缺血后处理和三磷酸腺苷后处理对心肌缺血再灌注损伤的影响

目的观察缺血后处理(IPO)、ATP和腺苷受体激动剂CGS-21680后处理对心肌缺血再灌注损伤的影响。方法健康新西兰大白兔48只,随机分为对照组、IPO组、ATP组、CGS-21680组,每组12只。测定肌酸激酶同工酶(CK-MB)、丙二醛水平及超氧化物歧化酶(SOD)活力;计算各组兔心肌梗死面积;HE染色观察心肌组织病理形态变化;TUNEL法检测心肌细胞凋亡;实时荧光定量RT-PCR检测心肌组织天冬氨酸特异性半胱氨酸蛋白酶3(caspase-3)mR NA和Bcl-2 mRNA的表达。结果与对照组比较,IPO组、ATP组和CGS21680组血清丙二醛、CK-MB水平及心肌梗死面积明显降低,SOD活力明显升高。IPO组、ATP组和CGS-21680组心肌细胞凋亡指数较对照组明显降低,心肌组织损伤明显减轻。IPO组、ATP组和CGS-21680组较对照组caspase-3 mRNA表达明显下调,Bcl-2 mRNA表达明显上调。结论 IPO与ATP后处理可通过激活腺苷A2a受体,减轻心肌缺血再灌注损伤,其机制可能与上调Bcl-2和下调caspase-3的表达,抑制氧自由基氧化应激损伤,减少细胞凋亡有关。     

瑞舒伐他汀对急性心肌梗死大鼠血清CRP、TNF-α、IL-6及组织中caspase-3基因表达的影响

目的探讨瑞舒伐他汀对急性心肌梗死(AMI)大鼠血清C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)及组织中caspase-3基因表达的影响。方法 40只雄性清洁级健康SD大鼠,随机选择10只纳入假手术组(Sham组),另30只以前降支结扎法构建大鼠AMI模型,建模成功后将术后24 h内存活的21只大鼠随机分为模型组(Model组,10只)、瑞舒伐他汀组(11只)。术后Sham、Model组予以1 mg/kg·d生理盐水灌胃处理,瑞舒伐他汀组予以1 mg/kg·d瑞舒伐他汀灌胃处理。4周后,采用酶联免疫吸附法检测3组大鼠血清CRP、TNF-α、IL-6水平,采用免疫组化SP法检测caspase-3基因蛋白阳性水平,采用逆转录-聚合酶链反应(RT-PCR)法检测caspase-3基因mRNA表达情况。结果 Model组、瑞舒伐他汀组大鼠血清CRP、TNF-α、IL-6水平及心肌组织caspase-3蛋白阳性指数、mRNA表达水平均高于Sham组大鼠,而瑞舒伐他汀组大鼠血清CRP、TNF-α、IL-6水平及心肌组织caspase-3蛋白阳性指数、mRNA表达水平均低于Model组大鼠,差异均具有统计学意义(P均0.05)。结论瑞舒伐他汀可明显降低急性心肌梗死大鼠血清CRP、TNF-α、IL-6水平,抑制心肌纤维化,下调心肌组织中caspase-3基因表达,从而抑制心肌细胞凋亡,改善大鼠心肌功能。     

