Mito-KATP在七氟醚延迟预处理减轻大鼠心肌缺血再灌注氧化损伤中的作用

目的:探讨线粒体ATP敏感性钾通道(mito-KATP)在七氟醚延迟预处理减轻大鼠心肌缺血再灌注(IR)氧化损伤中的作用。方法:健康雄性SD大鼠60只随机分为5组(n=12),假手术(Sham)组、IR组、七氟醚预处理(SPC)组、七氟醚预处理+5-羟基癸酸(SPC+5-HD)组和5-羟基癸酸(5-HD)组。灌注结束时检测血清肌钙蛋白(IcTnI)水平,氯化三苯四氮唑(TTC)染色确定心肌梗死面积。检测心肌丙二醛(MDA)、Ca2+含量、超氧化物歧化酶(SOD)、谷胱甘肽硫转移酶(GST)活性以及谷胱甘肽硫转移酶Mu(GSTM)表达。结果:IR组较Sham组心肌梗死面积和cTnI释放增加,心肌MDA含量和Ca2+浓度增加,SOD、GST活性和心肌GSTM表达降低(P<0.01);SPC组较IR组心肌梗死面积和cTnI释放减少,心肌MDA含量和Ca2+水平也减少,SOD和GST活性以及心肌GSTM增加(P<0.01);SPC+5-HD组较SPC组心肌梗死面积和cTnI释放增加,心肌MDA含量和Ca2+浓度增加,SOD、GST活性和心肌GSTM表达降低(P<0.01)。结论:七氟醚延迟预处理能减轻大鼠心肌缺血再灌注所致氧化损伤,mito-KATP在其中起调节作用。     

Heptanol预处理对细胞膜及线粒体Cx43参与的大鼠心肌细胞缺氧/复氧损伤的作用研究

目的通过对细胞膜及线粒体Cx43表达变化的研究,探讨不同浓度庚醇(Heptanol)预处理对大鼠心肌细胞缺氧/复氧损伤作用。方法将SD乳鼠培养的心肌细胞随机分为5组:正常对照组(control组),缺氧/复氧组(AR组),溶酶组(DMSO组),0.1mmol/L庚醇预处理组(0.1HT组),0.5mmol/L庚醇预处理组(0.5HT组),1.0mmol/L庚醇预处理组(1.0HT组),2.0mmol/L庚醇预处理组(2.0HT组)。除Control组外,H/R组,DMSO组以及各浓度heptonal预处理组均进行缺氧/复氧处理。检测Cx43mRNA水平,并提取心肌细胞线粒体蛋白,应用Western blot检测其含量。结果 AR组、0.1HT组和0.5HT组较control组的Cx43mRNA表达水平及线粒体Cx43含量明显减少,差异有统计学意义(P<0.01)。1.0 HT组和2.0HT组与AR组相比较,Cx43mRNA表达水平及线粒体Cx43含量明显增加,差异有统计学意义(P<0.01)。结论 heptanol预处理可以逆转I/R导致的细胞膜及线粒体Cx43的减少,但作用效果与浓度有关。线粒体Cx43可能参与了heptanol预处理的心肌保护作用。     

缺血预处理对离体心肌线粒体膜电位的影响

目的 研究缺血预处理(IP)对离体大鼠心肌线粒体膜电位的影响.方法 采用Langendorff装置建立大鼠离体心肌缺血再灌注模型,将SD大鼠随机分为正常对照组(CON)、缺血再灌注损伤组(IR)、缺血预处理组(IP)、5-羟葵酸(5-HD)拮抗缺血预处理组(5HD IP),每组6只.各组平衡末、缺血前、再灌注末分离心肌线粒体并测定线粒体膜电位.结果 再灌注末,缺血预处理组线粒体膜电位显著高于缺血再灌注组(P＜0.01),5HD IP组线粒体膜电位较lP组差异有显著性(P＜0.05).结论 缺血预处理能明显减轻离体心脏缺血/再灌注对大鼠心肌线粒体膜电位功能的损害,而5HD能部分废除该作用.     

