基质金属蛋白酶-2及其抑制物在糖尿病大鼠心肌间质重构中的作用

目的探讨糖尿病心肌病变发生的机制。方法将16只雄性Wistar大鼠随机分为对照组和观察组各8只，观察组腹腔注射链脲佐菌素（STZ）建立糖尿病模型。喂养4周后处死大鼠，取心脏称重，计算心脏质量指数；测定血清基质金属蛋白酶-2（MMP-2）及其抑制物TIMP-2含量，心肌组织MMP-2活性、TIMP-2蛋白、MMP-2 mRNA和TIMP-2 mRNA表达；VG染色观察心肌胶原容积分数（CVF）变化。结果与对照组比较，实验4周时观察组心脏质量、体质量显著下降，心脏质量指数升高，血清TIMP-2显著升高，心肌MMP-2活性和mRNA表达明显减弱，TIMP-2mRNA表达显著增强，心肌CVF明显升高；相关分析表明CVF与心肌MMP-2活性、mRNA表达呈明显负相关，而与TIMP-2mRNA表达呈明显正相关。结论糖尿病心肌组织中MMP-2活性和mRNA表达显著减弱、TIMP-2表达明显增强，其与间质胶原蓄积密切相关，是糖尿病心肌间质重构的重要原因之一；血清TIMP-2水平与心肌表达一致，可作为糖尿病心肌病早期预测和病情监测的指标之一。     

基质金属蛋白酶在心肌肥厚大鼠中的作用及强力霉素的干预效果

目的:观察心肌肥厚大鼠模型中基质金属蛋白酶(MMP)-2,MMP-9及其抑制剂(TIMP-1)的表达及强力霉素干预后对其影响。方法:24只大鼠随机分为对照组(A组,只给予0.9%氯化钠溶液腹腔注射);造模组(B组)和药物干预组(C组)均用去甲肾上腺素1.06mg/kg腹腔注射,bid,注射15d,建立大鼠心肌肥厚模型,C组造模同时给予强力霉素10mg/kg腹腔注射,qd,给药15d。全部动物于给药后16d处死测定全心质量指数、左室质量指数、心肌胶原含量、心肌组织MMP-2,MMP-9,TIMP-1、心肌胶原容积分数(CVF)。结果:与A组比较,B组全心质量指数、左室质量指数、MMP-2、MMP-9阳性表达率、心肌胶原含量及CVF均明显增加(P<0.05),TIMP-1阳性表达率明显降低(P<0.05)。与B组比较,C组全心质量指数、左室质量指数、MMP-2、MMP-9阳性表达率、心肌胶原含量及CVF均明显降低(P<0.05),TIMP-1阳性表达率增加(P<0.05)。结论:去甲肾上腺素诱导的心肌肥厚大鼠MMPs/TIMPs系统平衡破坏,使基质胶原降解与合成平衡破坏,从而导致心室重构。强力霉素可通过抑制MMP来逆转心室重构。     

益气活血方对急性心肌缺血大鼠模型MMP-9及TIMP-1表达的影响

目的观察益气活血方对急性心肌缺血大鼠模型基质金属蛋白酶-9(MMP-9)及基质金属蛋白酶特异性抑制物-1(TIMP-1)表达的影响。方法应用结扎冠状动脉左前降支方法建立Wistar大鼠急性心肌缺血模型,运用HE染色观察其病理改变,同时以ELISA法和SP免疫组化法检测血清TIMP-1含量及心肌组织中MMP-9的阳性表达。结果与假手术组比较,模型组大鼠出现显著的心肌缺血损伤的病理形态;与模型组比较,各药物干预组均可增加心肌缺血后大鼠血清TIMP-1含量(P<0.05),中药高剂量组血清TIMP-1含量显著高于低剂量组和阳性对照组(P<0.01);与模型组比较,各药物干预组大鼠心肌组织中MMP-9表达较有明显降低(P<0.01)。结论益气活血方对大鼠缺血心肌有显著的保护作用,其作用机制可能与影响TIMP-1及MMP-9的表达有关。     

