Urantide对缺血/再灌注损伤诱导的心肌细胞凋亡的影响(英文)

目的探讨urantide对大鼠心肌缺血/再灌注(I/R)或缺氧/复氧损伤(H/R)诱导的心肌细胞凋亡的影响及其相关机制。方法①在体实验采用冠状动脉左前降支缺血30 min/灌注60 min法建立大鼠在体心肌I/R模型。Urantide 3,10和30μg.kg-1分别于缺血前10 min经舌下静脉给药。TUNEL法检测心肌细胞凋亡,免疫组织化学方法检测心肌细胞内Bcl-2和Bax蛋白的表达水平。②离体实验乳大鼠心肌细胞行缺氧3 h/复氧3 h处理制备H/R模型。Urantide 0.1,1和10 nmol.L-1分别于缺氧前加入。Ho-echst33258染色和流式细胞术检测心肌细胞凋亡。结果①在体实验与假手术组相比,I/R组TUNEL阳性细胞数量明显升高(P<0.01);Bcl-2蛋白表达量轻度升高,但无统计学差异,Bax蛋白表达量显著升高(P<0.01),Bcl-2/Bax比值明显降低(P<0.01)。与I/R组相比,urantide 10,30μg.kg-1组心肌凋亡细胞显著降低,分别较模型组降低36.6%和57.2%(P<0.05);Bax蛋白表达量显著降低(P<0.05),Bcl-2/Bax比值明显升高(P<0.05);同时,urantide 30μg.kg-1组Bcl-2蛋白表达量也明显升高(P<0.05)。②离体实验与正常对照组相比,H/R组细胞凋亡率明显升高(P<0.01);Hoechst33258结果显示,与模型组相比,uran-tide 0.1,1和10 nmol.L-1组细胞凋亡率分别显著降低了27.9%,59.0%和75.4%(P<0.05)。流式细胞术结果显示,urantide 1和10 nmol.L-1组细胞凋亡率显著降低,分别较H/R模型组降低32.8%和64.7%(P<0.01)。结论 Urantide可减轻I/R或H/R损伤诱导的心肌细胞凋亡,其机制可能与增加Bcl-2蛋白表达,降低Bax蛋白表达有关。     

尼可地尔、谷氨酰胺、美托洛尔单独及合用对大鼠心肌缺血/再灌注损伤后心肌细胞抗凋亡和HSP70的影响

目的研究尼可地尔(nicorandil,Nic)、谷氨酰胺(glutamine,Glu)、美托洛尔(metoprolol,Met)三药联用对大鼠心肌缺血/再灌注损伤后心肌细胞抗凋亡能力和保护性蛋白HSP70表达的影响。方法将健康♂Wistar大鼠随机分为7组:1假手术(Sham)组,只实施冠状动脉左前降支(left anterior descending,LAD)穿线;2 I/R组,实施LAD 30 min缺血/120 min再灌注程序(ischemia/reperfusion,I/R);3 Nic组;4 Glu组;5 Met组;6三药联用(NGM)组;7三药联用低剂量(NGML)组。药物预处理组则在执行I/R程序前30 min腹腔注射Nic、Glu和Met,三药的初始给药剂量均为1mg·kg-1。TUNEL(terminal dexynucleotidyl transferase-mediated dUTP nick end labeling)法检测心肌细胞凋亡情况,通过凋亡指数衡量心肌细胞凋亡率;Western blot法检测凋亡相关蛋白Bcl-2、Bax以及保护性蛋白热休克蛋白70(heat shock protein 70,HSP 70)的表达情况。结果 I/R组中,缺血区的细胞凋亡率较高(36.9%±10.3%),细胞凋亡相关蛋白表达Bcl-2/Bax值较低(0.14±0.08);与I/R组相比,药物预处理组的细胞凋亡率明显降低(P<0.01),凋亡相关蛋白表达Bcl-2/Bax值明显升高(P<0.01);与Sham组相比,I/R组的HSP70表达明显增加(P<0.01);与I/R组相比,药物预处理组的HSP70表达明显增加(P<0.01);与药物单用组相比,3药联用组的HSP70表达更高(P<0.01)。结论对于大鼠在体I/R损伤,三药联用组与药物单用组相比细胞凋亡率明显降低,凋亡相关蛋白Bcl-2、Bax的表达有所改善;保护性蛋白HSP70的表达增加。     