Heptanol预处理对细胞膜及线粒体C×43参与的大鼠心肌细胞缺氧/复氧损伤的作用研究

目的 通过对细胞膜及线粒体Cx43表达变化的研究,探讨不同浓度庚醉(Heptanol)预处理时大鼠心肌细胞缺氧/复氧损伤作用.方法 将SD乳鼠培养的心肌细胞随机分为5组:正常对照组(control组),缺氧/复氧组(AR组),溶酶组(DMSO组),0.lmmol/L庚醉预处理组(0.1HT组),0.5mmol/L庚醉预处理组(0.5HT组),1.0mmol/L庚醉预处理组(1.0HT组),2.0mmol/L庚醇预处理组(2.0HT组).除Control组外,H/R组,DMSO组以及各浓度heptonal预处理组均进行缺氧/复氧处理.检测CX43mRNA水平,并提取心肌细胞线粒体蛋白,应用Western blot检测其含量.结果 AR组、0.1HT组和0.51HT组较control组的CX43mRNA表达水平及线粒体Cx43含量明显减少,差异有统计学意义(P＜0.01).1.0HT组和2.0HT组与AR组相比较,Cx43mRNA表达水平及线粒体 Cx43含量明显增加,差异有统计学意义(P＜0.01).结论 heptanol预处理可以逆转I/R导致的细胞膜及线粒体Cx43的减少,但作用效果与浓度有关.线粒体Cx43可能参与了heptanol预处理的心肌保护作用.     

mitoK(ATP)介导硫化氢预处理延迟相的心肌保护效应

目的:研究线粒体ATP敏感性钾通道[mitoK(ATP)]激活在硫化氢预处理延迟相对大鼠心肌细胞的保护效应。方法:将32只健康成年雄性SD大鼠随机分成假手术组(Sham组)、缺血再灌注组(IR组)、硫化氢预处理组(HS组)和5-羟葵酸(5-HD)+硫化氢预处理组(HD组),每组8只。Sham组仅穿线但不阻断左冠状动脉前降支(LAD);IR组结扎LAD30min,松解后再灌注120min;HS组静脉注射硫化氢供体NaHS50μg/kg,24h后同IR组处理;HD组于结扎前15min静脉注射5-HD5mg/kg,其他同HS组处理。检测心室面积、心肌缺血面积和梗死面积,计算缺血和梗死面积百分比;电镜下观察心肌细胞超微结构。结果:3组缺血面积百分比差别无统计学意义(P>0.05);HS组心肌梗死面积百分比低于IR组和HD组(P<0.01或P<0.05),HD组与IR组相比差异无统计学意义(P>0.05)。心肌细胞超微结构损伤程度HS组较IR组明显减轻,而HD组与IR组差异不大。结论:硫化氢预处理延迟相可保护缺血再灌注损伤的心肌,mitoK(ATP)介导了硫化氢预处理延迟相的心肌保护通路。     

缺血预处理对缺血-再灌注大鼠肾脏缝隙连接蛋白43表达的影响

目的 研究缺血预处理对缺血-再灌注大鼠肾脏缝隙连接蛋白43(Cx43)表达的影响,探讨Cx43在缺血-再灌注中的作用及其意义.方法 SD大鼠30只分3组:假手术Sham组、缺血-再灌注(I-R)组、缺血预处理(IPC)组.于再灌注2 h后检测肾组织匀浆一氧化氮(NO)、一氧化氮合酶(NOS)水平;肾组织切片HE染色行中性粒细胞(PMN)计数及Paller评分,量化肾损害程度;Western blot定量分析Cx43蛋白在肾组织中的表达.结果 IPC组肾组织中NO、总NOS(TNOS)、诱导型NOS(INOS)水平明显高于IR组;IPC组PMN计数及Paller评分明显低于IR组;IPC组Cx43蛋白表达明显高于IR组,IR组Cx43蛋白表达明显低于Sham组.结论 缺血预处理可能通过提高Cx43在肾组织中的表达减轻肾缺血再灌注损伤.     

