缺血后处理对不同时程冷保存大鼠心脏的作用研究

目的:研究缺血后处理(postconditioning)对不同时程冷保存大鼠心脏的作用及其机制。方法:利用Langendorff离体鼠心灌注法,观察大鼠心脏在Celsior液(4℃)中保存3 h或5 h后,在其后复灌60 min期间血流动力学的恢复情况,并对复灌期间心律失常严重程度进行定量分析。缺血后处理采用全心停灌30 s,复灌30 s,循环3次。结果:(1)与3 h冷保存对照组相比,大鼠心脏冷保存3 h后给予缺血后处理,在多个复灌时间点上可明显降低左室舒张末期压力,而心率、左室发展压、左室最大收缩/舒张速率、冠脉流出量、心率与发展压的乘积等的恢复率在复灌期明显高于3h对照组。心脏冷保存3 h后心律失常的发生率在复灌第0~10min时最高,缺血后处理可明显降低心律失常的发生率。(2)在缺血后处理短暂复灌期的K-H灌流液中加入100μmol/L的5-HD(线粒体ATP依赖性钾离子通道的阻断剂),可取消缺血后处理降低左室舒张末期压力,增高心率、左室发展压、左室最大收缩/舒张速率、冠脉流出量、心率与发展压乘积的作用。心律失常评分亦明显高于3 h缺血后处理组。(3)大鼠心脏冷保存5 h后给予缺血后处理,在复灌期间各项动力学指标以及心律失常评分上与5 h冷保存对照组无明显差异。结论:缺血后处理对于3 h冷保存的大鼠心脏有显著的保护作用,其作用机制可能是部分通过激活线粒体ATP依赖性钾离子通道起作用,而缺血后处理对于5 h冷保存的大鼠心脏并无保护作用。     

缺血后处理对小鼠肠缺血再灌注所致急性肺损伤保护作用中炎症介质的影响

目的:探讨缺血后处理对于肠缺血再灌注所致急性肺损伤保护作用及其机制.方法:健康雄性C57小鼠36只,随机分为如下3组:假手术组(S组,n=12)、缺血再灌注组(I/R组,n=12)、缺血后处理+缺血再灌注组(IPO+I/R组,n=12).采用小鼠肠缺血再灌注模型及缺血后处理模型,光镜下观察肺组织病理改变,检测肺水肿程度,每组半数小鼠取血检测肺血管通透性以检测肺功能改变,半数小鼠取血检测血清促炎因子TNF-α、IL-6,及抗炎因子IL-10的含量.结果:I/R组肺组织损伤程度明显增高(P＜0.05),肺水肿程度增加(P＜0.05),肺血管通透性增强(P＜0.05),I/R组血清促炎因子TNF-α、IL-6含量较之于C组显著增高(P＜0.05),抗炎因子IL-10的含量较之于C组显著降低(P＜0.05).进行缺血后处理后,IPO组较I/R组TNF-α、IL-6显著降低(P＜0.05),但仍高于C组(P＜0.05).IL-10较I/R组显著增高(P＜0.05).结论:肠缺血后处理的节律刺激干预可减轻肠缺血再灌注所致肺损伤.其保护作用机制可能为增加抗炎因子IL-10表达、抑制促炎因子TNF-α、IL-6表达,进而减轻肺损伤.     

阿魏酸钠缺血后处理对大鼠心肌缺血再灌注损伤的保护作用的研究

目的:探讨阿魏酸钠(SF)对大鼠心肌缺血再灌注损伤的保护作用及可能的机制。方法:40只Sprague-Dawley大鼠随机分为四组,A组:假手术组;B组:缺血/再灌注损伤组;C组:缺血后处理组;D组:SF后处理组。建立缺血后处理模型,实验结束后取出心脏,测定心肌梗死面积,TNF-α,IL-10的含量及核因子-κB的活性。结果:(1)心肌梗死面积的测定:与缺血/再灌注损伤组相比,SF后处理组明显减小了心肌梗死面积(P<0.05)。(2)心肌中TNF-α和IL-10含量的测定:TNF-α、IL-10在缺血再灌注组均升高,SF后处理组同缺血再灌注组比较TNF-α水平明显减低(P<0.05),IL-10含量则明显增高(P<0.05)。(3)NF-κB活性的测定:NF-κB活性在缺血再灌注组显著提高,与缺血再灌注组相比,SF后处理组显著阻止NF-κB活性的升高(P<0.05)。结论:适当剂量SF后处理可以减弱心肌缺血再灌注损伤,可能与其减轻NF-κB的活性,从而减弱肿瘤坏死因子-α的表达,减低由缺血再灌注损伤引起的炎症反应所致。     

