心肌缺血再灌注损伤的线粒体通透性转换机制

线粒体功能障碍存心肌缺血再灌注（ischema／reperfusion I／R）损伤中占有重要地位．近年研究发现线粒体的功能障碍和线粒体通透性转换孔道（mitochondfial permeability transition pore，mPTP）密切相关，     

线粒体通透性转换孔在缺血后适应减轻兔肠缺血再灌注损伤中的作用

目的 观察线粒体通透性转换孔(mPTP)在缺血后适应减轻兔小肠缺血再灌注(I/R)损伤中的作用.方法 将新西兰兔40只随机分为假手术组(Sham组)、L/R组、缺血后适应组(IPO组)、mPTP抑制剂环孢素A组(CsA组)、IPO+ mPTP开放剂苍术甙组(IPO+ Atr组).分别干预后采集各组兔部分小肠组织标本,苏木素-伊红(HE)染色,检测小肠组织丙二醛(MDA)活性,提取肠线粒体,检测mPTP开放,Chiu氏6级评分法观察肠黏膜损伤,原位缺口末端标记法(TUNEL)法检测肠上皮细胞凋亡.结果 与Sham组比较,I/R组mPTP开放明显增加(I/R组3.53±0.36比Sham组1.37 ±0.16,P＜ 0.05);MDA活性明显增高[I/R组(0.98±0.14) nmol/mg比Sham组(0.34±0.03) nmol/mg,P＜0.05];肠黏膜损伤评分明显增高[I/R组(4.66±0.41)分比Sham组(0.92±0.58)分,P＜0.05];肠细胞凋亡指数明显增高[I/R组(60.34±6.02)％比Sham组(4.65±1.68)％,P＜0.05].与I/R组比较,IPO组和CsA组mPTP开放明显减少(IPO组2.32 ±0.23、CsA组2.62±0.18比I/R组3.53 ±0.36,P＜0.05);MDA活性明显减低[IPO组(0.55 ±0.04) nmol/mg、CsA组(0.62±0.06) nmol/mg比I/R组(0.98 ±0.14) nmol/mg,P＜0.05];肠黏膜损伤评分明显减低[IPO组(3.25±0.27)分、CsA组(3.52 ±0.55)分比I/R组(4.66 ±0.41)分,P＜0.05];肠细胞凋亡指数明显减低[IPO组(28.33±3.20)％、CsA组(20.49±4.10)％比I/R组(60.34±6.02)％,P＜0.05],与IPO组比较,IPO+ Atr组mPTP开放明显增加(IPO+ Atr组1.05±0.16比IPO组2.32±0.23,P＜0.05);MDA活性明显增高[IPO +Atr组(1.08±0.18) nmol/mg比IPO组(0.55±0.04) nmol/mg,P＜0.05];肠黏膜损伤评分明显增加[IPO+ Atr组(4.57±0.32)分比IPO组(3.25±0.27)分,P＜0.05];肠细胞凋亡指数明显增加[IPO+ Atr组(40.35±2.18)％比IPO组(28.33±3.20)％,P＜0.05].结论 缺血后适应能减轻兔肠I/R损伤,其机制可能与抑制mPTP开放有关.     

肝脏缺血/再灌注后线粒体损伤与促凋亡蛋白的释放

肝脏缺血／再灌注（I／R）损伤是临床上较为常见的组织器官损伤之一，细胞凋亡在肝脏I／R损伤中起到了重要作用。近年来的研究发现，I／R导致线粒体通透性改变，由此引起线粒体膜电位的降低和促凋亡蛋白的释放等一系列变化，在细胞凋亡中发挥关键作用。     

缺血预处理和后处理减轻缺血/再灌注损伤的分子机制

背景 组织长时间缺血后再灌注能导致缺血/再灌注(ischaemia/reperfusion,I/R)损伤.研究证实缺血预处理和缺血后处理可减轻I/R损伤大约75％. 目的 综述缺血预处理和缺血后处理减轻I/R损伤的分子机制. 内容 缺血预处理和缺血后处理的分子机制涉及腺苷、缓激肽、阿片和大麻素激活的细胞表面G耦联蛋白受体.这些物质依次兴奋生长受体,继而激活细胞保护性通路,其中包括通过有丝分裂原激活蛋白激酶(mitogen-activated protein kinase,MEK)/细胞外信号调节激酶1/2(extracellular signal-regular kinase 1/2,ERK1/2)途径减少细胞凋亡以及通过磷脂酰肌醇-3激酶途径减少线粒体通透性转换孔(mitochondrial permeability transition pore,mPTP)开放.mPTp开放能够导致细胞死亡.最近研究提示,细胞表面激活的肿瘤坏死因子-α受体通过激活Janus激酶以及信号转导子和转录激活因子3途径而发挥细胞保护作用. 趋向 缺血预处理和缺血后处理减轻I/R损伤的分子机制目前仍在研究中,有望在对此更深入理解的基础上获得可转化为有意义的临床治疗措施.     