缝隙连接蛋白Cx43介导硫化氢后处理对大鼠心肌的保护作用

目的探讨缝隙连接蛋白Cx43是否参与硫化氢后处理减轻离体大鼠心脏缺血/再灌注(I/R)损伤。方法 72只♂SD大鼠随机分为6组(n=12):空白组(Sham组),缺血/再灌注组(I/R组),溶媒组(DMSO组),抑制剂18β-次甘草酸组(AGA组),硫化氢后处理组(NP组),硫化氢后处理+AGA组(N+A组)。采用离体心脏Langendorff灌注模型,平衡灌注20 min后,停灌30 min,复灌60 min。记录平衡末及灌注结束时的心率(HR)、左室舒张末期压(LV-EDP)、左室发展压(LVDP)、左室内压上升最大速率(+dp/dtmax)、左室内压下降最大速率(-dp/dtmax);灌注结束时,TTC染色法检测心肌梗死面积;Western blot半定量线粒体和胞质总的Cx43(total connexin 43,tCx43)和磷酸化Cx43(phosphorylated connexin 43,pCx43)表达水平。结果平衡灌注末各组间心功能指标差异无统计学意义。再灌注后,与I/R组比较,NP组明显改善再灌注损伤心功能的各项指标(P<0.05),减少心肌梗死面积[(24.4±4.8)%vs(49.4±4.2)%,P<0.05];tCx43表达在线粒体中明显升高,胞质中明显降低,pCx43表达线粒体中明显升高,胞质中明显降低。AGA逆转了硫化氢后处理产生的心肌保护效应及tCx43和pCx43在线粒体中表达的增加(P<0.05)。结论缝隙连接蛋白Cx43参与了硫化氢后处理减轻离体大鼠心脏I/R损伤过程。     

PI3K/Akt调节线粒体Cx43蛋白表达在H_2S后处理离体大鼠心肌中的保护作用

目的探讨PI3K/Akt信号通路是否通过调节线粒体缝隙连接蛋白Cx43而在硫化氢(H2S)后处理中减轻离体大鼠心脏缺血/再灌注(I/R)损伤。方法 56只♂SpragueDawley(SD)大鼠随机分为4组(n=14):缺血/再灌注组(I/R组),PI3K/Akt信号通路抑制剂LY294002组(LY组),硫化氢后处理组(NP组),硫化氢后处理+PI3K/Akt信号通路抑制剂LY294002组(N+L组)。采用离体心脏Langen-dorff灌注模型,平衡灌注20 min后停灌30 min复灌60 min。记录平衡末及灌注结束时的心率(HR)、左室舒张末期压(LVEDP)、左室发展压(LVDP)、左室内压上升最大速率(+dp/dtmax)、左室内压下降最大速率(-dp/dtmax);灌注结束时,TTC法染色心肌切片并计算心肌梗死面积百分比;TUNEL法检测心肌细胞凋亡,计算凋亡指数(AI);Westernblot半定量线粒体总的Cx43(total connexin 43,tCx43)和磷酸化Cx43(phosphorylated connexin 43,pCx43)表达水平。结果平衡灌注末各组间心功能指标差异无统计学意义。再灌注后,与I/R组比较,NP组心功能的各项指标明显改善(P<0.05);心肌梗死面积减少(26.5±4.2)%vs(44.5±5.3)%(P<0.05);凋亡指数降低(25.9±3.0)%vs(43.1±1.9)%(P<0.05);线粒体tCx43和pCx43蛋白表达水平明显升高。LY294002逆转了H2S后处理产生的心肌保护效应,使N+L组心功能指标及线粒体中tCx43和pCx43的表达水平降低(P<0.05),心肌梗死面积及凋亡指数均增加(P<0.05)。结论 PI3K/Akt信号通路通过上调线粒体缝隙连接蛋白Cx43蛋白的表达而在硫化氢(H2S)后处理中减轻离体大鼠I/R损伤。     

血小板激活因子及其拮抗剂银杏内酯B对大鼠心肌缺血再灌注损伤的影响(英文)

