应激活化蛋白激酶在大鼠缺血后适应中的变化及其对细胞凋亡影响的研究

目的:探讨应激活化蛋白激酶(JNK MAPK)在大鼠缺血后适应中的变化,并进一步分析其对细胞凋亡的影响.方法:60只SD大鼠随机分为假手术(Sham)、缺血再灌注(R/I)、后适应(Post)、JNK抑制剂(IJNK)、JNK激活剂+后适应(Ani+Post)和JNK激活剂(Ani)6组,建立急性心肌梗死再灌注和缺血后适应模型,在再灌注开始前5min经颈静脉注射抑制剂(SP600125,6mg/kg)和激动剂(anisomycin,2mg/kg).再灌注6h后处死取心肌组织测定磷酸化JNK(P-JNK)、TNFα、Caspase-8、Bcl-2、Bax,并提取胞浆测定其中细胞色素c(Cyt-c);各组其余大鼠再灌注24h后测定血流动力学,抽血测定心肌酶,取心脏进行TUNEL凋亡检测或使用伊文氏蓝-三苯基氯化四氮唑法检测心肌梗死面积.结果:后适应组可显著改善缺血对左室压力最大上升/下降速度、心率血压积的抑制,限制心肌梗死面积,减轻细胞凋亡和坏死,抑制了P-JNK的生成(1 12±0 21 vs 1 90±0 32,P<0 05);同时,伴随TNFα和Caspase-8表达显著减少,Bcl-2的升高和Bax的降低,胞浆Cyt-c(0 33±0 04 vs 1 00±0 11,P<0 05)含量明显减少.IJNK组可以模拟后适应在信号分子的上述变化,从而表现出显著的心肌保护作用[凋亡指数:(6 23±2 43)% vs (18 22±5 10)%,P<0 05;心肌梗死面积:(23 44±6 34)% vs (42 31±8 21)%,P<0 05].反之,Ani+Post则因为JNK激活剂的应用,部分抵消了后适应的保护效应,在心肌酶、心肌凋亡和梗死面积方面表现出保护作用的减弱[凋亡:(14 12±2 00)% vs (18 22±5 10)%,P>0 05;心肌梗死面积:(35 27±5 28)% vs (42 31±8 21)%,P>0 05].结论:后适应可以抑制JNK MAPK在再灌注损伤中的磷酸化,并通过P-JNK MAPK的减少抑制TNFα细胞受体途径和Bcl-2/Bax线粒体途径,从而减少细胞凋亡.     

活性氧的内源性心肌保护作用及其机制

既往认为在心肌缺血/再灌注过程中活性氧是一种有害的细胞损伤因子,但最近研究发现也是可产生细胞保护作用的信号分子.活性氧(reactive oxygen species,ROS)在缺血,再灌注及其内源性心肌保护作用中具有双重作用,内源性心肌保护过程中活性氧主要来自线粒体呼吸链,主要通过mKATP-ROS通路产生;活性氧通过改变细胞氧化还原状态和调节线粒体膜通透性转换孔道开放状态,传递线粒体和细胞之间的信息联系.因此.活性氧不单是缺血/再灌注氧化应激的损伤因子,也是产生内源性心肌保护作用的重要信号分子.     

缺血预处理联合后处理的肺保护作用研究进展

近年来,体外循环术、肺移植术、肺栓塞溶栓治疗术等技术水平的日渐成熟,然而肺缺血再灌注损伤仍然是最常见的术后并发症,造成患者术后肺功能不全,严重者甚至可造成患者死亡。随着缺血预处理和缺血后处理概念的提出,为再灌注肺损伤的保护方法提供了新的理论基础和研究方向。本文就预处理联合后处理的肺保护作用综述其研究进展。     

Protective effects of ischemic postconditioning against hypoxia-reoxygenation injury and hydrogen peroxide-induced damage in isolated rat hearts

OBJECTIVE: Ischemic preconditioning (PR) protects hearts from ischemia-reperfusion injury. The purpose of the present study was to examine the protective effect of PR and postconditioning (PT) against hypoxia-reoxygenation injury and H(2)O(2)-induced damage in isolated rat hearts. METHODS AND RESULTS: Hearts from male Sprague-Dawley rats were perfused with Krebs-Henseleit solution by Langendorff methods and subjected to two protocols. In protocol A, control hearts underwent 45 min of hypoxia and 30 min of reoxygenation. Three PT cycles of 10 s of ischemia and 10 s of reperfusion after 45 min of hypoxia increased the recovery of the pressure-rate product. Three PR cycles of 3 min of ischemia and 5 min of reperfusion before hypoxia were also protective, and decreased the release of glutamic oxaloacetic transaminase. A combination of PR and PT resulted in greater protection than either alone. In protocol B, control hearts underwent perfusion with H(2)O(2) (120 muM) until the left ventricular end-diastolic pressure was elevated to 50 mmHg, and then H(2)O(2) was washed out for 30 min. Three PT cycles of 30 s of ischemia and 30 s of reperfusion before the 30 min washout increased the level of recovery of the pressure-rate product and decreased left ventricular end-diastolic pressure to baseline levels. CONCLUSIONS: The results of the present study indicate that PT protects hearts from hypoxia-reoxygenation injury and H(2)O(2)-induced damage. In addition, PR combined with PT offers more effective protection than PR or PT alone.     

