Pre- and postconditioning effect of Sevoflurane on myocardial dysfunction after cardiopulmonary resuscitation in rats

Post-resuscitation myocardial dysfunction is an important cause of death in the intensive care unit after initially successful cardiopulmonary resuscitation (CPR) of pre-hospital cardiac arrest (CA) patients. Volatile anaesthetics reduce ischaemic–reperfusion injury in regional ischaemia in beating hearts. This effect, called anaesthetic-induced pre- or postconditioning, can be shown when the volatile anaesthetic is given either before regional ischaemia or in the reperfusion phase. However, up to now, little data exist for volatile anaesthetics after global ischaemia due to CA. Therefore, the goal of this study was to clarify whether Sevoflurane improves post-resuscitation myocardial dysfunction after CA in rats.     

渐进延长后适应通过MAPK途径减轻再灌注损伤

目的 探讨后适应不同模式对大鼠急性心肌缺血-再灌注损伤的影响,并进一步研究丝裂原活化蛋白激酶途径(MAPK)在其中的作用.方法 60只SD大鼠随机(随机数字法)分为假手术组(Sham)、缺血-再灌注组(I/R)、渐进缩短后适应组(GDR,后适应处理方案短暂再灌注/缺血时间为30/10-25/15-15/25-10/30s)、标准后适应组(ER,后适应处理方案为20/20s×4)和渐进延长后适应组(GIR,后适应处理方案短暂再灌注/缺血时间为10/30-15/25-25/15-30/10s)5组,建立急性心肌梗死和缺血后适应模型.再灌注6h后每组取3只处死,取心肌组织用Western Blot方法测定磷酸化细胞外信号调节蛋白激酶(P-ERK)、磷酸化应激活化蛋白激酶(stress activated protein kinase,P-JNK)、磷酸化p38 MAPK (P-p38)、肿瘤坏死因子-α(TNF-α)、半胱氨酸天冬氨酸蛋白酶-8 (Caspase-8)在心肌组织中的表达及细胞色素c在胞浆中的表达;各组其余大鼠再灌注24 h后测定血流动力学,抽血测心肌酶,取心脏进行TUNEL凋亡检测.统计学多组间比较应用单因素方差分析,组间差异两两比较应用q检验.结果 三种后适应处理组均有显著的心肌保护作用(P＜0.05),其中GIR组最为明显,其次是ER组,GDR组最不明显.GIR组同ER组相比,细胞凋亡指数和血清标志物水平更低;P-ERK表达水平高于ER组[(1.82±0.22)vs.(1.54±0.32),P＜0.05],同时P-p38[(0.82±0.26) vs.(1.63±0.24)],P-JNK[(0.76±0.28) vs.(1.33±0.21),TNF-α[(0.62±0.20)vs.(1.00±0.12)],Caspase-8[(0.61±0.21)vs.(1.00±0.30)],Cyt-c[(0.66±0.16) vs.(1.68±0.22)]表达水平低(以上P＜0.05).在以上指标中渐进延长后适应组均显著优于渐进缩短后适应组.结论 渐进延长后适应较标准后适应能显著减轻心肌再灌注损伤,MAPK途径在其中发挥了重要作用.     

缺血后适应对心肌无复流炎症-氧化应激机制的影响

心肌无复流(MNR)现象是再灌注治疗(包括经皮冠状动脉介入术)后的常见并发症,其发生率为20%⁷0%,与临床预后密切相关。目前MNR的发生机制尚不明确,大量研究表明炎症-氧化应激参与MNR的发生、发展。缺血后适应具有与缺血预适应类似的心脏保护作用,缺血预适应可以抑制炎症-氧化应激反应。该文主要对心肌无复流的炎症-氧化应激机制及缺血后适应对炎症-氧化应激机制的抑制作用进行综述。     

线粒体比较蛋白质组学在心肌保护领域的研究和展望

背景 线粒体是心肌保护中最为重要的细胞器之一,心肌缺血损伤抑或后处理,必然会影响细胞核DNA及线粒体DNA转录活性,引起相应表达的蛋白质的变化.比较蛋白质组学,为我们提供了在全貌性了解心肌线粒体蛋白质组表达差异的基础上,探索引起能量代谢障碍的上游分子机制或关键调控环节的手段. 目的 探讨线粒体比较蛋白质组学在心肌保护领域的研究和展望. 内容 对缺血/药物后处理及作用机制、后处理心肌保护的线粒体机制、线粒体蛋白组学研究现状及其与心肌保护、研究进展进行综述. 趋向 比较蛋白质组学技术为心肌保护研究提供了新的方法和思路.     

Endogenous neuroprotection: mitochondria as gateways to cerebral preconditioning?