吗啡后处理对大鼠离体心脏缺血再灌注损伤的影响

目的 评价吗啡后处理对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠,体重180～200 g,应用Langendorff灌流装置,采用全心停灌45 min、再灌注60 min的方法制备大鼠离体心脏缺血再灌注模型.实验一:取模型制备成功的心脏32个,随机分为4组(n=8):Ⅰ组～Ⅳ组,Ⅰ组不予处理,Ⅱ组～Ⅳ组于再灌注即刻分别灌注含0.3、3.0和30 μmol/L吗啡的K-H液10 min,随后灌注正常K-H液50 min;实验二:根据实验一的结果,选择对离体心脏缺血再灌注损伤影响最强的吗啡浓度,另取模型制备成功的心脏32个,随机分为4组(n=8):Ⅰ组～Ⅳ组,Ⅰ组不予处理,Ⅱ组～Ⅳ组于再灌注即刻分别灌注含吗啡的K-H液5、10和20 min,随后灌注正常K-H液50 min;实验三:根据实验二的结果,选取对离体心脏缺血再灌注损伤影响最强的吗啡后处理方法.另取模型制备成功的心脏37个,随机分为5组:Ⅰ组(n=8)不予处理;Ⅱ组(n=8)、Ⅲ组～Ⅴ组(n=7)于再灌注即刻分别灌注含吗啡、10 μmol/L非选择性阿片受体阻断剂纳洛酮和吗啡、5 μmol/L选择性κ受体阻断剂nor-binahorphimine和吗啡、5 μmol/L选择性δ受体阻断剂naltrindole和吗啡的K-H液,各组均再灌注正常K-H液50 min.于再灌注60 min时测定心肌肌酸激酶同工酶(CK-MB)活性,计算心肌缺血危险区/梗塞区(IS/AAR).结果 根据实验一、二的结果于再灌注即刻灌注含3.0 μmol/L吗啡的K-H液10 min行后处理.实验三的结果:与Ⅰ组比较,Ⅱ组和Ⅴ组心肌IS/AAR和CK-MB活性降低,Ⅳ组心肌CK-MB活性降低(P<0.05或0.01),Ⅲ组以上指标差异无统计学意义(P>0.05);与Ⅱ组比较,Ⅲ组和Ⅳ组心肌IS/AAR和CK-MB活性升高(P<0.01),Ⅴ组上述指标差异无统计学意义(P>0.05).结论 吗啡后处理可减轻大鼠离体心脏缺血再灌注损伤,此作用可能与激活心肌κ受体有关.     

Postconditioning in man

Acute myocardial infarction is the leading cause of morbidity and mortality in industrialized countries. Ischemic postconditioning, that consists of repeated brief episodes of ischemia-reperfusion performed just after reflow following a prolonged ischemic insult, dramatically reduces infarct size in animal models. Recent data indicate that it might involve the activation of the PI3-kinase—Akt—eNOS as well as PKC signalling pathways and inhibition of the opening of the permeability transition pore. A recent clinical study demonstrated that postconditioning protects the human heart. Repeated brief episodes of inflation-deflation of the angioplasty balloon performed immediately after re-opening of the culprit coronary artery reduced infarct size by 36%. Additional studies are required to determine whether infarct size limitation by postconditioning would improve functional recovery as well as patient’s outcome. Further research is needed to find new pharmacological agents that would mimick postconditioning in order to treat all patients with ongoing acute myocardial infarction.     