心磷脂与缺血/再灌注损伤

心磷脂（CL）是维持线粒体能量代谢所必需的一种磷脂，参与了众多重要生理过程。此文对CL的结构、合成和转化；在维持线粒体正常功能中的作用；缺血／再灌注（I／R）损伤中的改变以及和线粒体功能的关系等作了逐一阐述，说明CL与I／R损伤导致的细胞死亡关系密切，CL量或性质的改变在细胞凋亡中处于中心地位。     

缝隙连接蛋白43与心肌缺血／再灌注损伤机制的研究进展

背景研究表明,心肌缺血／再灌注（ischemia／reperfusion,I／R）损伤的发病机制与氧自由基过量产生、钙超载、线粒体损伤及心肌细胞凋亡等密切相关,最新研究发现缝隙连接（gapjunction,GJ）也参与心肌I／R损伤。目的现主要针对GJ连接蛋白（connexin,Cx）43与心肌I／R损伤的关系作一综述。内容Cx43在心肌I／R损伤中参与心肌保护作用,其机制可能与钙超载、在线粒体中的分布及细胞凋亡等因素相关。趋向未来研究需要进一步探究Cx43与心肌细胞凋亡之间的关系,同时为临床实际工作提供依据。     

大电导钙激活钾通道与心血管保护

背景 大电导钙激活钾通道(large conductance Ca2+-activated K+ channels,BKCa)可能是各类心脏疾病的重要治疗靶点. 目的 主要阐述如何通过调节心肌及血管平滑肌的BKCa通道而发挥保护心肌作用及其相关机制. 内容 在心肌细胞的线粒体上,BKCa通道能够有效地调节线粒体的活性氧、Ca2+和呼吸作用.在血管平滑肌细胞,BKCa通道能调节血管紧张度,促进血管扩张. 趋向 BKCa通道在心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤中有着重要的作用,包括改善心肌功能和减少梗死面积.     

线粒体通透性转换孔在肾脏缺血再灌注损伤中的作用

肾脏缺血再灌注损伤是在肾移植等术后发生的损伤，发生率高，发生机制复杂且尚不清楚，并缺乏有效的防治措施。在肾脏缺血再灌注损伤过程中，线粒体发挥重要作用，其中线粒体通透性转换孔( mPTP)这一大分子复合物在应激状态下持续开放将导致一系列功能紊乱进而介导组织损伤。理解mPTP的结构和功能会让我们更加了解肾脏缺血再灌注损伤的发生机制，有助于我们寻找新的治疗靶点，提出新的肾脏保护治疗方法。     

丙泊酚在正颌外科控制性降压中的脑保护作用机理

目的:通过大鼠实验,研究丙泊酚在大鼠脑缺血再灌注损伤时对线粒体通透性转换孔活性的影响程度,及其抑制神经细胞凋亡坏死的作用机制。以探讨其在正颌外科控制性降压中的脑保护作用机理。方法:选取健康雄性大鼠30只,体重250～300g,采用"双侧颈总动脉阻断法"建立前脑缺血再灌注模型,左侧侧脑室于假手术组(C组)、缺血再灌注组(I/R)组注射生理盐水1ml/kg,丙泊酚干预组(P组)射注丙泊酚1mg/kg,24h后断头提取海马组织线粒体,加入CaCl2于37℃下形成钙超载后孵育5min。电镜观察其微观组织形态学改变,采用紫外分光光度计法来观察线粒体通透性转换孔开放程度。结果:电镜下C组线粒体结构完整,排列密集;I/R组可见线粒体明显肿胀、嵴断裂、膜破裂;P组可见线粒体部分肿胀,嵴部分断裂,但损伤程度轻于I/R组。与C组相比较,I/R组和P组线粒体吸光度值明显下降(P<0.05);与I/R相比,P吸光度值下降幅度减小(P<0.05)。丙泊酚组细胞肿胀坏死明显减轻,凋亡细胞及坏死细胞明显减少。结论:丙泊酚能够改善大鼠前脑缺血再灌注后线粒体形态,其机制可能与其抑制线粒体通透性转换孔(MPTP)开放有关,从而改善线粒体功能,抑制神经细胞凋亡坏死,减轻脑缺血再灌注损伤。这说明丙泊酚在正颌外科控制性降压中使用时对大脑有良好的保护作用,可以大幅度提高手术安全效果,具有重要的临床指导意义。     

