一氧化氮合酶2抑制剂改善大鼠心肌梗死后心功能的作用

目的 :探讨一氧化氮合酶 2 (NOS2 )改善心肌梗死 (MI)后心功能障碍的作用。方法 :选用选择性NOS2抑制剂S 甲基硫脲 (SMT)抑制NOS2。于MI后 4周观察SMT对心功能的影响。结果 :MI组MI后 4周 ,心肌NOS2表达及血浆一氧化氮 (NO)水平均较假手术组升高 [(0 .2 6 1± 0 .0 2 5 )∶(0 .0 92± 0 .0 11)A·μm-2 ,P<0 .0 5 ];(4 6 .6± 4 .2 )∶(30 .6± 2 .1) μmol/L ,P <0 .0 5 ]。SMT干预 4周可使MI后血浆NO水平降低 [(2 6 .6±2 .2 )∶(4 6 .6± 4 .2 ) μmol/L ,P <0 .0 5 ],心室肥厚减轻 ,MI范围缩小 ,心功能改善 [左室舒张末压 (6 .1± 0 .7)∶(11.0± 1.2 )mmHg(1mmHg =0 .133kPa) ,P <0 .0 5 ];中心静脉压 (0 .8± 0 .1)∶(1.6± 0 .2 )mmHg ,P <0 .0 5 ]。结论 :抑制NOS2可以改善MI后心功能。NOS2及其产物NO在MI后心功能障碍的发生发展过程中起促进作用     

一氧化氮合酶mRNA在压力超负荷心肌肥厚中的作用

目的:研究一氧化氮合酶(NOS)mRNA在心肌肥厚发生发展中的作用以及卡托普利防治心肌肥厚的机制。方法:采用腹主动脉狭窄术建立压力超负荷心肌肥厚动物模型,应用RT-PCR方法于术后1、2、4周,分别检测对照组、心肌肥厚组和卡托普利组大鼠左心室心肌组织NOS mRNA表达的变化。结果:①与对照组相比,术后1、2、4周心肌肥厚组大鼠左室重/体重(LVW/BW)指标及SBP均显著升高;左心室eNOS mRNA表达降低,iNOS mRNA表达升高,nNOS mRNA表达无明显变化。②与心肌肥厚组相比,术后1、2、4周卡托普利组大鼠LVW/BW及SBP均显著降低;左心室eNOS mRNA表达升高,iNOS mRNA表达降低,接近对照组。结论: eNOS和iNOS参与心肌肥厚的发生发展过程,但二者起不同作用。卡托普利防治心肌肥厚的作用可能与其调节NOS mRNA表达密切相关。     

糖尿病心肌病早期心肌局部血管紧张素Ⅱ和一氧化氮的变化

目的 :观察糖尿病大鼠心功能改变早期心肌局部血管紧张素Ⅱ (AⅡ )和一氧化氮 (NO)的变化。方法 :实验动物分为 2组 ,对照组 8只 ,链脲左菌素 (STZ)诱导糖尿病大鼠 8只 ,正常饲养 3个月后杀检 ,测心功能、血压、心脏重量指数及AⅡ、血管紧张素转换酶 (ACE)、NO和一氧化氮合酶 (iNOS)表达。结果 :糖尿病 3个月时首先出现心脏舒张功能异常 ,-dp dtmax减低 ,血压无显著改变 ,心脏重量指数增加 ,血浆AⅡ、ACE明显增高 ,心肌局部AⅡ、ACE增高不明显 ,心肌局部NO明显减低 ,iNOS表达增强 ,血浆NO明显减低。结论 :糖尿病心功能改变早期AⅡ、ACE增高和NO的减低可能共同参与了糖尿病心肌病的发生。     

