组蛋白去乙酰化酶8对肾性高血压大鼠心肌肥大的影响

目的: 研究组蛋白去乙酰化酶8(histone deacetylase 8,HDAC8)在肾性高血压大鼠左心室肥厚中的表达变化及HDAC抑制剂丙戊酸钠(valproic acid sodium, VPA)对心肌肥厚的影响。方法: 建立2肾2夹肾性高血压大鼠模型,术后4周开始给药,VPA高剂量(400 mg·kg^-1·d^-1)组及VPA低剂量(200 mg·kg^-1·d^-1)组连续腹腔注射VPA给药4周,同时设立假手术组和阳性对照坎地沙坦(10 mg·kg^-1·d^-1)组,实验结束时测量左心室/体重比值,HE染色检测心肌组织形态学变化, RT-PCR检测心房利钠因子(atrial natriuretic factor,ANF)和HDAC8 mRNA表达,Western blotting检测HDAC8的表达情况。结果: HDAC8 mRNA和蛋白表达水平在肾性高血压大鼠心肌组织中明显上调;VPA能够剂量依赖性降低HDAC8的表达, 同时VPA治疗组与坎地沙坦组高血压大鼠的左心室肥厚得到明显逆转,表现为心室体重比降低, 肥大心肌形态明显改善且ANF的表达下调。结论: HDAC8参与了肾性高血压大鼠心肌肥厚的发病过程,VPA可以下调其表达并部分逆转心肌肥厚。     

L-精氨酸对肾性高血压心肌肥厚大鼠血浆内皮素及左心室肌原癌基因c-fosmRNA表达的影响

目的:研究L-精氨酸对肾性高血压心肌肥厚大鼠血浆内皮素及左室肌原癌基因c-fosmRNA表达的影响。方法:采用原位杂交方法检测原癌基因c-fosmRNA的表达,并用图像分析仪作半定量分析。用放射免疫法测定血浆内皮素含量。结果:经过8周治疗后,L-Arg使高血压心肌肥厚大鼠左室肌原癌基因c-fosmRNA表达显著减少(P＜0.01),并显著降低血浆内皮素含量(P＜0.01)。结论:L-Arg能降低高血压心肌肥厚大鼠血浆内皮素含量并使左室肌原癌基因c-fosmRNA的表达量减少。     

限钠或补钠对充血性心衰大鼠心钠素及心功能的影响

目的观察限钠或补钠对充血性心衰大鼠心钠素及心功能的影响.方法将充血性心衰大鼠随机分为3组(心衰组、心衰限钠组、心衰补钠组),假手术大鼠为对照组,用放射免疫分析法测定各组血浆和心肌心钠素水平,同时检测心功能.结果心衰限钠组血钠、心房心钠素及左室收缩压和动脉压显著低于心衰组,血浆和心室心钠素、右房压均显著高于心衰组;心衰补钠组血钠和动脉压与对照组无显著差别,血浆和心肌心钠素、右房压与心衰组无显著差别,左室收缩压显著高于心衰组,左室舒张末压显著低于心衰组.结论心衰后适量补钠维持血钠平衡有利于心钠素发挥排钠利尿作用,改善心功能.     

限钠或补钠对充血性心衰大鼠心钠素及心功能的影响

目的：观察限钠或补钠对充血性心衰大鼠心钠素及心功能的影响。方法：将充血性心衰大鼠随机分为3组（心衰组、心衰限钠组、心衰补钠组J）,假手术大鼠为对照组,用放射免疫分析法测定各组血浆和心肌心钠素水平,同时检测心功能。结果：心衰限钠组血钠、心房心钠素及左室收缩压和动脉压显著低于心衰组,血浆和心室心钠素、右房压均显著高于心衰组;心衰补钠组血钠和动脉压与对照组无显著差别,血浆和心肌心钠素、右房压与心衰组无显著差别,左室收缩压显著高于心衰组,左室舒张末压显著低于心衰组。结论：心衰后适量补钠维持血钠平衡有利于心钠素发挥排钠利尿作用,改善心功能。     

