自发性高血压大鼠心肌fas基因表达与左室肥厚关系探讨

目的探讨自发性高血压大鼠(SHR)心肌fas表达及其与左室肥厚的关系. 方法自发性高血压大鼠(SHR)与正常血压大鼠各16只,尾套法测收缩压,逆转录-聚合酶链反应(RT-PCR)法测心肌fas mRNA表达.结果与WKY相比,SHR心肌fas表达、左室重量指数(LVMI)均显著升高,且二者呈正相关.结论自发性高血压大鼠早期心肌肥厚时心肌fas表达已经升高,可能参与后期心衰的发生.     

清热解毒法对高血压左室肥厚大鼠心肌细胞CD62P及CD25的影响

目的探讨清热解毒法抗自发性高血压大鼠（SHR）左室肥厚的作用及机制。方法采用套尾法测定SHR清醒状态下尾动脉收缩压；采用天平称重法计算左室重量指数（LVW/BW）；采用常规病理、苏木精-伊红染色（HE）、光镜观测心脏病理改变；采用透射电镜观测心脏超微结构；采用荧光直标单抗方法测定心肌细胞单细胞悬液P-选择素（P-selectin，CD62P）和白细胞介素-2受体（IL-2R，CD25）蛋白表达。结果清热解毒法能够降低SHR尾动脉收缩压，降低心肌肥厚指数，减轻心肌病理损害，改善心肌超微结构，抑制心肌细胞CD62P、CD25的蛋白表达。结论清热解毒法具有抗高血压左室肥厚的作用，其机制与抑制心肌细胞CD62P、CD25蛋白表达、减轻细胞黏附与免疫炎性损害有关。     

复方七芍降压片对自发性高血压大鼠血压及左室肥厚的影响

目的探讨复方七芍降压片降压及逆转左室肥厚(LVH)的作用机制.方法以10只14周龄WKY大鼠为阴性对照,32只14周龄自发性高血压大鼠(SHR)随机分为4组,分别采用尾动脉法测血压、测左室重量指数(LVMI)、放射免疫法测定血浆及局部心肌血管紧张素Ⅱ(AngⅡ).结果 复方七芍降压片能够降低SHR血压、LVMI、血浆及心肌AngⅡ.结论复方七芍降压片能有效地降低SHR血压及逆转左室肥厚.     

Toll样受体在Goldblatt鼠左室心肌中的表达-炎症与左心室肥厚相关的一个证据

目的 观察肾血管性高血压大鼠（2K1C，Goldblatt高血压大鼠）左室心肌中Toll样受体4（Toll-like receptor4，TLR4）、核因子κB（NFκB）的表达情况并探讨其影响因素。方法 采用免疫组化法检测10只雄性Goldblatt高血压大鼠和6只正常雄性Sprague-Dawley（SD）大鼠左室心肌中TLR4、核因子κB的表达情况，维多利亚蓝一丽春红法行心肌胶原染色评价心肌纤维化程度，根据超声心动图评价左室结构和功能。结果 高血压大鼠左室心肌组织中TLR4和NFκB的表达水平升高（P〈0．01），两者呈高度正相关（r=0．824，P〈0．01）；TLR4表达水平与左室心肌纤维化呈正相关；TLR4表达水平与左室心肌肥厚程度、收缩功能指数显著相关。结论 TLR4信号通路的活化可能参与Goldblatt大鼠心肌肥厚的发生和发展。     

