体外反搏对心肌缺血时血管紧张素转换酶的抑制作用

目的 探讨体外反搏对心肌缺血时犬血管紧张素转换酶（ACE）的影响及机制。方法 采用冠状动脉结扎法复制犬急性心肌缺血模型,外加反博治疗,观测犬血流动力学指标及缺血心肌、主动脉局部血管紧张素Ⅱ水平、ACE活性的改变,用RT-PCR方法检测局部ACE mRNA的表达。结果 体外反搏能改善犬左心室舒缩功能,抑制缺血激活的缺血心肌、主动脉处ACE活性及血管紧张素Ⅱ水平,抑制缺血心肌、主动脉处ACE mRNA的表达。结论 体外反搏能通过抑制心血管局部ACE的表达抑制局部肾素-血管紧张素系统,这可能是体外反搏保护缺血心肌的作用机制之一。     

对心肌缺血与体外反搏时血管紧张素转换酶的研究

目的 :探讨体外反搏对心肌缺血犬循环和局部血管紧张素转换酶的影响及机制。方法 :采用冠状动脉结扎法复制犬急性心肌缺血模型 ,外加体外反搏治疗 ,观测循环血液中以及缺血心肌、肺组织局部ANGⅡ水平、ACE活性的改变 ,用RT PCR方法检测局部ACEmRNA的表达。结果 :循环ANGⅡ水平、ACE活性随缺血时间的延长逐步上升 ,反搏能抑制其活性 ;体外反搏还能抑制缺血激活的缺血心肌ACE活性、ANGⅡ水平 ;抑制缺血心肌、肺组织ACEmRNA的表达 ,其中肺脏ACE达正常水平。结论 :体外反搏能抑制缺血心肌局部ACE的表达抑制局部RAS ,还对循环RAS有抑制作用 ,这可能是体外反搏保护缺血心肌的作用机制之一     

血管紧张素转化酶2在心肌缺血再灌注损伤中的意义

目的:研究心肌缺血再灌注损伤不同时期、不同脏器血管紧张素转化酶2(ACE2)蛋白表达水平.方法:建立在体心肌缺血再灌注模型,于再灌注前后不同时点取心肌组织、肾脏、睾丸及肝脏等组织,采用免疫组化方法检测组织ACE2的表达.用放射免疫法测定血浆及心肌组织中血管紧张素Ⅱ(AngⅡ)含量.结果:缺血再灌注1～12 h肾小管上皮细胞ACE2表达增多,缺血再灌注12 h后心脏ACE2开始表达增加.肝脏无论再灌注早期还是再灌注晚期几乎都不表达.缺血再灌注1～12 h血浆及心肌组织中AngⅡ含量增高.结论:心脏缺血再灌注后血浆及心肌AngⅡ表达增高, ACE2主要由肾脏器官分泌产生,心肌在再灌注晚期表达ACE2.     

增强型体外反搏对急性心肌缺血时血管紧张素转换酶的影响

增强型体外反搏对急性心肌缺血时血管紧张素转换酶的影响     

体外反搏对冠状动脉闭塞犬心肌结构和细胞凋亡的影响

目的观察长期体外反搏后心肌结构和功能的变化,评价体外反搏对细胞凋亡的影响。方法雄性Beagle犬12只,随机分为对照组(n=6)和反搏组(n=6)。所有犬用心导管法建立定向冠状动脉闭塞模型3 d后,反搏组犬接受体外反搏处理,每日1h,共6周。利用常规苏木精-伊红(HE)染色和透射电镜观察心肌显微和超微结构的变化。电镜观察细胞凋亡的特征性改变。结果与对照组比较,光镜下反搏组犬受累区域心肌的病理改变程度较轻,电镜观察显示反搏组犬缺血心肌的肌原纤维排列大致整齐,线粒体肿胀不明显,大部分线粒体膜完整,血管内皮细胞基膜完整。未见明显的心肌和血管内皮细胞凋亡的超微结构改变。相反,对照组心肌组织内可见大量心肌及内皮细胞凋亡的特征性改变。此外,体外反搏后,左心室的射血分数(EF)明显改善,心室壁运动能力提高。结论长期体外反搏对保护心肌结构和功能有显著作用,并能拮抗心肌细胞和血管内皮细胞凋亡,有利于心肌功能结构的维护。     

