钙及活性氧在大鼠肾缺血再灌流损伤中的作用

目的和方法:应用电镜细胞化学方法,对缺血-再灌流损伤过程中活性氧的产生及细胞内钙变化情况进行研究。结果:缺血期,细胞内钙明显增多,而此时尚无H₂O₂产生;缺血后再灌流早期H₂O₂大量产生,细胞内钙与缺血期类似;再灌流晚期H₂O₂产生有所减少,而细胞内钙持续增高。结论:钙及活性氧都参与缺血再灌流损伤,但其参与时机及作用并不相同。     

大鼠肾缺血与再灌时近曲小管上皮细胞内钙含量变化

本实验采用细胞化学方法结合EDX微区分析及生化测试方法，从细胞水平研究了大鼠肾近曲小管上皮细胞内钙含量在缺血-再灌流损伤过程中的改变情况，并探讨了其机理。结果表明：缺血1h，可致细胞内钙含量增高，质膜Ca2 -ATPase活性下降；膜通透性无明显变化。再灌流期，细胞内钙含量持续增高；质膜Ca2 －ATPase活性在再灌流早期（2～4h）基本恢复至正常，在再灌流晚期（12～24h）下降；再灌流期膜通透性逐渐增大。肾小管上皮细胞内钙含量增加在缺血期、再灌流早期及晚期某机制并不相同。     

心肌肽素抗心律失常作用及对钙和钾离子通道的影响

目的：观察心肌肽素对室速、室颤发生率及心室肌细胞钙、钾电流的影响。方法：建立整体动物心肌缺血－再灌流损伤模型。以膜片钳技术记录单个心室肌细胞内向钙电流及电流－电压曲线、内向整流钾电流及延迟整流钾电流。结果：心肌肽素可降低低室速、室颤发生率,在一定浓度下对心肌细胞内向钙向电流有明显的抑制作用,且该作用具有一定的电压依赖性,而对内向整流钾电流及延迟整流钾电流均无作用。结论：心肌肽素能降低缺血－再灌流损     

管花苷B对抗H202诱导的PCI2细胞凋亡

目的:观察肉苁蓉提取物管花苷B对H:O:诱导的PCI2细胞损伤的影响.方法:用MTr法检测细胞存活率,以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化,DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生,并用荧光酶标仪测定caspase-3的活性.结果:100 μmol稬-1H2O2处理细胞24 h显著降低细胞的存活率;诱导细胞发生凋亡,凋亡率达48.O％;细胞内活性氧水平及caspase-3的活性显著升高;而线粒体膜电位却明显降低,红／绿荧光强度的比值由正常的5.97降低为0.41左右.而预先给予l、10或100 mg.L-1浓度的管花苷B处理细胞12 h,可显著提高细胞存活率;并可有效抑制DNA ladder的发生;流式细胞仪检测凋亡率分别降低到30.9％、18.3％和6.2％;激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平;并可逐渐恢复线粒体的高能量状态;easpase-3的活性不断降低,并呈现了一定的剂量依赖性.结论:管花苷B能显著地抑制H2O2诱导的PCI2细胞凋亡,其神经细胞保护作用可能与其降低细胞内活性氧水平,维持线粒体膜电位的高能状态和抑制caspase-3的活性有关.     

PTEN缺失对小鼠成纤维细胞Cu/Zn超氧化物歧化酶表达的影响及其意义

目的 探讨PTEN缺失是否影响小鼠成纤维细胞Cu/Zn超氧化物歧化酶(SOD)的表达水平及其意义.方法 采用Western blot验证及检测对照永生化小鼠胚胎成纤维细胞系PTEN+/+及PTEN缺失细胞系PTEN-/-内PTEN、磷酸化Akt、Cu/Zn SOD表达水平;Northern btot检测细胞内Cu/Zn SOD表达水平;单细胞碱性电泳检测细胞DNA损伤程度;荧光探针标记检测细胞内超氧阴离子水平;MTT法检测H2O2对细胞增殖状况的影响.结果 PTEN缺失细胞系PqEN-/-中,Cu/Zn SOD表达下调,Akt激酶磷酸化水平上调,细胞内超氧阴离子水平明显增高,空白组及H2O2处理后DNA损伤程度均较PTEN+/+细胞重,H2O2对其细胞增殖的抑制作用减弱.结论 PTEN缺失细胞内Cu/Zn SOD表达下调,并由此引起了细胞内活性氧持续高水平和氧化损伤累积以及活性氧对细胞增殖的抑制作用减弱.     

