Activation of Akt and cardioprotection against reperfusion injury are maximal with only five minutes of sevoflurane postconditioning in isolated rat hearts

It had been proved that administration of sevoflurane for the first two minutes of reperfusion effectively protects the heart against reperfusion injury in rats in vivo.Our aim was to investigate the duration of effective sevoflurane administration and its underlying mechanism in isolated rat hearts exposed to global ischemia/reperfusion(I/R) injury.Adult male Sprague-Dawley rats were randomly divided into six groups(n=12):a sham-operation group,an I/R group,and four sevoflurane postconditioning groups(S2,S5,S10,and S15).In the S2,S5,S10,and S15 groups,the duration times of sevoflurane administration were 2,5,10,and 15 min after the onset of reperfusion,respectively.The isolated rat hearts were mounted on the Langendorff system,and after a period of equilibrium were subjected to 40 min global ischemia and 120 min reperfusion.Left ventricular(LV) hemodynamic parameters were monitored throughout each experiment and the data at 30 min of equilibrium and 30,60,90,and 120 min of reperfusion were analyzed.Myocardial infarct size at the end of reperfusion(n=7 in each group) and the expression of myocardial phosphorylated Akt(p-Akt) after 15-min reperfusion were determined in a duplicate set of six groups of rat hearts(n=5 in each group).Compared with the I/R group,the S5,S10,and S15 groups had significantly improved left ventricular end-diastolic pressure(LVEDP),left ventricular developed pressure(LVDP),and the maximal rate of rise or fall of the LV pressure(±dP/dtmax),and decreased myocardial infarct size(P<0.05),but not the S2 group.After 15 min of reperfusion,the expression of p-Akt was markedly up-regulated in the S5,S10,and S15 groups compared with that in the I/R group(P<0.05),but not in the S2 group.Sevoflurane postconditioning for 5 min was sufficient to activate Akt and exert maximal cardioprotection against I/R injury in isolated rat hearts.     

Sevoflurane postconditioning reduces myocardial reperfusion injury in rat isolated hearts via activation of PI3K/Akt signaling and modulation of Bcl-2 family proteins

Sevoflurane postconditioning reduces myocardial infarct size.The objective of this study was to examine the role of the phosphatidylinositol-3-kinase(PI3K)/Akt pathway in anesthetic postconditioning and to determine whether PI3K/Akt signaling modulates the expression of pro-and antiapoptotic proteins in sevoflurane postconditioning.Isolated and perfused rat hearts were prepared first,and then randomly assigned to the following groups:Sham-operation(Sham),ischemia/reperfusion(Con),sevoflurane postconditioning(SPC),Sham plus 100 nmol/L wortmannin(Sham+Wort),Con+Wort,SPC+Wort,and Con+dimethylsulphoxide(DMSO).Sevoflurane postconditioning was induced by administration of sevoflurane(2.5%,v/v) for 10 min from the onset of reperfusion.Left ventricular developed pressure(LVDP),left ventricular end-diastolic pressure(LVEDP),maximum increase in rate of LVDP(+dP/dt),maximum decrease in rate of LVDP(?dP/dt),heart rate(HR),and coronary flow(CF) were measured at baseline,R30 min(30 min of reperfusion),R60 min,R90 min,and R120 min.Creatine kinase(CK) and lactate dehydrogenase(LDH) were measured after 5 min and 10 min reperfusion.Infarct size was determined by triphenyltetrazolium chloride staining at the end of reperfusion.Total Akt and phosphorylated Akt(phospho-Akt),Bax,Bcl-2,Bad,and phospho-Bad were determined by Western blot analysis.Analysis of variance(ANOVA) and Student-Newman-Keuls' test were used to investigate the significance of differences between groups.The LVDP,±dP/dt,and CF were higher and LVEDP was lower in the SPC group than in the Con group at all points of reperfusion(P0.05).The SPC group had significantly reduced CK and LDH release and decreased infarct size compared with the Con group [(22.9±8)% vs.(42.4±9.4)%,respectively;P0.05].The SPC group also had increased the expression of phospho-Akt,Bcl-2,and phospho-Bad,and decreased the expression of Bax.Wortmannin abolished the cardioprotection of sevoflurane postconditioning.Sevoflurane postconditioning may protect the isolated rat heart.Activation of PI3K and modulation of the expression of pro-and antiapoptotic proteins may play an important role in sevoflurane-induced myocardial protection.     