早期冠状动脉搭桥术对犬急性心肌梗死的范围和肾素系统的影响

目的:探讨犬急性心肌梗死(AMI)早期冠状动脉搭桥对心肌梗死(MI)范围和心肌局部肾素系统即血管紧张素与肾素活性(RA)的影响及其意义。方法:结扎犬冠状动脉前降支制备MI模型(30只)。分别在MI后1,2,4及6周行冠状动脉搭桥作为实验组,其中第2周4只,其余每组6只;对每个实验组分别设立MI不搭桥对照组,每组2只。8周后开胸切取心脏分别测量MI范围,每只犬分别切取梗死区标本及正常心肌标本,样本采用放射免疫方法测定MI心肌局部RA及血管紧张素Ⅱ(AngⅡ)。结果:每个实验组各存活4只,对照组均存活。1,2周实验组较4,6周实验组及对照组MI范围明显减小(P<0.05)。对照组RA及AngⅡ含量明显高于所有实验组及正常心肌(P<0.01),4,6周实验组RA及AngⅡ含量明显高于1,2周实验组及正常心肌(P<0.05)。结论:犬AMI早期冠状动脉搭桥可以明显改善心肌缺血,减少心肌局部RA及减少AngⅡ的分泌,从而减轻AngⅡ对局部心肌的损害。尤其2周内冠状动脉搭桥可以最大限度减轻RA及AngⅡ对局部心肌的损害,并可以减少MI范围。     

急性心肌缺血大鼠心肌组织中PAS系统的表达变化

目的 探讨急性心肌缺血大鼠心肌组织中肾素-血管紧张素系统(RAS)的表达变化.方法 通过结扎大鼠冠状动脉左前降支复制急性心肌缺血模型.采用RT-PCR方法 测定心肌组织中血管紧张素原(AGT)、血管紧张素转换酶(ACE)、血管紧张素1型受体(AT1)/血管紧张素2型受体(AT2)及水通道蛋白4(AQP4)mRNA的表达.结果 与假手术组相比,急性心肌缺血组大鼠心肌组织中AGT mRNA的变化不明显,ACE及AT1 mRNA的表达明显降低(P＜0.05),AT2 及AQP4 mRNA的表达明显升高(P＜0.05).结论 局部RAS及AQP4参与了急性心肌缺血的过程.     

糖尿病仓鼠心肌糜蛋白酶和血管紧张素转换酶基因表达的变化

目的观察糖尿病仓鼠心肌血管紧张素Ⅱ(ATⅡ)含量,糜蛋白酶和血管紧张素转换酶(ACE)基因表达变化,探讨糜蛋白酶和ACE在糖尿病心肌病变发生中的作用。方法测定正常对照(NC)组(n=10)和糖尿病(DM)组(n=10)仓鼠血浆和心肌ATⅡ含量;荧光定量PCR检测心肌糜蛋白酶和ACE基因表达;观察心肌Ⅰ、Ⅲ型胶原含量变化;测定血糖、糖化血清蛋白、血脂和胰岛素水平。结果与NC组相比,DM组仓鼠心肌Ⅰ、Ⅲ型胶原表达量分别为NC组的2.71和1.68倍,且Ⅰ/Ⅲ型胶原比值明显升高;心肌局部ATⅡ含量显著升高;糜蛋白酶基因表达显著高于NC组,而ACE基因表达在两组间差异无统计学意义。结论糖尿病仓鼠心肌病变时心肌局部升高的ATⅡ可能主要来源于糜蛋白酶途径,抑制糜蛋白酶的表达或活性可能对糖尿病心肌病变具有治疗价值。     