非选择性腺苷受体激动剂5’-N-乙基酰胺基腺苷的体外心肌保护作用及其机制研究

<正>目的:研究腺苷A2A和A2B受体是否参与NECA的抗心肌缺血再灌注损伤作用及其相关机制。方法:利用H9c2心肌细胞建立模拟缺血/再灌注损伤模型,给予非选择性腺苷受体激动剂5’-N-乙基酰胺基腺苷及选择性腺苷A2A、A2B受体拮抗剂,采用CCK-8法测定细胞活性,JC-1染色检测细胞线粒体膜电位(ΔΨm),Amplex Red过氧化氢/过氧化物酶试剂盒测定细胞内     

模拟缺血及再灌流对绵羊浦肯野细胞的损伤效应

应用细胞内微电极记录方法及电镜观察缺血及再灌流对绵羊浦肯野细胞电活动及超微结构的变化。用缺血溶液(低氧、无糖、高钾及高乳酸)灌流3小时,然后用正常台氏液再灌流2小时。缺血3小时和     

七氟醚预处理对缺血再灌注大鼠心肌活性氧产生的影响及其发挥心肌保护作用的机制

目的: 观察七氟醚预处理对缺血再灌注大鼠心肌活性氧以及一氧化氮(NO)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPx)、过氧化氢酶(CAT)活性的影响,进一步探讨活性氧在七氟醚预处理减轻心肌缺血再灌注损伤中的作用。方法: 60只SD大鼠随机分为8组。在体用2%七氟醚预处理30 min 后结扎冠状动脉前降支30 min,然后再灌注120 min。以心肌梗死面积和凋亡指数反映心肌损伤情况,心肌梗死面积用氯化三苯基四氮唑染色显示,细胞凋亡用TUNEL染色显示。活性氧用活性氧荧光探针二氢乙啶测量。使用活性氧清除剂N-(2-巯基丙酰基)甘氨酸(2-MPG)以及一氧化氮合酶抑制剂N^ω-硝基-L-精氨酸甲酯(L-NAME)作为阻滞剂,用酶标仪测定心肌匀浆的NO、SOD、GPx和CAT活性,并进一步分析阻断活性氧及NO产生对七氟醚减轻心肌缺血再灌注损伤的影响。结果: 与对照组比较,七氟醚预处理在缺血再灌注前诱导活性氧产生(12.0±0.8 vs 2.6±0.5, P<0.05),在缺血再灌注后减少活性氧产生(16.2 ±0.9 vs 24.9±1.3, P<0.05);在缺血再灌注前,2-MPG减少七氟醚预处理心肌活性氧产生(5.1±0.7 vs 12.0±0.8, P<0.05),在缺血再灌注后2-MPG+七氟醚预处理组与缺血再灌注组比较无显著差别(24.9±1.4 vs 24.9±1.3, P>0.05);与对照组比较,七氟醚预处理同样诱导NO产生(34.5±3.2 vs 15.9±1.4, P<0.05),增加SOD(1.5±0.5 vs 0.6±0.2, P<0.05)、GPx(22.8±2.5 vs 12.7±2.2, P<0.05)和CAT(15.5±1.8 vs 11.2±1.4, P<0.05)的活性;2-MPG消除了七氟醚对NO、SOD、CPx和CAT的诱导作用和对缺血再灌注心肌的保护作用; L-NAME同样消除七氟醚预处理对SOD、GPx和CAT的诱导作用和心肌保护作用。结论: 七氟醚预处理减少心肌梗死面积和凋亡指数;七氟醚预处理产生的亚损伤量的活性氧和NO诱导缺血再灌注心肌SOD、GPx和CAT的产生,进而抑制缺血再灌注活性氧的产生和心肌损伤。     