目的　探讨外源性血小板激活因子 (PAF)激活的多核形中性粒细胞 (PMN)是否具有低浓度氧自由基模拟缺血预适应 (IP)对缺血再灌注 (IR)所致心肌损伤的保护作用。方法　结扎冠脉左前降支 30min ,再灌注 3h制备大鼠心脏IR模型。以缺血前给予 2次 5min缺血 ,10min再灌注作为IP。实验分为6组 ,IR组、IR +PAF组和IR +银杏内酯B(GB、PAF拮抗剂 )组 ,分别于缺血前 2 5和 10miniv生理盐水、PAF(3μg·kg- 1)和GB (5mg·kg- 1) ;IP +IR组、IP +IR +PAF组和IP +IR +GB组分别于IP 2次 10min再灌注开始时iv相应药物。观察分析心功能、梗死面积、PMN计数、心肌髓过氧化物酶活性、TUNEL阳性细胞计数等指标。结果　给予PAF明显加重IR引起的心脏损伤、PMN浸润及凋亡的程度 ;GB对IR引起的心功能下降没有明显影响 ,但明显减少梗死面积、PMN浸润及凋亡细胞 ;PAF明显削弱IP的保护作用 ;GB对IP作用未见明显影响。结论　IR后PMN浸润可能是引起心肌细胞凋亡的一个重要原因 ;PAF激活PMN可能不具有模拟IP对IR所致心肌损伤的保护作用 ,反而取消IP的保护作用。     

芦荟苷预处理对缺血再灌注大鼠心肌细胞凋亡的影响

目的研究芦荟苷(Barb)对急性心肌缺血再灌注损伤大鼠心肌细胞凋亡的影响。方法结扎大鼠左冠状动脉前降支复制心肌缺血再灌注损伤模型,实验分为假手术组,缺血再灌注组(IR),Barb高、低剂量预处理组。采用原位缺口末端标记法(TUNEL)检测心肌细胞凋亡指数(AI),酶联免疫吸附试验(ELISA)法测定心肌细胞肿瘤坏死因子(TNF)-α水平,化学法测定线粒体Ca2+-ATPase活性。结果与IR组比较,Barb组AI和TNF-α水平显著降低(P<0.01或P<0.05),Ca2+-ATPase活性明显增高(P<0.05)。结论Barb能明显抑制IR引起的心肌细胞凋亡,其作用可能与降低TNF-α水平和提高Ca2+-ATPase活性有关。     

无创肢体缺血预处理联合后处理对心肌缺血/再灌注损伤的影响

目的 探讨无创肢体缺血预处理(NILIPC)和后处理(NILIPostC)联合应用对体外循环心脏手术中心肌缺血/再灌注损伤的保护作用.方法 60例风湿性心脏病拟行机械瓣膜置换者随机分为实验1、2、3组和对照组.实验1组在主动脉阻断前10 min右下肢实施NILIPC;实验2组在主动脉开放前10 min右下肢实施NILI...     

Mitochondrial K ATP channel activation is important in the antiarrhythmic and cardioprotective effects of non-hypotensive doses of nicorandil and cromakalim during ischemia/reperfusion: a study in an intact anesthetized rabbit model.

The roles of cardiomyocyte sarcolemmal ATP-sensitive K(+) (K(ATP)) and mitochondrial K(ATP) channels in the cardioprotection and antiarrhythmic activity induced by K(ATP) channel openers remain obscure, though the mitochondrial K(ATP) channels have been proposed to be involved as a subcellular mediator in cardioprotection afforded by ischemic preconditioning. In the present study, we investigated the effects of administration of non-hypotensive doses of ATP-sensitive K(+) channel (K(ATP)) openers (nicorandil and cromakalim), a specific mitochondrial K(ATP) channel blocker (5-hydroxydecanoate (5-HD)) and a specific sarcolemmal K(ATP) channel blocker (HMR 1883; (1-[5-[2-(5-chloro-o-anisamido)ethyl]-2-methoxyphenyl]sulfonyl-3-methylthiourea) prior to and during coronary occlusion as well as prior to and during post-ischemic reperfusion on survival rate, ischemia-induced and reperfusion-induced arrhythmias and myocardial infarct size in anesthetized albino rabbits.The thorax was opened in the left 4th intercostal space and after pericardiotomy the heart was exposed. In Group I (n=80), occlusion of the left main coronary artery and hence, myocardial ischemia-induced arrhythmias were achieved by tightening a previously placed loose silk ligature for 30min. In Group II (n=184), arrhythmias were induced by reperfusion following a 20 min ligation of the left main coronary artery.Both in Groups I and II, early intravenous infusion of nicorandil (100 micro g/kg bolus+10 micro g/kg/min), cromakalim (0.2 micro g/kg/min), HMR 1883 (3mg/kg)/nicorandil and HMR 1883 (3mg/kg)/cromakalim just prior to and during ischemia increased survival rate (75%, 67%, 86% and 75% versus 60% in the control subgroup in Group I; 75%, 75%, 75% and 67% versus 50% in the control subgroup in Group II), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. However, late intravenous administration of nicorandil or cromakalim at the onset and during reperfusion did neither increase survival rate nor confer any antiarrhythmic or cardioprotective effects. The antiarrhythmic and cardioprotective effects of both nicorandil and cromakalim were abolished by pretreating the rabbits with 5-HD (5mg/kg, i.v. bolus), a selective mitochondrial K(ATP) channel blocker but not by HMR 1883 (3mg/kg). In the present study, higher levels of malondialdehyde (MDA) and lower levels of reduced glutathione (GSH) and superoxide dismutase (SOD) in necrotic zone of myocardium in all the 16 subgroups in Group II suggest little anti-free radical property of nicorandil and cromakalim.We, therefore, conclude that intervention by intravenous administration of nicorandil and cromakalim (through the selective activation of mitochondrial K(ATP) channels), increased survival rate and exhibited antiarrhythmic and cardioprotective effects during coronary occlusion and reperfusion in anesthetized rabbits when administered prior to and during coronary occlusion. The mitochondrial K(ATP) channel may be a potential site of cardioprotection and antiarrhythmic activity.     

