心肌肥大时细胞核被膜核苷三磷酸酶活性及mRNA出核转运的 …

目的：探讨心肌肥大时心肌细胞ｍＲＮＡ出核转运率及被膜核苷三磷酸酶活性的变化。方法：采用腹主动脉缩窄法复制大鼠心肌肥大模型,密度梯度离心肌细胞核被膜,观察心肌肥大时对心肌ＮＴＰａｓｅ活性和成熟ｍＲＮＡ出核转运速率的影响。结果：早,晚期肥大心肌细胞核被膜ＮＴＰａｓｅ最大反应速率以ＡＴＰ为底物时较对照组增加２５％－６２％,以ＧＴＰ为底物时增加８％－４４％,其中晚期肥大组ＮＴＰａｓｅ最大反应速率增加幅度低     

异丙肾上腺素致大鼠心肌坏死时心肌细胞核钙转运功能的变化

目的：观察ＩＳＯ心肌坏死时大鼠心肌细胞核钙转运系统的改变。方法：大鼠心肌坏死模型采用皮下注射ＩＳＯ制备,心肌细胞核采用差速离心和密度梯度离心分离纯化,用酶学方法鉴定核的纯度及测定ＡＴＰａｓｅ活性,用４５Ｃａ２＋同位素法测定核钙摄取。结果：与对照组相比,ＩＳＯ坏死心脏组织呈显著的损伤和坏死,心系数增加３５％（Ｐ＜０．０１）,心肌组织ＭＤＡ和钙含量分别增加５７％和８０％（Ｐ＜０．０１）。与对照组相比,ＩＳＯ心肌坏死细胞核Ｃａ－ＡＴＰａｓｅ的［Ｃａ２＋］反应Ｖｍａｘ降低２７．５％（Ｐ＜０．０１）,Ｋａ无显著变化;对［ＡＴＰ］反应的Ｖｍａｘ无显著变化,而Ｋｍ增加６１．７％（Ｐ＜０．０５）;ＩＳＯ组４５Ｃａ２＋摄取显著降低（Ｐ＜０．０１）,Ｖｍａｘ与对照组相比降低４６．１％（Ｐ＜０．０１）,Ｋｍ无显著变化。结论：坏死心肌细胞核钙转运系统功能显著降低,可能与心肌坏死时细胞核功能紊乱有关     

预缺氧对急性缺氧大鼠心肌线粒体功能及ATP含量的影响

目的：观察预缺氧对急性缺氧大鼠心肌线粒体功能及ＡＴＰ含量的影响。方法：实验大鼠分三组。１常氧对照组;２急性缺氧组;３预缺氧组。测定了心肌ＡＴＰ含量及线粒体呼吸功能,以荧光偏振法测定线粒体膜流动性。结果：经预缺氧处理的大鼠遭受急性缺氧后ＡＴＰ含量从（３１８±２４２）ｍｇ１·ｇ－１增加到（６０５５±３．５２）ｍｇ－１·ｇ－１（Ｐ＜００１）;线粒体呼吸控制率（ＲＣＲ）从１８４±０５８上升到４５５±０３２（Ｐ＜００１）;线粒体膜流动性（ＭＭＦ）明显增加（Ｐ＜００５）,Ｆ０Ｆ１－ＡＴＰ酶及Ｎａ＋－Ｋ＋－ＡＴＰ酶活性分别提高６６％和２５％。结论：预缺氧可有效改善缺氧大鼠心肌能量代谢,其作用环节可能和提高线粒体膜流动性,改善线粒体呼吸功能有关。     

