浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用

目的:探究浅低温对心肌缺血-再灌注损伤合并脓毒症大鼠模型的心肌保护作用。方法:共15只SD大鼠随机分为心肌缺血-再灌注损伤合并脓毒症浅低温(MHT)组、心肌缺血-再灌注损伤合并脓毒症常温(NT)组和假手术常温组作为对照组。大鼠心肌缺血后再灌注同时给予内毒素,然后MHT组将大鼠置于冰床降温,15 min内达(33.0±0.5)℃,随后维持2 h。NT组及对照组实验全程维持在(37.0±0.5)℃。实验全程观察和记录血流动力学指标。浅低温或常温维持2 h后用酶联免疫吸附测定法检测血乳酸脱氢酶(LDH)、肌酸激酶同工酶(CK-MB),观察心肌梗死面积、病理学变化,免疫印迹法检测心肌烟酰胺腺嘌呤二核苷酸磷酸氧化酶2(NOX2),免疫组化检测心肌胱天蛋白酶-3(caspase-3)和肿瘤坏死因子-α(TNF-α)。结果:MHT组再灌注2 h心率较NT组降低[(396.63±39.93)次/min vs(.457.74±32.77)次/min,P<0.05];左心室最大收缩压升高[(129.14±34.05)mmHg vs.(85.63±14.74)mmHg,1 mmHg=0.133 kPa,P<0.05]。MHT组收缩期压力最大变化速率(+max dp/dt)、左心室舒张末期压力(LVEDp)和舒张期压力最小变化速率(-min dp/dt)再灌注2 h较NT组绝对值也有所增加,且均高于对照组,但差异无统计学意义。MHT组的LDH和CK-MB均较NT组显著降低[(1153.61±127.85)U/L vs(.2213.34±599.60)U/L,P<0.05;(1103.22±114.75)U/L vs(.1731.33±688.05)U/L,P<0.05]。心肌病理变化提示MHT组心肌坏死呈点状或灶状,心肌间质淤血程度轻且炎细胞浸润较少。NT组心肌出现水肿、灶状或片状坏死,心肌间质区淤血程度重及存在大量炎细胞浸润。此外,MHT组的心肌梗死面积比率明显小于NT组[(11.23±2.82)%vs.(19.25±4.45)%,P<0.05]。免疫印迹法显示,NOX2在MHT组中相对表达量较NT组减少,但差异无统计学意义(P>0.05)。MHT组的caspase-3相对表达量及TNF-α相对表达量均较NT组显著降低[(1.06±0.34)%vs.(3.27±0.67)%;(12.23±3.31)%vs(.31.14±1.69)%],差异均有统计学意义(P均<0.05)。结论:浅低温对心肌缺血-再灌注损伤合并脓毒症有心脏保护作用,可改善心功能,减少心肌梗死面积,减轻心肌损伤、炎症、氧化应激及凋亡。     

Non-coding RNAs as therapeutic targets for preventing myocardial ischemia-reperfusion injury

Introduction: New treatments are required to improve clinical outcomes in patients with acute myocardial infarction (AMI), for reduction of myocardial infarct (MI) size and preventing heart failure. Following AMI, acute ischemia/reperfusion injury (IRI) ensues, resulting in cardiomyocyte death and impaired cardiac function. Emerging studies have implicated a fundamental role for non-coding RNAs (microRNAs [miRNA], and more recently long non-coding RNAs [lncRNA]) in the setting of acute myocardial IRI.

Areas covered: In this article, we discuss the roles of miRNAs and lncRNAs as potential biomarkers and therapeutic targets for the detection and treatment of AMI, review their roles as mediators and effectors of cardioprotection, particularly in the settings of interventions such as ischemic pre- and post-conditioning (IPC & IPost) as well as remote ischemic conditioning (RIC), and highlight future strategies for targeting ncRNAs to reduce MI size and prevent heart failure following AMI.