厄贝沙坦和咪哒普利对自发性高血压大鼠左室肥厚和c-Jun表达的影响

目的探讨厄贝沙坦和咪哒普利对自发性高血压大鼠（SHR）左室肥厚和c-Jun表达的影响。方法选用13周龄的SHR 30只,雌性9只,雄性21只,体质量（229±39）g,随机分为3组:SHR组,厄贝沙坦组,咪哒普利组,每组雌性3只,雄性7只。另选同源同系、血压正常的Wistar-Kyoto大鼠（WKY）10只,雌性5只,雄性5只,体质量（206±49）g,作为正常对照组（WKY组）。实验期14周。观察指标:血压、左室质量/体质量（LVW/BW）、左室厚度/体质量、左心室肌c-Jun蛋白及mRNA水平。结果26周龄SHR组血压、LVW/BW与左室厚度/体质量均增高,左心室肌c-Jun蛋白和mRNA的表达明显增加;咪哒普利组、厄贝沙坦组血压、LVW/BW、左室厚度/体质量、左心室肌c-Jun蛋白和mRNA的表达均降低。结论自发性高血压可明显导致心肌肥厚,而咪哒普利、厄贝沙坦可明显降低血压、抑制心肌肥厚的发生。     

厄贝沙坦与咪达普利高血压大鼠心肌核因子—κBr jykt

目的：比较自发性高血压大鼠（SHR）和WKY大鼠心肌核因子－κB的表达以及厄贝沙坦和咪达普利对SHR心肌核因子－κB的影响。方法 将21只雄性自发性高血压大鼠（SHR）随机分成3组，每组7只。其中2组分别灌喂厄贝沙坦50mg/kg/d，和咪达普利3mg/kg/d，另一对照组给正常饮水，并与雄性同周龄Wistar Kyoto大鼠（WKY）6只比较。共13周，免疫组织化学方法检测四组大鼠心肌核因子－κB的表达。结果 SHR对照组心肌核因子－κB表达明显高于WKY组；用厄贝沙坦和咪达普利后核因子－κB表达下降，血压均显著抑制，明显低于高血压对照组（P＜0．01），两治疗组的心脏湿重／体重（HW／BW）也显著低于对照组（P＜0．01）。结论 厄贝沙坦和咪达普利对抑制血压和左室肥厚的同时也明显抑制心肌核因子－κB的激活，提示AT拮抗剂和ACEI对核因子－κB的抑制在抗高血压靶器官损伤过程中起一定的作用。     

左旋氨氯地平对自发性高血压大鼠左室肥厚及内皮素-1表达的影响

目的 观察左旋氨氯地平对自发性高血压大鼠(SHR)左室肥厚的影响,并探讨其对内皮素(ET-1)的作用.方法 20只SHR随机分为左旋氨氯地平治疗组和高血压对照组,同周龄的WKY大鼠作为正常对照组.给药12周,测量左室肥厚指标的变化,采用心室导管法检测心功能的变化,放免法测定左心室心肌ET-1含量,实时定量PCR法测定左心室心肌中前内皮素原(preproET-1) mRNA 的表达.结果 与高血压对照组相比左旋氨氯地平干预能够改善SHR左室收缩和舒张功能参数(+dp/dtmax/LVSP、-dp/dtmax/LVSP)(P<0.05),降低左室质量指数(P<0.01);左旋氨氯地平干预能够降低SHR心肌 ET-1含量(P<0.05),使心肌preproET-1 mRNA的表达降低约20%(P<0.05).结论 左旋氨氯地平能够抑制SHR的左室肥厚,并改善左室收缩和舒张功能,其作用机制可能与调节心肌ET-1的水平有关.     

不同降压药物对自发性高血压大鼠模型左室心肌细胞中TRPC3及TRPC6表达的影响

目的:探讨缬沙坦、雷米普利及氨氯地平对自发性高血压大鼠（SHR）左室心肌中瞬时受体通道蛋白C亚族3及6(TRPC3及TRPC6)表达的影响。方法: 将24只12周龄SHR大鼠随机分为4组,即SHR组、缬沙坦组、雷米普利组及氨氯地平组,每组6只。另以6只同龄的Wistar Kyoto大鼠(WKY)为正常对照组。给药4周后,检测各组大鼠的血压、左室质量指数、左室心肌细胞横径;RT-PCR及Western Blot检测TRPC3及TRPC6 mRNA 及其蛋白的表达。结果: SHR组血压、左室质量指数及左室心肌细胞横径均明显高于对照组（P<0.05）,3个药物组上述指标均较SHR组降低（P<0.05）;5个组均有TRPC3及TRPC6的表达,SHR组TRPC3及TRPC6 mRNA及其蛋白的表达显著高于对照组（P<0.05）,3个药物组TRPC3 mRNA及TRPC6 mRNA及其蛋白的表达均显著低于SHR组（P<0.05）,缬沙坦组TRPC3 mRNA及其蛋白表达的减少最显著（P<0.05）;3个药物组TRPC6 mRNA及其蛋白的表达有所下降,但组间比较差异无显著性。结论: SHR组及对照组大鼠均有TRPC3及TRPC6的表达,TRPC3及TRPC6可能共同参与调节心肌肥厚的病理生理过程;缬沙坦可能通过抑制TRPC3蛋白的表达参与逆转左室肥厚的过程。     