Postconditioning of sevoflurane and propofol is associated with mitochondrial permeability transition pore

Background: Sevoflurane and propofol are effective cardioprotective anaesthetic agents, though the cardioprotection of propofol has not been shown in humans. Their roles and underlying mechanisms in anesthetic postconditioning are unclear.Mitochondrial permeability transition pore (MPTP) opening is a major cause of ischemia-reperfusion injury. Here we investigated sevoflurane- and propofol-induced postconditioning and their relationship with MPTP. Methods: Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. During the first 15 min of reperfusion, hearts were treated with either control buffer (CTRL group) or buffer containing 20 μmol/L atractyloside (ATR group), 3% (v/v) sevoflurane (SPC group),50 μmol/L propofol (PPC group), or the combination of atractyloside with respective anesthetics (SPC ATR and PPC ATR groups). Infarct size was determined by dividing the total necrotic area of the left ventricle by the total left ventricular slice area (percent necrotic area). Results: Hearts treated with sevoflurane or propofol showed significantly better recovery of coronary flow,end-diastolic pressures, left ventricular developed pressure and derivatives compared with controls. Sevoflurane resulted in more protective alteration of hemodynamics at most time point of reperfusion than propofol. These improvements were paralleled with the reduction of lactate dehydrogenase release and the decrease of infarct size (SPC vs CTRL: (17.48±2.70)% vs (48.47±6.03)%,P＜0.05; PPC vs CTRL: (35.60±2.10)% vs (48.47±6.03)%, P＜0.05). SPC group had less infarct size than PPC group (SPC vs PPC:(17.48±2.70)% vs (35.60±2.10)%, P＜0.05). Atractyloside coadministration attenuated or completely blocked the cardioprotective effect of postconditioning of sevoflurane and propofol. Conclusion: Postconditioning of sevoflurane and propofol has cardioprotective effect against ischemia-reperfusion injury of heart, which is associated with inhibition of MPTP opening. Compared to propofol, sevoflurane provides superior protection of functional recovery and infarct size.     

针刺预处理对全脑缺血大鼠微血管损伤及脑水肿的保护作用

[目的]针刺预处理对全脑缺血大鼠微血管损伤及脑水肿的保护作用.[方法]采用四动脉阻断法制作大鼠全脑缺血模型,针刺预处理组:术前给予针刺,针刺7 d后给予全脑缺血10 min,干湿法测脑组织水含量,应用HE染色、TUNEL染色及透射电镜技术,观察大鼠脑缺血后,组织病理学及超微结构改变.[结果]与脑缺血组相比,针刺预处理组不引起明显的神经元损伤,全脑缺血10 m in后72 h,微血管损伤及脑水肿明显减轻,血管内皮细胞凋亡减少.[结论]针刺预处理能够通过减轻微血管损伤及脑水肿对脑缺血产生保护作用.     

线粒体ATP敏感性钾通道在心肌缺血保护中的作用

缺血预处理是指心肌反复多次短暂缺血/再灌注,对随后长时间心肌缺血/再灌注的一种保护.缺血预处理对心肌的保护机制十分复杂,一般公认为线粒体ATP敏感性钾通道(mitoKATP)是心肌缺血预处理保护机制的终末效应器之一.mitoKATP开放后可通过以下3条途径对抗心肌缺血损伤:减少线粒体膜Ca2 通道对Ca2 内流的驱动力,抑制Ca2 内流,减轻心肌细胞钙超载;保护线粒体呼吸链,减轻自由基释放引起的损伤;抑制线粒体转换孔开放,防止细胞色素C从线粒体释放,减少细胞凋亡.     

缺血预处理对大鼠脑缺血再灌注NO代谢的影响

目的:利用Bannisterr建立的颈动脉引流法制作大鼠急性脑缺血再灌注模型研究缺血预处理对一氧化氮(NO)代谢的影响.方法:将18只大鼠分为模型组、缺血预处理(IPC)组和对照组,观察血清和脑皮质中NO的变化.结果:模型组大鼠脑内及血清NO水平升高,较对照组有统计学差异(P＜0.01).IPC组和模型组相比血浆中NO含量增加(P＜0.01),脑皮质中NO含量降低(P＜0.01).结论:缺血预处理可通过抗自由基功能影响NO代谢并保护神经细胞.     