丙泊酚对失血性休克致兔心肌损伤Cx43表达的影响

目的 探讨丙泊酚对失血性休克兔心肌损伤缝隙连接蛋白43(Cx43)表达的影响.方法 将雄性新西兰白兔24只采用随机数字表法分为假手术(S)组、失血性休克(HS)组及丙泊酚处理(P)组.采用Wigger's改良法制作失血性休克动物模型;P组于放血前10 min注射丙泊酚5 mg/kg,并以20 mg/(kg·h)的速度持续输注至休克后120 min;S组及HS组输注等容量生理盐水.于放血前即刻(T0)、休克30 min(T1)、60 min(T2)、90 min(T3)和120 min(T4)采集动脉血.采用ELISA法测定兔血清肌钙蛋白I(cTnI)浓度;采用自动血气分析仪检测动脉血乳酸水平;采用HE染色观察心肌病理损伤;采用Western blot法检测兔心肌Cx43表达.结果 T1~T4时HS组与P组血清cTnI浓度和动脉血乳酸水平高于S组,且P组低于HS组(P<0.05);T1~T4时HS组和P组血清cTnI浓度和动脉血乳酸水平高于T0时,且逐渐升高(P<0.05).S组心肌细胞形态正常,肌纤维排列整齐,细胞核均匀一致;HS组心肌细胞肿胀,纤维排列不规则或断裂,间质内有大量炎性细胞浸润,胞核崩解;P组心肌细胞轻度变性,少量心肌纤维断裂,细胞间隙略增宽.HS组和P组心肌Cx43含量低于S组,但P组高于HS组(P<0.05).结论 丙泊酚可减轻失血性休克心肌损伤,其机制可能与上调Cx43表达有关.     

应用Albunex评估无复流时肌酸磷酸激酶同工酶和肌钙蛋白I释放动力学变化的实验研究

目的 :通过检测肌酸磷酸激酶同工酶MB(CK MB)和肌钙蛋白I(cTnI) ,了解无复流时CK MB和cTnI的变化与心肌微血管损害之间的关系 ,分析微血管损伤对CK MB和cTnI释放的影响。方法 :19只犬通过制作急性心肌缺血 再灌注动物模型 ,采用弹丸式注射声学造影剂Albunex进行心肌声学造影研究 ;测定外周循环中CK MB和cTnI在基础状态、6 0min心肌缺血 (T0 )、再灌注 6 0min时的浓度(T60 ) ,计算再灌注 6 0min时其上升斜率 (T60 -T0 6 0 )和相对增加值 (T60 -T0 T0 )。结果 :CK MB和cT nI在心肌缺血 6 0min时外周血液浓度明显高于基础状态 (P <0 .0 1) ,复流组明显高于无复流组 (P <0 .0 1) ;6 0min再灌注时CK MB和cTnI的浓度、上升斜率和相对增加值复流组仍显著高于无复流组 (P<0 .0 1和P <0 .0 0 1)。结论 :心肌微血管床的损害影响缺血再灌注心肌酶和结构蛋白的释放。     