卡托普利对二肾一夹高血压大鼠血浆β－内啡肽浓度的抑制作用

卡托普利对二肾一夹高血压大鼠血浆β－内啡肽浓度的抑制作用湖南省肿瘤医院（长沙４１０００６）刘人树湖南中医学院科研处李钟文用放射免疫法（ｒａｄｉｏｉｍｍｕｎｏａｓｓａｙ，ＲＩＡ）测定二肾一夹高血压大鼠（Ｇ－２ＫＩＣｒｅｎａｌｈｙｐｅｒｔｅｎｓｉｖｅｒａ...     

SHR心脏肥厚对心肌胶原及血管紧张素Ⅱ含量的变化

采用病理学及放射免疫方法检测 16、2 4和 32周龄自发性高血压大鼠 (SHR)心肌胶原容积分数 (CVF)和心肌血管周围胶原面积 (PVCA)、心脏肥厚指标及血浆和组织血管紧张素Ⅱ (AngⅡ )浓度 ,并以同龄Wister大鼠作对照 ,以探讨SHR心脏肥厚进展阶段心肌纤维化、心脏重构、血浆和组织血管紧张素Ⅱ浓度及其相互关系。结果显示各组SHR收缩压明显增高、心脏肥厚指标心脏重量 (HW )、左室重量 (LVW)、左室重量指数 (LVW BW)显著增加 ,血浆、心肌组织AngⅡ浓度明显增高 ;2 4、32周龄SHR的CVF和PVCA显著增加 ;SHR心肌组织AngⅡ浓度与CVF呈显著正相关。结果表明心肌纤维化可能参与SHR代偿性心脏肥厚阶段心脏重构病理过程 ,组织AngⅡ可能是导致SHR代偿性心脏肥厚阶段心肌纤维化的重要机制之一     

SHR心脏肥厚对心肌胶原及血浆紧张素Ⅱ含量的变化

采用病理学及放射免疫方法检测16、24和32周龄自发性高血压大鼠（SHR）心肌胶原容积分数（CVF）和心肌血管周围胶原面积（PVCA）、心脏肥厚指标及血浆和组织血管紧张素Ⅱ（AngⅡ）浓度,并以同龄Wister大鼠作对照,以探讨SHR心脏肥厚进展阶段心肌纤维化、心脏重构、血浆和组织血管紧张素Ⅱ浓度及其相互关系。结果显示,各组SHR收缩压明显增高、心脏肥厚指标心脏重量（HW）、左室重量（LVW）、左室重量指数（LVW／BW）显著增加,血浆、心肌组织AngⅡ浓度明显增高;24、32周龄SHR的CVF和PVCA显著增加;SHR心肌组织AngⅡ浓度与CVF呈显著正相关。结果表明心肌纤维化可能参与SHR代偿性心脏肥厚阶段心脏重构病理过程,组织AngⅡ可能是导致SHR代偿性心脏肥厚阶段心肌纤维化的重要机制之一。     