白藜芦醇预处理对心肌细胞缺血/再灌注损伤的细胞凋亡的影响

目的观察白藜芦醇预处理对心肌细胞缺血再灌注损伤的细胞凋亡的影响。方法培养乳鼠心肌细胞,模拟I/R损伤,随机分为阴性对照组、缺血再灌组及白藜芦醇预处理组,采用TUNEL染色法及Annexin V-FITC/PI双标记流式细胞术检测心肌细胞凋亡;底物酶解法检测caspase-3活性;免疫组织化学法结合计算机图像分析检测心肌细胞Bcl-2/Bax蛋白的表达。结果Res预处理使得心肌细胞凋亡率由(39.7±5.4)%降至(8.3±0.8)%,caspase-3的相对活性由5.9±0.7降至2.8±0.4,P<0.05。Res预处理可使Bcl-2表达的光密度值由99.5±4.8升至138.9±8.4,Bax表达的光密度值由140.7±8.6降至125.3±5.8,P<0.05。结论白藜芦醇预处理可通过促进抗凋亡蛋白Bcl-2的表达、抑制促凋亡蛋白Bax的表达,抑制凋亡过程中关键酶caspase-3的活性,减少I/R引起的心肌细胞凋亡。     

脂联素对大鼠缺血/再灌注心肌细胞凋亡及相关蛋白表达的影响

目的观察脂联素(adiponectin,APN)对大鼠缺血/再灌注(ischemia/reperfusion,I/R)诱导的心肌细胞凋亡与凋亡相关蛋白Bcl-2、Bax、Caspase-3表达的影响。方法将48只大鼠随机分成假手术组(sham group)、I/R组(I/R group)、脂联素预处理组(APN+I/R group),每组16只。结扎左冠状动脉前降支,建立大鼠心肌I/R模型。各组随机选取8只,采用Evans blue-TTC双染法测定心肌梗死面积;另外8只对心功能指标进行监测,实验结束后,采用透射电镜观察心肌组织损伤;原位末端标记(TUNEL)法观察心肌细胞凋亡情况;Western blot法测定心肌Bcl-2、Bax、Caspase-3蛋白的表达。结果脂联素明显减小I/R所致的大鼠心肌梗死面积(P<0.05),改善心脏血流动力学(P<0.05),减轻透射电镜下心肌细胞形态、细胞膜、细胞核、线粒体等结构改变,减少细胞凋亡,增加Bcl-2表达(P<0.05),降低Bax与Caspase-3蛋白表达(P<0.05)。结论脂联素对I/R损伤的保护作用与抑制心肌细胞凋亡,从而减少心肌细胞损失、减轻心脏功能障碍有关,其抗凋亡作用机制可能与上调Bcl-2表达,下调Bax及Caspase-3表达有关。     