丙泊酚对大鼠前脑缺血/再灌注诱导线粒体损伤及解耦联蛋白2表达的影响

目的 探讨丙泊酚对大鼠前脑缺血/再灌注(ischemia reprfnsion,I/R)诱导线粒体损伤及解耦联蛋白2(uncoupling protein 2,UCP 2)表达的影响.方法 45只健康雄性Wistar大鼠,体重250 g～300 g,按随机数字表法分为3组(n=15).采用"二血管阻断法"制备大鼠前脑I/R损伤模型.假手术组(C组):暴露双侧颈总动脉后,侧脑室注射生理盐水1 mg/kg;缺血/再灌注(I/R组):脑缺血后侧脑室注射生理盐水1 mg/kg;丙泊酚干预组(P组):脑缺血后侧脑室注射丙泊酚1 mg/kg.各组分别于再灌注后24 h断头取海马组织,提取海马组织线粒体,加入CaCl2于37℃下孵育5 min.透射电镜下观察线粒体形态学改变(n=3);紫外分光光度计法检测线粒体通透性转换孔(mitochondrial permeability transition pore,MPTP)活性(n=6);Western blotting法检测解耦联蛋白2的表达(n=6).结果 电镜下C组线粒体结构完整,I/R组可见线粒体显著肿胀、嵴断裂、膜破裂,P组损伤程度轻于I/R组.C组、I/R组和P组线粒体吸光度值均下降;与C组相比,I/R组和P组线粒体吸光度值明显下降(p<0.05);与I/R组(0.028±0.007)相比,P组(0.017±0.007)吸光度值下降幅度减小(P<0.05).与C组(0.62±0.05)相比,I/R组(0.88±0.14)和P组(1.32± 0.10)UCP2蛋白表达上调(P<0.05);P组UCP2蛋白表达高于I/R组(P<0.05).结论 丙泊酚能够改善大鼠前脑t/R后线粒体形态,促进神经细胞线粒体UCP2表达上调,抑制线粒体经ca2+诱导后MPTP开放,从而改善线粒体功能,这可能是丙泊酚减轻脑I/R损伤的机制之一.     

Prevention of I/R injury in fatty livers by ischemic preconditioning is associated with increased mitochondrial tolerance: the key role of ATPsynthase and mitochondrial permeability transition

Ischemia/reperfusion (I/R) injury is a commonly encountered clinical problem and occurs probably as a consequence of irreversible mitochondrial injury. The increased susceptibility of fatty livers to ischemic injury is associated with depletion of adenosine triphosphate (ATP) content, which is preserved by preconditioning. Mitochondria being the main ATP production source for the cell, we aimed to evaluate whether ischemic preconditioning (IPC) of fatty livers prevents the impairment in mitochondrial function induced by I/R. Lean and steatotic animals were subjected to 90 min of hepatic warm ischemia and 12 h of reperfusion. IPC effect was tested in fatty livers. After reperfusion, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. Mitochondrial membrane potential, mitochondrial respiration and susceptibility to mitochondrial permeability transition (MPT) were evaluated, as well as ATPase activity and adenine nucleotides. IPC of fatty livers decreased serum AST and ALT levels. Fatty animals subjected to I/R exhibited decreased mitochondrial membrane potential and a delay in the repolarization after a phosphorylation cycle, associated with increased state 4 respiration. Increased tolerance to MPT induction, preservation of F₁F_o-ATPsynthase activity and mitochondrial bioenergetics were observed in ischemic preconditioned fatty livers. Thus, IPC is an endogenous protecting mechanism that preserves mitochondrial function and bioenergetics in fatty livers.     

Age-associated differences in the inhibition of mitochondrial permeability transition pore opening by cyclosporine A

Background: Inhibiting mitochondrial permeability transition pore (mPTP) opening is a key protection of the myocardium from ischemia/reperfusion (I/R) injury. Here, we investigated age‐associated differences in the ability of cyclosporine A (CsA) to protect the heart and to modulate mPTP opening during I/R injury in vivo and its opening induced by reactive oxygen species (ROS) in vitro. Methods: Fischer 344 male rats were assigned from their respective age groups, young or old groups, to (1) I/R or (2) I/R+CsA. All animals were subjected to 30 min of ischemia following 120 min of reperfusion to determine myocardial infarct size in vivo. To measure mPTP opening in vivo, left ventricular tissues were collected 10 min after reperfusion and nicotinamide adenine dinucleotide (NAD⁺) levels were measured. In parallel experiments, rat ventricular myocytes were prepared from young and old hearts, loaded with tetramethylrhodamine ethylester and then subjected to oxidative stress in the presence or absence of CsA, and the mPTP opening time was measured using laser scanning confocal microscopy. Results: CsA reduced myocardial infarct size in young I/R rats. Whereas CsA failed to significantly affect myocardial infarct size in old I/R rats, NAD⁺ levels were better preserved in young CsA‐treated rats, but this relative improvement was not observed in old rats. CsA also significantly prolonged the time necessary to induce mPTP opening in young cardiomyocytes, but not in cardiomyocytes isolated from the old rats. Conclusions: mPTP regulation is dysfunctional in the aged myocardium and this could account for loss of cardioprotection with aging.     