乳化异氟醚后处理对兔在体心脏缺血/再灌注损伤的保护作用

目的观察乳化异氟醚后处理对兔在体心肌缺血/再灌注损伤的影响并探讨线粒体ATP敏感性钾通道(KATP)在其中的作用。方法76只♂新西兰白兔,建立心脏30min缺血/180min再灌注损伤模型,随机分为10组:缺血对照组(CON,n=8)、缺血后处理组(IPO,n=8)、1.0MAC吸入异氟醚后处理组(ISO,n=8)、1.0MAC乳化异氟醚后处理组(EPO,n=8)、脂肪乳组(INT,n=7)、Glibenclamide组(GLI,非选择性KATP通道阻滞剂,0.3mg.kg-1,n=7)、5-hydroxy-decanoate组(5-HD,线粒体KATP通道阻滞剂,5mg.kg-1,n=8)、0.3mg.kg-1GLI+1.0MAC EPO组(GLI+EPO,n=8)、5mg.kg-15-HD+1.0MAC EPO组(5-HD+EPO,n=7)、Dimethylsulfoxide组(DMSO,GLI的溶剂,n=7)。观察血流动力学指标,缺血区(AAR)重、梗死区(IS)重,心肌梗死面积(以IS/AAR表示),再灌注180min测定血清肌酸激酶(CK)、乳酸脱氢酶(LDH)活性。结果与CON组比较,IPO组、ISO组和EPO组IS/AAR及血清CK、LDH活性均明显降低(P<0.05);与EPO组比较,EPO+GLI组、EPO+5-HD组IS/AAR明显增加,血清CK、LDH活性明显升高(P<0.05)。结论乳化异氟醚可模拟缺血后处理减轻兔在体心肌缺血/再灌注损伤,这种心肌保护作用可能与线粒体KATP通道的激活有关。     

The role of mitochondrial K(ATP) channels in antiarrhythmic effects of ischaemic preconditioning in dogs

1. In the canine a single brief (5 min) coronary artery occlusion protects the myocardium against the severe ventricular arrhythmias and reduces the ischaemic changes that result from a subsequent, more prolonged (25 min) occlusion. The main purpose of the present study was to examine whether mitochondrial K(ATP) channels are involved in this protection. 2. In chloralose-urethane anaesthetized dogs, preconditioning (PC) was induced by a single 5 min period occlusion of the left anterior descending (LAD) coronary artery, 20 min prior to a 25 min occlusion of the same artery. In some of these PC dogs 5-hydroxydecanoate (5-HD; 150 micro g kg(-1) min(-1) by intracoronary infusion) was given over a period of 30 min either before, or after PC. In other dogs the mitochondrial K(ATP) channel opener diazoxide (1 mg kg(-1); i.c.) was given, either alone or in the presence of 5-HD. Control dogs (infused with saline) were simply subjected to a 25 min occlusion and reperfusion. 3. Compared to controls, both PC and diazoxide significantly reduced the number of ventricular premature beats (VPBs; 295+/-67 to 89+/-28 and 19+/-11, respectively; P<0.05), the number of episodes of ventricular tachycardia (VT; 8.3+/-4.2 to 1.6+/-0.9 and 0.2+/-0.1; P<0.05) and the incidences of VT (100 to 43 and 33%; P<0.05) and ventricular fibrilation (VF; 60 to 0 and 17%; P<0.05) during the 25 min occlusion of the LAD. Further, 43% of the PC dogs and 58% of the diazoxide treated dogs survived the combined ischaemia-reperfusion insult (cp. 0% in the controls; P<0.05). The protection afforded by PC and diazoxide was abolished by 5-HD, especially when it was given prior to the PC occlusion. In the presence of 5-HD, three out of 10 dogs fibrillated during the PC occlusion and another three dogs died following reperfusion. Furthermore, there were no survivors in this group from the prolonged ischaemia/reperfusion insult. 5-HD given after PC only attenuated the antiarrhythmic protection. 4. Opening of mitoK(ATP) channels prior to ischaemia by preconditioning and diazoxide protects the myocardium against ischaemia and reperfusion-induced arrhythmias. This protection is abolished if the opening of these channels is prevented by the prior administration of 5-HD but only attenuated if 5-HD is given after preconditioning. The results indicate that opening of mitoK(ATP) channels prior to ischaemia is mandatory for protection against ischaemia and reperfusion-induced arrhythmias.     