阿托伐他汀对自发性高血压大鼠心肌组织p21表达的影响及其意义

目的:观察阿托伐他汀(ATV)对自发性高血压大鼠(SHR)心肌组织中p21表达的影响,探讨其改善心肌肥厚的可能机制。方法:将16只8周龄SHR随机分为2组(n=8):ATV药物干预组(ATV组)与SHR模型对照组(SHR组),并以8只同周龄Wistar-Kyoto大鼠作为正常对照组(WKY组)。ATV组用ATV 50 mg/(kg·d)灌胃,SHR组与WKY组采用等容量蒸馏水每日同时灌胃。每隔2周测1次血压。10周后,观察大鼠血脂、心肌肥厚指标、p21 mRNA及其蛋白表达的改变。结果:干预10周后,ATV组及SHR组血脂、血压无明显差异。ATV组左室质量指数低于SHR组(P<0.01)。ATV组p21mRNA及蛋白的表达明显高于SHR组(P<0.01)。心肌组织p21mRNA的表达与全心质量与体质量比(HW/BW)呈负相关(r=-0.709,P<0.01),与左室质量与体质量比(LVW/BW)呈负相关(r=-0.665,P<0.01)。结论:ATV可上调SHR肥厚心肌组织中p21的表达,可有效改善左室肥厚。     

自发性高血压大鼠肥厚左室心肌组织微小RNA-1与内向整流钾通道2.1表达的改变及其意义

目的观察自发性高血压大鼠(SHR)肥厚的左室心肌组织微小RNA-1、内向整流钾通道2.1(Kir2.1)表达的变化及其关系,以探讨高血压左心室肥厚(LVH)发生室性心律失常的分子机制。方法取10只17周龄雄性SHR为LVH组,10只8周龄雄性SHR为阳性对照组,10只17周龄雄性WKY大鼠作为空白对照组,通过HE染色、心肌细胞横径测量、实时荧光定量聚合酶链反应(qRT-PCR)、免疫组织化学法及Western blot检测等方法,检测大鼠左室心肌组织病理学改变、微小RNA-1表达、Kir2.1蛋白表达水平的改变。结果①与空白对照组比较,LVH组和阳性对照组的收缩压、舒张压明显升高(分别P<0.01,P<0.05);②与两对照组相比,LVH组的左室质量指数及心肌细胞横径均明显增大(均P<0.05),左室心肌细胞明显肥大,心肌间质增多,伴随着微小RNA-1表达水平明显升高,Kir2.1蛋白表达水平显著降低(P<0.05);③LVH组大鼠左室心肌组织微小RNA-1与Kir2.1蛋白的表达水平呈负相关(r=-0.720,P<0.05)。结论SHR肥厚左室心肌组织微小RNA-1表达上调,并伴随Kir2.1表达下调。     