From single to multicellular organisms, protective mechanisms have evolved against endogenous and exogenous noxious stimuli. Preconditioning paradigms, in which stimulation below the threshold of injury results in subsequent protection of the brain, have played an important role in elucidating such endogenous protective mechanisms. Consequently, over the past decades numerous signaling pathways have been discovered by which the brain senses and reacts to such insults as neurotoxins, substrate deprivation, or inflammation. Research on preconditioning is aimed at understanding endogenous neuroprotection to boost it, or to supplement its effectors therapeutically once damage to the brain has occurred, such as after stroke or brain trauma. Another goal of establishing preconditioning protocols is to induce endogenous neuroprotection in anticipation of incipient brain damage. Currently several endogenous neuroprotectants are being investigated in controlled clinical trials. In the present review we will give a short overview on the signals, sensors, transducers, and effectors of endogenous neuroprotection. We will first focus on common mechanisms, on which pathways of endogenous neuroprotection converge, and in particular on mitochondria, which may be considered master integrators of endogenous neuroprotection. We will then discuss various applications of preconditioning, including pharmacological and anesthetic preconditioning, as well as postconditioning, and explore the prospects of endogenous neuroprotective therapeutic approaches.     

Morphine postconditioning attenuates ICAM-1 expression on endothelial cells

The purpose of this study is to determine 1) whether morphine post condition (MPostC) can attenuate the intercellular adhesion molecules-1 (ICAM-1) expression after reoxygenation injury and 2) the subtype(s) of the opioid receptors (ORs) that are involved with MPostC. Human umbilical vein endothelial cells (HUVECs) were subjected to 6 hr anoxia followed by 12 hr reoxygenation. Three morphine concentrations (0.3, 3, 30 μM) were used to evaluate the protective effect of MPostC. We also investigated blockading the OR subtypes' effects on MPostC by using three antagonists (a μ-OR antagonist naloxone, a κ-OR antagonist nor-binaltorphimine, and a δ-OR antagonist naltrindole) and the inhibitor of protein kinase C (PKC) chelerythrine. As results, the ICAM-1 expression was significantly reduced in the MPostC (3, 30 μM) groups compared to the control group at 1, 6, 9, and 12 hours reoxygenation time. As a consequence, neutrophil adhesion was also decreased after MPostC. These effects were abolished by co administering chelerythrine, nor-binaltorphimine or naltrindole, but not with naloxone. In conclusion, it is assumed that MPostC could attenuate the expression of ICAM-1 on endothelial cells during reoxygenation via the κ and δ-OR (opioid receptor)-specific pathway, and this also involves a PKC-dependent pathway.     

Microcirculatory and therapeutic effects of whole body periodic acceleration (pGz) applied after cardiac arrest in pigs

Aims

Cardiac arrest (CA) and resuscitation are models of whole body ischemia reperfusion injury. Interventions performed prior to (pre-treatment) or after (post-treatment) can result in cardioprotection. Myocardial stunning, characterized by microcirculatory and contractile dysfunction after CA, is an important component of the post-cardiac arrest syndrome. Periodic acceleration (pGz), produced by the cyclical motion of the supine body headward to footward, increases microcirculatory blood flow to vital organs and elicits production of endothelial derived cytoprotective factors in normal animals. We tested the hypothesis that application of pGz 30 min after return of circulation from CA, as a delayed post-treatment strategy, would improve regional microcirculatory blood flow to vital organs and functional indices of myocardial stunning in pigs.

Methods

8 min of unsupported VF followed by cardiopulmonary resuscitation and defibrillation was carried out in twenty anesthetized and paralyzed male swine who were randomized to delayed post-treatment with pGz (dPost) or none (CONT). pGz was begun 30 min after return of circulation along with conventional mechanical ventilation. Hemodynamics, echocardiogram, and regional blood flows were measured as well as biochemical index of cardiac tissue injury.

Results

All animals had spontaneous return of circulation after cardiopulmonary resuscitation (CPR) and defibrillation. dPost animals had less myocardial stunning and greater regional blood flows to the heart, brain, kidneys, ileum and stomach than CONT. Post-treatment with pGz blunted the increase in Troponin I produced by CA and resuscitation, and, induced a greater rise in endothelial derived nitric oxide synthase (eNOS) and its phosphorylation (p-eNOS).

Conclusions

Delayed post-treatment with pGz as a therapeutic strategy, protects against early myocardial stunning in VF cardiac arrest by improving microcirculatory blood flow to the heart and also protects other vital organs by this mechanism.     