促红细胞生成素后处理对大鼠再灌注损伤肺细胞凋亡的干预及机制

目的：探讨促红细胞生成素后处理对再灌注损伤肺细胞凋亡的干预作用及其机制。方法：健康雄性成年SD大鼠40只,随机分为假手术对照组（C组）、缺血/再灌注组（I/R组）、促红细胞生成素＋缺血/再灌注组（EPO组）、促红细胞生成素＋溶剂对照组1（0.4%DMSO的PBS溶液）（D组）和促红细胞生成素＋U0126（U组）。对比观察各组肺组织湿/干重比值（W/D）的变化;原位缺口末端标记法（TUNEL）检测肺组织细胞凋亡情况,计算凋亡指数（AI）;免疫组织化学方法测定肺组织Bcl-2、Bax蛋白的相对含量,RT-PCR法检测肺组织Bcl-2、Bax mRNA表达;光镜下观察肺组织的病理变化及测定肺泡损伤数（IQA）。结果：与C组比较,I/R组肺组织W/D显著升高,I/R组IQA显著升高,AI显著升高,Bcl-2蛋白和Bcl-2 mRNA表达明显下降,Bax蛋白和Bax mRNA表达明显上调,Bcl-2/Bax和Bcl-2 mRNA/Bax mRNA的比值降低（ P均〈 0.01）,肺组织形态学发生异常改变;与I/R组比较,EPO组、D组、U组的W/D显著降低,IQA显著降低,AI显著降低,Bcl-2蛋白和Bcl-2 mRNA表达增强,Bax蛋白和Bax mRNA表达减弱,Bcl-2/Bax和Bcl-2 mRNA/Bax mRNA的比值增高（P 〈0.05或P 〈0.01）,肺组织形态学结构异常改变有所减轻;与EPO组比较,D组的W/D、IQA、AI、Bcl-2蛋白和Bcl-2 mRNA、Bax蛋白和Bax mRNA及Bcl-2/Bax和Bcl-2 mRNA/Bax mRNA的比值均无明显差异（P〉0.05）,U组的W/D升高,IQA升高,AI显著升高,Bcl-2蛋白和Bcl-2 mRNA表达下降,Bax蛋白和Bax mRNA表达上调,Bcl-2/Bax和Bcl-2 mRNA/Bax mRNA的比值降低（P 〈0.05或P 〈0.01）,U组的肺组织形态学结构损伤较EPO组加重。结论：促红细胞生成素后处理能减轻肺缺血/再灌注损伤,其机制可能通过激活ERK1/2信号转导通路,上调凋亡抑制因子Bcl-2的表达,下调促凋亡基因Bax的表达,提高Bcl-2/Bax比值,使肺组织细胞凋亡减少。     

依那普利干预对缺血-再灌注大鼠模型心肌细胞凋亡Bcl-2和Bax基因蛋白表达的影响

目的探讨依那普利干预对缺血再灌注大鼠模型心肌细胞凋亡Bcl-2和Bax基因蛋白表达的影响。方法雄性Wistar大鼠45只,随机分成3组:①缺血-再灌注(I/R)组15只,结扎左冠状动脉45min,松解4h,结扎前15min以及再灌注1h分别静脉注射生理盐水2ml/kg。②依那普利组(L)组15只:结扎左冠状45min,松解4h,结扎前15min以及再灌注1h分别静脉注射依那普利10mg/kg(依那普利以5mg/kg溶于生理盐水)。③假手术(C)组15只,冠状动脉下穿线不结扎,持续4.75h股静脉注射生理盐水2ml/kg。于实验结束时,取出心脏于4%多聚甲醛固定、石蜡包埋切片,按TUNEL法检测凋亡细胞,以S-P免疫组化法检测Bcl-2和Bax基因蛋白表达。结果①I/R组和L组标本中分别有13例和11例心肌细胞发生凋亡,L组凋亡细胞百分数较I/R组明显减少,差异具有高度显著性(P<0.05)。C组15例样本中12例均未检测到TUNEL阳性细胞。②L组Bcl-2表达较I/R组和C组均增强,L组Bax阳性心肌细胞较I/R组明显减少(P<0.05)。结论缺血-再灌注心肌细胞存在明显的凋亡现象,且受Bax蛋白与Bcl-2基因蛋白下调影响,Bax蛋白与Bcl-2蛋白共同调节心肌细胞凋亡,依那普利干预可诱导心肌细胞表达Bcl-2,减少心肌细胞凋亡。     