肢体远隔缺血后适应对SD大鼠脑缺血再灌注损伤的影响

目的：研究肢体远隔缺血后适应（limbremoteisehemiepostconditioning,RIP）对脑缺血再灌注损伤的影响。方法：建造大脑中动脉闭塞模型,予以双下肢远隔缺血后适应,采用Bederson评分法对雄性SD大鼠脑缺血后12、24、72h进行评分,运用磁共振T2加权像（T2-WeightedImaging,T2WI）计算梗死体积。结果：RIP组大鼠24h后Bederson评分较再灌注模型组评分减少,差异有统计学意义（P〈0．05）,据T2WI算得RIP组脑梗死体积在12、24、72h均较再灌注模型组减少,差异有统计学意义（P〈0．05）。结论：RIP减少缺血后24h神经功能评分,减少梗死体积,具有减轻再灌注损伤作用。     

Cardioprotective effects of anesthetic preconditioning in rats with ischemia-reperfusion injury: propofol versus isoflurane

Objective: We compare the cardioprotective effects of anesthetic preconditioning by propofol and/or isoflurane in rats with ischemia-reperfusion injury. Methods: Male adult Wistar rats were subjected to 60 min of anterior descending coronary artery occlusion followed by 120 min of reperfusion. Before the long ischemia, anesthetics were administered twice for 10 min followed by 5 min washout. Isoflurane was inhaled at I MAC (0.016) in I group, whereas propofol was inhaled intravenously at 37.5 mg/(kg.h) in P group. A combination ofisoflurane and propofol was administered simultaneously in I+P group. Results: In control (without anesthetic preconditioning, C group), remarkable myocardial infarction and apoptosis accompanied by an increased level of cardiac troponin T were noted 120 rain after ischemia-reperfusion. As compared to those of control group, I and P groups had comparable cardioprotection. In addition, I+P group shares with I and P groups the comparable cardioprotective effects in terms of myocardial infarction and cardiac troponin T elevation. Conclusion: A combination of isoflurane and propofol produced no ad-ditional cardioprotection.     

缺血后适应脑保护机制的研究进展

如今延长溶栓时间窗、减轻再灌注损伤是缺血性脑血管病亟待解决的的问题,缺血后适应提供了一种可能的解决方法,故成为研究的热点。缺血后适应通常指的是在组织缺血-再灌注之后进行的一系列短暂血管闭塞/血管再灌注,诱导组织针对缺血-再灌注损伤产生内源性保护作用,减少组织器官缺血-再灌注损伤。该文将综述缺血后适应脑保护的基本机制：减少缺血-再灌注后脑血流的改变,减少氧化应激产物的产生,抗炎,相关信号传导通路改变。     

缺血预适应与心肌细胞信号转导

心肌缺血预适应是指心脏短暂缺血后能耐受较长时间的缺血现象,是一种有效的心肌保护方法。心肌缺血预适应与细胞信号转导密切相关。细胞信号转导系统包括:触发物质、中介物质、效应物质并通过这三个方面介导心肌缺血预适应。本文就缺血预适应和心肌细胞信号转导作一综述。     

药物预处理的脑保护作用

脑缺血性疾病是临床上常见的疾病,其致病率、致残率及致死率均较高,有研究表明采用轻度的脑缺血预处理可以改善致死性缺血性损伤所引起的神经元损害;基于对脑组织内源性保护作用缺血预处理的认识,近年来发现一些药物预处理可以诱导脑组织产生保护作用,称为药理性预适应,不同的药物诱导药理性预适应脑保护作用的具体机制方面存在一定差异;开发诱导药理性预适应的新药有望应用于神经外科及预防性脑保护作用。     