亚精胺对心肌梗死大鼠心肌线粒体功能及细胞凋亡的影响

目的:探讨亚精胺对心肌梗死大鼠心肌线粒体功能及细胞凋亡的影响。方法:选取健康SD大鼠32只,随机分为假手术组、模型组、模型+阿司匹林组、模型+亚精胺组,每组8只,利用在体结扎冠状动脉前降支法建立急性心肌梗死模型。造模成功后假手术组和模型组给予无菌生理盐水(2 mL)灌胃,模型+阿司匹林组以等体积阿司匹林(20 mg/kg)灌胃,模型+亚精胺组以等体积亚精胺(5 mmol/L)灌胃,连续4周。TTC染色、HE染色观察心肌组织梗死面积和病理学改变;透射电镜观察心肌线粒体形态;原位缺口末端标记(TUNEL)法检测心肌组织细胞凋亡水平;实时荧光定量PCR(qRT-PCR)检测Bax、Bcl-2、胱天蛋白酶-3(caspase-3)的mRNA表达水平;Western blot检测Bcl-2、Bax、caspase-3、细胞色素C(cytochrome C)的蛋白表达水平。结果:与假手术组比较,模型组大鼠心肌组织梗死区面积增加,心肌组织细胞凋亡明显增加,心肌组织Bax、caspase-3、cytochrome C表达水平明显升高,Bcl-2表达水平明显降低(P均<0.01);与模型组比较,模型+亚精胺组大鼠心肌组织梗死区面积减少,心肌组织细胞凋亡及Bax、caspase-3、cytochrome C表达水平均明显减少(P<均0.05);与模型+阿司匹林组比较,模型+亚精胺组心肌组织细胞凋亡明显降低(P<0.01),两组心肌组织Bax、caspase-3、Bcl-2、cytochrome C表达水平的差异无统计学意义。结论:亚精胺可改善心肌线粒体功能,抑制细胞凋亡,改善心肌梗死。     

芎归六君子汤对心肌梗死大鼠G-CSF含量和VEGF、bFGF表达的影响

目的探讨芎归六君子汤对心肌梗死大鼠粒细胞集落刺激因子(G-CSF)含量、血管内皮生长因子(VEGF)和碱性成纤维细胞生长因子(bFGF)表达的影响。方法将大鼠随机分为假手术组、模型组、消心痛组、复方丹参滴丸组和芎归六君子汤组。采用左冠状动脉前降支结扎法复制心肌梗死模型,假手术组只穿线不结扎。造模结束后,分别给予生理盐水及对应药物灌胃,1次/d,连续28 d。下腔静脉取血,检测外周血G-CSF含量;取梗死边缘心肌,测定VEGF和bFGF蛋白和基因表达。结果各给药组血清G-CSF含量升高,心肌梗死边缘VEGF、bFGF蛋白和基因表达增强,与模型组相比差异显著,且芎归六君子汤组上述指标优于复方丹参滴丸和消心痛组(P0.01)。结论芎归六君子汤能够通过提高G-CSF含量、改善VEGF和bFGF表达,促进梗死心肌微血管再生,提示从脾胃论治心肌梗死具有重要应用价值。     

水飞蓟宾对大鼠心肌缺血再灌注损伤后心肌细胞凋亡的影响

目的研究水飞蓟宾(Silibinin,SIL)对大鼠心肌缺血再灌注损伤后心肌细胞凋亡的影响及其机制。方法取100只实验用大鼠随机分为假手术组,模型组和SIL低(100mg/(kg·d))、中(200mg/[kg·d))、高(400mg/(kg·d))剂量预处理组(n=20),术前7d开始灌胃给药;采用结扎冠状动脉30min的方法建立大鼠心肌缺血再灌注损伤模型;再灌注6h后,通过高分辨率超声影像系统检测舒张末期左室内径(IVIDd)和收缩末期左室内径(LVIDs)、短轴缩短率(FS)、射血分数(EF)、每搏输出量(SV);TTC染色法计算心肌梗死面积,TUNEL法观察心肌细胞凋亡状况,RT-PCR法测定心肌组织bcl-2 mRNA、Bax mRNA表达,Western blotting法测定心肌组织caspase-3、NF-kB蛋白表达;比色法测定心肌组织中抗氧化酶活性和丙二醛(MDA)含量。结果与模型组比较,发现经SIL中、高剂量预处理能够显著降低急性心肌梗死大鼠LVIDd并显著提高FS、EF和SV,其中SIL高剂量预处理组LVIDs显著降低;显著降低心肌组织梗死面积,明显改善心肌细胞凋亡状况、显著降低心肌细胞凋亡指数(Apoptosis index,AI),显著上调bcl-2 mRNA表达并下调Bax mRNA表达、显著提高‘bcl-2/Bax比值,显著降低caspase-3、NF-kB蛋白表达量,显著提高抗氧化酶(SOD、CAT)活性并显著降低MDA含量,差异均具有统计学意义(P0.05,P0.01)。结论SIL具有抑制心肌缺血再灌注损伤大鼠心肌细胞凋亡的作用,其机制可能与SIL改善心功能、调节凋亡相关基因和蛋白表达以及抑制氧化应激损伤有关。     