氯化钆减轻肝脏缺血再灌注损伤的实验研究

目的:探讨氯化钆(Gadolinium Chloride,GdCl3)抑制肝脏枯否细胞对大鼠肝脏缺血再灌注损伤的保护作用。方法:雌性Wistar大鼠30只随机分为3组,对照组只开腹和关腹,术前24h、48h经鼠尾静脉注射生理盐水,每次7mL/kg;肝脏缺血再灌注(I/R)组术前24h、48h经鼠尾静脉注射生理盐水,每次7mL/kg;氯化钆 肝脏缺血再灌注(GdCl3 I/R)组,术前24h、48h经鼠尾静脉注射0.2%氯化钆溶液,每次7mL/kg。第3天进行肝脏部分缺血再灌注手术(10%水合氯醛麻醉,上腹正中开口)。缺血30min后,原位血液再灌注2h。取肝中叶组织,制备10%组织匀浆用于乳酸脱氢酶(LDH)活力的测定;分离肝细胞,进行细胞凋亡与坏死检验;抽提肝组织细胞总RNA,利用RT-PCR法检测IL-10mRNA表达。结果:部分肝脏缺血再灌注后,I/R组LDH活力明显低于对照组(P<0.05),也低于GdCl3 I/R组(P<0.05);I/R组肝细胞大量死亡,GdCl3 I/R组中有早期凋亡肝细胞和晚期凋亡肝细胞,死亡肝细胞大大减少;I/R组IL-10表达量明显增多,GdCl3 I/R组IL-10表达量相对较少,对照组IL-10基本不表达。结论:氯化钆能够抑制枯否细胞吞噬、分泌功能,具有减轻肝脏缺血再灌注的损伤作用。     

依达拉奉预处理对大鼠全脑缺血/再灌注损伤的保护作用

目的研究依达拉奉预处理对大鼠全脑缺血/再灌注损伤(I/R)大脑的保护作用,探讨其脑保护作用的可能机制。方法采用改良Pulsinelli法制作大鼠全脑I/R模型。依达拉奉(3mg·kg-1)腹腔内注射法进行预处理。35只健康雄性SD大鼠随机分为7组,每组5只:对照组(C)、缺血再灌注损伤组(I)、依达拉奉预处理组(E),根据再灌注时间(1d、3d、5d)I、E组依次分3个亚组。TUNEL法检测大鼠脑组织海马CA1区神经细胞凋亡数、免疫组织化学pv6001染色法检测Bcl-2、Bax及CytC(cytochromec)蛋白表达的变化。结果与相应I各亚组比较,E各亚组海马CA1区神经细胞凋亡数目显著减少;Bax、CytC蛋白的表达显著减少;Bcl-2蛋白的表达显著增加(P<0.05)。结论依达拉奉预处理可能通过调节凋亡相关调控基因Bcl-2、Bax、CytC的表达,明显减轻大鼠I/R的神经细胞凋亡,从而产生脑保护作用。     

巴戟天正丁醇提取物对缺氧复氧乳鼠心肌细胞凋亡的影响研究

目的:研究巴戟天正丁醇提取物(BEM)对缺氧复氧乳鼠心肌细胞凋亡的影响。方法:实验分6组,即正常、缺氧复氧模型(A/R)、丹参注射液(SM)及BEM高、中、低剂量组;通过电镜观察凋亡心肌细胞形态变化,原位缺口末端标记(TUNEL)检测心肌细胞凋亡指数,免疫组化染色法测心肌细胞B细胞淋巴瘤-2(Bcl-2)和B细胞淋巴瘤-2连接X蛋白(Bax)的表达。结果:细胞形态学显示BEM对缺氧复氧过程中的心肌细胞的形态具有显著的保护作用(P<0.01);TUNEL结果显示,BEM高、中、低剂量组与A/R组比较可显著降低心肌细胞的凋亡指数(P<0.01);SM及BEM高、中、低剂量组均可使A/R乳鼠心肌细胞Bcl-2阳性表达灰度值显著升高(P<0.01),细胞Bax阳性表达灰度值显著降低(P<0.01)。Bcl-2与Bax的表达呈负相关(r=-0.983)(P<0.01)。结论:BEM可抑制缺氧复氧乳鼠心肌细胞凋亡的发生,其机制可能与促进Bcl-2蛋白的表达、抑制Bax蛋白的表达有关。     