Pharmacological postconditioning with the phytoestrogen genistein

Estrogens are known to activate the phosphatidyl-inosityl 3-kinase (PI3K)/Akt pathway, which is central in the cardioprotection afforded by ischemic postconditioning. Therefore, our goal was to investigate whether a phytoestrogen, genistein, could induce a pharmacological postconditioning and to investigate potential mechanisms. We used low doses of genistein in order to avoid tyrosine kinases inhibition. Thus, pentobarbital-anesthetized rabbits underwent a coronary artery occlusion followed by 4 h of reperfusion. Prior to reperfusion, they randomly received an i.v. injection of either saline (Control), 100 or 1000 microg/kg of genistein (Geni(100) and Geni(1000), respectively), and 10 or 100 microg/kg of 17beta-estradiol (17beta(10) and 17beta(100), respectively). Infarct size (IS, % area at risk) was significantly reduced in Gen(100), Gen(1000) and 17beta(100) but not in 17beta(10) (6+/-2, 16+/-5, 12+/-3 and 29+/-7%, respectively) vs. Control (35+/-4%). A significant decrease in the percentage of TUNEL-positive nuclei within infarcted area was observed in Gen(100) and 17beta(100) vs. Controls. The estrogen receptor antagonist fulvestrant (1 mg/kg i.v.) and the PI3K inhibitor wortmaninn (0.6 mg/kg) abolished the cardioprotective effect of genistein. Western blots also demonstrated an increase in Akt posphorylation in Gen(100). In the same group, in vitro mitochondrial swelling studies demonstrated a significant inhibition of calcium-induced opening of mitochondrial transition pore vs. Controls. In conclusion, genistein exerts pharmacological postconditioning with a similar potency as 17beta-estradiol through a pathway involving activation of the estrogen receptor, of PI3K/Akt and mitochondrial preservation. Therefore, genistein should not be only considered as an inhibitor of tyrosine kinase but also as a cardioprotective estrogen.     

Transforming growth-beta 1 contributes to isoflurane postconditioning against cerebral ischemia–reperfusion injury by regulating the c-Jun N-terminal kinase signaling pathway

AimCerebral ischemia–reperfusion (I/R) injury is a devastating complication in the perioperative period. Transforming growth factor beta (TGF-β) is a key protein that can participate in the repair and control process responses after I/R injury. Isoflurane is widely used in neurosurgery. Previous studies have shown that isoflurane preconditioning plays an important role in neuroprotection. However, the effects of isoflurane postconditioning on cerebral I/R injury have not yet been elucidated. In the present study, we evaluated the protective effect of isoflurane postconditioning against cerebral I/R injury and investigated the role of the TGF-β signaling pathway and the downstream c-Jun N-terminal kinase (JNK) signaling pathway in neuroprotective mechanism. In particular, the JNK signaling pathway emerges as a possible target for brain repair after stroke.MethodsCerebral I/R injury was produced in SD rat by using the middle cerebral artery occlusion model for 90 min, followed by 24 h reperfusion. Postconditioning by inhalation of isoflurane was performed at different concentrations (1.5%, 3.0%, and 4.5%) for 1 h after ischemia at the starting time point of reperfusion. The protective effect was tested by neurological deficit scoring with 2,3,5-triphenyl tetrazolium chloride and propidium iodide (PI) staining. Apoptosis of CA1 cells in the hippocampus was detected by TUNEL method. Expression levels of TGF-β1, Smad 2/3, p-Smad2/3, JNK, and p-JNK were determined by immunostaining and Western blot.ResultsPostconditioning by isoflurane at 1.5% and 3.0% concentrations significantly decreased the neurobehavioral deficit scores and infarct volume compared with the I/R group, but no significant difference in neurobehavioral deficit score was detected between the I/R and 4.5% isoflurane postconditioning groups. Additionally, 1.5% isoflurane postconditioning decreased the numbers of PI-positive cells at 24 h after reperfusion compared with the I/R group. TGF-β1 and p-Smad2/3 protein gradually increased after I/R injury, with the highest values observed in the 1.5% and 3% isoflurane postconditioning groups. For Smad2/3 protein expression, no differences existed among all groups. After inducing the TGF-β/SMAD3 signaling pathway specific blocker (LY2157299), the neurological deficit scores increased, infarct volumes enlarged, apoptosis increased, and PI-positive CA1 cells in the hippocampus also increased. The expression levels of TGF-β1 and p-Smad2/3 proteins were downregulated. During the pre-injection of LY2157299, the expression levels of TGF-β1 and p-Smad2/3 decreased significantly, but compared with the sham group, the expression level of p-JNK significantly increased. When the injection of LY2157299 was abolished, the expression of p-JNK significantly decreased. The expression levels of p-JNK and TGF-β1 significantly decreased when LY2157299 and SP600125 were injected simultaneously. However, the protective effect mediated by SP600125 completely disappeared, and the role of LY2157299 became dominant. Compared with the sham group, the expression of TGF-β1 was almost unchanged by the injection of SP600125 alone, but the expression of p-JNK significantly decreased.ConclusionsUp to 1.5% isoflurane can upregulate the expression of TGF-β1 and downregulate that of p-JNK, which significantly mitigated I/R injury, leading to cerebral injury. However, this protective effect was abrogated when the TGF-β1 signaling pathway was blocked by LY2157299. Overall, the present results provided valid evidence to demonstrate that TGF-β1 contributes to isoflurane postconditioning against cerebral I/R injury by inhibiting the JNK signaling pathway.     