氯沙坦协同辛伐他汀对心力衰竭大鼠心室基质金属蛋白酶2、9及其组织抑制因子1、2基因表达的影响

目的 探讨心力衰竭(心衰)时心脏基质金属蛋白酶2(MMP-2)、9(MMP-9)及其组织抑制因子1(TIMP-1)、2(TIMP-2)基因表达及其与心肌纤维化的关系.方法 用降主动脉缩窄术建立心衰模型.SD大鼠随机分成6组.分别在氯沙坦5 mg/kg、辛伐他汀2 mg/kg以及两药合用(联合投药组)投药后1、3,5周动态测定左室舒张末期内径、左室收缩末期内径及左室后壁厚度、左室短轴缩短率.ELISA法检测B型利钠肽浓度.Masson染色观察心肌胶原情况.RT-PCR法检测心室MMP-2、MMP-9和TIMP-1、TIMP-2基因表达.结果 投药后5周各组胶原容积分数比较差异有统计学意义(P<0.01),投药各组较降主动脉缩窄(模型)组下降(P<0.05),尤其联合投药组下降更明显(P<0.01).MMP-2 mRNA和MMP-9 mBNA在投药各组与模型组差异无统计学意义(P>0.05);但TIMP-1 mRNA和TIMP-2 mRNA在投药各组明显低于模型组(P<0.01),联合投药组降低更明显(P<0.05).结论 心衰模型大鼠MMP-2 mRNA、MMP-9 mRNA和TIMP-1 mRNA、TIMP-2 mRNA表达升高可能是压力负荷大鼠心肌胶原含量增加的分子机制之一,氯沙坦、辛伐他汀以及联合投药均能下调TIMP-1 mRNA、TIMP-2 mRNA水平,缓解心肌重构,尤其联合投药组效果更明显.     

间充质干细胞移植对心肌基质金属蛋白酶-9及抑制因子-1表达的影响

目的:探讨骨髓间充质干细胞移植对阿霉素诱导的心力衰竭大鼠心功能及心肌细胞基质金属蛋白酶(MMP)-9及其抑制因子(TIMP)-1表达的影响.方法:Wister大鼠分为正常对照组、心力衰竭对照组和细胞移植组,后2组腹腔注射阿霉素建立扩张型心肌病模型.细胞移植组尾静脉注射骨髓间充质干细胞.移植后4周,超声心动图测量左室射血分数,免疫组化检查MMP-9、TIMP-1表达情况.结果:与心力衰竭对照组比较,细胞移植组LVEF和MMP-9明显增高,TIMP-1明显下降(P<0.05),接近正常对照组(P>0.05).结论:经静脉移植骨髓间充质干细胞能改善心力衰竭大鼠心功能,调节MMP-9/TIMP-1表达,影响心室重塑.     

硫化氢通过调控转化生长因子-β及基质金属蛋白酶-9/基质金属蛋白酶抑制剂-1改善糖尿病大鼠肾小管间质纤维化

目的探讨硫化氢(H_2S)气体信号分子对糖尿病大鼠肾小管间质纤维化及转化生长因子(TGF)-β、基质金属蛋白酶(MMP)-9/基质金属蛋白酶抑制剂(TIMP)-1表达的影响。方法单次腹腔注射链脲佐菌素(STZ)建立糖尿病模型将成年雄性SD大鼠64只随机分为正常对照组(Control组)、STZ组、STZ+H_2S组、H_2S组。造模72 h后采尾静脉血检测,若血糖>16.7 mmol/L表明造模成功。H_2S组和STZ+H_2S组大鼠腹腔注射Na HS溶液100μmol·kg~(-1)·d~(-1),Control组和STZ组腹腔注射同等量生理盐水。8 w后取标本,Masson染色观察大鼠肾脏组织病理形态学改变,Western印迹检测大鼠肾脏TGF-β、MMP-9、TIMP-1、Ⅳ型胶原蛋白的表达水平。结果与Control组相比,STZ组存在明显肾小管间质纤维化,同时肾脏组织中Ⅳ型胶原、TGF-β、TIMP-1蛋白的表达升高,MMP-9蛋白的表达水平下降(P<0.05);与STZ组大鼠相比,STZ+H_2S组肾小管间质纤维化减轻,肾组织TGF-β、TIMP-1、Ⅳ型胶原蛋白的表达降低,MMP-9蛋白表达水平升高(P<0.05)。结论 H_2S可改善糖尿病大鼠肾小管间质纤维化,其机制可能与调控MMP-9/TIMP-1失衡以及TGF-β蛋白的表达水平有关。     