Dyrk1A经ASF调控CaMKⅡδ可变剪接在肾血管性高血压大鼠心肌肥厚中的作用

 目的：探讨双特异性酪氨酸磷酸化调节激酶1A (Dyrk1A) 经可变剪接因子(ASF)对钙/钙调素依赖蛋白激酶Ⅱδ（CaMKⅡδ）可变剪接的调控在肾血管性高血压大鼠心肌肥厚中的作用。方法：制备两肾一夹肾血管性高血压大鼠模型,给予Dyrk1A抑制剂表没食子儿茶素没食子酸酯（EGCG）和哈尔碱（harmine）干预,观察大鼠血压及心肌肥厚程度变化,逆转录-多聚酶链反应法检测CaMKⅡδ可变剪接的改变,免疫印迹法检测大鼠心肌Dyrk1A和ASF蛋白质表达的变化。结果：两肾一夹术后8周,与假手术组相比,手术组大鼠血压显著升高（P<0.05）,大鼠左室重、左室重/体重比值及心肌细胞面积均增高（P<0.05）,同时该组大鼠心肌中Dyrk1A蛋白表达增加,ASF蛋白表达下降（P<0.05）,CaMKⅡδ亚型可变剪接表现为CaMKⅡδA、δB mRNA表达升高,δC mRNA表达降低（P<0.05）;与手术组相比,EGCG和哈尔碱组大鼠左室重、左室重/体重比值和心肌细胞面积下降,同时大鼠心肌中Dyrk1A蛋白表达降低,ASF蛋白表达上调,CaMKⅡδ亚型可变剪接逆转（均P<0.05）。结论：Dyrk1A可通过ASF调控CaMKⅡδ的可变剪接,从而参与肾血管性高血压大鼠心肌肥厚的发生。     

肾性高血压大鼠左心室肌球蛋白重链同型基因的表达

目的和方法：用二肾一夹（２Ｋ１Ｃ）肾性高血压大鼠模型，利用分子生物学实验方法，探讨心肌肥厚发生和逆转以及肌球蛋白重链（ＭＨＣ）基因表达的改变。结果：（１）２Ｋ１Ｃ肾性高血压大鼠术后第２～１２周，动脉血压持续升高；左心室重量和体重比值明显升高；左心室α－ＭＨＣｍＲＮＡ表达明显减弱；β－ＭＨＣｍＲＮＡ表达明显增强。（２）在术后第４周给予巯甲丙脯酸和术后第８周切除肾动脉狭窄侧肾脏可使２Ｋ１Ｃ肾性高血压大鼠动脉血压下降；左心室肥厚发生逆转；抑制左心室α－ＭＨＣｍＲＮＡ表达减弱和β－ＭＨＣｍＲＮＡ表达增强。结论：在２Ｋ１Ｃ肾性高血压过程中，动脉血压升高是左心室肥厚、左心室肌球蛋白ＭＨＣ基因表型转换的重要因素；血管紧张素Ⅱ可能参与２Ｋ１Ｃ肾性高血压过程中的心肌肥厚和ＭＨＣ同型基因表型的转换     

肾性高血压大鼠血浆ET、CGRP、AngⅡ水平变化及缬沙坦、贝那普利干预的影响

目的:研究肾性高血压大鼠血浆内皮素(ET)、降钙素基因相关肽(CGRP)、血管紧张素Ⅱ(AngⅡ)等血管活性物质的变化及降压药物缬沙坦、贝那普利干预对收缩压和ET、CGRP、AngⅡ的影响。方法:采用两肾一夹方法复制肾性高血压大鼠模型,成模大鼠随机分为缬沙坦组(30mg/kg/天,n=8)、贝那普利组(10mg/kg/天,n=8)、肾性高血压模型组(n=8);假造模大鼠作为假手术组(n=10),前两组以缬沙坦和贝那普利溶液、后两组以等量生理盐水每日灌胃。分别于术前及术后每周末测定各组大鼠收缩压变化,并在灌药治疗8周后用放免法测定各组血浆ET、CGRP、AngⅡ含量变化。结果:两肾一夹术后4周可形成稳定肾性高血压大鼠模型。缬沙坦组、贝那普利组大鼠经灌胃治疗8周后血压明显下降(P<0.01)。肾性高血压模型组ET、CGRP、AngⅡ血浆浓度均高于假手术组(P<0.05或P<0.01);缬沙坦组、贝那普利组CGRP浓度高于肾性高血压模型组(P<0.05),贝那普利组AngⅡ浓度低于肾性高血压模型组和缬沙坦组(P<0.05);肾性高血压模型组血浆ET与AngⅡ浓度呈正相关(r=0.62,P<0.05)。结论:肾性高血压大鼠血浆ET、CGRP、AngⅡ浓度增高,缬沙坦、贝那普利可能通过调节血管活性物质水平而降低收缩压。     