穿心莲提取液减轻心肌缺血－再灌注过程中钙超负荷的机制探讨

本文采用整体犬急性心肌缺血－再灌注模型以探讨穿心莲提取液减轻钙超负荷的机制。结扎冠脉左前降支上１／３处９０ｍｉｎ后再灌注６０ｍｉｎ较持续结扎１５０ｍｉｎ，缺血中心区心肌细胞内Ｃａ２＋增加（Ｐ＜０．０５）、Ｎａ＋明显增加（Ｐ＜０．０１），心肌细胞膜Ｃａ２＋－ＡＴＰａｓｅ活性明显降低（Ｐ＜０．０１），心肌组织ＭＤＡ含量显著增高（Ｐ＜０．０１）。而在再灌注前４５ｍｉｎ静脉给予穿心莲提取液，则见其缺血中心区心肌细胞内Ｃａ２＋降低（Ｐ＜０．０５）、Ｎａ＋明显降低（Ｐ＜０．０１），心肌细胞膜Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ、Ｃａ２＋－ＡＴＰａｓｅ活性明显增加（Ｐ＜０．０１）。心肌组织ＭＤＡ含量显著降低（Ｐ＜０．０１）。说明穿心莲提取液减轻心肌缺血－再灌注过程中钙超负荷与减轻氧自由基危害、保护心肌细胞膜ＡＴＰａｓｅ活性、降低钠超负荷有关。     

地奥心血康对心肌缺血再灌犬心肌细胞膜Na~＋，K~＋—ATP酶活性与LPO含量

１６只成年杂种犬复制心肌缺血再灌模型。分为地奥心血康治疗组（ＤＡＸＸＫＧ）和生理盐水对照组（ＮＳＣＧ）。差速离心分离心肌细胞质膜，无机磷法测定心肌细胞膜Ｎａ￣＋，Ｋ￣＋－ＡＴＰ酶活性，荧光法测定心肌细胞膜与血清脂质过氧化物（ＬＰＯ）含量。结果表明：（１）ＤＡＸＸＫＧＮａ￣＋，Ｋ￣＋－ＡＴＰ酶活性明显高于ＮＳＣＧ（Ｐ＜０．０１）；（２）血清ＬＰＯ含量，随着再灌时间延长，ＮＳＣＧ呈上升趋势，ＤＡＸＸＫＧ略下降，再灌２４０ｍｉｎ两组比较差异显著（Ｐ＜０．０１）；心肌细胞膜ＬＰＯ含量，ＤＡＸＸＫＧ低于ＮＳＣＧ（Ｐ＜０．０５）；（３）心肌细胞膜Ｎａ￣＋，Ｋ￣＋－ＡＴＰ酶活性与ＬＰＯ含量呈明显负相关（ｒ＝－０．８３，Ｐ＜０．０１）。这些结果提示ＤＡＸＸＫ可通过抗脂质过氧化而实现其保护心肌细胞膜的效应。     

钙超载大鼠心肌细胞核钙转运功能的改变

目的：观察钙超载对大鼠心肌细胞核钙转运系统的影响。方法：大鼠心肌钙超模型采用腹腔注射ＶｉｔＤ３制备,心肌细胞核采用差束离心和密度梯度离心分离纯化,用酶的纯度及测定ＡＴＰａｓｅ活性,用＾４５Ｃａ＾２＋测定核钙摄取。结果：钙超载大鼠心肌钙含量与对照组相经增加４２％,核钙含量增加５５％,钙超载大鼠心肌细胞核Ｃａ－ＡＴＰａｓｅ活性降低,其Ｖｍａｘ降低２４％,Ｋｍ无显著改变;「＾４５Ｃａ＾２＋」摄取也无显著     

糖尿病大鼠心肌MDA含量、SOD和Na￣ -K￣ -ATP酶活性的变化

实验用四氧嘧啶破坏Ｗｉｓｔａｒ大鼠胰腺诱发糖尿病模型，观察糖尿病人鼠心肌组织ＭＤＡ含量，ＳＯＤ和Ｎａ＋－Ｋ＋－ＡＴＰ酶活性的变化以及氧自由基清除剂（ＶｉｔＥ．亚硒酸钠）对糖尿病大鼠心肌的保护作用。结果表明：（１）糖尿病大鼠心肌组织ＭＤＡ含量显著增加（Ｐ＜０．０５），而心肌细胞膜上Ｎａ＋－Ｋ＋一ＡＴＰ酶的活性显著下降（Ｐ＜０．０１）．（２）ＶｉｔＥ和亚硒酸钠能显著降低糖尿病大鼠心肌组织ＭＤＡ含量，并能提高ＳＯＤ和Ｎａ＋－Ｋ＋－ＡＴＰ酶活性。以上结果说明糖尿病大鼠心肌组织的脂质过氧化反应可能是导致心肌细胞膜上Ｎａ＋－Ｋ＋－ＡＴＰ酶活性下降的原因之一     