急性心肌缺血大鼠诱生型一氧化氮合酶的检测

目的 观察诱生型一氧化氮合酶(inducible nitric oxide sythase,iNOS)蛋白在心肌梗死后早期大鼠心脏的表达变化.方法 将12只大鼠随机分为心肌梗死组和假手术组.采用开胸结扎冠状动脉左前降支的方法建立心肌缺血模型,用免疫组织化学方法检测大鼠心肌梗死后24 h缺血心脏iNOS蛋白颗粒的表达.结果 在大鼠冠状动脉结扎后24h,梗死周围区心肌组织细胞出现大量iNOS蛋白表达,与假手术组相比差异有统计学意义(P＜0.01)假手术组未见iNOS蛋白表达.结论 正常心肌组织无iNOS蛋白表达,心肌梗死后早期缺血心肌组织检测到大量iNOS蛋白表达.     

低声压级水平次声对心肌梗死大鼠心肌纤维化的影响及机制研究

目的:观察次声对心肌梗死后大鼠心肌纤维化的影响及相关机制研究。方法:将30只SD大鼠随机分为3组,即假手术组、心肌梗死组及次声治疗组,每组10只。采用低声压级水平次声对心肌梗死大鼠治疗1周(2次/d,0.5 h/次),观察心肌胶原和血浆NO和血管紧张素-Ⅱ(AngⅡ)及大鼠心功能的变化。结果:与心肌梗死组大鼠比较(未治疗组),次声治疗组大鼠心肌胶原表达明显减少,血浆NO含量显著增加(P0.01),血浆AngⅡ含量显著降低(P0.01),心功能明显改善(P0.01)。结论:低声压级水平次声治疗能够明显减轻心肌梗死后大鼠心肌纤维化,其作用可能与血浆NO及AngⅡ含量变化有关。     

阿霉素对大鼠心肌诱导型一氧化氮合酶mRNA表达的影响

目的研究阿霉素(ADM)对大鼠心肌诱导型一氧化氮合酶(iNOS)mRNA表达的影响。方法将雄性wistar大鼠24只,随机分为ADM组和对照组,每组12只,ADM组按每次给ADM 2 mg/kg腹腔注射,隔日一次共6次;对照组给等体积的生理盐水腹腔注射。于实验第30 天,应用生化方法测定心肌组织中的一氧化氮(NO)水平及iNOS的活性;用TUNEL法检测心肌细胞的凋亡指数;用RT—PCR方法检测心肌组织iNOS mRNA的表达。结果与对照组比较ADM组大鼠心肌组织NO、iNOS活性增加(P< 0.01),心肌细胞凋亡指数及iNOS mRNA的表达均显著增高(P< 0.01)。结论ADM能诱导大鼠心肌细胞iNOS mRNA表达增加,使NO合成增多,引起细胞凋亡而参与对心肌的损害。     

N-乙酰半胱氨酸对阿霉素致心力衰竭兔心肌细胞凋亡的作用

目的:探讨慢性心力衰竭(HF)兔心肌核因子-κB(NF-κB)活化、诱生型一氧化氮合酶(iNOS)与心肌细胞凋亡的关系以及N-乙酰半胱氨酸(NAC)对心肌细胞凋亡的作用。方法:设立对照组,剩余动物以阿霉素复制HF模型,随机分为HF组和NAC组,药物干预4周。观测3组心肌细胞凋亡指数、血清和心肌一氧化氮(NO)浓度、iNOS蛋白在心肌细胞中表达的水平,以及NF-κB p65的核表达和结合活性的改变,观察NAC对上述指标的影响。结果:与对照组比较,HF组心肌细胞凋亡指数增高,iNOS蛋白表达增多,NF-κB p65易位和核内表达增多,血清和心肌NO浓度升高(P<0.001),NF-κB p65活化与iNOS表达呈直线相关(r=0.973,P<0.001)。NAC组结果示NAC可显著减少NF-κB p65核内表达及iNOS蛋白的表达,降低血清和心肌NO水平,降低心肌细胞凋亡指数(P<0.01～0.001)。结论:HF时心肌细胞中NF-κB的活化及其促进iNOS的转录合成导致NO大量生成,参与了心肌凋亡的发生。NAC可显著拮抗NF-κB的大量活化核表达,减弱iNOS的表达上调,抑制NO的生成,减少心肌细胞凋亡。NF-κB的活化可能是iNOS表达的重要调控机制之一。     