Depolarization pattern of ventricular epicardium in two-kidney one-clip hypertensive rats

The present study is the first attempt to examine the effect of left ventricular hypertrophy (LVH) on the excitation pattern of the ventricular epicardium in experimental hypertensive rats. The left renal artery was clipped in Wistar rats (n = 8; 6-8 months old; weight, 174-295 g) to produce two-kidney one-clip (2K1C) hypertension. After 4 weeks, blood pressure was measured, and epicardial potential mapping was performed under sinus rhythm from 64 unipolar electrodes regularly distributed over the ventricular epicardium. Systolic blood pressure was approximately 40% higher in the rats with a clipped renal artery (162 +/- 14 mmHg, mean +/- s.d.) than in the normotensive rats (115 +/- 3 mmHg). LVH (approximately 23% increase in the ratio of the left ventricular weight to the body weight, P < 0.05) was observed in the 2K1C hypertensive rats. The depolarization pattern of the ventricular epicardium in the normotensive rats was similar to that in the rats with 2K1C hypertensive LVH. The duration of ventricular epicardial activation was shown to increase (approximately 35%, P < 0.05) in the hypertensive rats as compared to the normotensive animals. This study provides an explanation for alterations of the body surface potential distribution in hypertensive patients with LVH.     

Decreased myocardial Na+-K+-ATPase activity in one-kidney, one-clip hypertensive rats

We have previously shown that Na+-K+ pump activity (ouabain-sensitive 86Rb uptake) is decreased in vascular tissue of animals with various forms of low renin hypertension. In the present study we measured Na+-K+-ATPase activity, the energy source for Na+-K+ pumping, in membrane fractions prepared from myocardial tissue of rats with chronic one-kidney, one-clip hypertension and their one-kidney normotensive controls. Membranes were prepared by two independent methods: microsomal fractions (method 1) and fractions prepared by the hypotonic LiBr method of Dhalla et al. (method 2). In membranes prepared from left ventricles of the hypertensive rats (by method 1) Na+-K+-ATPase activity was decreased, Mg2+-ATPase activity was increased, and the sialic acid content and 5'-nucleotidase activity (two putative membrane markers) were unchanged relative to the control rats. The sensitivity of cardiac Na+-K+-ATPase to inhibition by ouabain was also unchanged. Na+-K+-ATPase activity was also decreased in the right ventricles (method 1) of these hypertensive rats, suggesting that this defect is probably not pressure related. In membranes prepared from the left ventricles of the hypertensive rats by method 2, Na+-K+-ATPase activity was again reduced, whereas the Mg2+-ATPase and 5'-nucleotidase activities were unchanged relative to the controls. These studies suggest that myocardial Na+-K+-ATPase activity is suppressed in rats with this low renin form of hypertension and the possible effect of this suppression on myocardial contractile activity is discussed.     

Reversibility of exercise-induced translocation of Na+-K+ pump subunits to the plasma membrane in rat skeletal muscle