培多普利抑制心肌重构的动物实验研究

目的:本研究采用Wistar大鼠冠脉结扎心梗后心衰模型,以培多普利作为观察药物,探讨肾素血管紧张素系统(RAS)在心肌重构中的地位和血管紧张素转换酶抑制剂(ACEI)对心肌重构的干预作用.方法:将Wistar大鼠分为梗塞组、梗塞治疗组和假术组.梗塞组结扎左冠状动脉,梗塞治疗组在前者基础上用培多普利治疗2mg/kg/天,假手术组不结扎左冠状动脉.三月后测血流动力学参数,血液及组织内血管紧张素Ⅱ(AngⅡ)含量、血管紧张素转换酶(ACE)活性和观察组织形态学变化.结果:三月后,与假术组相比,梗塞组出现了克血性心衰(DHF)的血流动力学改变;心肌局部AngⅡ含量、ACE活性显著差增高,但血液AngⅡ含量和ACE活性无明显改变;心脏重量指数显著上升;残存心肌细胞肥大,间质增生,胶原蛋白沉积.培多普利可以改善血流动力学参数,减少AngⅡ的生成、抑制ACE活性并减轻心肌细胞肥大、间质增生和胶原蛋白沉积的程度.结论:心肌组织局部的RAS参与了心肌重构的病理生理过程,血液RAS与心肌重构无显著相关,ACEI可以有效地防治心肌重构及心衰.     

卡托普利对自发性高血压大鼠血压和心肌血管组织肾素血管…

本工作观察了卡托普利对自发性高血压大鼠（ＳＨＲ）血压及心肌，主动脉组织肾素血管紧张素系统（ＲＡＳ）的影响，实验结果表明，ＳＨＲ心肌，主动脉组织血管紧张素Ⅱ含量（ＡＴＩＩ）和血管紧张素换酶（ＡＣＥ）活性显著高于正常血压大鼠（ＷＫＹ）。卡托普列能显著抑制ＳＨＲ心肌，主动脉组织ＡＣＥ活性；降低ＡＴＩＩ含量，并使血压明显降低。提示，血管紧张素转换酶抑制剂（ＡＣＥＩ）对心血管局部组织ＲＡＳ的抑制作用在其降压     

法舒地尔对大鼠心肌血管紧张素转换酶2和血管紧张素(1-7)的影响

目的探讨法舒地尔对压力超负荷大鼠心肌血管紧张素转换酶2(ACE2)和血管紧张素(1-7)[Ang(1-7)]的影响。方法 50只SD大鼠制备压力超负荷模型,术后4周末,将存活36只大鼠随机分为假手术组8只、模型组10只、法舒地尔高剂量组(高剂量组)9只和法舒地尔低剂量组(低剂量组)组9只。术后8周末,计算各组左心室质量指数(LVMI);观察心肌组织HE和Masson胶原染色;碱水解法测定心肌羟脯氨酸(HYP)含量;免疫组织化学分析ACE和ACE2水平;RT-PCR和ELISA法分别检测ACE2mRNA表达、AngⅡ和Ang(1-7)浓度。结果与假手术组比较,模型组心肌间质大量胶原蛋白沉积,LVMI、HYP、ACE和AngⅡ明显升高,ACE2、ACE2mRNA及Ang(1-7)明显降低(P<0.01);与模型组比较,高剂量组和低剂量组LVMI、HYP明显降低,间质胶原蛋白沉积明显减轻,ACE和AngⅡ明显降低(P<0.05),ACE2、ACE2mRNA和Ang(1-7)明显升高(P<0.01)。结论法舒地尔抑制压力超负荷诱导的心肌纤维化的作用可能与局部ACE-AngⅡ及ACE2-Ang(1-7)的改善有关。     

Elevated vascular angiotensin converting enzyme in chronic two-kidney, one clip hypertension in the dog