沉默信息调节因子相关酶3在自发性高血压大鼠心肌高表达与左心室肥厚相关

目的观察沉默信息调节因子相关酶3(sirtuin3)在自发性高血压大鼠(SHR)心肌中的表达,并探讨sirtuin3在高血压所致左心室肥厚(LVH)中的作用。方法 24只29周龄SHR随机分为SHR30周龄组(喂养1周,n=11)和SHR38周龄组(喂养9周,n=13),另选20只29周龄Wistar-Kyoto(WKY)大鼠随机分为WKY30周龄组(喂养1周,n=10)和WKY38周龄组(喂养9周,n=10)作为正常对照。各组测定尾动脉收缩压和左心室质量(LVM)/体质量。Masson染色法分析左心室肌间质纤维化程度,心脏超声测定心功能。采用免疫组化,Western-blot及实时荧光定量PCR来检测心肌组织中sirtuin3的蛋白及mRNA表达。结果与WKY30、38周龄组大鼠比较,SHR30、38周龄组的收缩压[30周龄(189.0±6.8)比(103.4±3.6)mmHg;38周龄(205.6±10.9)比(116.3±4.3)mmHg]、LVM/体质量[30周龄(2.94±0.11)比(2.56±0.21);38周龄(3.21±0.15)比(2.68±0.24)]、左心室收缩末期内径[30周龄(4.27±0.13)比(3.59±0.08)mm;38周龄(5.46±0.14)比(4.21±0.08)mm]、舒张末期室间隔厚度[30周龄(2.63±0.15)比(2.09±0.06)mm;38周龄(2.82±0.09)比(2.35±0.08)mm]、舒张末期左心室后壁厚度[30周龄(2.78±0.12)比(2.15±0.09)mm;38周龄(2.99±0.12)比(2.44±0.07)mm]、sirtuin3mRNA和蛋白表达升高(均P<0.05);左心室短轴缩短率、左心室舒张末期内径降低(均P<0.05),SHR大鼠表现出左心室明显肥厚,左心室收缩及舒张功能明显减低,并随着周龄的延长,心肌肥厚及心功能障碍加重(P<0.05)。结论心肌组织sirtuin3高表达与左心室肥厚密切相关。     

Regression of cardiac hypertrophy in spontaneously hypertensive rats by enalapril and the expression of contractile proteins

Several experimental models involving the development of cardiac hypertrophy in adult rats are characterized by the reexpression of the fetal isoform of myosin heavy chain (V3). To determine whether a similar adult-to-fetal shift in the expression of the thin-filament proteins occurs during cardiac hypertrophy, we have examined the expression of the isoforms of myosin, tropomyosin, and troponin T in the left ventricle of young spontaneously hypertensive rats (SHR) with and without treatment using enalapril, an angiotensin converting enzyme inhibitor. Phosphorylation of tropomyosin, which is predominant in the fetal state, was also analyzed. Twelve-week-old SHR were treated with enalapril for 2, 5, 8, and 9 weeks followed by withdrawal of treatment for 9 weeks. Control SHR, without drug treatment, were weight- and age-matched. After 9 weeks of enalapril treatment, mean arterial blood pressure was reduced (from 166 +/- 11 to 89 +/- 5 mm Hg), and left ventricular weight/body weight ratio was regressed (from 2.53 +/- 0.14 to 1.96 +/- 0.05 g/kg) to normotensive levels. During the 9-week treatment period, the percent V3 decreased in SHR substantially from 35 +/- 3% to 13 +/- 1%. There was a significant correlation between the left ventricular hypertrophy and the percent V3 myosin expression in the SHR during regression (r = 0.697, p less than 0.001). However, only the adult isoforms of tropomyosin and troponin T were detected in the SHR with or without enalapril treatment, and the level of tropomyosin phosphorylation remained constant irrespective of the degree of left ventricular hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cosegregation analysis in genetic crosses suggests a protective role for atrial natriuretic factor against ventricular hypertrophy.