The aim of our study was to clarify whether atrial (ANP) and brain (BNP) natriuretic peptides and the hypotensive peptide adrenomedullin (ADM) are regulated differently in the rat heart in the two-kidney, one-clip model of renovascular hypertension. We assessed messenger ribonucleic acid (mRNA) abundance and distribution of ANP, BNP and ADM in the ventricles and atria of rats after unilateral renal artery stenosis (clipping). Rats were clipped for 6 h or 1, 2 or 4 days and mRNA levels were assessed semiquantitatively in left and right atria and ventricles by RNase protection assay. Left ventricular BNP mRNA up-regulation (4.3-fold after 6 hours) preceded ANP up-regulation (4.5-fold after 1 day) and seemed to be transient, whereas ANP mRNA levels were still elevated at day 4 (2.4-fold vs. sham). The right ventricle and the atria did not participate in these responses. Despite the massive changes of natriuretic peptide mRNAs, ADM mRNA did not change in either the ventricles or the atria. In contrast to ANP and BNP mRNA, which predominate in atrial tissue, mRNA for adrenomedullin is equally distributed in ventricles and atria. Plasma levels of immunoreactive (ir)-ANP and ir-BNP changed in parallel with left ventricular mRNA levels. Our findings suggest that renovascular hypertension induced by clipping the renal artery leads to immediate, but independent, up-regulation of ANP and BNP mRNA in the left ventricle whereas adrenomedullin mRNA is not changed.     

Increased oxytocinergic system activity in the cardiac muscle in spontaneously hypertensive SHR rats

IntroductionThe present study aimed to determine whether the presence of cardiac hypertrophy due to arterial hypertension is associated with a change in the activity of the oxytocinergic system in cardiomyocytes.Material and methodsThe experiments were performed on male, spontaneously hypertensive rats (SHR, n = 10) and normotensive Wistar-Kyoto rats (WKY, n = 12). Blood samples were collected from both SHR and WKY animals to asses plasma oxytocin (OT) concentration; the rats were sacrificed by decapitation. Samples of the left and right ventricles were harvested for the analysis of the OT and oxytocin receptor (OTR) protein by ELISA, and OT and OTR mRNA expression by RT-PCR. Immunohistopathological studies were performed to confirm the presence of OTR receptors in the cardiac muscle of the ventricles.ResultsPlasma OT concentration did not differ between SHR and WKY rats. In the SHR rats, the expression of OT mRNA and the OT protein level was higher in the left and the right ventricle, while OTR mRNA expression was significantly lower in both the left and the right ventricle. However, the level of OTR protein was higher only in the left ventricle of the SHR rats. The presence of OTR receptors was confirmed by immunohistochemical analysis in the muscle of the right and left ventricle.ConclusionsThe presence of arterial hypertension is associated with increased activity of the oxytocinergic system in the heart, especially in the area of the left ventricle. These findings support the important role of this system in the maintenance of cardiovascular homeostasis.     

In vivo protein synthetic rates of atrial, ventricular, and pulmonary tissue proteins in aortic constriction, goldblatt, and bromoethylamine models of hypertension

Changes in tissue protein synthesis in hypertension have usually been measured in vitro in heart from acutely hypertensive rats without consideration of changes in atrial or pulmonary tissue or changes occurring in long-standing hypertension. The objective of the study was to investigate the in vivo changes in cardiopulmonary protein synthesis in three different rat models of chronic hypertension. Hypertension in aortic constriction, the Goldblatt model, and the bromoethylamine model were induced in rats for 30 days. At the end of the experimental period, in vivo rates of protein synthesis were measured with a flooding dose of [3H]phenylalanine (a method which effectively considers precursor pools). Concomitant measurements included quantification of contractile protein and RNA and DNA contents. Indices of protein breakdown were also assessed by selective measurement of protease activities. At the end of 30 days, aortic constriction induced marked increases in protein contents of the left ventricle, septum, left atria, and lungs. Accompanying changes included concomitant increases in RNA and DNA contents. Left ventricular myofibrillary, sarcoplasmic, and stromal protein contents increased in the aortic constriction model. Less marked changes occurred in the Goldblatt model, though the left atria were not significantly affected. In contrast, the bromoethylamine model had no effect on the protein or RNA contents of any region. In all cardiac regions of all three models, fractional rates of protein synthesis were not significantly affected. However, protein synthesis increased in the lungs of both the Goldblatt and bromoethylamine models at 30 days. Protease activities were decreased in the left ventricles of all three models at 30 days, with lysosomal protease activities declining in the aortic constriction model and cytoplasmic protease activities declining in the other two models. The failure of chronic hypertension to increase ventricular synthesis rates may represent inherent limitations in the time frame for measuring protein synthesis in vivo. However, at earlier time points (i.e., 10 days), the aortic constriction model was characterized by marked increases in left ventricular and atrial protein contents, RNA contents, and fractional rates of protein synthesis. This was consistent with the supposition that, in acute phases of hypertrophy, rates of protein synthesis increase, whereas in established hypertrophy, synthesis rates remain unchanged or decrease. The applicability of the aortic constriction model was investigated by examining the effects of the angiotensin converting enzyme inhibitor lisinopril (5 mg/kg/day). After 30 days treatment, lisinopril impeded the increase in left ventricular mixed and myofibrillar proteins. This effect was accompanied by an apparent increase in protein synthesis. In conclusion, although all three chronic models are able to induce hypertension, varying degrees of hypertrophy develop, which are more pronounced in the aortic constriction model. Accompanying changes include hypertrophy in the atria, reduced rates of ventricular proteolytic activity, and altered rates of protein metabolism in the lungs.     