灯盏花素对缺血再灌注大鼠心肌Caspase-9蛋白及mRNA表达的影响

目的观察灯盏花素(Bre)对缺血再灌注(IR)大鼠心肌Caspase-9蛋白及mRNA表达的影响。方法 40只SD大鼠随机分为假手术组、模型组、BreⅠ组(25 mg.kg-1.d-1腹腔注射,7 d)和BreⅡ组(50 mg.kg-1.d-1腹腔注射,连续7 d)。采用结扎大鼠左冠状动脉前降支方法制备心肌IR模型。应用TTC染色的方法检测各组大鼠心肌梗死面积,western印迹技术检测大鼠心肌组织Caspase-9蛋白表达的变化,RT-PCR技术检测大鼠心肌组织Caspase-9 mRNA表达的变化。结果与假手术组比较,模型组大鼠心肌梗死面积明显增加(P<0.01),Bre明显改善了IR大鼠心肌梗死面积,BreⅡ组比BreⅠ组心肌梗死面积小(P<0.05);模型组大鼠的Caspase-9蛋白及mRNA表达水平较假手术组明显增加(P<0.01),Bre组大鼠心肌的Caspase-9蛋白及mRNA表达水平较模型组明显减少(P<0.01)且BreⅡ组大鼠心肌的Caspase-9蛋白及mRNA表达水平比BreⅠ组减少(P<0.05)。结论 Bre可以减轻IR大鼠心肌梗死面积,其机制可能与减少大鼠心肌的Caspase-9蛋白及mRNA表达有关。Bre对IR损伤心肌的保护作用呈剂量依赖性。     

Caspase-3在慢性心力衰竭大鼠心肌重塑中动态表达及意义

目的 探讨慢性心力衰竭大鼠心肌内半胱氨酸天冬氨酸蛋白酶3(caspase-3)表达及意义.方法 40只雄性Wistar大鼠随机分为四组,假手术组、心力衰竭1 d组、7 d组、14 d组各10只.以缩窄大鼠腹主动脉,造成左心室压力负荷,制备慢性心力衰竭大鼠模型.观察和比较成模后1 d、7 d、14 d及假手术组左心室肌重量指数,Masson染色后对比心肌胶原含量,免疫组化法测定心肌中caspase-3蛋白表达水平.结果 腹主动脉缩窄术后各组大鼠均发生左室重塑和纤维化,左心室肌重量指数、胶原含量及caspase-3蛋白表达均明显高于假手术组;caspase-3于正常心肌内表达较少,而在心力衰竭后心肌内表达则明显增多,且随着心力衰竭程度的加重而表达增多.结论 caspase-3可能参与了大鼠压力负荷性心肌重塑的发生和发展,其水平的高低与慢性心力衰竭的严重程度密切相关.     

Caspase-3在慢性心力衰竭大鼠心肌重塑中动态表达及意义

目的探讨慢性心力衰竭大鼠心肌内半胱氨酸天冬氨酸蛋白酶3（caspase-3）表达及意义。方法40只雄性Wistar大鼠随机分为四组,假手术组、心力衰竭1d组、7d组、14d组各10只。以缩窄大鼠腹主动脉,造成左心室压力负荷,制备慢性心力衰竭大鼠模型。观察和比较成模后1d、7d、14d及假手术组左心室肌重量指数,Masson染色后对比心肌胶原含量,免疫组化法测定心肌中caspase-3蛋白表达水平。结果腹主动脉缩窄术后各组大鼠均发生左室重塑和纤维化,左心室肌重量指数、胶原含量及caspase-3蛋白表达均明显高于假手术组;caspase-3于正常心肌内表达较少,而在心力衰竭后心肌内表达则明显增多,且随着心力衰竭程度的加重而表达增多。结论caspase-3可能参与了大鼠压力负荷性心肌重塑的发生和发展,其水平的高低与慢性心力衰竭的严重程度密切相关。     

