大鼠心脏缺血-再灌注损伤对心肌L-Arg/NO途径的影响

为探讨大鼠心脏缺血-再灌注损伤(IRI)期间一氧化氮(NO)生成增加的环节和过程。本实验用离体灌流大鼠心脏,预灌流15 min,停灌45 min,取30 ml KH 液循环灌流15 min,观察冠脉流出液中细胞胞浆酶(LDH)、蛋白质、肌红蛋白漏出量和NO     

缺血预处理降低大鼠心室易颤性

本实验应用离体大鼠Ｌａｎｇｅｎｄｏｒｆｆ灌流模型,研究模拟缺血预处理（ＩＰ）对心脏的保护作用。发现ＩＰ可引起心室颤动阈（ＶＦＴ）升高、心律失常发生率和严重程度降低、心室有效不应期短时延长。ＩＰ对心脏的保护作用在预缺血后３０ｍｉｎ已基本消失。提示ＩＰ对离体大鼠心肌有保护作用,且时间较为短暂。     

海州香薷总黄酮对大鼠离体心脏缺血/再灌注损伤的保护作用

目的：探讨海州香薷总黄酮（TrES）预处理对大鼠离体心脏缺血/再灌注损伤的保护作用及其可能机制。方法：应用Lgendorff心脏灌流系统建立离体大鼠心脏缺血/再灌注模型,采用全心停灌的处理方法,平衡后,停止灌流30min,再灌注120min作为缺sk/再灌注过程。设立正常对照组,模型对照组,药物预处理组（1,10,100tμg/mlTrES）,利用RM6240BD型多道生理信号采集处理系统实时监测左心室血流动力学各项指标,用TIE染色法测定心肌梗死面积,测定再灌注期间冠脉流出液中乳酸脱氢酶（LDH）含量,以及在520mm处测定由200pmol/LCaC12引起心肌线粒体渗透性转换孔的开放情况。结果：海州香薷总黄酮预处理可以明显改善缺血/再灌注后所引起的左心室收缩功能下降、心肌梗死面积增加的现象、降低复灌期间冠脉流出液中LDH的含量以及能够明显降低由CaC12引起的线粒体在520am处吸光度值,且上述作用具有剂量依赖性。结论：海州香薷总黄酮能够对抗大鼠心肌缺血再灌注损伤,且具有剂量依赖性,其心脏保护机制与抑制线粒体渗透性转换孔（MPTP）的开放有关。     

青霉胺对缺血后再灌注心肌损伤的保护作用

为了解青霉胺对缺血后再灌注心肌损伤的影响,我们采用Ｌａｎｇｅｎｄｒｏｆ离体大鼠心脏灌注模型,先灌注１５ｍｉｎ后停止灌注,模拟缺血６０ｍｉｎ,然后再灌注６０ｍｉｎ。动物分为对照组及青霉胺处理组（３０ｍＭ）。分别测定缺血前及再灌注后心肌组织内三磷酸腺苷（ＡＴＰ）、谷胱甘肽（ＧＳＨ）及谷胱甘肽氧化酶（ＧＳＨ－Ｐｘ）的含量变化,再灌注过程中冠状动脉血流阻力及冠脉流出液中磷酸肌酸激酶（ＣＰＫ）的释放量。结果显示,青霉胺处理组再灌注后心肌组织的ＡＴＰ、ＧＳＨ、ＧＳＨ－Ｐｘ含量均明显高于对照心肌组织中的含量,而青霉胺处理组在再灌注过程中ＣＰＫ的总释放量及平均冠状血流动脉阻力明显低于对照组ＣＰＫ总释放量及平均冠状动脉血流阻力。提示青霉胺可以减轻缺血后再灌注的心肌的损伤,起到保护作用     