钙网蛋白在心肌组织细胞氧化应激与缺血损伤构建中的表达与应用

背景：生物体内钙网蛋白具有调节细胞凋亡、应激、心血管炎症反应等多种生理和病理生理过程的功能。 目的：分析钙网蛋白在缺血再灌注损伤中的表达与应用。 方法：由作者检索1996/2010 PubMed数据库与中国知网数据库有关钙网蛋白结构、功能及在自身免疫、心脏发育中的作用、在缺血缺氧过程中表达的变化等方面的文献后,对钙网蛋白在氧化应激与缺血损伤中的表达变化进行了实验观察。 结果与结论：钙网蛋白通过协助蛋白质正确折叠和维持细胞内Ca2+稳态而参与调节细胞凋亡、黏附、类固醇敏感基因表达等,在心脏发生、发育和病理变化中发挥着重要作用。作者应用大鼠心肌缺血再灌注损伤模型,通过酶联免疫吸附试验、免疫组织化学及RT-PCR 3种不同的检测方法,观察了钙网蛋白在心肌缺血再灌注损伤中的表达,结果显示缺血再灌注损伤诱导钙网蛋白高表达,进而激活内质网凋亡信号途径,诱导细胞损伤,加重心肌损伤。     

生脉注射液减轻兔肾缺血再灌流损伤的作用研究

用自制的肾缺血再灌流损伤模型,在20只新西兰兔,研究了生脉注射液在肾缺血再灌流操作中的作用。结果表明:肾缺血再灌流24小时后,单纯缺血再灌流组动物血尿素氮和肌酐较缺血前显著升高;生脉防治组血尿素氮较缺血前显著升高,但肌酐无显著变化;在再灌流2小时和24小时,血中过氧化脂质(LPO)的含量,单纯缺血再灌流组较缺血前呈升高趋势,生脉防治组呈降低趋势,但差异均无显著性;再灌流24小时肾组织中LPO含量,生脉防治组较单纯缺血再灌流组肾脏呈严重坏死改变,生脉防治组仅有轻度变性。结果揭示:生脉注射液具有减轻兔肾缺血再灌流损伤的作用。     

Superoxide generation by neutrophils and Kupffer cells during in vivo reperfusion after hepatic ischemia in rats.

Kupffer cells and polymorphonuclear leukocytes (PMNs) contribute to the severe reperfusion injury of the liver after ischemia at different time points. The objective of this study was to identify the cellular source(s) of reactive oxygen formation during the PMN-induced injury phase. Kupffer cells and PMNs were isolated from the liver after 45 min of ischemia and 5 h or 24 h of reperfusion using collagenase-pronase digestion and a centrifugal elutriation method. Spontaneous superoxide anion (O2-) formation by large Kupffer cells (basal value 0.65 +/- 0.16 nmol/h/10(6) cells) was increased (up to 550%) during the entire reperfusion period. No enhanced O2- generation by the small Kupffer cell fraction was observed at any time. Control PMNs generated only small amounts of O2- spontaneously (0.25 +/- 0.05 nmol O2-/h/10(6) cells), but hepatic PMNs generated significantly more superoxide: 1.90 +/- 0.58 nmol O2-/h/10(6) cells at 5 h and similarly at 24 h of reperfusion. All cell types were significantly primed for enhanced O2- formation during reperfusion; the priming effect was consistently higher for stimulation with opsonized zymosan (receptor-mediated signal transduction pathway) compared to phorbol myristate acetate (protein kinase C activation). Our data support the hypothesis that PMNs and large Kupffer cells are predominantly responsible for the postischemic oxidant stress during the later reperfusion injury phase after hepatic ischemia in vivo.     