The possible role of the vascular angiotensin converting enzyme (ACE) in the development of two-kidney, one clip (2-K, 1C) hypertensive dogs was studied in different blood vessels. Vascular ACE activity per mg protein differed in a variety of blood vessels; the activity appeared to vary inversely with the outer diameter of arteries. The systemic blood pressure in mongrel dogs increased after partial occlusion of the left renal artery, and the hypertension lasted for 8 months. Plasma renin activity (PRA) was raised only for the first 4 weeks after the operation and then returned to the original level in the chronic stage of hypertension. Plasma ACE activity did not alter during the experimental period. In contrast, ACE activities in the jejunal, pulmonary and renal arteries, aorta, lung and cerebral cortex, significantly increased in the chronic hypertensive stage (8 months after occlusion). The production of angiotensin II (ANG II) from ANG I was significantly greater in isolated arteries from 8-month hypertensive dogs than in those from normotensive dogs when assessed by the contractile responses to ANG I and ANG II. These results indicate that acceleration by increased vascular ACE activity of the production of ANG II in the vascular wall may contribute to the maintenance of hypertension in the chronic stage of 2-K, 1C hypertensive dogs having normal PRA and plasma ACE activity.     

Influence of angiotensin-converting enzyme inhibition on cardiac function in myocardial infarction

Cardiac function in myocardial infarction (MI) depends on the extent of damage in ischemic myocardium and the compensatory response of residual myocardium. Because thrombolytic therapy is performed in many patients, reperfusion of ischemic myocardium may take place at various stages of progression of the ischemic insult. If perfusion is reestablished before necrosis occurs, myocardium may recover immediately or after hours to weeks ("stunned myocardium"). If coronary occlusion persists, necrosis develops in the subendocardium, propagates transmurally and forms a scar after the healing phase. Residual myocardium responds to loss of contractile tissue and material properties of the ischemic zone by hypertrophy and dilatation. This study shows that left ventricular dilatation is accompanied by an increase in stroke volume from 4 days to 4 weeks; however, left ventricular dilatation progresses while stroke volume remains constant from 4 weeks to 6 months, suggestive of noncompensatory left ventricular dilatation. Angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce lactate production after 60 seconds, and infarct size after 6 hours of coronary occlusion in dogs. Stunned myocardium recovers faster in animal experiments and pacing-induced myocardial ischemia may be prevented by ACE inhibitors. Left ventricular dilatation and mortality is reduced by ACE inhibitors in rats after MI. Several potential mechanisms are discussed to establish a favorable action of ACE inhibitors at various stages of MI. Clinical evidence is still pending; however, large studies are ongoing to clarify potential indications of ACE inhibitors in ischemic heart disease in humans.     

Combination Angiotensin Converting Enzyme and Direct Renin Inhibition in Heart Failure following Experimental Myocardial Infarction

Aims: Diminishing the activity of the renin–angiotensin system (RAS) plays a pivotal role in the treatment of heart failure. In addition to angiotensin converting enzyme (ACE) inhibitors and angiotensin‐receptor blockers, direct renin inhibition has emerged as a potential adjunctive treatment to conventional RAS blockade. We sought to determine the effectiveness of this strategy after myocardial infarction (MI) in the setting of preexisting hypertension, a common premorbid condition in patients with ischemic heart disease. Methods and Results: Ten‐week‐old female heterozygous hypertensive (mRen‐2)27 transgenic rats (Ren‐2), were randomized to one of five groups (n = 8 per group); sham, MI, MI + aliskiren, MI + lisinopril and MI + combination lisinopril and aliskiren. Cardiac function was assessed by echocardiography and in vivo cardiac catheterization. Untreated MI animals developed heart failure with hypotension, dilation, reduced ejection fraction (EF), and raised left ventricular end‐diastolic pressure (LVEDP). Treatment with single agent treatment had only modest effect on cardiac function though combination therapy was associated with significant improvements in EF and LVEDP when compared to untreated MI animals (P < 0.05). Histologic analysis demonstrated increase extracellular matrix deposition and cardiomyocyte hypertrophy in the noninfarct region of all MI groups when compared with sham operated animals (P < 0.05) that was reduced by ACE inhibitor monotherapy and combination treatment but not by aliskiren alone. Conclusion: In a hypertensive rat model that underwent experimental MI, EF, and LVEDP, key functional indices of heart failure, were improved by treatment with combination ACE and direct renin inhibition when compared with either agent used alone.     