海马神经细胞线粒体通透性转换孔在富氢液减轻大鼠全脑缺血再灌注损伤中的作用

目的 评价海马神经细胞线粒体通透性转换孔(mPTP)在富氢液减轻大鼠全脑缺血再灌注损伤中的作用.方法 雄性SD大鼠72只,体重250 ～ 300 g,采用随机数字表法,将其随机分为6组(n=12):假手术组(S组)、缺血再灌注组(IR组)、生理盐水组(NS组)、富氢液组(H组)、苍术苷组(A组)和富氢液+苍术苷组(HA组).采用四血管阻塞法建立大鼠全脑缺血再灌注模型,缺血15 min后恢复灌注.H组和HA组于再灌注即刻腹腔注射富氢液5 ml/kg,其余组腹腔注射等容量生理盐水;A组和HA组于再灌注前10 min行侧脑室注射苍术苷15 μl,NS组和H组侧脑室注射等容量生理盐水.再灌注24h时行神经行为学损伤评分后各组随机处死8只大鼠,迅速断头,分离海马神经细胞线粒体,采用分光光度计法测定mPTP的开放程度,Rhodamine123法测定线粒体膜电位.再灌注72 h时各组处死4只大鼠,取海马组织,光镜下观察CA1区病理学结果,计数该区神经细胞存活数.结果 与S组比较,其余组再灌注24h时行为学损伤加重,mPTP活性升高,线粒体膜电位降低(P＜0.05);与IR组比较,H组和HA组再灌注24h时行为学损伤减轻,mPTP活性降低,线粒体膜电位升高(P＜0.05);与H组比较,HA组行为学损伤加重,mPTP活性升高,线粒体膜电位降低(P＜0.05).再灌注72 h时HA组较IR组神经细胞存活数增加(P＜0.05),H组海马CA1区神经元损伤较IR组、NS组、A组和HA组减轻.结论 富氢液可减轻大鼠全脑缺血再灌注损伤,其机制与抑制海马神经细胞mPTP开放,减少线粒体膜电位降低,从而维持线粒体功能有关.     

The mitochondrial permeability transition pore and its role in anaesthesia-triggered cellular protection during ischaemia-reperfusion injury

This review summarises the most recent data in support of the role of the mitochondrial permeability transition pore (mPTP) in ischaemia-reperfusion injury, how anaesthetic agents interact with this molecular channel, and the relevance this holds for current anaesthetic practice. Ischaemia results in damage to the electron transport chain of enzymes and sets into play the assembly of a non-specific mega-channel (the mPTP) that transgresses the inner mitochondrial membrane. During reperfusion, uncontrolled opening of the mPTP causes widespread depolarisation of the inner mitochondrial membrane, hydrolysis of ATP, mitochondrial rupture and eventual necrotic cell death. Similarly, transient opening of the mPTP during less substantial ischaemia leads to differential swelling of the intermembrane space compared to the mitochondrial matrix, rupture of the outer mitochondrial membrane and release of pro-apoptotic factors into the cytosol. Recent data suggests that cellular protection from volatile anaesthetic agents follows specific downstream interactions with this molecular channel that are initiated early during anaesthesia. Intravenous anaesthetic agents also prevent the opening of the mPTP during reperfusion. Although by dissimilar mechanisms, both volatiles and propofol promote cell survival by preventing uncontrolled opening of the mPTP after ischaemia. It is now considered that anaesthetic-induced closure of the mPTP is the underlying effector mechanism that is responsible for the cytoprotection previously demonstrated in clinical studies investigating anaesthetic-mediated cardiac and neuroprotection. Manipulation of mPTP function offers a novel means of preventing ischaemic cell injury. Anaesthetic agents occupy a unique niche in the pharmacological armamentarium available for use in preventing cell death following ischaemia-reperfusion injury.     