骨髓干细胞心肌内移植增加诱生型一氧化氮合酶的表达

目的:通过研究骨髓干细胞心肌内移植是否影响心脏血管内皮舒张功能相关的一氧化氮合酶(NOS)基因的表达,探讨骨髓干细胞心肌内移植对血管舒张功能的影响机制。 方法:对Lewis大鼠进行冠状动脉前降支结扎和骨髓干细胞梗死区域心肌内移植,术后梗死区域心脏取材。分为急性心肌梗死组、骨髓干细胞心肌内移植组各15只,及正常组3只。用逆转录多聚酶链反应(RT-PCR)方法检测诱生型一氧化氮合酶(iNOS)和内皮源性一氧化氮合酶(eNOS)的表达。 结果:急性心肌梗死组心肌组织中iNOS的表达在1天时明显增高,3天后迅速减低;骨髓干细胞心肌内移植组,心肌组织中iNOS的表达进一步增高,可维持1个月(P<0.01)。急性心肌梗死组以及骨髓干细胞心肌内移植组,心肌组织eNOS的表达没有增加(P>0.05)。 结论:骨髓干细胞心肌内移植增加心肌组织iNOS的表达,延长其表达时间,但不影响心肌组织eNOS的表达。     

L-精氨酸对肾性高血压心肌肥厚大鼠左心室肌原癌基c-fos蛋白表达及血浆NO含量的影响

目的:探讨L-精氨酸对肾性高血压心肌肥厚大鼠左室肌原癌基因c-fos表达及血浆NO含量的影响.方法:采用免疫组织化学方法测定左室肌原癌基因c-fos蛋白表达,用比色法测定血浆一氧化氮含量.结果:通过8周治疗后,L-Arg使高血压心肌肥厚大鼠c-fos蛋白表达显著减少(P<0.005),使血浆中NO含量显著升高(P<0.001)结论:L-Arg治疗高血压心肌肥厚大鼠能减轻c-fos表达和提高血浆中NO含量.     

安心颗粒对心力衰竭大鼠血清一氧化氮及心肌JAK_1蛋白表达的影响

目的探讨安心颗粒对心力衰竭大鼠血清一氧化氮(NO)及心肌JAK1蛋白表达的影响。方法 72只SD大鼠随机分为6组:正常对照组(A组)、模型组(B组)、卡托普利组(C组)、安心颗粒小剂量组(D组)、安心颗粒中剂量组(E组)、安心颗粒大剂量组(F组)。采用阿霉素腹腔注射造模。同时,各用药组分别灌胃给药,每周1次,连续6周。6周后测定各组心功能、血清一氧化氮(NO)、一氧化氮合酶(NOS)水平及心肌JAK1蛋白表达。结果 B组NO、NOS水平与心肌JAK1蛋白表达活性均高于A组(P0.01);C组、D组、E组、F组NO、NOS水平和心肌JAK1蛋白表达活性均低于B组(P0.05或P0.01)。结论安心颗粒可抑制JAK活性,降低血清NO、NOS浓度,改善左心室功能。     

Inhibition of NOS2 ameliorates cardiac remodeling,improves heart function after myocardial infarction in rats