极端冷环境对急性心肌梗死大鼠心肌凋亡的影响

目的探讨极端冷环境对急性心肌梗死大鼠心肌凋亡的影响。方法 40只雄性SD大鼠分为假手术常温组(NN组,n=10,26℃),假手术寒冷组(NC组,n=10,4℃),心梗后常温组(GN组,n=10,26℃),心梗后寒冷组(GC组,n=10,4℃),分别处理4天后各组大鼠经彩超检测心脏收缩舒张功能,并留取心肌标本测心梗面积,HE染色显示心肌形态改变,免疫组化检测凋亡相关蛋白Bim的表达,western blot检测Bim,caspase-3的表达。结果 (1)NN组与NC组心脏彩超各指标无明显差异,P>0.05,GC组射血分数(0.594±0.042)及短轴缩短率(0.265±0.029)明显低于GN组(0.663±0.045,0.337±0.0.046),P<0.01,GC组左室收缩末径(0.486±0.029)及舒张末径(0.772±0.033)明显大于GN组(0.391±0.022,0.648±0.039),P<0.01。(2)GN组心肌HE染色可见纤维组织增生,炎症细胞浸润,细胞边界不清,GC组心肌病理改变较GN组严重。(3)NN组与NC组Bim、caspase-3的表达无明显差异,P>0.05,GC组Bim、caspase-3表达(0.180±0.016,0.613±0.103)显著高于GN组(0.130±0.003,0.338±0.027),P<0.01。结论极端冷环境增加急性心梗大鼠的心肌凋亡,恶化心功能。     

缺血后处理对心肌缺血再灌注损伤大鼠内质网应激相关蛋白葡萄糖调节蛋白78及半胱氨酸天冬氨酸蛋白酶-12的影响

目的探讨心肌缺血再灌注损伤大鼠使用缺血后处理对内质网应激相关蛋白葡萄糖调节蛋白(GRP)78及半胱氨酸天冬氨酸蛋白酶(caspase)-12表达的影响。方法将30只雄性Wistar大鼠随机分为A组(空白对照组)、B组(心肌缺血再灌注损伤组)、C组(心肌缺血后处理组),每组10只,分别进行假手术、心肌缺血再灌注损伤及心肌缺血后处理操作,分析3组大鼠心肌的缺血面积及梗死面积百分比,对比心肌内质网应激相关蛋白GRP78及caspase-12的表达,并对3组大鼠的神经行为进行评估。结果 A组大鼠心肌组织无缺血及梗死病灶,C组大鼠心肌组织的缺血面积及梗死面积百分比均显著低于B组,差异有统计学意义(P0.05);A组相应部位心肌组织GRP78及caspase-12蛋白表达均显著低于B组及C组,C组caspase-12蛋白表达显著低于B组,而GRP78蛋白表达高于B组,差异均有统计学意义(均P0.05);神经行为学评估结果显示3组各项神经运动功能量化数值之间比较差异无统计学意义(P0.05)。结论大鼠心肌缺血再灌注损伤使用缺血后处理能够抑制心肌细胞的凋亡,同时能够增加内质网的应激反应,其与心肌细胞凋亡减少及心肌梗死面积减少相关。     