Expert opinion: Investigating the roles of miRNAs and lncRNAs in the setting of AMI has provided new insights into the pathophysiology underlying acute myocardial IRI, and has identified novel biomarkers and therapeutic targets for detecting and treating AMI. Pharmacological and genetic manipulation of these ncRNAs has the therapeutic potential to improve clinical outcomes in AMI patients.     

黄芩素调节心肌缺血/缺氧损伤相关信号通路的研究进展

心肌缺血/缺氧通常会导致心脏结构和功能的损伤,黄芩素是广泛分布的一种黄酮类物质,近年研究发现黄芩素能够通过调节细胞信号通路,干预信号通路中关键信号分子的磷酸化过程,对缺血/缺氧心脏发挥保护作用。这些信号通路包括磷脂酰肌醇-3-激酶-丝氨酸/苏氨酸激酶(PI3K/Akt)、丝裂原活化蛋白激酶家族(MAPKs)和核因子-κB(NF-κB)等,及其下游通路蛋白HMGB1、MMP-2/-9、e NOS和凋亡蛋白。现就黄芩素与心肌缺血/缺氧相关信号通路的相互作用机制进行综述。     

Quantity and Quality Relationships in Cardiovascular Medicine

Hospital volume and often also operator volume have documented impacts on the quality of care for aortic and aortocoronary bypass surgery, for percutaneous angioplasty and for radiofrequency ablation for arrhythmias, whereas data are less consistent for treatment of acute myocardial infarction. A review of this research is given. In the Nordic countries hospitals are small, and often the plateau of the learning curve cannot be reached. To discourage low-volume centers from embarking upon too complicated interventional or surgical procedures, the author suggests that a minimal number should be set for certain major procedures, both for hospitals and for physicians.     

Volatile anaesthetics and cardioprotection – lessons from animal studies

Volatile anaesthetics emerged as important cardioprotective agents in both animal models of ischaemia/reperfusion injury and humans with coronary artery disease. Their administration before a prolonged ischaemic episode is known as anaesthetic preconditioning, whereas when given at the very onset of reperfusion, the strategy is termed anaesthetic postconditioning. Both types of anaesthetic conditioning reduce, albeit not to the same degree, the extent of myocardial injury. They share similar, albeit not identical, intracellular signal transduction pathways with their widely investigated counterparts, ischaemic pre‐ and postconditioning. Despite a wealth of preclinical evidence for cardioprotection for anaesthetic conditioning strategies, their translation into clinical therapy has been rather disappointing. This review highlights the major findings on the cardioprotective effects of volatile anaesthetics in experimental settings. It explores hypotheses that may explain the lack of efficacy observed in several past clinical studies paving the way for future preclinical and translational studies.     

The role of nicorandil in the treatment of myocardial ischaemia

Nicorandil is an anti-anginal agent that has been used in the United Kingdom for over 6 years and is becoming increasingly popular. It induces coronary and peripheral vasodilatation via a dualistic mode of action, mediated by the opening of potassium-ATP channels (K_ATP) and its nitrate effect by stimulation of adenyl cyclase, with an increase in cGMP levels. Comparison to nitrates and other anti-anginal agents have shown it to be of equal efficacy in relieving ischaemic symptoms. Recent evidence suggests a role for nicorandil as a myocardial preconditioning agent but this may be limited by systemic vasodilatation. There is ongoing research into its role in improving the long-term outcome of patients with ischaemic heart disease (IHD). It has been shown to be of proven efficacy in the treatment of IHD and further research will clarify other uses of this agent.     

