Novel cardioprotective effects of pravastatin in human ventricular cardiomyocytes subjected to hypoxia and reoxygenation: beneficial effects of statins independent of endothelial cells

Cardioprotective strategies are needed to prevent perioperative myocardial dysfunction in high-risk patients undergoing cardiac surgery. Despite accumulating evidence that statins exert lipid-independent cardioprotective effects, these have been ascribed primarily to improvements in endothelial function and neutrophil-endothelial interaction. The direct effects of statins on cardiomyocytes (independent of endothelial cells) remain unknown. Using a well-characterized model of low-volume hypoxia and reoxygenation, we studied the effects of pravastatin on human ventricular cardiomyocytes. Cardiomyocytes were subjected to 90 min of low-volume hypoxia and 30 min of reoxygenation in the presence and absence of pravastatin (1, 10, and 100 microm) (n = 10 per group). In some experiments, the effects of endothelin (ET) receptor blockade (with bosentan) and nitric oxide synthase (NOS) inhibition (with L-NAME) on pravastatin-mediated cardioprotection were evaluated. Cell survival, NO, and ET-1 production and protein kinase Akt activation were determined. Pravastatin treatment prevented cardiomyocyte cell death following simulated hypoxia and reoxygenation (P < 0.01). This effect was mediated via an increase in NO release, decrease in myocyte ET-1 production/action, and an increase in protein kinase Akt activation. We demonstrate, for the first time, novel protective effects of pravastatin in human ventricular cardiomyocytes independent of endothelial cells or other cell types. Statin therapy may restore ischemic hearts to full functional integrity during cardioplegic arrest through a direct effect on cardiomyocyte survival.     

Chemoprotective effect of plant phenolics against anthracycline-induced toxicity on rat cardiomyocytes. Part III. Apigenin, baicalelin, kaempherol, luteolin and quercetin

Flavonoids are found universally in plants and act as free radical scavenging and chelating agents with antiinflammatory, antiischemic, vasodilating and chemoprotective properties. In this study, the antilipoperoxidative and cytoprotective effects of apigenin, baicalein, kaempferol, luteolin and quercetin against doxorubicin-induced oxidative stress were investigated in isolated rat heart cardiac myocytes, mitochondria and microsomes. After preincubation of cardiomyocytes with the test compounds for 1 h the cardiomyocytes were treated with the toxic agent, doxorubicin (100 micro M for 8 h). Cardiomyocyte protection was assessed by extracellular LDH and cellular ADP and ATP production. Cytoprotection was concentration dependent for baicalein > luteolin congruent with apigenin > quercetin > kaempferol. All test compounds had signi fi cantly better protective effects than dexrazoxan, an agent currently used for adjuvant therapy during anthracycline antibiotic therapy. In microsomes/mitochondria the IC(50) values of lipid peroxidation inhibition for quercetin, baicalein, kaempferol, luteolin, and apigenin were 3.1 +/- 0.2/8.2 +/- 0.6, 3.3 +/- 0.3/9.6 +/- 0.5, 3.9 +/- 0.3/10.1 +/- 0.8, 22.9 +/- 1.7/18.2 +/- 0.7, and 338.8 +/- 23.1/73.1 +/- 6.4 mM, respectively. The antilipoperoxidative activity of apigenin differed from its cytoprotective effects, but correlated with the free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl radical and half peak oxidation potential (E(p/2)). Apigenin was the least effective of the flavonoids studied in all models except the cardiomyocyte model where its cardiomyocyte cytoprotective effect was comparable to other compounds.     

Multiple injury approach and its use for toxicity studies

We present an experimental approach that allows exposure of cells plated on a single coverslip to multiple distinct environments. The original chamber design created a small region of injury using geometrically defined flows of the control and ischemic solutions. Modifications of the original chamber design presented in this article produce a range of flow patterns that can be advantageous for a variety of imaging applications. These applications include: experiments that address effects of different treatments applied to a cell network, parallel testing of negative and positive controls using a single coverslip, border effect studies, evaluation of the treatment’s reversibility, and simultaneous monitoring of a cell layer loaded with different fluorescent indicators. The method also can be used to reveal both micro- and macroscopic features of propagation, conduction, and cell coupling in a normal or altered cardia cell network. These possibilities are illustrated in cultures of neonatal rat cardiomyocytes using oxidant-and calcium-sensitive fluorescent indicators.     

Cardioprotective functions of atrial natriuretic peptide and B-type natriuretic peptide: a brief review

1. If one was to design a hormone to protect the heart, it would have a number of features shown by the cardiac natriuretic peptides atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP). These hormones are made in cardiomyocytes and are released into the circulation in response to atrial and ventricular stretch, respectively. Atrial natriuretic peptide and BNP can reduce the preload and after-load in normal and failing hearts. They reduce blood volume over the short term by sequestering plasma and over the longer term by promoting renal salt and water excretion and by antagonizing the renin-angiotensin-aldosterone system at many levels. Each of these actions affords indirect benefit to a volume- or pressure-threatened heart. 2. Recent studies have identified additional modes of action of the natriuretic peptides that may also confer cardioprotective benefits, especially in heart disease. The emerging findings are: (i) that ANP and BNP antagonize the cardiac hypertrophic action of angiotensin II and continue working under conditions where endothelial nitric oxide (NO) function is compromised, such as in the presence of high glucose in diabetes; (ii) they potentiate the bradycardia caused by inhibitory ('autoprotective') cardio-cardiac reflexes; and, furthermore, (iii) BNP can suppress cardiac sympathetic nerve activity in humans, including those with heart failure. Thus, it appears that natriuretic peptides can shift sympathovagal balance in a beneficial direction (away from the sympathetic). The vagal reflex and antihypertrophic actions of the peptides are mediated by particulate guanylyl cyclase (pGC) natriuretic peptide receptors. 3. The multiple synergistic actions of the natriuretic peptides make them and their pGC receptors attractive targets for therapy in heart disease. Encouragingly, exogenous natriuretic peptides remain effective even when endogenous peptide levels are raised, as is the case in heart failure. They also remain effective in disease states where other protective mechanisms, such as the NO system, have become ineffective, offering yet further encouragement for the therapeutic use of the natriuretic peptides.     