Urantide对大鼠心肌缺血/再灌注后心肌细胞凋亡的作用及机制研究

目的观察urantide对大鼠缺血/再灌注心肌组织氧化应激损伤的作用和心肌细胞凋亡的影响及其与PI3K/Akt及PKC信号通路的关系。方法可逆性冠脉左前降支结扎造成心肌缺血/再灌注模型,给予大鼠心脏缺血30 min再灌注90 min。80只大鼠随机分为假手术组、缺血/再灌注(I/R)组、urantide低、中、高剂量组(3,10,30μg.kg-1)、维拉帕米对照组(1.6 mg.kg-1)、urantide+CHE组(30μg.kg-1+1 mg.kg-1)、urantide+LY294002组(30μg.kg-1+0.3 mg.kg-1)。Urantide低、中、高剂量组中urantide于缺血前5 min舌下静脉1 min内一次性推注,urantide+CHE组与urantide+LY294002组中,在穿线稳定后舌下静脉分别快速推注CHE与LY294002,5 min后舌下静脉快速推注uran-tide 30μg.kg-1,稳定10 min后再行缺血/再灌注操作。实验结束后测定大鼠血清中超氧化物歧化酶(SOD)、一氧化氮合酶(NOS)活力和丙二醛(MDA)含量以及一氧化氮(NO)含量。TUNEL法检测凋亡细胞指数(AI),免疫组化法检测心肌组织Bcl-2、Bax的蛋白表达。结果与I/R组相比,urantide 30μg.kg-1能明显升高SOD活性(P<0.01),明显减少血清中MDA的含量(P<0.05),明显提高NOS活力(P<0.01),使NO含量增加(P<0.01);Bax蛋白表达和心肌细胞凋亡指数降低(P<0.01),Bcl-2蛋白表达增加(P<0.05);urantide+CHE组与urantide+LY294002组与urantide30μg.kg-1组相比,SOD活力和NO含量下降,MDA含量上升,心肌组织中Bax蛋白表达和心肌细胞凋亡指数上升,而Bcl-2蛋白表达下降,与I/R组比较差异无统计学意义(P>0.01)。结论 Urantide能够通过激活PKC和PI3K/Akt信号转导通路,减少心肌组织氧自由基的含量,进一步调控Bcl-2和Bax蛋白的表达,抑制心肌缺血/再灌注大鼠心肌细胞的凋亡,从而对大鼠心肌缺血/再灌注具有一定保护作用。     

紫草酸镁B抑制缺血/再灌注心肌细胞c-Jun N-末端激酶3 mRNA的表达

目的探讨c-Jun N-末端激酶3(c-Jun N-terminal kinase 3, JNK3)在缺血／再灌注心肌细胞损伤中的作用,及紫草酸镁B对缺血／再灌注心脏具有保护作用的机制。方法复制大鼠Langendorff心肌缺血/再灌注损伤模型, 用原位杂交技术检测心肌细胞JNK3 mRNA的表达，并观察紫草酸镁B对JNK3表达的影响。结果图像分析显示，心肌缺血30 min/再灌注30 min时，JNK3表达明显高于非灌注组和对照组。0.1,1和10 μmol·L^-1紫草酸镁B可以抑制缺血／再灌注时JNK3 mRNA的表达。结论紫草酸镁B可通过抑制JNK3的表达以降低JNK的功能，从而减少心肌细胞凋亡的发生，对缺血／再灌注心脏产生保护作用。     

Comparative effects of flavonoids on oxidant scavenging and ischemia-reperfusion injury in cardiomyocytes

Since flavonoids scavenge reactive oxygen species, they may potentially protect against ischemia/reperfusion injury. This study compared the scavenging capacity of specific flavonoids towards different reactive oxygen species. Whether the differential oxidant scavenging capacity correlated with their protective efficacy in ischemia/reperfusion injury of cardiomyocytes was determined. The free radical scavenging capacity of five flavonoids (wogonin, baicalin, baicalein, catechin and procyanidin B2) was analyzed using electron spin resonance spectrometry for 3 radicals: 1,1-diphenyl-2picrylhydrazyl (DPPH), superoxide and hydroxyl radical. A well-established chick cardiomyocyte model of ischemia (1 h)/reperfusion (3 h) was used to evaluate flavonoid-induced protection against ischemia/reperfusion injury in chronic treatment (pretreated 72 h and treated through ischemia/reperfusion) and acute treatment protocols (during ischemia/reperfusion or only at reperfusion). The cell viability was assessed by propidium iodide. The DPPH scavenging was most significant with catechin, followed by procyanidin B2, baicalein, baicalin, and wogonin. The superoxide scavenging was, similarly, most significant with catechin, followed by baicalein, procyanidin B2, and baicalin. For hydroxyl radical, only baicalein showed a significant scavenging capacity (>50% reduction in ESR signal). For the cardiomyocyte studies, all flavonoids but wogonin showed protection against ischemia/reperfusion injury in the chronic treatment protocol. When flavonoids were administered only during ischemia/reperfusion, baicalein, procyanidin B2, and catechin significantly reduced cell death. If flavonoids were administered just at reperfusion, only baicalein and procyanidin B2 had protective effects, and the efficacy was less. Flavonoids possess specific but differential radical scavenging capacity, which, in conjunction with the timing of treatment, affects their protective efficacy in cardiomyocytes exposed to ischemia/reperfusion.     