Cardiac toxicity of singlet oxygen: implication in reperfusion injury

Oxygen-derived free radicals (O2.-, H2O2, and .OH) that are produced during postischemic reperfusion are currently suspected to be involved in the pathogenesis of tissue injury. Another reactive oxygen species, the electronically excited molecular oxygen (1O2), is of increasing interest in the area of experimental research in cardiology. In this review are discussed the main potential sources of singlet oxygen in the organism, particularly in the myocardium, the various cardiovascular cytotoxic effects induced by this reactive oxygen intermediate, and the growing evidence of its involvement in ischemia/reperfusion injury.     

Accumulation of 4-hydroxynonenal-modified proteins in hippocampal CA1 pyramidal neurons precedes delayed neuronal damage in the gerbil brain

It has been proposed that reactive oxygen species and lipid peroxidation have a role in the delayed neuronal death of pyramidal cells in the CA1 region. To explore the in situ localization and serial changes of 4-hydroxy-2-nonenal-modified proteins, which are major products of membrane peroxidation, we used immunohistochemistry of the gerbil hippocampus after transient forebrain ischemia with or without preconditioning ischemia. The normal gerbil hippocampus showed weak immunoreactivity for 4-hydroxy-2-nonenal-modified proteins in the cytoplasm of CA1 pyramidal cells. 4-hydroxy-2-nonenal immunoreactivity showed no marked changes after preconditioning ischemia. In the early period after ischemia and reperfusion, there was a transient increase of nuclear 4-hydroxy-2-nonenal immunoreactivity in CA1 pyramidal neurons. In contrast, cytoplasmic immunoreactivity transiently disappeared during same period and then increased markedly from 8h to seven days. One week after ischemia, 4-hydroxy-2-nonenal immunoreactivity was observed within reactive astrocytes in the CA1 region. Early nuclear accumulation of 4-hydroxy-2-nonenal in CA1 neurons may indicate a possible role in signal transduction between the nucleus and cytoplasm/mitochondria, while delayed accumulation of 4-hydroxy-2-nonenal-modified proteins in the cytoplasm may be related to mitochondrial damage.We conclude that 4-hydroxy-2-nonenal may be a key mediator of the oxidative stress-induced neuronal signaling pathway and may have an important role in modifying delayed neuronal death.     

大鼠脑缺血区局部炎症反应的实验探查

目的:研究脑缺血区血管细胞粘附分子-1(VCAM-1)表达和单核/巨噬细胞浸润与脑缺血的病理联系。方法:运用免疫组化染色方法和局部脑缺血/再灌流模型探查40只SD大鼠脑缺血区VCAM-1阳性血管和单核/巨噬细胞的数量变化及其变化发生的时程。结果:大鼠脑缺血区微血管内皮细胞VCAM-1表达发生在脑缺血1h,并在16h的再灌流期间,其表达逐渐增加,显示明显的时间依赖性变化。单核/巨噬细胞在脑缺血区的浸润发生在脑缺血1h/再灌流2h,并随再灌流时间的延长,其数量逐渐增加,在再灌流16h,其数量最多,其浸润也显示明显的时间依赖性变化。脑缺血区血管内皮细胞VCAM-1表达的时相与单核/巨噬细胞浸润的时相基本一致。结论:脑缺血诱导缺血性血管内皮细胞表达VCAM-1和诱导单核/巨噬细胞在脑缺血区浸润。此结果提示VCAM-1和单核/巨噬细胞可能参与缺血性脑损伤的病理过程。     

Antioxidant N-acetylcysteine and AMPA/KA receptor antagonist DNQX inhibited mixed lineage kinase-3 activation following cerebral ischemia in rat hippocampus

We measured the MLK3 expression, activity and backphosphorylation following cerebral ischemia. Our data showed that MLK3 protein levels were unalterable during ischemia and reperfusion. However, during ischemia MLK3 activity gradually increased and reached its peak at 30 min of ischemia. While its backphosphorylation reduced from 5 min of ischemia to 30 min of ischemia. In addition, we also detected MLK3 alteration at various time points of reperfusion after 15 min of ischemia, which showed that MLK3 activity increased twice, whereas MLK3 backphosphorylation was similarly consistent with its activity during reperfusion. To further analyze the reason of MLK3 activation, antioxidant N-acetylcysteine (NAC) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionate (AMPA)/kainate (KA) receptor antagonist 6,7-dinitroquinoxaline-2,3(1H, 4H)-dione (DNQX) were given to the rats 20 min prior to ischemia. The results illustrated that NAC preferably inhibited the MLK3 activation during the ischemia and the early reperfusion, whereas DNQX effectively attenuated the MLK3 activation of the late reperfusion. We think that MLK3 activation is certainly associated with reactive oxygen species (ROS) and AMPA/KA receptor in response to ischemic insult.     