阿托伐他汀对心肌缺血复合冷应激大鼠左室心肌组织中Bim、Caspase-3蛋白表达的影响

目的研究阿托伐他汀对心肌缺血复合冷应激大鼠左室心肌组织中Bim和Caspase-3表达的影响。方法 42只雄性SD大鼠随机分为:心肌缺血组、心肌缺血复合冷应激组、阿托伐他汀组。以永久性左冠状动脉前降支结扎术+4℃冷刺激(8 h/d,4 d)建立心肌缺血复合冷应激模型。阿托伐他汀组复合应激前3 d及后4 d给以阿托伐他汀灌胃(20 mg.kg-1.d-1)。实验结束时观察血脂水平,超声心动图评价左室收缩功能,TTC染色法测定心肌梗死面积,Western印迹法检测心肌组织Bim、Caspase-3蛋白表达。结果各组大鼠血脂指标无统计学差异。心肌缺血复合冷应激使梗死面积增大(P<0.01)、左室收缩功能降低;阿托伐他汀干预后心功能改善、梗死面积缩小(P<0.01),Bim、Caspase-3表达下降(P<0.01)。结论阿托伐他汀改善心肌缺血复合冷应激大鼠左室收缩功能,其机制可能通过下调Bim、Caspase-3表达实现。     

浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用

目的:探究浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用。方法:共15只SD大鼠随机分为心肌缺血-再灌注损伤合并脓毒症浅低温(MHT)组、心肌缺血-再灌注损伤合并脓毒症常温(NT)组和假手术常温组作为对照组。大鼠心肌缺血后再灌注同时给予内毒素,然后MHT组将大鼠置于冰床降温,15 min内达(33.0±0.5)℃,随后维持2 h。NT组及对照组实验全程维持在(37.0±0.5)℃。实验全程观察和记录血流动力学指标。浅低温或常温维持2 h后用酶联免疫吸附测定法检测血乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK-MB),观察心肌梗死面积、病理学变化,免疫印迹法检测心肌烟酰胺腺嘌呤二核苷酸磷酸氧化酶2(NOX2),免疫组化检测心肌胱天蛋白酶-3(caspase-3)和肿瘤坏死因子-α(TNF-α)。结果:MHT组再灌注2 h心率较NT组降低[(396.63±39.93)次/min vs(.457.74±32.77)次/min,P<0.05];左心室最大收缩压升高[(129.14±34.05)mmHg vs.(85.63±14.74)mmHg,1 mmHg=0.133 kPa,P<0.05]。MHT组收缩期压力最大变化速率(+max dp/dt)、左心室舒张末期压力(LVEDp)和舒张期压力最小变化速率(-min dp/dt)再灌注2 h较NT组绝对值也有所增加,且均高于对照组,但差异无统计学意义。MHT组的LDH和CK-MB均较NT组显著降低[(1153.61±127.85)U/L vs(.2213.34±599.60)U/L,P<0.05;(1103.22±114.75)U/L vs(.1731.33±688.05)U/L,P<0.05]。心肌病理变化提示MHT组心肌坏死呈点状或灶状,心肌间质淤血程度轻且炎细胞浸润较少。NT组心肌出现水肿、灶状或片状坏死,心肌间质区淤血程度重及存在大量炎细胞浸润。此外,MHT组的心肌梗死面积比率明显小于NT组[(11.23±2.82)%vs.(19.25±4.45)%,P<0.05]。免疫印迹法显示,NOX2在MHT组中相对表达量较NT组减少,但差异无统计学意义(P>0.05)。MHT组的caspase-3相对表达量及TNF-α相对表达量均较NT组显著降低[(1.06±0.34)%vs.(3.27±0.67)%;(12.23±3.31)%vs(.31.14±1.69)%],差异均有统计学意义(P均<0.05)。结论:浅低温对心肌缺血-再灌注损伤合并脓毒症有心脏保护作用,可改善心功能,减少心肌梗死面积,减轻心肌损伤、炎症、氧化应激及凋亡。     

Granulocyte Colony-Stimulating Factor Mediates Cardioprotection Against Ischemia/Reperfusion Injury via Phosphatidylinositol-3-Kinase/Akt Pathway in Canine Hearts