钠泵功能改变及内质网应激在大鼠离体心脏缺血/再灌注损伤中的作用

目的：探讨钠泵活性改变及内质网应激（ERS）在大鼠离体心脏再灌损伤中的作用及其机制。方法：将60只雄性SD大鼠随机分为6组（n=10）：正常对照组（NC组）、缺血/再灌损伤组（I/R组）、哇巴因-缺血/再灌损伤组（OUA-I/R组）、地高辛抗血清-缺血/再灌损伤组（Anti-Dig-I/R组）、Src抑制剂PP2-哇巴因-缺血/再灌损伤组（PP2-OUA-I/R组）、PLC抑制剂U73122-哇巴因-缺血/再灌损伤组（U73122-OUA-I/R组）。建立全心缺血30 min,再灌注120min的Langendorff大鼠离体心脏缺血再灌损伤模型。检测各组相同时间点心功能恢复率、冠脉流出液中乳酸脱氢酶（LDH）和肌酸激酶（CK）活性,心肌中Na⁺-K⁺-ATP酶活性和钙离子水平。流式细胞仪检测心肌细胞凋亡率,Western blot检测心肌钠泵α1亚基、葡萄糖调节蛋白78（GRP78）、C/EBP同源蛋白（CHOP）及凋亡蛋白Bcl-2/Bax的表达。结果：与I/R组相比,给予哇巴因预处理可使心功能恢复率明显下降,心肌酶漏出增多,Na⁺-K⁺-ATP酶的活性降低,心肌细胞内钙水平升高,细胞凋亡率增多,心肌钠泵α1亚基和Bcl-2表达降低,GRP78、CHOP和Bax表达升高;而Anti-Dig-I/R组与I/R组相比各指标均明显改善;给予Src抑制剂PP2或PLC抑制剂U73122后,哇巴因对心肌的损伤作用被部分阻断,表现为心功能恢复率升高,心肌酶漏出减少,Na⁺-K⁺-ATP酶的活性明显恢复,Ca²⁺水平下降,细胞凋亡率下降,心肌钠泵α₁亚基和Bcl-2表达增多,GRP78和Bax表达减少。结论：钠泵功能改变和内质网应激共同参与大鼠离体心脏缺血再灌损伤,钠泵通路（Src和PLC）介导内质网应激是引起大鼠离体心脏缺血再灌损伤细胞凋亡机制之一。     

大鼠心肌整体缺血及离体再灌注致生物膜的损伤作用

目的和方法：利用整体大鼠异丙肾上腺素损伤（ISO）和离体大鼠全心停灌／再灌（I／R）两种模型,观察了心肌缺血和缺血／再灌注对心肌生物膜－线粒体膜及肌纤维膜损伤的影响。结果：ISO（5mg/kg,皮下注射）和I／R（20min/20min)可导致大鼠心脏生物膜产生严重损伤,表现为心肌线粒体脂质过氧化产物明显增加,线粒体磷脂酶A2（PLA2）激活,从而导致线粒体膜磷脂（PL）含量减少,磷脂分解产物游离脂肪酸（FFA）增加,膜脂流动性（LFU）降低,线粒体Ca^2 -ATPase及肌纤维膜Na^ ,K^ -ATPase活性降低,线粒体呼吸功能降低、呼吸链氧化磷酸化解偶联,高能磷酸化合物生成减少。结论：整体ISO和离体I／R可导致大鼠心肌线粒体、肌纤维膜结构和功能损伤。     

间歇性低压低氧方式对发育大鼠心脏缺血/再灌注损伤的影响

本研究旨在探讨两种不同形式的间歇性低压低氧（intermittent hypobaric hypoxia,IHH）对发育大鼠心脏缺血,再灌注损伤的影响。雄性Sprague-Dawley（SD）新生大鼠72只,随机分为三组：对照组、IHH3000in组（IHH3000）、IHH5000m组（IHH5000）。低氧组大鼠出生后立即于低压氧舱分别接受28d、42d和56d（海拔5000m、每天6h：海拔3000m、每天5h）的低压低氧处理。应用Langendorff离体心脏灌流技术,给予心脏缺血（停灌30min）／再灌注（复灌60min）处理,分别在缺血前5min及复灌后l、5、10、20、30、60min记录心功能和冠状动脉流量变化,并测定乳酸脱氢酶（1actate dehydrogenase,LDH）活性。实验结束时测定心脏重量。结果显示：（1）IHH3000组大鼠体重增长与对照组无明显差异;IHH5000组大鼠体重增长明显慢于对照组及IHH3000组大鼠（P〈0．01）。（2）IHH3000组人鼠表现明显的心脏保护效应。与对照组相比较,在心脏停灌,再灌注60min时,心功能（LVDP、±LVdp／drmax）恢复增强（P〈0．05）、LDH活性降低（P〈0．05）、冠状动脉流量增多（P〈0．05）;心脏重量与对照组大鼠无差异;IHH42d处理的大鼠心功能恢复明显好于IHH28d处理的大鼠（P〈0．05）。（3）IHH5000组大鼠表现出明显的心脏损伤效应,各项心功能指标（LVDP、±LVdp／dtmax）的恢复均低于对照组（P〈0．05）,复灌过程中LDH活性明显高于相应对照组（P〈0．05）,右心室重量明显高于对照组大鼠（P〈0．05）。结果表明,适当的IHH增强发育大鼠心脏对缺血,再灌注损伤的抵抗能力;间歇性低氧方式是影响其心脏保护作用的重要因素。     