MMP-9与TGF-β1在肾性高血压大鼠心肌纤维化中的作用及阿托伐他汀的干预研究

目的探讨基质金属蛋白酶-9(MMP-9)和转化生长因子-β1(TGF-β1)在心肌纤维化中的作用及阿托伐他汀的干预研究。方法采用两肾一夹方法建立肾性高血压大鼠模型,将24只大鼠随机分为对照组、高血压组、阿托伐他汀组,每组8只。术后测量左心室重量指数(LVMI),检测心肌羟脯氨酸(HC)浓度,苦味酸-酸性品红(VG)染色检测心肌胶原容积分数(CVF),免疫组化法检测MMP-9与TGF-β1的表达水平。结果高血压组LVMI、HC、CVF与对照组比较均显著升高(P<0.01),MMP-9与TGF-β1的表达水平显著增强(P<0.01)。阿托伐他汀组较高血压组LVMI、HC、CVF均明显降低(P<0.05),MMP-9与TGF-β1的表达水平亦明显减弱(P<0.01)。结论MMP-9与TGF-β1可能与心肌纤维化的形成有关,阿托伐他汀可以抑制大鼠心肌纤维化的形成,其机制可能与降低MMP-9与TGF-β1的表达水平密切相关。     

雷帕霉素在大鼠实验性三硝基苯磺酸结肠炎发病中的作用

目的 观察转录激活因子3(STAT3)特异性抑制剂雷帕霉素(RPM)对大鼠实验性三硝基苯磺酸结肠炎的作用,以及对基质金属蛋白酶(MMPs)、基质金属蛋白酶组织抑制剂(TIMPs)表达的影响,探讨信号转导和转录激活因子-3(STAT3)信号转导通路在大鼠结肠炎发病机制中的作用.方法 建实验性大鼠结肠炎模型后,给予RPM腹腔注射治疗一周后处死大鼠,观察结肠炎症改变并做出评分,SYBR Green Ⅰ实时荧光定量RT-PCR检测结肠组织MMP-1、MMP-2、MMP-3、TIMP-1及TIMP-2的mRNA表达.结果 RPM治疗组肠道损伤积分为(5.17±1.80),低于对照组(P<0.05);MMP-1、MMP-2的mRNA表达量在RPM组均明显降低(P<0.05),而MMP-3、TIMP-1和TIMP-2 mRNA表达无明显差异(P>0.05).结论 RPM通过阻断STAT3信号通路的活化能缓解大鼠结肠炎的病情,这一作用可能是通过抑制MMP-1和MMP-2的表达实现的.     

肝纤维化大鼠肝组织基质金属蛋白酶9及其抑制因子1基因表达的动态变化及下瘀血汤对其影响

[目的]研究免疫性肝纤维化大鼠肝组织基质金属蛋白酶9(MMP-9 mRNA)和基质金属蛋白酶组织抑制因子1(TIMP-1 mRNA)基因表达的动态变化及下瘀血汤对其影响,探讨下瘀血汤抗肝纤维化的机制。[方法]猪血清腹腔注射复制大鼠肝纤维化模型,造模8周后灌胃给予下瘀血汤流浸膏干预治疗,用药4周后和造模过程中的1、2、4、8周动态处死大鼠,获取标本,检测指标。[结果]与正常组相比,模型组1、8、12周MMP-9 mRNA表达明显降低(P0.05,0.01),2周MMP-9 mRNA表达显著升高(P0.01),4周表达无明显变化。与模型组12周相比,下瘀血汤组MMP-9 mRNA表达明显升高(P0.05)。与正常组相比,1、2、4、8和12周模型组TIMP-1 mRNA表达均有显著升高(P0.05,0.01))。与12周模型组相比,下瘀血汤组TIMP-1 mRNA表达显著降低(P0.01)。[结论]大鼠猪血清免疫性肝纤维化存在着MMP-9 mRNA和TIMP-1 mRNA的动态变化,下瘀血汤可通过促进MMP-9 mRNA表达和抑制TIMP-1 mRNA表达而发挥抗肝纤维化的作用。     