Purpose Recent studies suggest that G-CSF prevents cardiac remodeling following myocardial infarction (MI) likely through regeneration of the myocardium and coronary vessels. However, it remains unclear whether G-CSF administered at the onset of reperfusion prevents ischemia/reperfusion injury in the acute phase. We investigated acute effects of G-CSF on myocardial infarct size and the incidence of lethal arrhythmia and evaluated the involvement of the phosphatidylinositol-3 kinase (PI3K) in the in vivo canine models. Methods In open-chest dogs, left anterior descending coronary artery (LAD) was occluded for 90 minutes followed by 6 hours of reperfusion. We intravenously administered G-CSF (0.33 μ/kg/min) for 30 minutes from the onset of reperfusion. Wortmannin, a PI3K inhibitor, was selectively administered into the LAD after the onset of reperfusion. Results G-CSF significantly (p<0.05) reduced myocardial infarct size (38.7±4.3% to 15.7±5.3%) and the incidence of ventricular fibrillation during reperfusion periods (50% to 0%) compared with the control. G-CSF enhanced Akt phospholylation in ischemic canine myocardium. Wortmannin blunted both the infarct size-limiting and anti-arrhythmic effects of G-CSF. G-CSF did not change myeloperoxidase activity, a marker of neutrophil accumulation, in the infarcted myocardium. Conclusion An intravenous administration of G-CSF at the onset of reperfusion attenuates ischemia/reperfusion injury through PI3K/Akt pathway in the in vivo model. G-CSF administration can be a promising candidate for the adjunctive therapy for patients with acute myocardial infarction. Takahama and Hirata contributed equally to this work.     

Temporal and spatial development of myocardial infarcts in porcine hearts without significant collateral blood flow

To evaluate the time-dependent beneficial effect of reperfusion on infarct size, we investigated the temporal and spatial development of infarcts in porcine hearts. The left anterior descending coronary artery was occluded in 17 pigs for different periods of time. Ischemia was always followed by 4 hours of reperfusion. After 60 minutes of ischemia, transmural needle biopsies subdivided into subendocardial and subepicardial halves were removed from the ischemic apex to determine the tissue concentrations of adenosine triphosphate and nicotinamide adenine dinucleotide. The myocardium at risk was determined with a fluorescent dye, and the infarcted tissue with nitroblue tetrazolium stain. Infarct size was expressed as the ratio of the infarcted myocardium over the risk region. Ischemic cell death began in the jeopardized left ventricular subendocardial septum after about 30 minutes of ischemia. Further progress involved the right subendocardial septum and the subendocardium of the left anterior free wall. After 75 minutes of ischemia, most of the myocytes were already irreversibly injured. Tissue damage from the infarctions was complete after 90 to 120 minutes of ischemia. These results indicate that in hearts without a significant collateral blood flow, reperfusion can only reduce infarct size if initiated within 60 to 75 minutes of ischemia. As in canine hearts, infarctions in porcine hearts progress from the ischemic subendocardium toward the outer layers.     

腺苷A_1受体激动剂R-苯异丙基腺苷介导的大鼠心肌延迟预适应

目的　研究腺苷A1受体激动剂R 苯异丙基腺苷 (R PIA)能否介导大鼠心脏产生延迟预适应。方法　取雄性Wistar大鼠 48只 ,随机分为 3组。A组 :生理盐水 0 .2ml/只 ;B组 :R PIA 0 .0 3mg/kg ;C组 :R PIA 0 .0 3mg/kg +DPCPX 0 .2mg/kg。大鼠经皮下注射给药后 2 4h开胸 ,结扎左冠状动脉前降支 30min、再灌注 12 0min ,摘取心脏 ,用于梗死范围测定 (TTC染色法 )、原位心肌细胞凋亡 (TUNEL法 )检测。结果　大鼠体重及左室重量组间差别无显著性 (P >0 .0 5 )。R PIA组心肌梗死范围显著低于生理盐水组及R PIA +DPCPX组 (P均 <0 .0 1) ,而生理盐水组与R PIA +DPCPX组比较差异无显著性意义 (P >0 .0 5 )。生理盐水组、R PIA组及R PIA +DPCPX组心肌凋亡细胞计数 (个 /高倍视野 )组间差异无显著性意义 (P >0 .0 5 )。结论　R PIA可使大鼠在体心脏产生延迟预适应 (显著降低心肌梗死范围 ) ;R PIA对 2 4h后缺血再灌注损伤所致的心肌细胞凋亡可能无影响。     