缺血/再灌注心肌肌浆网肌钙调控蛋白mRNA表达的变化

目的：研究缺血／再灌注损伤心肌肌浆网四种钙调控蛋白mRNA表达的变化。方法：将SD大鼠分为正常对照组和缺血／再灌注损伤组,采用Langendorff离体灌流技术,全心停灌15min后行45min复灌制备缺血／再灌注模型,记录心脏收缩功能各项参数（左室发展压、＋dp／dtmax、-dp／dtmax）,进行心律失常评分,同时对两组心肌标本进行半定量RT-PCR检测,测定SERCA、PLB、IP3R2和RyR2四种蛋白质的mRNA表达水平的变化。结果：与正常对照组比较,各时间点缺血再灌注心脏左室发展压、＋dp／dtmax、-dp／dtmax均显著下降,再灌注阶段的心律失常评分明显增高,同时发现心脏SERCA,IP3R2,RyR2mRNA表达降低,然而PLBmRNA表达未出现变化。结论：缺血再灌注损伤造成心脏功能减退,心律失常增多,并可诱导心室肌钙调控蛋白SERCA、IP3R2、RyR2mRNA表达下调。     

L-精氨酸对大鼠心肌相对缺血/再灌注损伤保护作用的研究

目的:探索L-精氨酸(L-Arg)对心肌相对缺血/再灌损伤的保护作用,为研究抗心肌损伤的保护措施提供依据.方法:Wastar大鼠24只,随机分为对照组、相对缺血损伤组和相对缺血损伤 L-精氨酸组.采用高频阈上电刺激大鼠离体心脏建立离体心肌相对缺血/再灌注模型,分别于相对缺血前、缺血后15 min和30 min收集冠脉流出液,测定丙二醛(MDA)含量、肌酸激酶(CK)和乳酸脱氢酶(LDH)活性;采用Pclab生物信号采集处理系统测定相对缺血损伤后5 min、10 min、20 min和30 min时的心率脉压乘积(PRP)、左心室收缩压变化速率( DP/dtmax)和舒张压变化速率(-Dp/dtmAx)的恢复率.结果:L-精氨酸组的PRP、 DP/dtmax和-Dp/dtmax恢复率,明显优于相对缺血损伤组(P＜0.05);L-精氨酸组的冠脉流出液和心肌组织中的丙二醛(MDA)含量、肌酸激酶(CK)和乳酸脱氢酶(LDH)活性,低于相对缺血损伤组(P＜0.05),而L-精氨酸组的心肌超氧化物歧化酶(SOD)活性高于缺血组(P＜0.01).结论:L-精氨酸对心肌相对缺血/再灌损伤具有一定的保护作用.     

氟烷,七氟醚对缺血再灌注心肌功能和ATP酶活性的影响

心肌缺血再灌注过程中细胞内存在着严重的Ｃａ２＋、Ｎａ＋紊乱。Ｃａ２＋ＡＴＰ酶和Ｎａ＋,Ｋ＋ＡＴＰ酶在维持细胞内外离心平衡中起着重要作用。本文用大鼠离体心脏Ｌａｎｇｅｎｄｏｒｆ模型结合缺血前后心功能指标的变化,研究氟烷、七氟醚对缺血前、缺血期、复灌...     

支链氨基酸对心肌缺血大鼠线粒体损伤的保护作用

目的和方法：本文用异丙肾上腺素（Ｉｓｏ） 造成大鼠心肌缺血动物模型,观察支链氨基酸（ＢＣＡＡ）对大鼠心肌缺血时线粒体结构和功能损伤的预防作用。结果：ＢＣＡＡ 能显著降低心肌缺血后心肌线粒体中丙二醛（ＭＤＡ） 水平、维持线粒体模平均微粘度（－η） 、线粒体呼吸链中细胞色素氧化酶及心肌肌球蛋白ＡＴＰａｓｅ活力。结论：给予ＢＣＡＡ对保护大鼠心肌线粒体的结构和功能免受缺血性损伤具有一定效果     