Abstract. Objective: Previous studies have shown increased expression of nitric oxide synthase 2 (NOS2) in rat heart several weeks after myocardial infarction (MI). The aim of this study was to examine the effect of chronic administration of S-methylisothurea (SMT), a selective NOS2 inhibitor, commenced one week after MI on hemodynamic parameters and left ventricular (LV) remodeling in rats. Methods: Rats with MI induced by left coronary ligation were given SMT (0.5 mg/kg/d) or saline by gavage starting one week after MI. After chronic administration for five weeks, hemodynamic and cardiac morphologic studies were performed, and lung water content, plasma NO_x concentration, NOS2 protein level, myocyte size and collagen volume fraction of noninfarct LV area were quantified. Results: The NO_x concentration in plasma and the NOS2 protein level in noninfarct myocardium in MI rats were higher than controls. When compared with the MI rats receiving saline, chronic administration of SMT reduced myocyte size (15.1 ± 1.6 µm vs 16.9 ± 2.3 µm, P < 0.05), collagen volume fraction of noninfarct LV area (4.4% ± 1.1% vs 5.7% ± 1.2%, P < 0.01) and lung water content (77.4% ± 1.4% vs 79.3% ± 0.9%, P < 0.01), without affecting infarct size. Administration of SMT had no significant effect on heart rate and mean arterial pressure, but decreased LV end-diastolic pressure (8.7 ± 2.1 mmHg vs 13.4 ± 3.1 mmHg, P < 0.01), central venous pressure (0.9 ± 0.3 mmHg vs 1.5 ± 0.5 mmHg, P < 0.01) and inner LV diameter (6.9 ± 0.3 mm vs 7.2 ± 0.3 mm, P < 0.05) in the MI rats. Plasma level of NO_x in the MI rats receiving SMT was reduced to control level. Conclusions: Chronic administration of SMT had beneficial effects on LV remodeling and cardiac dysfunction in MI rats, suggesting the possibility that inhibition of NOS2 could be a therapeutic tool for cardiac dysfunction after MI.     

Borderzone contractile dysfunction is transiently attenuated and left ventricular structural remodeling is markedly reduced following reperfused myocardial infarction in inducible nitric oxide synthase knockout mice.

OBJECTIVES: We sought to determine the effect of inducible nitric oxide synthase (iNOS) expression on regional contractile function and left ventricular (LV) remodeling after reperfused myocardial infarction (MI). BACKGROUND: Inducible nitric oxide synthase is known to contribute to global LV dysfunction after a large MI, but the mechanisms underlying this dysfunction remain unclear. METHODS: We used immunohistochemistry to investigate the distribution of iNOS expression in wild-type (WT) and iNOS knockout (KO) mice early (day 1) and late (day 28) after reperfused MI. We also used serial cardiac magnetic resonance imaging at baseline and at 1, 7, and 28 days after MI to assess LV volumes, ejection fraction (EF), regional circumferential strain (E(cc)), and day 1 infarct size. RESULTS: At baseline, LV volumes and EF were similar between groups. Day 1 infarct size was also similar between groups. Immunohistochemistry revealed that iNOS expression was abundant throughout the heart in WT mice on day 1 after MI, particularly near the infarct borderzone. On day 7 after MI, E(cc) in KO mice was significantly improved in some borderzone sectors compared with WT. The LV volumes were significantly lower in KO mice at days 7 and 28 compared with WT. The EF on days 7 and 28 was significantly higher in KO mice compared with WT. The circumferential extent of wall thinning was also significantly reduced in KO versus WT mice at days 7 and 28. CONCLUSIONS: Expression of iNOS contributes importantly to post-infarction contractile dysfunction and subsequent LV remodeling, suggesting new strategies to combat heart failure resulting from large MI.     

Involvement of inducible nitric oxide synthase in the inflammatory process of myocardial infarction

Inducible nitric oxide synthase (iNOS), which catalyzes the reaction of -arginine to -citrulline and nitric oxide (NO), plays an important role in immune-mediated cardiac disorders. The present report summarizes and discusses findings on the induction of NOS in myocardial infarction of rabbits. iNOS was significantly increased in infarcted myocardium 48 h after coronary artery ligation. The effect persisted for 14 days and declined thereafter. Immunohistochemical localization revealed macrophages as a major source of iNOS expression; iNOS expression was also present in infarcted human myocardium. Increased iNOS activity appeared to be related to the induction of apoptosis in infiltrating macrophages and cardiomyocytes. Moreover, preferential inhibition of iNOS by S-methylisothiourea sulfate (SMT) resulted in significant improvement of left ventricular performance and increased regional myocardial blood flow. These findings suggest that selective inhibition of iNOS activity may provide a therapeutic strategy in cardiac disorders such as myocardial infarction.     