犬急性心肌缺血早期心肌葡萄糖、脂肪酸代谢相关酶变化的初步研究

目的探讨急性心肌缺血早期,心肌葡萄糖、脂肪酸代谢相关酶信使核糖核酸(mRNA)及蛋白表达的变化。方法采用12只美国比格犬,分为对照组(假手术组)、心肌缺血组,缺血组分为心肌缺血20min组、心肌缺血40min组2个亚组,分别取非缺血区、缺血区心肌组织样品各1份。应用实时定量PCR(SYBRGreenRT-PCR)方法,测定磷酸果糖激酶(PFK)、甘油醛-3-磷酸酯脱氢酶(GAPDH)、葡萄糖转运蛋白1(GLUT1)和葡萄糖转运蛋白4(GLUT4)、链乙酰辅酶-A-脱氢酶(MCAD)、心脏脂肪酸结合蛋白(H-FABP)等基因mRNA的表达量。应用免疫组织化学检测GLUT1的表达。应用TUNEL阳性细胞计数法检测心肌细胞凋亡程度。结果(1)与对照组比较,缺血组mRNA表达明显增加的基因有GLUT1(P=0.044);mRNA有增加趋势的基因是PFK(P=0.065)。mRNA表达明显降低的基因有H-FABP(P=0.008)。(2)心肌缺血20min与40min组之间的比较发现,在缺血40min组心脏脂肪酸结合蛋白mRNA的表达呈下降的趋势,GLUT1、GLUT4、PFK和MCAD呈上升状态,但差异无统计学意义。(3)心肌缺血20min与40min组GLUT1的免疫组织化学检测结果都有阳性表达。(4)TUNEL阳性细胞计数法测得阳性细胞数,缺血组的平均值均高于假手术组,假手术组为(6.4±0.9)%,缺血20min组(28.0±3.7)%(P=0.008),缺血40min组(38.4±1.9)%(P=0.008)。结论即使是在急性心肌细胞缺血早期,心肌葡萄糖、脂肪酸代谢相关酶mRNA及蛋白的表达都有改变,这些酶mRNA表达的增减与无氧糖代谢的增强可能关系密切。     

Myocardial infarction in the dog: Effects of intravenous propranolol

The effects of propranolol on myocardial perfusion and metabolism during acute myocardial infarction were studied in 18 mongrel dogs. A reversible snare was placed on the left anterior descending coronary artery; regional myocardial perfusion was continuously measured using the short-lived isotope krypton-81m, and myocardial metabolism was assessed using the epicardial electrocardiogram and measurement of release of creatine kinase activity from the affected segment of myocardium. Six dogs with no arterial occlusion acted as “sham operated” dogs; six others in which the snare was occluded acted as a control group and a third group of six were given propranolol, 0.5 mg/kg, 30 minutes after coronary occlusion. All variables were recorded before and for 5 hours after coronary occlusion. Dogs treated with propranolol showed a significant improvement in regional myocardial perfusion to the affected segment, decreased loss of electrically active myocardium at the end of each experiment for any given degree of early S-T segment elevation and a delay in the local release of creatine kinase activity compared with that in the control dogs. These results suggest that propranolol exerts a beneficial effect on the progress of ischemic myocardial damage when given shortly after the onset of infarction.     