JNK通路在缺血预处理诱导海马神经元保护中的作用

目的探讨JNK通路在缺血预处理诱导海马神经元保护中的作用。方法♂蒙古沙土鼠,随机分为假手术组(SH)、缺血/再灌注组(I/R)、缺血预处理组(IP)、Anisomy-cin组(AN)、Curcumin组(CU)、Anisomycin复合IP组(AP)、Curcumin复合IP组(CP)及溶剂对照组(VE),每组据再灌注15min、2、4、6h、1、3、5及7d又分8个亚组。预定时间点行TUNEL海马CA1区凋亡细胞检测、免疫组化SP法检测p-JNK及Jun蛋白在海马CA1区的表达变化。结果IP、CU及CP可减少海马CA1区凋亡锥体细胞数(vsI/R,P<0.01),减弱CA1区再灌注各点p-JNK及Jun蛋白的表达水平(vsIR,P<0.01),该效应CP组>IP组>CU组。AN增加CA1区凋亡锥体细胞数(vsIR,P<0.01),增强CA1区再灌后1d内各点p-JNK及再灌后1～7d各点Jun蛋白表达水平(vsIR,P<0.01)。AP部分抵消IP保护效应。结论JNK通路激活参与沙土鼠海马CA1区缺血性神经元凋亡,缺血预处理可通过抑制CA1区JNK磷酸化、减少Jun蛋白表达而保护海马细胞和功能。抑制JNK通路激活可发挥缺血预处理相似的保护作用。     

The effects of isosteviol against myocardium injury induced by ischaemia-reperfusion in the isolated guinea pig heart

1. This study aimed to investigate the protective effects of isosteviol against myocardial ischaemia-reperfusion (IR) injury and its effects on mitochondrial adenosine triphosphate (ATP)-sensitive potassium channel (mitoK(ATP)) activity in vitro. 2. Groups of eight guinea pigs were treated as follows: constant perfusion control (PC), IR control, ischaemic preconditioning (IPC) + IR, isosteviol (50, 250 or 500 nmol) + IR, 5-hydroxydecanoate acid (5-HD) (5 micromol) + isosteviol (500 nmol) + IR. The guinea pig heart was isolated and perfused in Langendorff mode with modified Tyrode solution at a flow rate of 10 mL/min. Ischaemia was introduced for 30 min followed by reperfusion for 20 min. Cardiac function, coronary arterial flow rate, lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the perfusate were measured prior to ischaemia and at the end of reperfusion. 3. There were no significant (P > 0.05) changes in cardiac function or markers of cell damage (i.e. activities of LDH and CK) in the PC group. In contrast, cardiac function was adversely affected in the IR group, with significant (P < 0.05) decreases in left ventricular developing pressure (LVDevP), dP/dt(max) and dP/dt(min) compared with baseline and the PC group. In addition, there were increases in activity of LDH (20%) and CK (67%) compared with baseline and the PC group. 4. Ischaemic preconditioning and pretreatment with isosteviol, at all dose levels, resulted in a significant (P < 0.05) attenuation of IR injury. Lactate dehydrogenase and CK activities were not significantly (P < 0.05) different compared with baseline. Isosteviol did not increase coronary flow, suggesting that the protective effect of isosteviol on the myocardium was not mediated by dilation of the coronary blood vessels. 5. Pretreatment with the mitoK(ATP) blocker 5-HD partially antagonized the effects of 500 nmol isosteviol, with a statistically significant attenuation of its protective effects on HR, LVDevP, dP/dt(max) and dP/dt(min) compared with isosteviol alone pretreatment. 6. The IR injury on the Langendorff perfused guinea pig heart was alleviated by isosteviol, which appears to mediate its effects through mitoK(ATP) channels. Future research might aim to investigate the interaction of isosteviol with mitoK(ATP) channels in order to clarify its mechanism of action.