Hydrogen peroxide changes in ischemic and reperfused heart. Cytochemistry and biochemical and X-ray microanalysis.

Active oxygen species including hydrogen peroxide (H2O2) play a major role in ischemia-reperfusion injury. In the present study, changes in myocardial H2O2 content as well as its subcellular distribution were examined in rat hearts subjected to ischemia-reperfusion. Isolated perfused rat hearts were made globally ischemic for 20 or 30 minutes and were reperfused for different durations. H2O2 content in these hearts was studied biochemically and changes were correlated with the recovery of function. These hearts were also analyzed for subcellular distribution of H2O2. Optimal conditions of tissue processing as well as incubation medium were established for reacting cerium chloride with H2O2 to form cerium perhydroxide, an insoluble electron-dense product. The chemical composition of these deposits was confirmed by x-ray micro-analysis. Global ischemia caused complete contractile failure in minutes and after 30 minutes of ischemia, these was a > 250% increase in the myocardial H2O2 content. Depressed contractile function recovery in the early phase of reperfusion was accompanied by approximately a 600% increase in the myocardial H2O2 content. Brief pre-fixation with low concentrations of glutaraldehyde, inhibition of alkaline phosphatase, glutathione peroxidase, and catalase, post-fixation but no post-osmication, and no counterstaining yielded the best cytochemical definition of H2O2. In normal hearts, extremely small amounts of cerium hydroperoxide precipitates were located on the endothelial cells. X-ray microanalysis confirmed the presence of cerium in the reaction product. Ischemia resulted in a stronger reaction, particularly on the sarcolemma as well as abluminal side of the endothelial cells; and upon reperfusion, cerium precipitate reaction at these sites was more intense. In the reperfused hearts, the reaction product also appeared within mitochondria between the cristae as well as on the myofibrils, but Z-lines were devoid of any precipitate. The data support a significant increase in myocardial H2O2 during both the phase of ischemia and the first few minutes of reperfusion. A stronger reaction on the sarcolemma and abluminal side of endothelial cells may also indicate enhanced H2O2 accumulation as well as vulnerability of these sites to oxidative stress injury.     

钙敏感受体在大鼠心肌缺血/再灌注损伤的表达变化及与心肌损伤关系

目的： 观察钙敏感受体（CaSR）在大鼠心肌缺血/再灌注时的表达变化，揭示其与心肌缺血/再灌注损伤的关系。方法： Wistar大鼠随机分为5组：假手术组（sham组）、缺血再灌注1、2、4和6 h组（I/R 1 h、2 h、4 h、6 h组）。采用冠状动脉结扎和松结的方法，复制大鼠在体心肌缺血/再灌注损伤模型，记录左室收缩压（LVSP）和左室内压最大变化速率（±dp/dtmax），测定血清LDH、SOD活性和MDA含量，透射电镜观察心肌超微结构变化， RT-PCR法检测心肌组织中CaSR mRNA的表达变化。结果：LVSP、左室内压±dp/dtmax及SOD活性随再灌注时间延长而减低，LDH活性和MDA含量在再灌注2 h时最高；心肌超微结构损伤在再灌注1 h、2 h较重，随再灌注时间延长而减轻；大鼠心肌缺血/再灌注1 h、2 h心肌组织CaSR的mRNA表达升高，再灌注4 h、6 h后降低。结论： CaSR mRNA表达多时心肌损伤较重，CaSR可能参与了心肌缺血/再灌注损伤。