Myocardial bioenergetic abnormalities in a canine model of left ventricular dysfunction

Objectives. The purpose of this study was to assess high energy phosphate compound metabolism in remodeled left ventricular myocardium.Background. The development of heart failure several years after myocardial infarction is often unexplained. Certain abnormalities of remodeled myocardium suggest that structural changes occurring in viable myocardium after discrete myocardial damage may contribute to the later appearance of heart failure. Whether these abnormalities alter metabolism in the surviving muscle and thereby possibly contribute to ventricular dysfunction is unknown.Methods. High energy phosphate compound metabolism was assessed using spatially localized phosphorus-31 nuclear magnetic resonance spectroscopy. Eleven dogs with documented left ventricular dysfunction, resulting from infarction produced by transmyocardial direct current shock, were compared with eight normal dogs. Analyses were performed at baseline and during coronary hyperperfusion induced by intravenous adenosine. Myocardial blood flow was measured with radioactive microspheres.Results. The creatine phosphate/adenosine triphosphate (CP/ATP) ratio was significantly reduced in the left ventricular dysfunction group in both the subepicardium ([mean ± SE] 1.94 ± 0.08 vs. 2.32 ± 0.13, p = 0.019) and the subendocardium (1.71 ± 0.07 vs. 2.05 ± 0.07, p = 0.004). Intravenous adenosine produced significant coronary hyperemia in both groups but was less marked in dogs with left ventricular dysfunction. The improvement in myocardial perfusion was accompanied by a significant increase in the subendocardial CP/ATP ratio (from 1.71 ± 0.07 to 1.92 ± 0.08, p = 0.01) in dogs with left ventricular dysfunction.Conclusions. An abnormal transmural distribution of high energy phosphate compounds is evident in remodeled myocardium. This abnormality may be related in part to mismatch of oxygen delivery and demand.     

Failure of iloprost to protect the regionally ischemic, reperfused porcine heart.

The effect of iloprost (Schering AG, Berlin), a stable prostacyclin analogue, was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery (LAD) was distally occluded in 18 pigs for 45 min followed by 3-d of reperfusion. Nine pigs were continuously treated with iloprost at a dose of 25 ng/kg per min. Treatment was started as intracoronary infusion into the proximal LAD 10 min before occlusion. The intercoronary infusion was replaced by an intravenous infusion after 45 min of reperfusion, which was continued until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Myocardial concentrations of adenosine triphosphate were evaluated at the end of the experiment. Generation of free radicals by stimulated polymorphonuclear neutrophils was determined by luminol-enhanced chemiluminescence. Histologic and immunohistologic techniques were applied to characterize the myocardial inflammatory response. Global hemodynamics did not differ between the two groups. Neither infarct size (control group 68 +/- 18%, treated group 74 +/- 14%), recovery of systolic shortening (control group 3 +/- 6%, treated group 6 +/- 6%), nor myocardial adenosine triphosphate concentrations were improved by iloprost treatment. Myocardial inflammatory response remained unaffected by this treatment. The capacity of coronary venous, stimulated polymorphonuclear neutrophils to generate free radicals was slightly suppressed in the treated group before ischemia, at the end of ischemia and during early reperfusion. In this preparation, iloprost did not exhibit any beneficial effect on infarct size, recovery of systolic shortening and myocardial adenosine triphosphate concentrations.     