电刺激大鼠蓝斑核区对实验性急性心肌缺血性损伤的影响

本实验在大鼠尾静脉注射垂体后叶素造成急性心肌缺血性损伤,以心电图肢体导联 S-T_Ⅱ段和 T_Ⅱ以及心率为指标,观察了电刺激蓝斑核区对大鼠急性心肌缺血性损伤的影响。实验结果表明蓝斑核区电刺激组的缺血性心电图恢复时间与对照组相比显著提前,前者为18.8±8.31分,后者为67±12.74分(P<0.01)。脑非蓝斑核区电刺激组的缺血性心电图恢复时间为69.2±6.8分。蓝斑核埋藏电极组的恢复时间为44.5±9.97分,与蓝斑核区电刺激组相比,其差异均非常显著(P<0.01)。这些结果说明蓝斑核区的刺激对大鼠急性心肌缺血性模型的恢复有促进作用。     

A possible mechanism for the hypoxia-hypoglycemia-induced release of excitatory amino acids from cultured hippocampal astrocytes

In order to elucidate the mechanism of release of excitatory amino acid (EAA) induced by hypoxiahypoglycemia (in vitro ischemia) from cultured hippocampal astrocytes, we compared the EAA release by in vitro ischemia with those by other treatments. The EAA release induced by in vitro ischemia treatment was rapid and reversible. The amount of released aspartate was comparable to that of glutamate, although the endogenous content of aspartate was one sixth that of glutamate. High-K (100 mM) treatment and the addition of 5 mM NaCN induced a rapid EAA release and the glutamate release was much greater than aspartate. Addition of 5 mM iodoacetate, a glycolysis inhibitor, induced a slow EAA release, and the amount of released aspartate was much higher than that of glutamate. On the other hand, the in vitro ischemia treatment and the addition of 5 mM NaCN induced only 20% reduction in ATP content for initial 5 min, whereas the addition of 5 mM iodiacetate induced a marked reduction. Our data suggest that ischemia-induced EAA release from astrocytes is a complex process in which local energy failure, inhibition of glycolysis, and depolarization of the cell membrane are involved.Abbreviations used EAA excitatory amino acids - PEI polyethyleneimine - DMEM Dulbecco's modified Eagle medium - HKR Hepesbuffered Krebs-Ringer solution     

缺血预适应对大鼠肢体缺血/再灌注后肺损伤的影响

目的:观察肢体缺血预适应对大鼠肢体缺血/再灌注(I/R)后肺损伤的影响并探讨其机制。方法:将雄性Wistar大鼠随机分为4组(n=8):对照组(C),肢体缺血/再灌注组(LI/R),缺血预适应组(IPC)和L-NAME组。各组大鼠均于肢体缺血4h再灌注4h处死,分别测定其动脉血氧分压(PaO2)和二氧化碳分压(PaCO2),血浆及肺组织丙二醛(MDA)、一氧化氮(NO)、内皮素(ET)含量,计算血浆NO/ET比值;以及肺湿干比(W/D)、肺系数(LI),肺组织髓过氧化物酶(MPO)含量。结果:大鼠LI/R后4h,PaO2明显降低;W/D、LI、血浆及肺组织的MDA、NO、ET和肺组织MPO活性均明显增加,而血浆NO/ET比值明显减小。与LI/R组比较,IPC组各项损伤指标明显减轻,NO水平升高,血浆NO/ET比值明显增大。与对照组和IPC组比较,L-NAME处理组,各项损伤指标数值明显增加,NO水平降低;血浆NO/ET比值明显减小,差异均具有显著性。各组大鼠PaCO2的变化无显著性。结论:缺血预适应对肢体缺血/再灌注后肺损伤具有保护作用,其机制可能与内源性NO合成增加有关。     

Brief antecedent anoxia preserves mitochondrial function after sustained undersupply: A subcellular correlate to ischemic preconditioning?

Background: There is increasing evidence that mitochondria – owning a high degree of autonomy within the cell – might represent the target organelles of the myocardial protection afforded by ischemic preconditioning. It was the aim of the study to investigate a possible subcellular correlate to ischemic preconditioning at the mitochondrial level. In addition, we tested whether this protection depends on mitochondrial ATP-dependent potassium channels (K _ATP) and an might involve an attenuation of mitochondrial ATP hydrolysis during sustained anoxia.Methods and Results: Sustained anoxia (A, 14 min) and reoxygenation (R) completely inhibited state 3 and state 4 respiration of isolated ventricular mitochondria from Wistar rats. An antecedent brief anoxic incubation (4 min) followed by reoxygenation (2 min) prevented this loss of mitochondrial function. The protection afforded by anoxic preconditioning could be mimicked by the K _ATP opener diazoxide (30 μmol/l) and was completely inhibited by the K _ATP blocker 5-hydroxydecanoic acid (300 μmol/l). Structural mitochondrial integrity, as estimated from externalization of the mitochondrial enzymes creatine kinase and glutamateoxalacetate transaminase, remained unchanged between the groups, as did mitochondrial ATP loss during anoxia.Conclusion: For the first time, we provide direct evidence for a subcellular preconditioning-like functional mitochondrial adaptation to sustained anoxia. This effect apparently depends on opening of K_ATP but is independent of ATP preservation.     