Inhibition of HtrA2/Omi ameliorates heart dysfunction following ischemia/reperfusion injury in rat heart in vivo

High temperature requirement A2 (HtrA2)/Omi is a mitochondrial serine protease that is released into the cytosol from mitochondria and in turn promotes caspase activation by proteolyzing inhibitor of apoptosis proteins. Here we asked whether treatment with an HtrA2/Omi inhibitor, 5-[5-(2-nitrophenyl)furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101), restores heart dysfunction following ischemia/reperfusion injury in vivo. Rats underwent a 30-min ischemia by occluding the left anterior descending artery, followed by 24 h reperfusion. UCF-101 (0.75 or 1.5 micromol/kg, i.p.) was administered 10 min before reperfusion. UCF-101 treatment significantly recovered the mean arterial blood pressure and ameliorated contractile dysfunction of the left ventricle 72 h after reperfusion with concomitant reduction of infarct size. Cardio-protection mediated by UCF-101 was correlated with reduced X-linked inhibitor of apoptosis protein (XIAP) degradation and inhibition of Caspase-9, Caspase-3, and Caspase-7 processing. Furthermore, UCF-101 prevented loss of membrane integrity by inhibiting fodrin breakdown in cardiomyocytes. UCF-101-induced cytoprotection was also correlated with reduced Fas ligand expression and inhibition of FLIP degradation following ischemia/reperfusion. These results suggest that UCF-101 rescues cardiomyocytes from ischemia/reperfusion injury by inhibiting XIAP degradation and Fas/Fas-ligand-induced apoptosis, thereby ameliorating ischemia/reperfusion-induced myocardial dysfunction.     

Naloxone Postconditioning Alleviates Rat Myocardial Ischemia Reperfusion Injury by Inhibiting JNK Activity

To investigate the alteration of c-Jun N-terminal kinase (JNK) activity after myocardial ischemia reperfusion injury (MIRI) and further explore the effect of naloxone postconditioning on MIRI. Forty male Sprague Dawley rats were randomly divided into five groups: sham operation (sham, n=8); ischemia reperfusion (IR, n=8); IR+naloxone 0.5 mg/kg (Nal L, n=8); IR+naloxone 1.0 mg/kg (Nal M, n=8); IR+naloxone 2.0 mg/kg (Nal H, n=8). Pathological changes of myocardial tissue were visualized by HE staining. The expression of p-JNK, and the apoptosis of cardiomyocytes were investigated with Western blotting and the TUNEL assay, respectively. Irregular arrangement and aberrant structure of myocardial fibers, cardiomyocytes with granular or vacuolar degeneration, and inflammatory cells infiltrating the myocardial interstitial regions characterized MIRI in the IR group. Signs of myocardial injury and inflammatory infiltration were less prominent in the Nal-treated groups. The expression of p-JNK in the sham group and in all Nal-treated groups was significantly lower than that in the IR group (p<0.01). The apoptosis index of cardiomyocytes in the IR group was significantly higher than in the sham group (p< 0.01). The apoptosis indices of cardiomyocytes in all Nal-treated groups were significantly reduced to 55.4%, 26.2%, and 27.6%, respectively, of the IR group (p< 0.01). This study revealed that Naloxone postconditioning before reperfusion inhibits p-JNK expression and decreases cell apoptosis, thus alleviating MIRI.     