The content and distribution of troponin I, troponin T, myoglobin, and alpha-hydroxybutyric acid dehydrogenase in the human heart

We studied the content and distribution of heart-specific markers troponin I and troponin T in relation to conventional non-heart specific myoglobin and alpha-hydroxybutyric acid dehydrogenase (HBD) in the hearts of 34 patients who died of various causes. Tissue was obtained from the right and left ventricles, the interventricular septum, and the right and left atria. We found significant differences in the contents expressed per gram wet weight tissue in the right and left ventricles for troponin I (by 1 of the 2 methods used), troponin T, myoglobin, and HBD and no differences per gram of protein. The biochemical contents per gram wet weight tissue and per gram protein were significantly lower in the right and left atria for all studied markers compared with the right and left ventricles. No significant differences were found in biochemical contents between the right and left atria. These findings imply that estimation of myocardial damage through cardiac markers levels in serum depends on the site of injury (atrium or ventricle). Comparison of myocardial injury among individuals using marker levels in serum is not reliable because of the varied ranges of markers in tissue contents.     

妊娠期高血压疾病患者血清尾加压素Ⅱ对心脏形态及功能影响的研究

目的探讨妊娠期高血压疾病患者血清尾加压素Ⅱ（UrotensinⅡ，UⅡ）水平对心脏形态及功能变化的影响。方法采用美国HP-5500型彩色多普勒超声诊断仪测量96例妊娠期高血压疾病患者及20例正常妊娠者孕晚期心脏房室腔大小、左室壁厚度，记录左室射血分数（EF）、心输出量（CO）、心脏指数（CI）作为评价心功能的指标，同时采用放射免疫法检测外周血中血清UⅡ水平。结果（1）与正常妊娠组对比，妊娠期高血压疾病组左室舒张末期室间隔厚度（IVSTd）、左室后壁厚度（LVPWTd）、左房收缩末期内径（LAD）均增加（P〈0．01或〈0．05），血清UⅡ水平升高，且其水平与上述各项指标均呈显著正相关关系（P均〈0．05）。（2）左室功能比较，妊娠期高血压疾病各组CO、CI、EF与正常妊娠组相比，差异无显著性意义（P均〉0．05）。结论妊娠期高血压疾病患者妊娠晚期血清UⅡ水平与心脏形态及功能改变有关，UⅡ可能参与妊娠期高血压疾病的心脏变化过程。     

Contractile and Electrical Functions of Rat Heart during Left Ventricular Hypertrophy

Left ventricular hypertrophy of the hearts in Wistar rats caused by renovascular hypertension prolongs depolarization of epicardial surface of the ventricles and increases the duration of excitation phase in the left ventricular epicardium. Sex-related differences in changes of myocardial contractility were revealed during hypertrophy of the left ventricle caused by renovascular hypertension.