Cytokine-induced nitric oxide inhibits mitochondrial energy production and induces myocardial dysfunction in endotoxin-treated rat hearts

The mechanism responsible for cardiac depression in septic shock remains unknown. The present study examined whether nitric oxide (NO) overproduced by inducible NO synthase (iNOS) can inhibit aerobic energy metabolism and impair the myocardial function in endotoxin-treated rat hearts. Lipopolysaccharide (LPS) significantly decreased systolic blood pressure (BP) to 44% of control during the 48 h treatment. Hearts from control and LPS-treated rats were perfused in a Langendorff apparatus. After LPS injection, left ventricular (LV) developed pressure (LVDP) was significantly depressed, plasma NO2-/NO3- (NO(x)) concentration was markedly increased, and myocardial adenosine 5'-triphosphate (ATP), creatine phosphate (CrP), and the ratio of ATP/adenosine 5'-diphosphate were progressively decreased with time. Immunological examination showed a significant expression of iNOS protein in the LPS-treated myocytes. Aminoguanidine, an inhibitor of iNOS, significantly attenuated these LPS-induced functional and metabolic changes. Myocardial cyclic guanosine 3',5'-monophosphate (cGMP) content was significantly increased after LPS injection. Methylene blue, an inhibitor of soluble guanylate cyclase, blunted this increase in cGMP and significantly restored the LPS-induced contractile dysfunction 6 h after LPS injection. In addition, there was a significant negative correlation between LVDP and myocardial cGMP levels as well as a significant negative correlation between LVDP and plasma NO(x) levels. In contrast, 48 h after LPS injection, methylene blue no longer affected cardiac performance, and there was a significant positive correlation between LVDP and myocardial ATP content. Furthermore, the normalized activities (as a ratio of the citrate synthase activity) of mitochondrial NADH-CoQ reductase, succinate-CoQ reductase, and ATPase, were significantly inhibited, and the swelling or disruption of mitochondria cristae was seen in the 48 h LPS treatment. These LPS-induced functional and morphological disorders in the mitochondria were significantly improved by aminoguanidine. The findings suggest that sustained production of NO by iNOS leads to contractile dysfunction via cGMP in the early stage, but that it can directly impair the mitochondrial function, lower myocardial energy production, and contribute significantly to the myocardial dysfunction in the later stage of septic shock.     

Efeitos do Exercício Aeróbico Tardio na Remodelação Cardíaca de Ratos com Infarto do Miocárdio Pequeno

Background:Physical exercise has been considered an important non-pharmacological therapy for the prevention and treatment of cardiovascular diseases. However, its effects on minor cardiac remodeling are not clear.Objective:To evaluate the influence of aerobic exercise on the functional capacity, cardiac structure, left ventricular (LV) function, and gene expression of NADPH oxidase subunits in rats with small-sized myocardial infarction (MI).Methods:Three months after MI induction, Wistar rats were divided into three groups: Sham; sedentary MI (MI-SED); and aerobic exercised MI (MI-AE). The rats exercised on a treadmill three times a week for 12 weeks. An echocardiogram was performed before and after training. The infarction size was evaluated by histology, and gene expression was assessed by RT-PCR. The significance level for statistical analysis was set at 5%.Results:Rats with MI lower than 30% of the LV total area were included in the study. Functional capacity was higher in MI-AE than in Sham and MI-SED rats. The infarction size did not differ between groups. Infarcted rats had increased LV diastolic and systolic diameter, left atrial diameter, and LV mass, with systolic dysfunction. Relative wall thickness was lower in MI-SED than in the MI-AE and Sham groups. Gene expression of the NADPH oxidase subunits NOX2, NOX4, p22^phox, and p47^phox did not differ between groups.Conclusion:Small-sized MI changes cardiac structure and LV systolic function. Late aerobic exercise is able to improve functional capacity and cardiac remodeling by preserving the left ventricular geometry. NADPH oxidase subunits gene expression is not involved in cardiac remodeling or modulated by aerobic exercise in rats with small-sized MI.     