阿尔茨海默病模型大鼠脑海马内MMP-9和TIMP-1 mRNA的表达

目的探讨基质金属蛋白酶(MMP)-9和基质金属蛋白酶组织抑制因子(TIMP)-1在阿尔茨海默病(AD)模型大鼠脑海马CA1区的mRNA表达水平。方法将30只雄性Wistar大鼠,随机分为A、B、C、D、E组,每组6只。A组注射5μl生理盐水,B、C、D、E组双侧海马注射凝胶态Aβ25~355μl(依次含有Aβ25~350.5,1.0,5.0,10.0μg),大鼠于14 d后处死。取各组大鼠新鲜血清采用酶联免疫吸附试验(ELISA)检测肿瘤坏死因子(TNF)-α和白细胞介素(IL)-1β的表达量;取新鲜脑海马组织提取mRNA,qRTPCR技术检测MMP-9和TIMP-1 mRNA表达量。结果血清TNF-α含量D、E组明显高于A、B、C组(P<0.01);血清IL-1β含量D、E组明显高于A、B、C组(P<0.01)。MMP-9 mRNA表达量D、E组明显高于A、B、C组(P<0.01);TIMP-1 mRNA表达D、E组明显高于A、B、C组(P<0.01)。结论 Aβ所致AD大鼠脑内发生了炎症反应,MMP-9表达上调,而TIMP-1可与MMP-9特异性结合,进而抑制其活性,因此随着MMP-9上调,TIMP-1表达量也随之增加。     

A nonerythropoietic derivative of erythropoietin protects the myocardium from ischemia-reperfusion injury

The cytokine erythropoietin (EPO) protects the heart from ischemic injury, in part by preventing apoptosis. However, EPO administration can also raise the hemoglobin concentration, which, by increasing oxygen delivery, confounds assignment of cause and effect. The availability of EPO analogs that do not bind to the dimeric EPO receptor and lack erythropoietic activity, e.g., carbamylated EPO (CEPO), provides an opportunity to determine whether EPO possesses direct cardioprotective activity. In vivo, cardiomyocyte loss after experimental myocardial infarction (MI) of rats (40 min of occlusion with reperfusion) was reduced from approximately 57% in MI-control to approximately 45% in animals that were administered CEPO daily for 1 week (50 microg/kg of body weight s.c.) with the first dose administered intravenously 5 min before reperfusion. CEPO did not increase the hematocrit, yet it prevented increases in left ventricular (LV) end-diastolic pressure, reduced LV wall stress in systole and diastole, and improved LV response to dobutamine infusion compared with vehicle-treated animals. In agreement with the cardioprotective effect observed in vivo, staurosporine-induced apoptosis of adult rat or mouse cardiomyocytes in vitro was also significantly attenuated ( approximately 35%) by CEPO, which is comparable with the effect of EPO. These data indicate that prevention of cardiomyocyte apoptosis, in the absence of an increase in hemoglobin concentration, explains EPO's cardioprotection. Nonerythropoietic derivatives such as CEPO, devoid of the undesirable effects of EPO, e.g., thrombogenesis, could represent safer and more effective alternatives for treatment of cardiovascular diseases, such as MI and heart failure. Furthermore, these findings expand the activity spectrum of CEPO to tissues outside the nervous system.     

氨甲酰化促红细胞生成素抗大鼠慢性心力衰竭的实验研究

目的探讨氨甲酰化促红细胞生成素（CEPO）抗慢性心力衰竭（CHF）的作用及其可能的机制。方法 90只Wistar大鼠随机分为心衰组、干预组及对照组。心衰组及干预组均采用腹腔注射异丙肾上腺素（ISO）法建立大鼠CHF模型,干预组予以CEPO干预4周后,测定各组大鼠血流动力学指标、血清诱生型一氧化氮合酶（iNOS）及超氧化物歧化酶（SOD）水平。结果心衰组及干预组左室内压峰值（LVSP）、左室内压上升/下降最大速率（±dp/dtmax）及血清SOD水平较对照组均显著降低（P〈0.05）,而左室舒张末压（LVEDP）、心率（HR）及血清iNOS水平均显著增高（P〈0.05）;干预组LVSP、±dp/dtmax及血清SOD水平较心衰组均显著增高（P〈0.05）,而LVEDP、HR及血清iNOS水平均显著降低（P〈0.05）。结论 CEPO具有抗CHF的作用,可能与抑制过度的NO释放及清除氧自由基有关。     

秋水仙碱对肝纤维化大鼠肝脏基质金属蛋白酶-1及其抑制因子-1表达的影响

目的 观察秋水仙碱对纤维化肝脏基质金属蛋白酶-1(MMP-1)、基质金属蛋白酶组织抑制因子-1(TIMP-1)表达的影响,从胶原降解的角度探讨秋水仙碱对肝纤维化有无逆转作用及可能存在的机制.方法 制备免疫性大鼠肝纤维化模型,并给予秋水仙碱治疗;通过RT-PCR检测MMP-1、TIMP-1的表达,并作Ⅰ、Ⅲ型胶原的免疫组化以及Masson胶原染色.结果 发现秋水仙碱对肝纤维化大鼠MMP-1的表达无明显影响(P>0.05),但可以抑制TIMP-1的表达(P<0.05),促进Ⅰ、Ⅲ型胶原的降解(P<0.05);然而在病理形态学的观察中,未发现秋水仙碱治疗组与肝纤维化模型组之间存在的显著性差异(P>0.05).结论 秋水仙碱可以抑制纤维化肝脏TIMP-1的表达,从而增强间质胶原酶的活性,促进Ⅰ、Ⅲ型胶原的降解,产生抗肝纤维化的作用,但其作用有限.     

