Glutamate protects against Ca2+ paradox‐induced injury and inhibits calpain activity in isolated rat hearts

This study determined the effects of glutamate on the Ca²⁺ paradoxical heart, which is a model for Ca²⁺ overload‐induced injury during myocardial ischaemia and reperfusion, and evaluated its effect on a known mediator of injury, calpain. An isolated rat heart was retrogradely perfused in a Langendorff apparatus. Ca²⁺ paradox was elicited via perfusion with a Ca²⁺‐free Krebs‐Henseleit (KH) solution for 3 minutes followed by Ca²⁺‐containing normal KH solution for 30 minutes. The Ca²⁺ paradoxical heart exhibited almost no viable tissue on triphenyltetrazolium chloride staining and markedly increased LDH release, caspase‐3 activity, cytosolic cytochrome c content, and apoptotic index. These hearts also displayed significantly increased LVEDP and a disappearance of LVDP. Glutamate (5 and 20 mmol/L) significantly alleviated Ca²⁺ paradox‐induced injury. In contrast, 20 mmol/L mannitol had no effect on Ca²⁺ paradox. Ca²⁺ paradox significantly increased the extent of the translocation of μ‐calpain to the sarcolemmal membrane and the proteolysis of α‐fodrin, which suggests calpain activation. Glutamate also blocked these effects. A non‐selective inhibitor of glutamate transporters, dl ‐TBOA (10 μmol/L), had no effect on control hearts, but it reversed glutamate‐induced cardioprotection and reduction in calpain activity. Glutamate treatment significantly increased intracellular glutamate content in the Ca²⁺ paradoxical heart, which was also blocked by dl ‐TBOA. We conclude that glutamate protects the heart against Ca²⁺ overload‐induced injury via glutamate transporters, and the inhibition of calpain activity is involved in this process.     

丹参素结构中醇羟基的修饰与初步活性评价

目的设计合成系列在丹参素醇羟基部位修饰的新衍生物,初步探索醇羟基在丹参素生物活性中的作用。方法丹参素的酚羟基以及羧基经苄基保护后,其醇羟基与相应的基团在不同的催化剂下缩合生成醚键以及酯键化合物,然后脱除保护基得到醇羟基修饰的衍生物。通过体外的心肌细胞氧化损伤模型初步评价新衍生物的生物活性,分析其构效关系。结果合成了11个丹参素新衍生物,并进行了结构确证;活性实验显示,醇羟基上醚键与酯键修饰的衍生物活性均没有明显高于母药丹参素。结论裸露的醇羟基可能是丹参素发挥作用的必需基团。     

七氟烷缺血后处理对离体大鼠心肌细胞的保护作用

目的观察七氟烷缺血后处理对离体大鼠心肌细胞凋亡的影响。方法20只♂Wistar大鼠随机分为缺血对照组(A组)和七氟烷缺血后处理组(B组),每组10例。两组离体鼠心均用Langendorff离体心脏灌注模型,以改良Kreb-Henseleit液灌流平衡20min后,停灌40min,再灌注60min。B组在复灌时以平衡有1.0Mac的七氟烷灌注液灌注15min。以Powerlab Chart 5软件动态监测左室展压(LVDP)、左室压力变化最大速率(±dp/dtmax),心率(HR)。计量平衡20min、复灌15min和复灌60min的冠状动脉灌注流量(CF)。以2,3,5-氯三苯四唑染色(TTC)染色心肌切片,并以Image J 1.37软件计算心肌梗死面积。TUNEL法检测染色凋亡细胞,尼康高倍光学显微镜(Nikon Eclipse,E400,日本)视野拍照并存档,以Leica Qwin Plus V3软件分析,计算凋亡指数(AI)。结果和A组比,B组复灌后的LVDP、±dp/dtmax、CF和HR均明显升高(P<0.05);B组复灌后心梗面积明显减小且AI明显降低(P<0.05)。和基础值比,复灌15min以及复灌60min的LVDP、±dp/dtmax、CF和HR均显著降低(P<0.05)。结论七氟烷缺血后处理抑制离体大鼠心肌的细胞凋亡,提示对缺血再灌注(I/R)心肌具有心肌保护作用。     