Thioredoxin reduces post-ischemic myocardial apoptosis by reducing oxidative/nitrative stress

BACKGROUND AND PURPOSE: Thioredoxin (Trx) is an oxidoreductase that prevents free radical-induced cell death in cultured cells. Here we assessed the mechanism(s) underlying the cardioprotective effects of Trx in vivo. EXPERIMENTAL APPROACH: The effects of myocardial ischemia (30 min) and reperfusion were measured in mice, with assays of myocardial apoptosis, superoxide production, NOx and nitrotyrosine content, and myocardial infarct size. Recombinant human Trx (rhTrx, 0.7-20 mg kg(-1), i.p.) was given 10 min before reperfusion. KEY RESULTS: Treatment with 2 mg kg(-1) rhTrx significantly decreased myocardial apoptosis and reduced infarct size (P<0.01). Nitrotyrosine content of cardiomyocytes was markedly reduced in rhTrx-treated animals (P<0.01). To further identify the mechanisms by which rhTrx may exert its anti-nitrative effect, iNOS expression and production of NOx and superoxide were determined. Treatment with rhTrx had no significant effect on iNOS expression or NOx content in the ischemic/reperfused heart. However, it markedly upregulated mSOD and reduced tissue superoxide content. To further establish a causative link between the anti- peroxynitrite effect and the cardioprotective effect of rhTrx, cultured adult cardiomyocytes were incubated with SIN-1, a peroxynitrite donor, (50 microM for 3 h) resulting in a nitrotyrosine content comparable to that seen in the ischemic/reperfused heart and causing significant cardiomyocyte apoptosis (P<0.01). Treatment with rhTrx markedly decreased SIN-1 induced apoptosis (P<0.01). CONCLUSIONS AND IMPLICATIONS: These results demonstrate that Trx is a novel anti-apoptotic and cardioprotective molecule that exerts its cardioprotective effects by reducing ischemia/reperfusion-induced oxidative/nitrative stress.     

Luteolin improves contractile function and attenuates apoptosis following ischemia-reperfusion in adult rat cardiomyocytes

Luteolin occurs in a variety of plants and possesses antioxidant and anti-inflammatory properties. However, its role in protection against ischemia-reperfusion injury in Sprague-Dawley rats has not been elucidated. In the present study, we tested the contractile function of left ventricular cardiomyocytes with different concentrations of luteolin: 0.5, 1.5, 2.5 and 5.0 μg/ml after simulated. We investigated the direct effect of luteolin against necrosis and apoptosis following ischemia-reperfusion in cardiomyocytes. We further observed the function of isolated hearts subjected to ischemia-reperfusion with or without 10.0 μg/ml luteolin pretreatment. Following 24h incubation with or without luteolin, adult rat cardiomyocytes were subjected to 3h of ischemia followed by 2h of reperfusion for contractile function and necrosis (trypan blue exclusion and lactate dehydrogenase release) or 18 h of reperfusion for apoptosis studies. The cardiomyocyte shortening amplitude depended on different concentrations of luteolin, increasing significantly at 2.5 μg/ml luteolin (P<0.01). Necrosis and apoptosis were reduced by luteolin at 2.5 μg/ml. In addition, the expression of Bcl-2 was upregulated by luteolin and the ratio of Bax to Bcl-2 was decreased. Luteolin inhibited the activation of Caspase3 after ischemia-reperfusion in cardiomyocytes. Furthermore, luteolin at 10.0 μg/ml improved ischemia-reperfusion induced myocardial function, by improving heart rate, +dp/dt(max) and -dp/dt(max), and also limiting the decline of left ventricular systolic pressure (LVSP) and elevation of left ventricular end-diastolic pressure (LVEDP) to some extent. Our results demonstrated that luteolin prevents ischemia-reperfusion injury by reducing necrosis and apoptosis in rat cardiomyocytes.     