Alterative and plastic insufficiency of cardiomyocytes: isoproterenol-induced damage to myocardium during anthracycline cardiomyopathy

The development of regenerative and plastic myocardial insufficiency induced by anthracycline antibiotic rubomycin is accompanied by a decrease in cardiomyocyte sensitivity to damage produced by synthetic catecholamine isoproterenol. The incidence and the size of coagulation necrosis foci of cardiomyocytes developed 6 h after isoproterenol injection significantly decreased with increasing in the interval between rubomycin injection and subsequent administration of isoproterenol. In Wistar rats receiving rubomycin 3-5 days prior to isoproterenol and exhibiting signs of regenerative and plastic insufficiency, no cardiomyocyte contracture, intracellular myocytolysis, or lump degradation characteristic of cardiac insufficiency induced by endo- and exogenous catecholamines were found.     

Anthracycline-induced cardiomyopathy is manifested in decreased protein synthesis, impaired intracellular regeneration, and non-necrotic death of cardiomyocytes

The cytostatic anthracycline antibiotic daunomycin hydrochloride led to the development of plastic myocardial insufficiency characterized by impaired intracellular regeneration of cardiomyocytes and progressive involution of cytoplasmic structures. Morphological signs of plastic myocardial insufficiency included fragmentation, annulation, or collapse of nucleoli in cardiomyocyte nuclei, lysis of myofilaments, sarcomeres, or myofibrils, focal degradation of the cytoplasm, and intensive autophagy. Fatal anthracycline-induced cardiac insufficiency was associated with massive cardiomyocyte loss due to their non-necrotic death and elimination. Our findings indicate that anthracycline-induced cardiomyopathy in laboratory animals is a convenient model for studying general mechanisms underlying the pathogenesis of regenerative and plastic cardiac insufficiency in humans.     

神经肽Y对大鼠心肌细胞胞浆钙及钙瞬变的影响

目的观察神经肽Y（neuropeptideY，NPY）对静息状态下心肌细胞胞浆钙含量及兴奋-收缩耦联过程中心肌细胞钙瞬变的影响。方法用NPY（100nmol／L）刺激Sprague—Dawley乳鼠心肌细胞24h，用荧光染料Fluo 4-AM负载胞浆钙，记录静息状态下心肌细胞胞浆钙浓度，并用场刺激诱发胞浆钙瞬变。所有钙影像均由LeicaSP2激光共聚焦显微镜记录。结果NPY组心肌细胞胞浆钙含量明显高于对照组（P〈0.05）；场刺激诱导下NPY组心肌细胞胞浆钙瞬变幅度明显高于对照组（P〈0.01），NPY组钙瞬变恢复时间明显缩短（P〈0．01），钙瞬变上升时阍则无显著差别。结论长时间的NPY刺激可显著影响兴奋-收缩耦联过程中钙的动态活动，并导致胞浆内钙含量增加。     

山奈酚、芹菜素、大豆苷元对H2O2诱导的心肌细胞凋亡的影响

目的 观察不同种类黄酮类化合物山萘酚(KA)、芹菜素(AP)、大豆苷元(DA)对H2O2诱导的心肌细胞凋亡及Bcl-2、Bax、Caspase-3蛋白表达的影响.方法 取Wistar大鼠新生乳鼠心肌细胞做原代培养,MTT法检测几种黄酮的细胞毒浓度;H2O2(100μmol/L)诱导心肌细胞凋亡;Tunel法、流式细胞仪检测细胞凋亡率;免疫组化方法测定Bcl-2、Bax、Caspase-3蛋白表达.结果 MTT法显示各组药物在5、30μmol/L没有显著的细胞毒作用.KA、AP、DA均显著减小H2O2诱导的细胞凋亡率、Caspase-3蛋白表达,增加Bcl-2/Bax比值(P＜0.05),其中KA效果最显著(P＜0.01).结论 这些黄酮类化合物有抑制H2O2诱导的心肌细胞凋亡作用,其机制与其抗氧化活性有关,可能是通过调节Bcl-2、Bax、Caspase-3蛋白表达,起到心肌细胞保护作用,其中KA效果最好.     

野生型p53基因转移对心肌细胞生长的抑制作用

为了探讨野生型ｐ５３基因对心肌细胞生长的抑制作用及应用于高血压和肥厚型心肌病等疾病所致心肌肥厚的基因治疗可能性,本实验将野生型ｐ５３基因重组腺病毒转染体外培养的乳兔心肌细胞。应用生化染色方法,免疫组化法及聚合酶链反应技术,检测了野生型ｐ５３基因的转染效率及表达效果。采用ＭＴＴ方法及光镜技术进一步观察了野生型ｐ５３基因对心肌细胞生长的调节作用。结果显示,腺病毒载体能有效地将外源基因导入心肌细胞中并使