米诺环素后处理对大鼠缺血再灌注损伤的影响及其机制

目的探讨米诺环素后处理对大鼠心肌缺血再灌注损伤的作用及其可能机制。方法 96只雄性Wistar大鼠随机分为假手术组、缺血再灌注组、低剂量米诺环素组(3 mg/kg)和高剂量米诺环素组(10 mg/kg)。通过结扎大鼠左冠状动脉前降支45 min,再灌注2 h及24 h。再灌注2 h,检测各组心肌缺血危险区、梗死范围;血清、心肌组织TNF-α、IL-1β含量及心肌组织MPO活性;心肌凋亡指数(AI)以及心肌组织形态学改变。再灌注24 h,检测大鼠心脏血流动力学、心肌缺血危险区、梗死范围。结果与缺血再灌注组比较,低剂量、高剂量米诺环素均能降低左心室舒张末压、心肌梗死范围、AI以及血清、心肌组织TNF-α、IL-1β含量及心肌组织MPO活性,同时升高心率、左心室收缩压、±dp/dtmax(P0.05或P0.01)。结论米诺环素后处理能够显著抑制心肌缺血再灌注损伤诱导的大鼠心肌细胞凋亡,减少梗死范围,明显改善心功能,其机制与减少局部与系统的炎症反应有关。     

苯那普利后处理对离体大鼠心肌缺血再灌注损伤的保护作用

目的观察苯那普利后处理对离体大鼠心肌缺血再灌注（I／R）损伤的保护作用，初步探讨其可能的作用机制。方法应用Langendroff离体灌流装置，采用完全停灌复灌方法制作离体大鼠心肌缺血再灌注模型。32只SD大鼠随机等分为4组：对照组、I／R组、缺血预处理组和苯那普利后处理组。测定各组稳灌20min和再灌60min时的冠脉流量，改良亮绿变色酸法（GCA）观察心肌损害程度，免疫组化法检测心肌组织中核因子-κB（NF—κB）和肿瘤坏死因子（TNF—α）的表达。结果与对照组比，I／R组，再灌注60min时的冠脉流量减少（P〈0．01），心肌损害程度增加（P〈0．01），免疫组织化学染色可见NF—κB蛋白表达显著增强且主要表达在心肌细胞核（P〈0．01），TNF—α主要表达在心肌细胞胞质，呈强阳性。与I／R组相比，苯那普利后处理组再灌注60min时的冠脉流量增多[（4．3±0．4）ml／min和（3．5±0．5）ml／min，P〈0．05]，GCA染色心肌变性减轻，阳性率减低（14％±7％和40％±7％，P〈0．01），NF—κB表达减少（34．8％±4．7％和49．3％±9．7％，P〈0．05），TNF—α表达为弱阳性。苯那普利后处理组和预处理组相比较，差异无统计学意义（P〉0．05）。结论苯那普利后处理对缺血再灌注心肌具有保护作用，其机制可能与苯那普利后处理抑制NF—κB活性，减少TNF—α的表达有关。     

吸人麻醉药后处理心肌保护作用机制的研究进展

背景 吸入麻醉药后处理（inhalational anesthetics postconditioning,APO）是指在缺血后再灌注早期给予一定浓度吸入麻醉药处理。APO具有心肌保护作用,其作用机制目前尚未完全阐明。目的 对APO心肌保护作用机制的研究进展进行回顾和总结。内容 APO的心肌保护的信号转导机制与缺血后处理有很多相似之处,可能是通过刺激心肌产生触发物,活化相关信号通路,激活效应因子,发挥后处理效应。目前研究已证实APO心肌保护作用与激活再灌注损伤补救激酶（reperfusion injury salvage kinase,RISK）,抑制再灌注心肌细胞凋亡及线粒体等有关。趋向 APO心肌保护作用机制错综复杂,弄清这些复杂的信号转导机制对于揭示APO效应的原理,促进临床推广具有重要的指导意义。