U50,488H抑制中性粒细胞在大鼠缺血/再灌注心肌中的聚集和TNF-α生成

目的:观察К-阿片受体激活对大鼠心肌缺血/再灌注(MI/R)局部心肌中性粒细胞聚集的影响及其相关机制。方法:将60只成年健康SD大鼠随机分为假手术组、缺血/再灌注(I/R)生理盐水组、К-阿片受体激动剂(U50,488H)组、U50,488H+Nor-BNI组、U50,488H+Wortmannin组及U50,488H+L-精氨酸甲酯(L-NAME)组,每组9~10只大鼠。使心肌局部缺血30 min再灌注3 h后处死动物,检测大鼠心梗面积并按相应试剂盒提供方法检测血清肌酸激酶(CK)、心肌中髓过氧化物酶(MPO)活性、一氧化氮(NO)及心肌和血清中肿瘤坏死因子-α(TNF-α)的水平。结果:与I/R生理盐水组相比较,U50,488H组的心梗面积(P0.05)、血清CK活性(P0.05)、心肌MPO(P0.05)及心肌和血清TNF-α(P0.05)的水平明显下降,同时心肌中NO(P0.05)的水平上升;而К-阿片受体的选择性阻断剂(Nor-BNI)、PI3K的选择性抑制剂(Wortmannin)及NO合成酶(NOS)抑制剂(L-NAME)均可消除U50,488H的上述作用(P0.05)。结论:U50,488H可通过激活К-阿片受体,发挥对心脏的保护作用。U50,488H的保护作用可能与其激活PI3-激酶,增加心肌中NO的合成,减少中性粒细胞向I/R损伤心肌的聚集和MI/R诱导的TNF-α生成有关。     

Proteomic Mechanism of Myocardial Angiogenesis Augmented by Remote Ischemic Training of Skeletal Muscle in Rabbit

Aims: This study was designed to evaluate the proteomic mechanism of myocardial angiogenesis augmented by a remote ischemic training (RIT) of skeletal muscle in a controlled myocardial ischemia model. Methods: The rabbits were grouped by RIT, myocardial ischemia without RIT (MI), and sham‐operation (Sham). Controlled myocardial ischemia was modeled by a balloon constrictor implanted on their left ventricular branch (LVB) in a New Zealand rabbit. RIT was induced by four cycles of 10‐minute ischemia followed by 10 minutes of reperfusion using tourniquets on the hind limbs of the myocardial ischemia models for 4 weeks. The myocardial samples were subjected to two dimensional electrophoresis and MALDI TOF for protein identification. The angiogenesis was documented by using microspheres to measure the relative regional blood flow, immunohistochemistry to assess capillary density (Factor VIII), and Western blotting to measure the vascular endothelial growth factor (VEGF) levels. Results: Thirty‐eight differentially expressed protein spots between RIT and MI were separated by two‐dimensional gel electrophoresis, and of those, 22 proteins were identified by mass spectrometry. The regional blood flow, capillary density and VEGF in RIT were 35%, 49% and 28% higher than MI (p < 0.01). The increase of regional blood flow and capillary density were highly correlated with VEGF (r= 0.74 and r= 0.67, respectively; p < 0.01). Both RIT and MI groups exhibited stronger angiogenesis than sham treatment (p < 0.01). Conclusions: Augmentation of angiogenesis in ischemic myocardium by RIT has identical identified proteomic findings with differentially expressed proteins.     

BH3-only protein Bim is involved in myocardial injury induced by co-stress of ischemia and cold stress in rats

Objectives To investigate the effect of co-exposure of myocardial ischemia and cold stress on myocardial injury in rats and the relative mechanism.Methods Myocardial ischemia model was established by ligation of left coronary artery.SD rats were randomly allocated to 4 groups; sham+normal temperature(S group),sham+cold stress(SC group),myocardial ischemia+ normal temperature(Ⅰgroup), myocardial ischemia+cold stress(IC group).On the condition of 26℃,SC and IC groups were keeped in a 4℃artificial chamber for 8h(8;00-16:00) for 4 consecu- tive days.Car diac function was assessed by echocardiography;pathological change was analyzed by HE staining;myocardial infarct size was determined by TTC staining;Bim,Caspase-3 expression in myocardium was determined by western blotting.Results It was demonstrated that co-exposure of myocardial ischemia and cold stress could significantly make the cardiac muscle in abnormal shape,increase the infarct size and the expression of Bim and Caspase-3.Conclusions Co-exposure of myocardial ischemia and cold stress may aggravate the cardiac injury,pro- apoptosis protein Bim is involved.