Postconditioning Prevents Reperfusion Injury by Activating [delta]-Opioid Receptors

Background: While postconditioning has been proposed to protect the heart by targeting the mitochondrial permeability transition pore (mPTP), the detailed mechanism underlying this action is unknown. The authors hypothesized that postconditioning stimulates opioid receptors, which in turn protect the heart from reperfusion injury by targeting the mPTP.

Methods: Rat hearts (both in vivo and in vitro) were subjected to 30 min of ischemia and 2 h of reperfusion. Postconditioning was elicited by six cycles of 10-s reperfusion and 10-s ischemia. To measure nitric oxide concentration, cardiomyocytes loaded with 4-amino-5-methylamino-2',7'-difluorofluorescein were imaged using confocal microscopy. Mitochondrial membrane potential was determined by loading cardiomyocytes with tetramethylrhodamine ethyl ester.

Results: In open chest rats, postconditioning reduced infarct size, an effect that was reversed by both naloxone and naltrindole. The antiinfarct effect of postconditioning was also blocked by the mPTP opener atractyloside. In isolated hearts, postconditioning reduced infarct size. Morphine mimicked postconditioning to reduce infarct size, which was abolished by both naltrindole and atractyloside. N-nitro-l-arginine methyl ester and guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one blocked the action of morphine. Further experiments showed that morphine produces nitric oxide in cardiomyocytes by activating [delta]-opioid receptors. Moreover, morphine could prevent hydrogen peroxide-induced collapse of mitochondrial membrane potential in cardiomyocytes, which was reversed by naltrindole, N-nitro-l-arginine methyl ester, and the protein kinase G inhibitor KT5823.     

肠缺血／再灌注损伤与防治措施

背景肠缺血／再灌（ischemia／reperfusion,I／R）损伤是外科实践中常见的组织器官损伤之一,在严重感染、创伤、休克、心肺功能不全等疾病的病理生理演变过程中起重要作用。目的就肠I／R损伤产生机制以及防治措施的研究进展进行综述,为今后临床工作提供指导。内容针对肠I／R损伤机制（氧自由基、能量缺乏、细胞内Ca^2＋超载、炎症反应、细胞异常凋亡）及其防御措施的研究进展展开论述。趋向肠I／R损伤是综合性原因引起,采取综合性防治措施可防治肠I／R损伤。     

葛根素对大鼠肝缺血再灌注损伤脑组织c-fos和Bcl-2表达的影响

目的：观察肝缺血再灌注损伤时c-fos、Bcl-2与脑细胞凋亡的关系及葛根素对其影响的可能机制。方法：建立肝缺血再灌注损伤动物模型。选健康雄性SD大鼠56只,随机分为对照组、缺血30min组（I组）、缺血30min即刻再灌注组（I/R组）、缺血30min再灌注1h组（I/R1h）、缺血30min再灌注2h组（I/R2h）、30min再灌注4h组（I/R4h）及葛根素预处理组（PUE＋I/R4h组）,每组8只。观缺血察各组肝、脑HE染色;应用免疫组织化学方法测定各组大鼠脑组织c-fos、Bcl-2的表达;应用原位细胞凋亡法测定脑细胞凋亡。结果：I/R2h组、I/R4h组肝组织中散在分布大量炎症细胞,肝细胞明显肿胀,有的呈空泡状变性,肝脏结构紊乱;PUE＋I/R4h组上述改变明显改善。I/R2h、I/R4h组脑组织水肿明显,PUE＋I/R4h组明显改善。与对照组比较,其余各组脑组织c-fos表达均增高﹙P〈0.01）,I/R4h组水平最高,PUE＋I/R4h组较I/R1h组、I/R2h组、I/R4h组明显降低（P〈0.01）。与对照组比较,其余各组脑组织Bcl-2表达增高（P〈0.01）,I/R4h组与I/R2h组差异无统计学意义﹙P〉0.05）,PUE＋I/R4h组较对照组、组表达增多（P〈0.01）,较I/R1h组、I/R2h组、I/R4h组明显降低（P〈0.01）。I组、I/R组细胞I凋亡指数较对照组明显增加（P〈0.01）,随着再灌注时间的延长细胞凋亡指数逐渐增加。PUE＋I/R4h组较I/R2h组、I/R4h组明显降低（P〈0.01）。结论：肝缺血再灌注损伤可引起脑组织的损伤及脑细胞凋亡。随着再灌注时间的延长,脑组织中c-fos表达增高,脑细胞凋亡与c-fos的表达有关。Bcl-2在缺血期发挥了抑凋亡的作用,随着再灌注时间的延长,其作用减弱,脑细胞凋亡指数增加。葛根素可能通过抑制c-fos的表达、增加Bcl-2的表达发挥减轻肝缺血再灌注损伤所致脑细胞凋亡的作用。