葡萄籽原花青素对缺血再灌注肝脏氧化损伤和细胞凋亡的影响

目的：探讨葡萄籽原花青素对大鼠肝缺血再灌注损伤的抗氧化作用、凋亡相关蛋白Bcl-2和Bax表达的影响。方法：SD雄性大鼠30只,复制肝缺血再灌注损伤模型。随机分为：假手术组;HIRI模型组;葡萄籽原花青素预处理（GSPE）组（160 mg/kg）,每组10只。于再灌注后3 h检测肝组织谷胱甘肽过氧化物酶（GSH-Px）、超氧化物歧化酶（SOD）、丙二醛（MDA）含量及血清谷丙转氨酶（ALT）、谷草转氨酶（AST）的含量;光镜下比较各组肝组织形态学的变化;免疫组化法检测GSPE对凋亡相关蛋白Bcl-2,Bax表达的影响。结果：与HIRI模型组比较,GSPE预处理组血清ALT、AST水平明显降低（P〈0.05）;肝组织GSH-Px、SOD的活性明显升高（P〈0.05）,而MDA含量下降（P〈0.05）。光镜下GSPE预处理组肝细胞损伤程度较模型组明显减轻;免疫组化结果显示,GSPE预处理组肝组织Bcl-2蛋白的表达量较模型组明显增多,而Bax蛋白的表达量则较模型组明显减少。结论：GSPE对缺血再灌注肝脏具有一定的抗氧化损伤和抗凋亡的作用。     

Respiratory face mask: a novel and cost-effective device for use during the application of myocardial ischemia in rats

To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction, we use a novel device comprised of a face mask and a head/neck retainer in this study. We report the basic design of the novel respiratory face mask (RFM) and evaluate its performance in a rat model of myocardial ischemia. The device is cost-effective and easier to handle than other devices, such as tracheal intubation. Compared with conventional tracheal intubation, we found that RFM shortens operation time significantly while keeping blood indices normal; the mean operation time for rats in the mask group was (32±3) min, and that for the intubation group was (45±7) min (P<0.05). Moreover, the size and shape of the RFM can be changed according to the body weight of rats. In conclusion, RFM is an appropriate device for the establishment of myocardial infarction or ischemia-reperfusion in rats.     

应用新技术观察生脉注射液对左室舒张变化率的影响

本实验采用心导管技术，以左心室舒张末期压力下降最大变化速率（每分钟－dp/dt）为指标，观察了生脉液对家兔急性心肌缺血引起的心舒末期每分钟－dp/dt的影响。其结果表明,脉液可以改善由于心肌缺血而致的左心舒张力功能的不足，使每分钟－dp/dt明显增加。     

线粒体ATP敏感性钾通道与心肌缺血预适应

心肌缺血预适应是指心肌短暂缺血后，恢复血流再灌注，心肌在随后出现更长时间的缺血中得到保护，它是近年来心血管领域研究热点之一。大量研究表明其中涉及ATP敏感性钾通道。最初认为是细胞膜上钾通道参与了缺血预适应，然而，最近多项研究表明是残粒体ATP敏感性钾通道起了重要作用。     

后适应在接受直接PCI治疗的急性ST段抬高性心肌梗死患者中的临床疗效:基于随机对照试验的meta分析(英文)

目的:探讨后适应对接受直接经皮冠状动脉介入(PCI)治疗的急性ST段抬高性心肌梗死(STEMI)患者心血管不良事件的影响。创新点:进一步明确后适应处理对STEMI患者临床预后的影响。方法:对符合入选标准的随机对照临床试验进行meta分析。结论:缺血后适应显著降低ST段抬高性心肌梗死患者心衰风险。     

大鼠脑缺血不同时相神经功能评分、脑梗死灶体积、血清神经元特异性烯醇化酶含量的变化

目的：观察线栓法致大鼠局灶性脑缺血模型后,不同时相神经功能评分、脑梗死灶体积、血清神经元特异性烯醇化酶（neuron specific enolase,NSE）含量的变化.方法：大鼠随机分为脑缺血模型组和假手术组,每组大鼠又随机分为缺血1、6、12、24、72 h组与120 h组6个时相组.采用线栓法建立大鼠局灶性脑缺血模型,观察记录大鼠大脑中动脉栓塞（middle cerebral artery occlusion,MCAO）后不同时相神经功能评分、测定血清NSE含量的变化,TTC染色观察脑梗死灶体积.结果：假手术组神经功能评分均为0;模型组在缺血1h神经功能评分就明显升高,24 h达到最高,持续到120 h.假手术组脑梗死灶体积均为0;模型组在缺血6h脑梗死灶体积才明显升高,24 h达到最高,72 h明显下降,120 h再次升高.假手术组血清NSE含量在各个时相没有明显变化;模型组在缺血1h血清NSE含量就明显升高,12h达到最高,24 h明显下降,一直持续到120 h.结论：脑缺血后神经功能评分、脑梗死灶体积、血清中NSE含量都明显升高,但三者在不同时相的变化是不一致的.     