AMPK抑制剂P5499拮抗无钙预处理心肌保护作用

目的:观察腺苷酸活化的蛋白激酶(AMPK)抑制剂P5499对短暂无钙预处理心肌保护作用的影响。方法:对健康SD雄性大鼠心脏行Langendorff离体灌流,实验全程记录心脏冠脉流量(CF)、左心室内压(LVP)、左室舒张末压(LVEDP)、室内压最大变化速率(±dp/dtmax)及心率(HR),并计算左室发展压(LVDP)和心率-压力乘积(RPP)评价心功能的变化。再灌注结束后,采用2、3、5-氯化三苯基四氮唑(TTC)染色法评价心肌梗死(MI)面积的变化。结果:缺血/再灌注(I/R)后,心功能显著降低,CF明显减少(P<0.01),MI面积的比率为(39.6±1.49)%。短暂无钙预处理(CPC)可使LVEDP明显降低(P<0.05),CF、LVDP、±dp/dtmax及RPP均明显改善(P<0.01),MI面积显著缩小(P<0.01)。缺血前单独给予P5499对心功能、CF及MI面积无明显影响,但其可显著逆转CPC的心肌保护作用(P<0.01)。结论:AMPK可能是Ca2+预处理产生心肌保护信号的下游分子。     

Measurement of myocardial infarction fraction using single photon emission computed tomography

Although infarct size correlates generally with prognosis after acute myocardial infarction, an absolute measure of infarct size may have differing prognostic significance depending on absolute left ventricular mass. To test the hypothesis that single photon emission computed tomography can accurately measure myocardial infarct size as a percent of total left ventricular mass ("infarction fraction"), thallium-201 and technetium-99m pyrophosphate tomograms were acquired in 21 dogs 24 to 48 hours after fixed occlusion of the left anterior descending or circumflex coronary artery. Pathologic infarct weight was measured as the myocardial mass that showed no staining with triphenyltetrazolium chloride. Scintigraphic infarct mass by technetium-99m pyrophosphate was calculated from the total number of left ventricular volume elements (voxels) demonstrating technetium-99m pyrophosphate uptake X voxel dimension [( 0.476 cm]3) X specific gravity of myocardium (1.05 g/cm3). Scintigraphic left ventricular mass was calculated in a similar fashion using an overlay of the thallium-201 and technetium-99m pyrophosphate scans. The "infarction fraction" was calculated as: infarction fraction = infarct mass/left ventricular mass. There was good correlation between single photon emission computed tomography and pathologic measurements of infarct mass (technetium-99m pyrophosphate mass = 1.01 X pathologic infarct mass + 0.96; r = 0.98), left ventricular mass (single photon emission computed tomographic left ventricular mass = 0.60 X pathologic left ventricular mass + 37.4; r = 0.86) and "infarction fraction" (single photon emission computed tomographic infarction fraction = 1.09 X pathologic infarction fraction - 1.7; r = 0.94).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mobilization of Mesenchymal Stem Cells by Granulocyte Colony-stimulating Factor in Rats with Acute Myocardial Infarction

PURPOSE: Intravenous delivery of mesenchymal stem cells (MSCs), a noninvasive strategy for myocardial repair after acute myocardial infarction (MI), is limited by the low percentage of MSCs migration to the heart. The purpose of this study was to test whether granulocyte colony-stimulating factor (G-CSF) would enhance the colonization of intravenously infused MSCs in damaged heart in a rat model of acute MI. METHODS: After induction of anterior MI, Sprague-Dawley rats were randomized to receive: (1) saline (n = 9); (2) MSCs (n = 15); and (3) MSCs plus G-CSF (50 mug/kg/day for 5 consecutive days, n = 13). RESULTS: Flow cytometry revealed that G-CSF slightly increased surface CXCR4 expression on MSCs in vitro. After completion of G-CSF administration, MSCs showed a significantly lower colonization in bone marrow and a trend toward higher localization in the infarcted myocardium. At 3 months, vessel density in the infarct region of heart was significantly increased in MSCs group and trended to increase in MSCs + G-CSF group. However, echocardiographic and hemodynamic parameters, including left ventricular (LV) end-diastolic diameters, ejection fraction, and +/-dP/dt (max), were not statistically different. Morphological analysis showed that infarct size and collagen content were similar in the three groups. Immunohistochemistry revealed that the combined therapy accelerated endothelial recovery of the blood vessels in the ischemic myocardium. However, myocardial regeneration resulting from MSCs differentiation was not observed. CONCLUSIONS: G-CSF enhanced the migration of systemically delivered MSCs from bone marrow to infarcted heart. However, the beneficial effect of this kind of migration is limited, as cardiac function did not improve.