线粒体融合素2通过Ras-PI3K-Akt信号途径抑制缺血再灌注诱导的乳鼠心肌细胞凋亡

目的：研究线粒体融合素2（Mfn2）基因对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响及其相关的信号通路。方法：乳鼠心肌细胞经缺氧/复氧（H/Re）处理模拟心肌缺血再灌注损伤。用Mfn2基因的重组腺病毒（Adv-Mfn2）感染经缺氧复氧处理的乳鼠心肌细胞。采用TUNEL染色、ELISA、流式细胞术等方法检测Mfn2对缺血再灌注诱导的乳鼠心肌细胞凋亡的影响。Western blot分析线粒体凋亡路径中Bcl-2蛋白、Bax蛋白、Caspase-9以及磷酸化蛋白激酶B（p-Akt）的表达变化。结果：TUNEL染色发现Adv-Mfn2感染乳鼠心肌细胞后,细胞凋亡较H/Re组和Adv-LacZ组显著减少。ELISA和流式细胞仪检测结果表明,Adv-Mfn2组心肌细胞凋亡较H/Re组及Adv-LacZ组明显减少,且这一作用呈时间依赖性。Western blot结果显示,Adv-Mfn2组中Bcl-2蛋白表达较H/Re组和Adv-LacZ感染组上升,Bax蛋白表达下降,各组中Caspase-9的表达变化与Bax相同,Adv-Mfn2组的p-Akt蛋白表达水平则较H/Re组和Adv-LacZ感染组明显上升。结论：Mfn2基因主要通过正向调控RasPI3K-Akt信号通路,促进Akt的磷酸化水平,使Bcl-2蛋白表达量增加,Bax蛋白表达量降低,抑制Caspase-9活化,从而抑制缺血再灌注诱导的乳鼠心肌细胞凋亡。     

大鼠局灶性脑缺血/再灌注后NF-kB表达和细胞凋亡

目的:研究脑缺血再灌注后大鼠脑组织半暗区核因子(nuclear factor kappa B,NF-kB)基因表达的变化与神经细胞凋亡的关系。方法:用插线法制作大鼠大脑中动脉(M CAO)栓塞/再灌注模型,原位杂交法检测大鼠脑重度缺血(3h)及再灌注损伤不同时间点(2、3d)半暗区NF-kB表达;TUNEL法测定凋亡细胞。结果:脑缺血再灌注后,缺血半暗区NF-kB的表达明显升高(P<0.01)。凋亡细胞数量亦显著增加(P<0.01)。细胞凋亡的时程变化与NF-kB的表达基本一致。结论:局灶性重度脑缺血再灌注后可引起NF-K b表达的增加,参与缺血再灌注神经细胞损伤机制。     

Bridging innate immunity and myocardial ischemia/reperfusion injury: the search for therapeutic targets

Myocardial infarction necessitates new therapeutic interventions, since it still results in high morbidity and mortality worldwide. Reperfusion therapy itself results in (acceleration of) apoptosis, called myocardial ischemia/reperfusion (I/R) injury. For several decades it is known that the inflammatory response during reperfusion is the major cause of myocardial I/R injury. Therapeutic options are limited by lack of (detailed) understanding of intra- and intercellular mechanisms between inflammatory cells and cardiomyocytes. Furthermore, clinical trials generally fail to reproduce experimental successes, because essential factors are not taken into account in animal studies: risk factor for coronary artery disease, duration of ischemia and reperfusion, time of intervention. Above all, there is no specific therapeutic target for inhibiting the inflammatory response, in which cardiomyocytes are involved. The identification of Toll-like receptors (TLRs) on cardiomyocytes, has given rise to, not only new insights on the inflammatory response initiated by cardiomyocytes themselves, but also provided potential targets to reduce myocardial I/R injury. Experimental and clinical studies show that inflammatory responses are also involved in tissue repair responses. Since certain TLRs are expressed on inflammatory cells and cardiomyocytes, it ensures specific targeting of either detrimental effects or tissue repair responses in the inflammatory response during reperfusion. Which TLRs are involved in the 'good' and which in the 'bad' effects of the inflammatory response remains to be addressed. This review will discuss both experimental and clinical research on inflammatory reactions that occur after myocardial ischemia/reperfusion (I/R). Data and conclusions concerning potential therapeutic targets in both experimental as clinical research settings will be reviewed.