卒中型高血压大鼠心肌线粒体Ca~（2＋），Mg~（2＋）—ATPase及膜流动

本文比较了卒中型自发往高血压鼠（ＳＨＲｓｐ）和京都Ｗｉｓｔａｒ正常血压鼠（ＷＫＹ）心肌线粒体Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力及膜流动性。用定磷法测得ＷＫＹ和ＳＨＲｓｐ的Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力（２５℃）分别为０．２８７±０．０１６及０．２１８±０．０１７μｍｏｌ／（ｍｉｎ．ｍｇ）（－ｘ±Ｓｘ）。ＳＨＲｓｐ心肌线粒体Ｃａ￣（２＋），Ｍｇ￣（２＋）－ＡＴＰａｓｅ活力降低２４．７％，两组比较有显著差异（Ｐ＜０．０１，ｎ＝９）．以ＤＰＨ标记心肌线粒体膜，测得ＷＫＹ和ＳＨＲｓｐ的荧光偏振值分别为０．１８７±０．００３及０．１８１±０．００３（Ｐ＞０．０５，ｎ＝６）。     

牛磺酸对离体大鼠脊髓缺氧／复氧损伤的保护作用

本文在孵育的离体大鼠脊髓组织切片上，观察牛磺酸对缺氧／复氧损伤的影响，缺氧／复氧损伤引起大鼠脊髓组织ＡＴＰ含量减少和ＬＤＨ漏出增多，ＮＯ生成和ＮＯＳ活性明显增加，Ｌ－精氨酸转运Ｖｍａｘ增加９７％（Ｐ〈０．０１），Ｋｍ值无明显变化，用１０和２０ｍｍｏｌ／Ｌ牛磺酸卵育与单纯缺氧／臭氧组比较，显著减轻了缺氧／复氧引起的组织ＡＴＰ减少和ＬＤＨ漏出，ＮＯ生成分别低３４％（Ｐ〈０．０１）和４０％（Ｐ〈０．０１     

维生素E对冷适应大鼠红细胞膜钠-钾-ATP酶活性及丙二醛含量的影响

目的：研究膳食维生素Ｅ（ＶＥ）增强冷适应的机理。方法：用ＳＤ大鼠为研究对象，分别饲以高ＶＥ饲料（２３０ｍｇ／ｋｇ．饲料）和低ＶＥ饲料（３０ｍｇ／ｋｇ．饲料）。观察大鼠红细胞膜钠－钾－ＡＴＰ酶（Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ）活性和丙二醛（ＭＤＡ）含量的变化。结果：冷适应大鼠红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性明显高于对照组（Ｐ＜０．０５），高ＶＥ摄入大鼠红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性明显高于低ＶＥ摄入组大鼠（Ｐ＜０．０５）；高ＶＥ摄入组大鼠红细胞膜ＭＤＡ含量明显低于低ＶＥ摄入组大鼠（Ｐ＜０．０５）；膜Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性和ＭＤＡ含量间呈明显负相关。结论：膳食ＶＥ可以提高冷适应大鼠红细胞膜Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性，降低膜ＭＤＡ含量     

The alteration of protein prenylation induces cardiomyocyte hypertrophy through Rheb–mTORC1 signalling and leads to chronic heart failure