Enhanced therapeutic effects of mesenchymal stem cells on myocardial infarction by ischemic postconditioning through paracrine mechanisms in rats

Ischemic postconditioning (IPC) is cardioprotective against ischemia–reperfusion injury which impairs the myocardial micro-environment and reduces the survival of transplanted cells. We tested the hypothesis that IPC may improve the survival of transplanted cells and enhance their therapeutic effects. In this study, bone marrow-derived mesenchymal stem cells (BMSCs) from Sprague–Dawley rats were infected with lentivirus carrying green fluorescent protein (GFP) gene. The left main coronary arteries of rats were occluded for a 30-min ischemia, followed by a 72 h or 28 d reperfusion. IPC was induced by 3 cycles of 10 s reperfusion and 10 s ischemia before sustained reperfusion. GFP–BMSCs were intramyocardially injected at 2 h reperfusion. At 70 h after transplantation, IPC treatment increased the level of interleukin-10, B-cell leukemia-lymphoma-2 (BCL-2), and vascular endothelial and basic fibroblast growth factor (VEGF and bFGF), and decreased the level of tumor necrosis factor-α, interleukin-1β and BCL-2-associated X protein by ELISA or PCR or western blotting. The BMSCs therapy with IPC produced more surviving GFP-positive cells than the BMSCs therapy alone by fluorescent staining [at 70 h, (90 ± 14)/mm² vs. (61 ± 12)/mm², and at 28 days, (55 ± 14)/mm² vs. (26 ± 8)/mm², P < 0.01, respectively]. At 28 days, it, when compared with the Control, IPC treatment, and BMSCs therapy, demonstrated higher left ventricular ejection fraction by echocardiography (62% ± 8%, 69% ± 6%, and 75% ± 4% vs. 82% ± 4%, P < 0.05, respectively), higher expression of VEGF and bFGF by western blotting and PCR, less myocardial fibrosis by Masson's trichrome staining, and higher capillary density by immunohistochemistry. These results suggest that ischemic postconditioning promotes the survival of transplanted cells and enhances their repair of infarcted myocardium through paracrine mechanisms.     

后处理减轻心肌缺血/再灌注损伤与HIF-1α-iNOS-cGMP通路激活的关系

目的 探讨后处理减轻缺血/再灌注所致的心肌损伤效应是否与低氧诱导因子-1α （HIF-1α）及其下游通路有关.方法 建立大鼠心肌缺血/再灌注及后处理模型,检测心肌组织中HIF-1α及其下游基因诱导性一氧化氮合酶（iNOS）的表达情况及cGMP的含量.结果 后处理缩小缺血/再灌注所致的心梗面积[（27.30±4.16）%比 （36.00±5.29）%,P＜0.01],减少心肌细胞凋亡（Caspase 3比活性：（1.85±0.50）比（3.79±0.64）,P＜0.01）,上调心肌组织中HIF-1α表达[（5.76±0.55） 比（2.85±0.13）,P＜0.01）的同时,提高了iNOS的表达及其cGMP的含量.预先给予HIF-1α脯氨酸羟化酶抑制剂DMOG使后处理心肌组织中HIF-1α表达进一步上调后,iNOS的表达及cGMP含量随之增加,同时后处理减轻心肌损伤的效应[心梗面积：（17.95±2.00）% 比 （27.30±4.16）%,P＜0.01; Caspase3比活性：0.43±0.13比1.85±0.50,P＜0.01]也进一步增强.结论 后处理减轻缺血/再灌注所致心肌损伤的效应可能与其激活心肌组织中HIF-1α-iNOS-cGMP通路有关.     

瑞芬太尼后处理对大鼠心肌缺血-再灌注损伤的影响

目的探讨瑞芬太尼后处理对缺血-再灌注心肌的影响及其机制。方法清洁级健康雄性SD大鼠78只,体重200~250g,随机分为六组:假手术组(S组)、单纯缺血-再灌注组(IR组)、纳洛酮拮抗剂组(NAL组)、瑞芬太尼5μg·kg~(-1)·min~(-1)后处理组(R1组)、瑞芬太尼10μg·kg~(-1)·min~(-1)后处理组(R2组)和瑞芬太尼20μg·kg~(-1)·min~(-1)后处理组(R3组),每组13只。S组仅在冠状动脉左前降支处穿线,但不结扎;IR组结扎冠状动脉左前降支,缺血45 min,再灌注24h;R1、R2和R3组在缺血35min时,分别静脉输注瑞芬太尼5、10和20μg·kg~(-1)·min~(-1),10min后再灌注24h;NAL组在心肌缺血25min时,静脉注射纳洛酮0.1mg·kg~(-1),10min后静脉输注瑞芬太尼10μg·kg~(-1)·min~(-1),10min后再灌注24h。观察心肌梗死面积和心肌病理学变化,同时测定血清肌钙蛋白I(cTnI)、乳酸脱氢酶(LDH)、肌酸激酶同工酶MB(CK-MB)的浓度。结果与S组比较,IR、NAL、R1、R2和R3组血清cTnI、LDH、CK-MB浓度明显升高,心肌梗死面积百分比明显增大(P0.05),心肌细胞损伤增多;与IR组比较,R1、R2和R3组血清cTnI、LDH、CK-MB浓度明显降低,心肌梗死面积百分比明显减小(P0.05),心肌细胞损伤减少(P0.05)。结论瑞芬太尼后处理可减轻大鼠心肌缺血-再灌注损伤,其机制与瑞芬太尼激活阿片受体有关,此作用具有量效"封顶"效应。