Edaravone attenuates cerebral ischemic injury by suppressing aquaporin-4

Aquaporin-4 (AQP4) plays a role in the generation of post-ischemic edema. Pharmacological modulation of AQP4 function may thus provide a novel therapeutic strategy for the treatment of stroke, tumor-associated edema, epilepsy, traumatic brain injury, and other disorders of the central nervous system (CNS) associated with altered brain water balance. Edaravone, a free radical scavenger, is used for the treatment of acute ischemic stroke (AIS) in Japan. In this study, edaravone significantly reduced the infarct area and improved the neurological deficit scores at 24 h after reperfusion in a rat transient focal ischemia model. Furthermore, edaravone markedly reduced AQP4 immunoreactivity and protein levels in the cerebral infarct area. In light of observations that edaravone specifically inhibited AQP4 in a rat transient focal ischemia model, we propose that edaravone might reduce cerebral edema through the inhibition of AQP4 expression following cerebral infarction.     

SIRT6在缺血再灌注损伤中的作用机制及研究进展

缺血性损伤后恢复血液供应会导致缺血再灌注（ischemia reperfusion, IR）损伤,这会导致组织损伤进一步加剧。IR损伤伴随着一系列机制,包括谷氨酸兴奋性毒性、钙超载、氧化应激、炎症和细胞凋亡,最终导致细胞死亡。IR损伤过程均由Sirtuins家族调控,在Sirtuins家族中,特异性定位于细胞核中的SIRT6可以促进对DNA损伤和氧化应激的抵抗,抑制基因组的不稳定性,在代谢稳态中发挥作用,同时SIRT6在人重要脏器中处于高度表达状态。但SIRT6在IR损伤中研究较少,结合国内外最新的研究进展,对SIRT6在IR损伤中的作用进行了回顾性的总结和分析,希望对国内外学者对于SIRT6在IR损伤中的研究提供一些参考依据。     

Species-dependent neuroprotection by activated protein C mutants with reduced anticoagulant activity

Activated protein C (APC) is a protease with anticoagulant and cytoprotective activities. APC is neuroprotective in rodent models of stroke. But, an APC variant with reduced anticoagulant activity, 3K3A-APC, compared to wild-type APC shows greater neuroprotection with no risk for bleeding in stroke models. To determine whether 3K3A-APC exhibits species-dependent neuroprotection similar to that as seen with wild-type APC, we studied murine and human recombinant 3K3A-APC mutants which show approximately 80% reduced anticoagulant activity. Murine 3K3A-APC (0.2 mg/kg i.v.) administered at 4 h after embolic stroke improved substantially functional outcome and reduced by 80% the infract volume 7 days after stroke. Human 3K3A-APC was neuroprotective after embolic stroke in mice, but at significantly higher concentrations (i.e. 2 mg/kg i.v.). Species-dependent neuroprotection, i.e. murine > human 3K3A-APC, was confirmed in a mouse model of permanent middle cerebral artery occlusion. Human 3K3A-APC had by fivefold greater cytoprotective activity than murine 3K3A-APC in oxygen-glucose deprivation model in human brain endothelial cells, whereas murine 3K3A-APC was by 2.5-fold more potent than human 3K3A-APC in a mouse model of NMDA-induced neuronal apoptosis. Thus, 3K3A-APC exhibits species-dependent neuroprotection which should be taken into account when designing human trials for ischemic stroke with APC mutants.     

心肌缺血后处理胞内信号转导研究进展

缺血后处理对心肌再灌注损伤的保护是多因素参与的复杂过程。后处理对心肌的保护除了通过减少活性氧类物质的产生、抑制线粒体内钙超载、减轻内皮功能失调等被动作用外,还可主动激活再灌注损伤补救激酶（reperfusion injury salvage kinase,RISK）途径及其他蛋白激酶而实现。本文将对心肌缺血后处理中RISK通路的研究进展作一综述。