曲美他嗪联合阿托伐他汀对经皮冠状动脉介入治疗病人的心脏保护作用

目的:探讨术前给予常规剂量的阿托伐他汀和曲美他嗪对经皮冠状动脉介入治疗(PCI)病人围手术期心肌损伤的影响。方法:将323例欲行PCI的急性冠状动脉综合征病人随机分为对照组(162例)和试验组(161例)。对照组给予常规剂量阿托伐他汀钙片(20 mg/次,1次/晚),试验组给予常规剂量阿托伐他汀钙片加服盐酸曲美他嗪(20 mg/次,tid),治疗3 d;随后分别行PCI。测定PCI术前及术后24 h的血清肌酸激酶-MB同工酶(CK-MB)、心脏肌钙蛋白I(cTnI)、超敏C反应蛋白(hs-CRP)浓度和髓过氧化物酶(MPO)活性,随访PCI后4周时病人的左室射血分数。结果:试验组病人PCI术后24 h的cTnI水平显著低于对照组(P<0.05),MPO活性升高值明显低于对照组(P<0.05)。两组病人在术后24 h的CK-MB活性和hs-CRP水平变化无显著差异(P>0.05)。结论:术前3 d给予常规剂量的阿托伐他汀和曲美他嗪联合治疗,对PCI围手术期病人的心肌损伤具有一定的保护作用。     

氯离子参与心肌细胞缺氧复氧损伤机制的研究

目的研究氯离子参加心肌细胞缺氧/复氧(A/R)损伤的机制。方法采用原代培养新生大鼠的心肌细胞A/R损伤模型,去除细胞外的氯离子(Cl--free),或分别给予Na+-K+-2Cl-共同转运体阻断剂bumetanide,Cl-/HCO3-离子交换系统抑制剂SITS和氯通道阻断剂9-AC,观察细胞存活率、MDA含量、LDH、SOD、GSH-Px酶活性变化及细胞内的钙含量、NF-κB活性变化。结果A/R组与对照组比,MDA含量、LDH活性、细胞内的钙含量、NF-κB活性升高,细胞存活率、SOD、GSH-Px活性降低;bumetanide及9-AC组与A/R组比,各项指标无统计学意义。Cl--free、SITS处理后较A/R组,MDA含量、LDH活性、细胞内的钙含量、NF-κB活性降低,而细胞存活率、SOD、GSH-Px明显升高。结论Cl-/HCO3-离子交换系统在心肌细胞A/R损伤中起了重要作用,Cl-参与心肌A/R损伤的机制与钙超载及NF-κB活性升高有关。     

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.     

热休克蛋白70对兔未成熟心肌和心肌间质的影响

目的: 探讨热休克蛋白70(HSP70)对未成熟心肌和心肌间质的影响. 方法:健康新生长耳大白兔12只随机分为2组. 对照组(C组):ip生理盐水0.4 mL,24 h后取离体心脏,常规建立Langendorff离体心脏灌注模型,灌注15 min转为工作心15 min后停灌45 min,恢复灌注15 min改为工作心30 min;实验组(E组):ip去甲肾上腺素, 24 h后取离体心脏,方法同对照组. 测定心肌细胞中HSP70含量、血流动力学指标、心肌含水量(MWC)、心肌肌酸激酶(CK)和乳酸脱氢酶(LDH)漏出率、三磷酸腺苷(ATP)含量、超氧化物歧化酶(SOD)和丙二醛(MDA)含量、心肌组织羟脯氨酸(HP)含量、内皮素(ET) 含量、心肌细胞内Ca2 含量、心肌线粒体Ca2 -ATPase活性及其Ca2 含量、心肌线粒体合成ATP能力[ATP]m,心肌超微结构. 结果:E组HSP70含量明显高于C组(P<0.01);MWC低于C组(P<0.05);ATP含量、SOD活性、心肌线粒体Ca2 -ATPase活性、[ATP]m, HP含量优于C组(P<0.01),MDA含量、CK, LDH漏出率、心肌细胞内Ca2 含量、心肌线粒体Ca2 含量、ET含量低于C组(P<0.01),心肌超微结构损伤较C组明显减轻. 结论:HSP70对缺血再灌注未成熟心肌和心肌间质具有明显的保护作用.     

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.     

11,12-EET对大鼠心脏缺血/再灌注损伤保护作用研究

目的观察不同质量浓度11,12-EET对心肌缺血/再灌注损伤的影响及给药后不同时间11,12-EET保护作用的变化,以期了解11,12-EET对心肌保护作用的特点。方法复制大鼠心脏缺血/再灌注模型,给予不同浓度的11,12-EET,观察不同时间点的心功能变化。结果给予6.24×10-7.5mol/L、6.24×10-8mol/L 11,12-EET均可改善心肌缺血/再灌注损伤的大鼠心功能,6.24×10-9mol/L 11,12-EET作用较弱;给药24 h后11,12-EET拮抗大鼠心肌缺血/再灌注损伤的作用也减弱。结论11,12-EET的浓度及给予11,12-EET的时间对心脏保护作用有一定的影响。