G protein‐regulated cell function is crucial for cardiomyocytes, and any deregulation of its gene expression or protein modification can lead to pathological cardiac hypertrophy. Herein, we report that protein prenylation, a lipidic modification of G proteins that facilitates their association with the cell membrane, might control the process of cardiomyocyte hypertrophy. We found that geranylgeranyl diphosphate synthase (GGPPS), a key enzyme involved in protein prenylation, played a critical role in postnatal heart growth by regulating cardiomyocyte size. Cardiac‐specific knockout of GGPPS in mice led to spontaneous cardiac hypertrophy, beginning from week 4, accompanied by the persistent enlargement of cardiomyocytes. This hypertrophic effect occurred by altered prenylation of G proteins. Evaluation of the prenylation, membrane association and hydrophobicity showed that Rheb was hyperactivated and increased mTORC1 signalling pathway after GGPPS deletion. Protein farnesylation or mTORC1 inhibition blocked GGPPS knockdown‐induced mTORC1 activation and suppressed the larger neonatal rat ventricle myocyte size and cardiomyocyte hypertrophy in vivo, demonstrating a central role of the FPP–Rheb–mTORC1 axis for GGPPS deficiency‐induced cardiomyocyte hypertrophy. The sustained cardiomyocyte hypertrophy progressively provoked cardiac decompensation and dysfunction, ultimately causing heart failure and adult death. Importantly, GGPPS was down‐regulated in the hypertrophic hearts of mice subjected to transverse aortic constriction (TAC) and in failing human hearts. Moreover, HPLC–MS/MS detection revealed that the myocardial farnesyl diphosphate (FPP):geranylgeranyl diphosphate (GGPP) ratio was enhanced after pressure overload. Our observations conclude that the alteration of protein prenylation promotes cardiomyocyte hypertrophic growth, which acts as a potential cause for pathogenesis of heart failure and may provide a new molecular target for hypertrophic heart disease clinical therapy. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Decreased KCNE2 expression participates in the development of cardiac hypertrophy

AIM: To investigate whether KCNE2 participates in the development of pathological hypertrophy. METHODS: Bidirectional manipulations of KCNE2 expression were performed by adenoviral overexpression of KCNE2 or knockdown of KCNE2 with RNA interference in PE-induced neonatal rat ventricular myocytes. Then overexpression of KCNE2 in mouse model of left ventricular hypertrophy induced by transverse aortic constriction( TAC) by ultrasound microbubble-mediated gene transfer were used to detect the therapeutic function of KCNE2 in the development of hypertrophy. RESULTS: KCNE2 expression was significantly decreased in PE-induced hypertrophic cardiomyocytes and in hypertrophic hearts produced by TAC. Knockdown of KCNE2 in cardiomyocytes reproduced hypertrophy,whereas overexpression of KCNE2 attenuated PE-induced cardiomyocyte hypertrophy. Knockdown of KCNE2 increased calcineurin activity and nuclear NFAT protein level,and pretreatment with nifedipine or FK506 attenuated decreased KCNE2-induced cardiomyocyte hypertrophy. Overexpression of KCNE2 in heart by ultrasound microbubble-mediated gene transfer suppressed the development of hypertrophy and activation of calcineurin-NFAT and MAPK pathways in TAC mice. CONCLUSION: These findings demonstrate that cardiac KCNE2 expression is decreased and contributes to the development of hypertrophy via activation of calcineurin-NFAT and MAPK pathways.     

金属硫蛋白对羟自由基损伤的大鼠肝细胞核核苷三磷酸酶的保护作用

目的:研究金属硫蛋白(MTs)是否对羟自由基(hydroxylradical,·OH^-)损伤的大鼠肝细胞核核苷三磷酸酶(NTPase)具有保护作用。方法:以羟自由基发生系统Fe³⁺/H₂O₂单独或与MTs共同孵育大鼠离体肝细胞核,检测分别用ATP和GTP作底物时大鼠肝细胞核NTPase活性。结果:不同浓度Fe³⁺/H₂O₂(μmol·L^-1/μmol·L^-1:0.1/0.5、0.5/2.5、1/5、5/25)孵育肝细胞核,浓度依赖地增强核NTPase活性,与对照组差异显著(P＜0.01)。用不同浓度的MT(10^-9-10^-4mol·L^-1)与Fe²⁺/H₂O₂(1μmol·L^-1/5μmol·L^-1)共孵育,浓度依赖地拮抗Fe³⁺/H₂O₂诱导的效应(P＜0.01)。用MT单独孵育肝细胞核对NTPase的活性没有影响(P＞0.05)。结论:Fe³⁺/H₂O₂系统产生的·OH对核NTPase活性具有强烈的抑制效应,MT浓度依赖地拮抗·OH导致的NTPase活性降低。     