Selective NOS inhibition restores myocardial contractility in endotoxemic rats; however, myocardial NO content does not correlate with myocardial dysfunction

The role of nitric oxide (NO) in lipopolysaccharide (LPS)-induced myocardial dysfunction remains controversial as some investigators concluded that inhibition of NO synthesis improves left ventricular (LV) contractility, whereas others did not. We investigated the relationship between LPS-induced LV dysfunction and LV NO production. We postulated that high myocardial NO concentrations would correspond to decreased contractility and low NO concentrations would correspond to recovery. In a rat model of endotoxemia, we used the isolated papillary preparation to assess inotropic dysfunction. We measured LV NO content and hemodynamics at baseline, 4, 16, and 48 h after LPS administration. LPS caused a decrease in LV contractility at 16 h with recovery at 48 h. Myocardial NO levels were elevated at all time periods. However, at 48 h in spite of normalization of LV contractility, myocardial NO content remained elevated. Pretreatment of LPS animals with the nonselective nitric oxide synthase (NOS) inhibitor N (G)-nitro-L-arginine methyl ester (L-NAME) worsened LV contractility, decreased LV NO content, and increased mortality. However, pretreatment with the relatively selective inducible NOS (iNOS) inhibitor S-methylisothiourea sulfate (SMT) restored LV contractility. Myocardial NO content in the SMT was lower than that of the LPS only group, but higher than the L-NAME group. We conclude that SMT is beneficial to myocardial contractility in this model of endotoxemia, whereas pretreatment with L-NAME is associated with further deterioration of contractility and increased mortality. Moreover, our data indicate that high myocardial NO concentrations do not necessarily correlate with decreased contractility.     

Prognostic implications of left ventricular diastolic dysfunction with preserved systolic function following acute myocardial infarction

The contribution of diastolic dysfunction in patients with preserved left ventricular (LV) systolic function to impaired functional status and cardiac mortality in myocardial infarction (MI) is unknown. In the present study, assessment of LV diastolic function was performed by Doppler analysis of the mitral and pulmonary venous flow, and the propagation velocity of early mitral flow by color M-mode Doppler echocardiography in 183 consecutive patients at day 5-7 following their first acute MI. Patients were classified into four groups: group A: preserved LV systolic and diastolic function (n = 73); group B: LV systolic dysfunction with preserved diastolic function (n = 10); group C: LV diastolic dysfunction with preserved systolic function (n = 60); group D: combined LV systolic and diastolic dysfunction (n = 40). The cardiac mortality rate at 1 year was significantly higher in groups C (13%) and D (38%) compared to A (2%) (p < 0.01). Multivariate regression analysis identified LV diastolic dysfunction (p = 0.001), Killip class >or=II (p = 0.006), and age (0.008) as predictors of cardiac death or readmission due to heart failure. The presence of LV diastolic dysfunction with preserved systolic dysfunction is associated with increased morbidity and mortality following acute MI.     

The relationship between renal function and cardiac structure, function, and prognosis after myocardial infarction: the VALIANT Echo Study.