The influence of the human microbiome and probiotics on cardiovascular health

Cardiovascular disease (CVD) is a major cause of death worldwide. Of the many etiological factors, microorganisms constitute one. From the local impact of the gut microbiota on energy metabolism and obesity, to the distal association of periodontal disease with coronary heart disease, microbes have a significant impact on cardiovascular health. In terms of the ability to modulate or influence the microbes, probiotic applications have been considered. These are live microorganisms which when administered in adequate amounts confer a benefit on the host. While a number of reports have established the beneficial abilities of certain probiotic bacterial strains to reduce cholesterol and hypertension, recent research suggests that their use could be more widely applied. This review presents an up-to-date summary of the known associations of the microbiome with CVD, and potential applications of probiotic therapy.     

Ischaemic Preconditioning of Myocardium

Myocardium has the innate potential to adapt to transient sublethal ischaemia so that it becomes more resistant to a subsequent, more severe, ischaemic insult. The response is called ischaemic preconditioning and protection of the myocardium is manifested by a slowing of adenosine triphosphate decline, limitation of ischaemic necrosis and a reduction in dysrhythmia severity. Protection conferred by preconditioning occurs in two distinct temporal phases. An early phase of protection is observed immediately but wanes within two to three hours (classic preconditioning). This is followed many hours later by a second window of protection (delayed preconditioning). The cellular mechanisms underpinning both forms of protection are currently being intensively investigated. There is evidence that human myocardium can be preconditioned ex vivo and also in situ during elective procedures such as angioplasty and coronary artery bypass grafting. Furthermore, evidence points to the possibility that preconditioning occurs naturally in some ischaemic syndromes, particularly warm-up angina and preinfarction angina. Ultimately, investigation of the mechanisms of preconditioning may contribute to the development of rational therapies for protecting the ischaemic myocardium and, perhaps more importantly, enhance our understanding of the molecular basis of ischaemic heart disease.     

Therapeutic potential of A1 adenosine receptor ligands: a survey of recent patent literature

Background: In recent years, a number of companies, universities and other institutions have invested in research on new molecules acting as agonists, antagonists and enhancers on A₁ adenosine receptors (ARs) and in the evaluation of their new therapeutic applications. Objective: To review recent patenting activity on this topic. Methods: The first part of this article describes the compounds patented, subdivided by functional activity, and the second part the most relevant therapeutic applications or new uses for A₁ AR ligands, with a focus on compounds in or soon to be in clinical trials. Conclusion: Although a number of potential therapeutic applications are proposed in the recent literature, at present, in the authors' opinion, very few A₁ ligands are close to coming on the market, probably due to limited selectivity towards the target tissue or organ.     

Melatonin receptor‐mediated protection against myocardial ischemia/reperfusion injury: role of SIRT1

Melatonin confers cardioprotective effect against myocardial ischemia/reperfusion (MI/R) injury by reducing oxidative stress. Activation of silent information regulator 1 (SIRT1) signaling also reduces MI/R injury. We hypothesize that melatonin may protect against MI/R injury by activating SIRT1 signaling. This study investigated the protective effect of melatonin treatment on MI/R heart and elucidated its potential mechanisms. Rats were exposed to melatonin treatment in the presence or the absence of the melatonin receptor antagonist luzindole or SIRT1 inhibitor EX527 and then subjected to MI/R operation. Melatonin conferred a cardioprotective effect by improving postischemic cardiac function, decreasing infarct size, reducing apoptotic index, diminishing serum creatine kinase and lactate dehydrogenase release, upregulating SIRT1, Bcl‐2 expression and downregulating Bax, caspase‐3 and cleaved caspase‐3 expression. Melatonin treatment also resulted in reduced myocardium superoxide generation, gp91^phox expression, malondialdehyde level, and increased myocardium superoxide dismutase (SOD) level, which indicate that the MI/R‐induced oxidative stress was significantly attenuated. However, these protective effects were blocked by EX527 or luzindole, indicating that SIRT1 signaling and melatonin receptor may be specifically involved in these effects. In summary, our results demonstrate that melatonin treatment attenuates MI/R injury by reducing oxidative stress damage via activation of SIRT1 signaling in a receptor‐dependent manner.