心脏缺血再灌注损伤有减轻作用,其机制与激活 PI3K-Akt 通路有关。     

A selective inhibitor of Na+/Ca2+ exchanger, SEA0400, preserves cardiac function and high-energy phosphates against ischemia/reperfusion injury

The Ca2+ overload by Ca2+ influx via Na+/Ca2+ exchanger (NCX) is a critical mechanism in myocardial ischemia/reperfusion injury. We investigated protective effects of a novel selective inhibitor of NCX, SEA0400, on cardiac function and energy metabolism during ischemia and reperfusion. Langendorff-perfused rat hearts were exposed to 35 minutes global ischemia and 40 minutes reperfusion. Using 31P nuclear magnetic resonance spectroscopy, cardiac phosphocreatine (PCr), ATP, and pHi were monitored. SEA0400 did not change the basic cardiac function, but improved the recovery of left ventricular developed pressure (LVDP) after reperfusion (27.6 +/- 4.9 mm Hg in control, 101.2 +/- 19.3 mm Hg in 0.1 microM, and 115.5 +/- 13.3 mm Hg in 1 microM SEA0400, means +/- SE, n = 6, P < 0.05). SEA0400 reduced left ventricular end-diastolic pressure and increased coronary flow after reperfusion. SEA0400 improved the recoveries of cardiac phosphocreatine and ATP after reperfusion, but did not affect pHi. There were significant linear correlations between left ventricular developed pressure and cardiac phosphocreatine (r = 0.79, P < 0.05), and left ventricular developed pressure and ATP (r = 0.80, P < 0.05). However, SEA0400 increased the incidence and duration of reperfusion ventricular arrhythmias. SEA0400 added only after reperfusion also improved both the contractile function and energy metabolism. It is concluded that the selective inhibition of NCX may be effective to preserve high-energy phosphates and to improve cardiac function after reperfusion, but may not be able to prevent fatal arrhythmias.     

JAK-STAT信号通路在离体大鼠心肌缺血再灌注损伤激活时程的研究

目的观察JAK-STAT信号通路在离体大鼠心肌缺血再灌注损伤过程中激活的时程及意义。方法采用Langendorff离体灌流模型,将42只雄性Wistar大鼠随机分为7组:对照组:用改良的KH液持续灌流180 min;I/R组:按再灌注时间分为R0、R5、R15、R30、R60、R120 6组,用改良的KH液灌流平衡30 min后,全心停灌30 min,分别再灌注0、5、15、30、601、20 min。连续监测左室发展压(LVDP)、左室压力最大升降速度(+dp/dtmax)以评价心功能,采用改良的Gonori变色酸(GCA)亮绿特殊染色法观察心肌缺血程度;免疫印迹法检测再灌注不同时程磷酸化的STAT1、STAT3蛋白表达的变化。结果与对照组相比,再灌注不同时程LVDP及+dp/dtmax明显降低((P<0.01),GCA特殊染色显示缺血变性的心肌细胞数量明显增多(P<0.01),再灌注各时程STAT1、STAT3均处于激活状态,与对照组相比差异有统计学意义(P<0.01)。但二者表达存在时间差异,p-STAT1在缺血30 min增高不明显,再灌注过程中处于显著激活状态(P<0.01);p-STAT3在缺血30 min即明显升高(P<0.01),而再灌注期未见进一步升高(P>0.05),p-STAT1/p-STAT3与LVDP及GCA特殊染色阳性率呈显著的相关性。结论JAK-STAT信号通路参与了心肌缺血再灌注损伤的发生,磷酸化的STAT1与STAT3的比例可能决定了再灌注损伤的严重程度。