大鼠肥厚心脏卸负荷后心室逆重塑相关的信号通路改变

目的： 研究肥厚心脏心室重塑及逆重塑过程中Akt/GSK3β、MAPKs和NF-κB信号通路的变化。方法：以Lewis大鼠行腹主动脉缩窄术,建立压力超负荷性心肌肥厚模型。将肥厚心脏移植到同源Lewis大鼠腹部,建立压力卸负荷模型。对各组心肌取材进行病理学评价。Western blotting法检测心肌组织中相关信号通路蛋白的表达。结果：在心肌肥厚大鼠心脏中Akt/GSK3β、MAPKs和NF-κB磷酸化水平均显著升高,移植卸负荷后除p38 MAPK和JNK外,其它蛋白磷酸化水平均显著降低。结论：肥厚心脏经异位移植卸负荷后产生逆重塑现象,Akt/GSK3β、ERK1/2和NF-κB信号通路的改变参与其中,该结果为临床心室逆重塑的研究提供了实验依据。     

丙戊酸抑制血管紧张素Ⅱ致大鼠心肌细胞肥大

目的 探讨丙戊酸在血管紧张素Ⅱ（AngⅡ）致心肌细胞肥大过程中的抑制作用。方法 常规方法培养大鼠原代心肌细胞,分为3组：对照组、肥大组、丙戊酸组。利用AngⅡ刺激心肌细胞造成肥大模型,并给予丙戊酸进行干预。反转录聚合酶链反应观察β-肌球蛋白重链（β-MHC）mRNA表达;相差显微镜和电镜观察心肌细胞的表面积和超微结构变化;免疫组织化学法检测c-fos蛋白的表达。结果 原代心肌细胞在AngⅡ作用下表面积增加,超微结构发生改变;β-MHC mRNA和c-fos蛋白表达增加（P < 0.05）。给予丙戊酸干预后,上述变化显著缓解（P < 0.05）。结论 丙戊酸抑制AngⅡ刺激引起的心肌细胞肥大,为临床上治疗心肌肥厚提供一条新的思路。     

PPAR-α参与高糖高胰岛素诱导的心肌细胞肥大

目的： 研究过氧化物酶体增殖物激活受体-α(PPAR-α）在高糖高胰岛素(HGI)诱导心肌肥大中的作用。方法: 利用乳鼠心肌细胞培养,以细胞表面积、蛋白含量和心房利钠因子（ANF)mRNA表达为心肌肥大反应指标,观察PPAR-α激动剂非诺贝特（FF）对HGI致肥大作用的影响。利用RT-PCR和Western blotting方法检测mRNA及蛋白水平的表达。结果: HGI诱导细胞表面积、总蛋白含量和ANF mRNA表达增加（P<0.01）;但PPAR-α mRNA和蛋白的表达明显降低（P<0.05）;而其下游因子环氧酶-2（COX-2）的表达则增加（P<0.05）。FF浓度依赖性地抑制HGI诱导的心肌细胞肥大（P<0.01）,并上调PPAR-α的表达,同时阻遏COX-2的表达（P<0.05）。PPAR-α阻断剂MK 886可完全取消FF的上述作用（P<0.05）,使COX-2表达增加至HGI模型组水平。结论: PPAR-α可能参与了HGI诱导的心肌肥大,同时COX-2可能是其重要下游因子。     