Augmented input from cardiac sympathetic afferents inhibits baroreflex in rats with heart failure

It has been established that the baroreflex is markedly decreased in chronic heart failure (CHF). Our recent study has indicated that activation of the cardiac sympathetic afferent reflex (CSAR) inhibits the baroreflex in normal rats, and in the rats with CHF the CSAR is significantly enhanced, which is related to augmented central angiotensin II (Ang II) mechanism. Therefore, the hypothesis is that the augmented CSAR in the CHF state tonically inhibits the baroreflex via central AT1 receptor. To test the hypothesis, the rats with myocardial infarction-induced CHF or sham surgery were anesthetized with alpha-chloralose and urethane, vagotomized, and recordings were made of the mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). We found: (1) left ventricular epicardial application of capsaicin or electrical stimulation of the central end of the left cardiac sympathetic nerve blunted the baroreflex in both sham and CHF rats; (2) left ventricular epicardial application of lidocaine had no significant effects on the baroreflex in sham rats but improved the baroreflex in CHF rats (maximum slope, 1.7+/-0.3 to 2.9+/-0.2%/mm Hg; P<0.01); and (3) intracerebral ventricular injection of losartan had no significant effect on baroreflex in sham rats but improved the baroreflex in CHF rats (maximum slope 1.9+/-0.2 to 3.1+/-0.2%/mm Hg; P<0.01). These results suggest that tonic cardiac sympathetic afferent input plays an important role in the blunted baroreflex associated with CHF, which is mediated by central AT1 receptors.     

Imbalance of angiotensin type 1 receptor and angiotensin II type 2 receptor in the rostral ventrolateral medulla: potential mechanism for sympathetic overactivity in heart failure

Upregulation of angiotensin II type 1 receptors (AT(1)R) in the rostral ventrolateral medulla (RVLM) contributes to the sympathoexcitation in the chronic heart failure (CHF). However, the role of angiotensin II type 2 receptor (AT(2)R) is not clear. In this study, we measured AT(1)R and AT(2)R protein expression in the RVLM and determined their effects on renal sympathetic nerve activity, blood pressure, and heart rate in anesthetized sham and CHF rats. We found that (1) although AT(1)R expression in the RVLM was upregulated, the AT(2)R was significantly downregulated (CHF: 0.06+/-0.02 versus sham: 0.15+/-0.02, P<0.05); (2) simultaneously stimulating RVLM AT(1)R and AT(2)R by angiotensin II evoked sympathoexcitation, hypertension, and tachycardia in both sham and CHF rats with greater responses in CHF; (3) stimulating RVLM AT1R with angiotensin II plus the specific AT(2)R antagonist PD123319 induced a larger sympathoexcitatory response than simultaneously stimulating AT(1)R and AT(2)R in sham rats, but not in CHF; (4) activating RVLM AT(2)R with CGP42112 induced a sympathoinhibition, hypotension, and bradycardia only in sham rats (renal sympathetic nerve activity: 36.4+/-5.1% of baseline versus 102+/-3.9% of baseline in artificial cerebrospinal fluid, P<0.05); (5) pretreatment with 5,8,11,14-eicosatetraynoic acid, a general inhibitor of arachidonic acid metabolism, into the RVLM attenuates the CGP42112-induced sympathoinhibition. These results suggest that AT(2)R in the RVLM exhibits an inhibitory effect on sympathetic outflow, which is, at least partially, mediated by an arachidonic acid metabolic pathway. These data implicate a downregulation in the AT(2)R as a contributory factor in the sympathoexcitation in CHF.     