急性局灶性脑挫裂伤对大鼠脑微循环及神经组织超微结构的影响

目的:探讨大鼠脑损伤后脑微循环障碍、脑缺血及神经组织超微结构的变化规律,为临床改善脑损伤后脑微循环障碍、治疗脑缺血、促进神经功能恢复提供理论依据。方法:采用Feeney's自由落体撞击法建立急性局灶性脑挫裂伤模型,共81只大鼠,随机均分为9组,每组6只行内源性过氧化物酶(EGPO)组织化学染色、脑含水量测定,并进行图象分析。每组3只电镜观察微血管内皮细胞和神经组织超微结构改变。结果:①脑损伤后30min伤区可见出血灶,伤区内无血管染色,伤区周围存在"微无血管区"。"微无血管区"的存在持续至伤后72h。②脑损伤后30min微血管面密度明显下降,伤后48h达到高峰,直到伤后168h才有所恢复,但仍未达到正常水平。③脑损伤后30 min微血管平均光密度明显下降,伤后24h、48h回升,72h再次下降,至168h仍未恢复正常。④脑损伤后30 min,微血管内皮细胞有轻度受损迹象,伤后2h毛细血管腔内有微绒毛形成,伤后6h微绒毛增多。伤后12~72h毛细血管腔明显狭窄。⑤脑损伤后30min,神经细胞超微结构改变不明显,随时间的延长,神经细胞超微结构逐渐恶化,至伤后168h细胞结构完全丧失。结论:EGPO组织化学染色方法能准确反应脑损伤后脑微循环的改变;脑损伤后即发生脑缺血改变,神经细胞、毛细血管内皮细胞的损害继发于脑损伤后的缺血性改变,而脑缺血的发生源于脑损伤后脑微血管结构的破坏和微循环灌注的不足。     

心肌缺血对左室心肌细胞凋亡和凋亡相关基因表达的影响及其分子机制

目的:研究缺血对左室心肌细胞凋亡和凋亡相关基因表达的影响,探讨心肌细胞凋亡的分子机制。方法:采用结扎冠脉左前降支(LAD)法制作大鼠心肌缺血模型;运用DNA琼脂糖凝胶电泳技术鉴定基因组DNA的断裂情况;使用Northern Blot检测缺血心肌细胞p53、c-myc及bcl-2的表达活性。结果;a.缺血能够诱导左室心肌细胞凋亡;b.缺血明显上调p53基因的转录;c.缺血的左室心肌细胞c-myc mRNA含量显著增加;d.缺血减弱了bcl-2基因的转录。结论:内源性促凋亡基因p53、c-myc及抗凋亡基因bcl-2表达活性的改变介导了缺血诱导的心肌细胞凋亡,凋亡是心肌缺血时心肌细胞缺失的一个重要原因。     

Cross-modality transfer effects in conditioning-enhanced neophobia in chicks (Gallus domesticus): Evidence for the separability of novelty from specific stimulus characteristics

In this study, we investigated the separability of novelty from specific stimulus characteristics (e.g., color or taste quality) in the transfer of aversion effects. Ninety-six chicks (Gallus domesticus) received a novel visual (red water) or taste (3.0% vinegar) CS paired with an injection of lithium chloride or saline. The chicks were then tested for aversion to the CS or for conditioning-enhanced neophobia in response to a different novel visual cue (green water) or taste cue (1.0% saline). Aversions to the CSs were reliable and similar to each other. Reliable evidence of conditioning-enhanced neophobia occurred with respect to each test stimulus, irrespective of the type of CS, but conditioning with the vinegar CS produced reliably greater enhancement of neophobia than did conditioning with red water. For each CS, postconditioning neophobia was more persistent in testing with saline than with green water. The results for postconditioning neophobia suggested that novelty is a general stimulus property that is separable from specific stimulus characteristics.