过表达miR-130a-3p对心肌细胞肥大的缓解作用研究

本研究旨在探索miR-130a-3p对心肌细胞肥大的作用及其可能机制。通过胸主动脉缩窄法(TAC)构建压力超负荷所致心肌肥厚小鼠模型。使用去甲肾上腺素(NE)刺激SD乳鼠原代心肌细胞(NRCMs)及H9c2大鼠心肌细胞系,诱导这两种心肌细胞发生肥大表型转变。检测miR-130a-3p的表达变化,并进一步探索其对心肌细胞肥大是否有调控作用。结果表明,miR-130a-3p在肥厚心肌组织、肥大NRCMs及H9c2细胞中的表达均明显降低。给予miR-130a-3p mimics使其过表达后,H9c2细胞中肥大标志基因心房利钠肽(ANP)、脑利钠肽(BNP)和肌球蛋白重链β(β-MHC)的表达较对照组(mimics N.C.+NE组)明显下调,且细胞面积明显减小。而给予miR-130a-3p inhibitor抑制其表达后,肥大心肌细胞中ANP、BNP、β-MHC的表达进一步上升,且细胞面积进一步增加。Western blot检测发现,过表达miR-130a-3p后心肌细胞中磷酸化Akt和磷酸化mTOR的表达水平下调。以上结果提示,miR-130a-3p mimics可缓解心肌细胞肥大的程度;其inhibitor则可使心肌细胞肥大进一步加剧。过表达miR-130a-3p可能通过影响Akt通路来缓解H9c2心肌细胞肥大的程度。     

PPARβ及NO在高糖高胰岛素诱导心肌细胞肥大中的作用

目的:观察过氧化物酶体增殖物激活受体β(PPARβ)及一氧化氮(NO)相关信号通路在高糖高胰岛素(HGI,25.5 mmol/L葡萄糖+0.1μmol/L胰岛素)诱导心肌肥大中的作用。方法:体外培养乳鼠心肌细胞,以细胞表面积、蛋白含量和心房钠尿因子(ANF)mRNA表达作为心肌肥大的指标;利用real-time PCR、Western blotting、硝酸还原酶法和分光光度法分别检测mRNA表达、蛋白表达、NO含量和NO合酶(NOS)活性。结果:HGI诱导心肌细胞出现肥大(P0.01),PPARβmRNA和蛋白表达明显降低(P0.05),诱导型NOS(i NOS)mRNA和蛋白的表达则升高(P0.01),NO含量和NOS活性增加(P0.01)。PPARβ激动剂GW0742能抑制HGI诱导的心肌肥大(P0.01),上调PPARβ的表达,降低i NOS的表达,使NOS活性和NO含量恢复正常(P0.01)。PPARβ拮抗剂GSK0660可阻断GW0742对心肌肥大的保护作用,取消其对PPARβ、i NOS mRNA和蛋白表达水平以及NOS活性和NO含量的作用(P0.05)。结论:PPARβ下调,激活i NOS-NO信号通路参与高糖高胰岛素诱导心肌肥大过程。     

Temporal characteristics of cardiomyocyte hypertrophy in the spontaneously hypertensive rat.

BACKGROUND: The spontaneously hypertensive rat (SHR) is frequently used as model of cardiovascular disease, with considerable disparity in reported parameters of hypertrophy. The aim of this study was to assess the temporal changes occurring during the development and progression of cardiomyocyte hypertrophy in SHR, subsequent to pressure overload, compared to changes associated with normal aging using the normotensive Wistar-Kyoto (WKY) rat. METHODS: Ventricular cardiomyocytes were isolated from rats at 8, 12, 16, 20 and 24 weeks, and parameters of hypertrophy (cell dimensions, protein mass, de novo protein synthesis, and gene expression) and function (contraction and hypertrophic responsiveness in vitro) were assessed. RESULTS: Hypertension was evident at > or =7 weeks in SHRs. Heart:body mass ratio, cardiomyocyte protein mass and width were elevated (P<.05) in SHRs at 16-20 weeks compared to WKYs. In SHRs compared to WKYs at 16 weeks, there was a transient increase (P<.05) in protein synthesis, enhanced hypertrophic responsiveness to phorbol-12-myristate-13-acetate, and induced hypertrophic responsiveness to isoprenaline. Skeletal-alpha-actin mRNA was detected in SHR but not WKY cells at all ages. ANP mRNA was lower in SHR than in WKY cells at 8-20, but progressively increased (P<.05) from 12 to 24 weeks within SHRs. Contractile function increased (P<.05) at 20 weeks in SHR compared to WKY rats. CONCLUSION: Structural and functional changes occurring at the cellular level in the myocardium of SHR follow a distinct pattern, such that pressure overload was initially accompanied by expressional changes (8-12 weeks), followed by active hypertrophic growth and enhanced function (16-20 weeks), which subsequently decelerated as stable compensation was attained.