Catabolism of adenine nucleotides favors adenosine production following exercise in patients with chronic heart failure

BackgroundAdenosine 5′-triphosphate is catabolized to adenosine 5′-monophosphate (AMP), which is further degraded by 2 pathways: deamination to inosine 5′-monophosphate and ammonia by AMP deaminase, or dephosphorylation to adenosine and inorganic phosphate by 5′-nucleotidase. Because adenosine is believed to be cardioprotective and we have reported that ammonia production decreased after exercise in patients with chronic heart failure (CHF), we determined if plasma adenosine levels after exercise increases in patients with CHF.Methods and ResultsMaximal ergometer exercise tests with expired gas analysis were performed in 51 patients with CHF (age = 61 ± 2 years, New York Heart Association [NYHA] class I/II/III = 19/18/14) and 20 age-matched normal controls. Serial changes in both plasma ammonia and adenosine levels were determined. The ratio for Δammonia to peak work rate became smaller (control, NYHA I/II/III: 0.59 ± 0.13/0.41 ± 0.06/0.37 ± 0.10/0.22 ± 0.11 μg/dL·watts, respectively) and the ratio for Δadenosine to peak work rate was significantly higher in class III CHF (control, NYHA I/II/III: 0.93 ± 0.21/0.86 ± 0.14/1.11 ± 0.27/2.92 ± 0.67 nmol/L·watts, respectively).ConclusionIn patients with CHF after exercise, the plasma levels of adenosine increased along with the decrease in the plasma levels of ammonia. Considering the physiologic cardioprotective actions of adenosine, the enhanced adenosine production after exercise may be an important adaptive response in patients with CHF.     

Mechanisms of combined treatment with celiprolol and candesartan for ventricular remodeling in experimental heart failure.

BACKGROUND: Both beta-adrenergic blockers and angiotensin-II receptor blockers were reported to improve the prognosis of patients with heart failure, but the efficacy of combination therapy with these agents has not been fully elucidated. Also the efficacy of celiprolol, a beta1-selective adrenoceptor antagonist with partial beta2-agonist properties, for heart failure treatment is still controversial. We examined the cardioprotective effects and mechanisms of the therapy with celiprolol or candesartan, an angiotensin-II receptor blockers and their combination in heart failure induced by isoproterenol (ISO). METHODS AND RESULTS: ISO 300 mg/kg was injected in rats to produce heart failure. Two months after the injection, the ISO-injected rats were divided into 4 groups (8 rats each) and treated for 4 weeks as follows: (a) vehicle; (b) celiprolol 10 mg/kg per day (BB); (c) candesartan 0.2 mg/kg per day (ARB); and (d) their combination BB+ARB. ISO significantly elevated left ventricular (LV) end-diastolic pressure, decreased peak-negative dP/dt and LV ejection fraction. BB and ARB similarly ameliorated cardiac dysfunction due to ISO, but BB+ARB were more potent than the individual therapies. Separately, ARB preserved the histological structure in LV myocardium. In contrast, BB ameliorated calcium handling, as shown by the increased ratio of SERCA2 to phospholamban protein, despite having little effect on the histology. CONCLUSION: Both celiprolol and candesartan showed cardioprotective effects in this heart failure model. The potential use of the combination treatment in heart failure might result in a synergistic effect through the different cardioprotective mechanisms of celiprolol and candesartan.     

Endothelial dysfunction in congestive heart failure: ACE inhibition vs. angiotensin II antagonism

BACKGROUND: Endothelial dysfunction of the vasculature contributes to the elevated peripheral resistance and reduced myocardial perfusion in congestive heart failure (CHF). The present study systematically investigated the effect of angiotensin II (AT(1))- receptor blockade on vascular superoxide (O(2)(-)) production and endothelial dysfunction. METHODS AND RESULTS: Vasodilator responses and O(2)(-) production were determined in aortic rings from Wistar rats with experimental CHF 10 weeks after extensive myocardial infarction and compared with sham-operated animals (Sham). Rats were either treated with placebo (P), with the AT(1)-receptor antagonist Irbesartan (50 mg kg(-1) day(-1)) or with the ACE inhibitor Trandolapril (0.3 mg kg(-1) day(-1)). In CHF-P, endothelium-dependent, acetylcholine-induced relaxation was significantly attenuated compared with Sham-P. Chronic treatment with Trandolapril or Irbesartan significantly improved endothelium-dependent relaxation. Aortic O(2)(-) formation was markedly increased in CHF, and was not significantly affected by Trandolapril treatment, while it was reduced by Irbesartan. eNOS expression was reduced in CHF and normalised by both treatments. CONCLUSION: Endothelial vasomotor function in CHF rats was normalised by long-term treatment with an ACE inhibitor or an AT(1)-antagonist. Reduced aortic eNOS expression was normalised by both treatments, whereas aortic superoxide formation was only reduced by the AT(1)-antagonist Irbesartan.