OBJECTIVES: The purpose of this study was to determine whether alterations in cardiac structure or function contribute to the increased risk associated with renal impairment after myocardial infarction (MI). BACKGROUND: Renal impairment is associated with adverse cardiovascular outcomes after MI. METHODS: Echocardiography was performed on 603 patients with left ventricular (LV) dysfunction, heart failure (HF), or both after MI. Patients were grouped according to their estimated glomerular filtration rate (eGFR), and measures of cardiac structure and function were related to baseline eGFR. The relationship between eGFR and cardiac structure and function and clinical outcomes of death or HF was assessed with multivariable Cox regression. RESULTS: Ejection fraction, infarct segment length, right ventricular function, and mitral deceleration time were not influenced by renal function. Patients with reduced eGFR had smaller LV and larger left atrial (LA) volumes and higher left ventricular mass index (LVMI) and LV mass/LV volume ratio. A greater proportion of the patients with reduced eGFR had LV hypertrophy. The relationship between eGFR and the outcome of death or HF was attenuated by including baseline differences in LVMI, and both LVMI and LA volume conferred additional prognostic information in a multivariable model. CONCLUSIONS: Renal impairment was associated with smaller LV and larger LA volumes and increased LVMI. Systolic function was similar when compared with patients with normal renal function. Thus, reduced systolic function cannot account for worse outcomes in patients with renal impairment after MI. Indirect measures of diastolic function suggest that diastolic dysfunction might be an important mediator of increased risk in this population.     

Induction of left ventricular remodeling and dysfunction in the recipient heart after donor heart myocardial infarction: new insights into the pathologic role of tumor necrosis factor-alpha from a novel heterotopic transplant-coronary ligation rat model

OBJECTIVES: The present study investigated the effects of tumor necrosis factor (TNF)-alpha and angiotensin II (ANG II) on cardiac remodeling and dysfunction at the early stage of acute myocardial infarction (MI) by using a novel heterotopic cardiac transplantation-coronary ligation model. BACKGROUND: A recent clinical study has demonstrated a possible role of monocytosis in the development of left ventricular (LV) remodeling in patients with acute MI reperfusion. METHODS: We performed isogenic heterotopic cardiac transplantation and simultaneous coronary ligation to produce MI in the donor heart and to evaluate the hearts of both donors and recipients in Lewis rats. RESULTS: A significant decrease in LV fractional shortening and positive rate of rise in LV pressure and a significant increase in LV end-diastolic dimension/body weight and LV end-diastolic pressure were observed in the recipient hearts in the ligation group on day 7. TNF-alpha was significantly elevated not only in the plasma but also in the recipient hearts in the ligation group. In contrast, ANG II was significantly increased only in the infarct region of the donor hearts, but not in the plasma. Furthermore, the recipients' transient LV remodeling and dysfunction were completely abolished by the intravenous administration of a TNF-alpha antagonist. CONCLUSIONS; We developed a novel cardiac transplantation-coronary ligation model capable of inducing MI in the absence of downstream hemodynamic effects and allowing differential quantification of indexes of cardiac remodeling in vivo, including the local and remote effects of ANG II and TNF-alpha on cardiac remodeling.     

Risk factors for sudden death after acute myocardial infarction: two-year follow-up

The risk of sudden coronary death after myocardial infarction (MI) was assessed in 533 patients who survived 10 days after MI and were followed for up to 24 months (mean 18) in the Multicenter Investigation of the Limitation of Infarct Size. Analysis of multiple clinical and laboratory variables determined before hospital discharge revealed that frequent ventricular premature beats (VPBs) (greater than or equal to 10/hour) on ambulatory electrocardiographic monitoring and left ventricular (LV) dysfunction (radionuclide LV ejection fraction less than or equal to 0.40) were independently significant markers of risk for subsequent sudden death believed to be the result of a primary ventricular arrhythmia. The incidence of sudden death was 18% in patients with both LV dysfunction and frequent VPBs (11 times that of patients with neither of these findings). Seventy-nine percent of all sudden deaths occurred within 7 months after the index MI. In 280 survivors reclassified 6 months after MI with regard to the presence or absence of frequent VPBs and LV dysfunction, these risk factors could not be associated with sudden coronary death over a further follow-up period of up to 18 months; the overall incidence of sudden cardiac death was low (1.4%) after 6 months. Thus, the presence of frequent VPBs in association with LV dysfunction early after MI identifies patients at high risk for sudden death over the next 7 months.