In most rat models studied to date, increased ventricular mass is associated with high ventricular expression of the atrial natriuretic factor (ANF) gene. However, it is unknown whether ANF plays a beneficial or detrimental role in the course of left ventricular hypertrophy or whether ANF gene expression could be genetically linked to cardiac mass. To address such questions, we performed a cosegregation analysis in genetic crosses of inbred strains of rats. To select strains with the appropriate phenotypic characteristics, we first compared the ventricular abundance of ANF mRNA to ventricular mass (corrected for body weight) in 2 recombinant inbred strains derived from Wistar-Kyoto (WKY)/spontaneously hypertensive rat (SHR) hybrid crosses, ie, WKY-derived hyperactive (WKHA) and WKY-derived hypertensive (WKHT) rats, as well as in their parental inbred strains. In the 2 such strains that were normotensive, we observed that ventricular mass was higher in WKHA than in WKY rats, yet ventricular ANF mRNA was less abundant in WKHA than in WKY rats. Within a segregating population of F2 animals generated from a cross between WKY and WKHA genitors, the abundance of ventricular ANF mRNA and peptide correlated inversely with left ventricular mass, in contrast to the positive correlation observed with beta-myosin heavy chain mRNA. Finally, in the equally hypertensive SHR and WKHT strains, we found that ventricular mass was higher in SHR than in WKHT, yet ventricular ANF mRNA was less abundant in SHR than in WKHT. These results demonstrate for the first time that low ventricular ANF gene expression can be linked genetically to high cardiac mass independently of blood pressure and are consistent with a protective role for ANF against left ventricular hypertrophy.     

Differential regulation of cardiac adrenomedullin and natriuretic peptide gene expression by AT1 receptor antagonism and ACE inhibition in normotensive and hypertensive rats

OBJECTIVE: To study the effects of long-term treatment with the type 1 angiotensin (AT1) receptor antagonist losartan and the angiotensin-converting enzyme (ACE) inhibitor enalapril, on cardiac adrenomedullin (ADM), atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) gene expression. METHODS: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were given losartan (15 mg/kg per day) or enalapril (4 mg/kg per day) orally for 10 weeks. The effects of drugs on systolic blood pressure, cardiac hypertrophy, ANP, BNP and ADM mRNA and immunoreactive-ANP (IR)-ANP, IR-BNP and IR-ADM levels in the left ventricle and atria were compared. RESULTS: Losartan and enalapril treatments completely inhibited the increase of systolic blood pressure occurring with ageing in SHR. The ratio of heart to body weight was reduced in both losartan- and enalapril-treated SHR and WKY rats. Treatment with losartan or enalapril reduced left ventricular ANP mRNA and IR-ANP in both strains, and ventricular BNP mRNA levels in SHR rats. Inhibition of ACE, AT1 receptor antagonism, changes in blood pressure or cardiac mass had no effect on left ventricular ADM gene expression in SHR and WKY rats. In addition, atrial IR-ANP and IR-ADM levels increased in SHR whereas IR-BNP levels decreased in WKY and SHR rats in response to drug treatments. CONCLUSIONS: Our results show that ventricular ADM synthesis is an insensitive marker of changes in haemodynamic load or cardiac hypertrophy. Furthermore, the expression of ADM, ANP and BNP genes is differently regulated both in the left ventricle and atria in response to AT1 receptor antagonism and ACE inhibition.     

Pumping ability of the hypertrophying left ventricle of the spontaneously hypertensive rat.

Cardiac pumping ability was assessed during the natural development of left ventricular hypertrophy by elevating venous pressure by infusing Tyrode's solution intravenously to produce peak cardiac output. This experiment was performed on spontaneously hypertensive rats (SHR) of three age groups (11, 24, and 83 weeks). From 11 to 24 weeks, peak cardiac output of SHR increased in direct proportion to the abnormally increased ventricular mass; Thus peak cardiac output per gram of left ventricle (LV) remained stable. Similar results were obtained for two strains of normotensive rats at each of the same three age groups. Thus, in the normotensive animal peak cardiac output per gram of LV remained stable over a wide range of ages and varying left ventricular weights. However, with progressive elevation of arterial pressure in aging SHR (83 weeks), we observed severe ventricular hypertrophy (100% increases in left ventricular to body weight ratio). In this oldest SHR group, unlike age-matched normotensive rats, there was a marked reduction in the pumping ability per gram of LV. Thus, during the natural development of left ventricular hypertrophy SHR demonstrated both a stable stage of hypertrophy in which the increased left ventricular mass maintained its pumping ability, and a later stage of deterioration in which there was a loss of the normal relationship between ventricular mass and pumping ability.