缺氧后处理对成年大鼠心肌细胞缺氧复氧损伤的保护作用

目的：通过建立成年大鼠心肌细胞缺氧复氧模型观察缺氧后处理的心肌保护机制。方法雄性SD大鼠,体质量250～350 g ,随机分为3组：正常组（NOR组）、缺氧组（H／R组）、缺氧后组（HP组）。采用激光共聚焦显微镜检测心肌细胞线粒体膜电位（mitochondrial membrane potential , MMP）、细胞内钙离子荧光强度以及 Western blot方法测定磷酸化 p38丝裂原活化蛋白激酶（p‐p38MAPK）表达量。结果（1）与正常组比较,H／R组和 HP组 MMP显著降低（P＜0．05）;HP组MMP明显高于 H／R组（P＞0．05）;（2）与正常组和 HP组比较,H／R组细胞内钙离子荧光强度显著升高（P＜0．01）;HP组和正常组间差异无统计学意义（P＞0．05）;（3）与正常组和 HP组比较,H／R组p‐p38MAPK表达量显著升高（P＜0．05）;HP组和正常组间表达量差异无统计学意义（P＞0．05）。结论缺氧后处理可对缺氧复氧成年大鼠心肌细胞产生保护作用,其机制可能与下调心肌细胞p‐p38M A PK 表达量、抑制线粒体膜电位下降以及防止钙超载进而抑制凋亡有关。     

舒芬太尼后处理对犬心肌缺血/再灌注Bcl-2、Bax的影响及其与JAK2-STAT3信号通路的关系

目的 研究舒芬太尼后处理对心肌缺血/再灌注损伤(ischemiia/reperfusion injury,I/RI)细胞凋亡的影响以及与信号通路JAK2-STAT3的关系.方法 健康杂种家犬24只,体重10 kg～15 kg,按随机数字表法分为4组(每组6只):假手术组(Sham组,只穿线,不结扎),心肌缺血/再灌注(ischemia/reperfusion,I/R)组,舒芬太尼后处理组(SPO组,于再灌注前5min静脉注射舒芬太尼0.6 μg/kg),舒芬太尼后处理+AG490组(SPO+AG490组,于再灌注前5 min静脉注射l mg/kg AG490,特异性的JAK2抑制剂),除Sham组外,所有犬心脏都经历30 min缺血和120 min再灌注.再灌注120 min时,取各组缺血区心肌组织,采用末端脱氧核苷酸转移酶介导的dUTP原位切口末端标记(terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling,TUNEL)法测定心肌细胞的凋亡情况,免疫组化法测定各组Bcl-2、Bax以及磷酸化STAT3 (p-ATAT3)蛋白的表达,并计算Bcl-2和Bax表达的比值(Bcl-2/Bax).结果 再灌注120 min时,可在I/R组缺血区心肌组织中检测到大量凋亡心肌细胞(63.9±4.0)％,而舒芬太尼后处理显著降低心肌细胞凋亡指数(30.7±1.5)％;与Sham组比较,I/R组、SPO组和SPO+AG490组Bcl-2与Bax表达上调,I/R组Bcl-2/Bax比值降低,SPO组Bcl-2/Bax比值升高;舒芬太尼后处理使p-STAT3表达明显增加,特异性的阻断剂AG490抑制了舒芬太尼后处理对心肌I/RI凋亡的作用,即抑制p-STAT3表达的增加. 结论 舒芬太尼后处理对心肌I/RI细胞凋亡有一定的抑制作用,通过激活JAK2-STAT3信号转导通路上调Bcl-2蛋白和下调Bax蛋白来发挥作用.     

瑞芬太尼后处理及其联合异丙酚后处理对大鼠肝脏缺血再灌注损伤的影响

目的 评价瑞芬太尼后处理及其联合异丙酚后处理对大鼠肝脏缺血再灌注损伤的影响.方法 健康雄性SD大鼠30只,体重220 ～ 280 g,采用随机数字表法,将其随机分为5组(n=6):假手术组(Ⅰ组)、缺血再灌注组(Ⅱ组)、异丙酚后处理组(Ⅲ组)、瑞芬太尼后处理组(Ⅳ组)和异丙酚联合瑞芬太尼后处理组(Ⅴ组).Ⅱ组～Ⅴ组采用夹闭门静脉和肝动脉30 min的方法制备肝脏缺血再灌注损伤模型,Ⅰ组仅开腹.Ⅲ组、Ⅳ组和Ⅴ组再灌注即刻分别静脉输注异丙酚30 mg· kg-1·h-1、瑞芬太尼1μg·kg -1·min -1和异丙酚30 ng·kg-1·h-1+瑞芬太尼1μg·kg-1·min-1 1 h,Ⅱ组给予等容量生理盐水.于再灌注1h时采集静脉血样,测定血清AST、ALT活性、IL-8、IL-10的浓度,然后处死大鼠,取肝组织,测定肝细胞c-fos和c-jun表达,电镜下观察肝组织病理学结果.结果 与Ⅰ组比较,Ⅱ组～Ⅴ组血清AST、ALT活性及IL-8、IL-10的浓度升高,肝细胞c-fos和c-jun表达上调(P＜0.05或0.01);与Ⅱ组比较,Ⅲ组～Ⅴ组血清AST、ALT活性及IL-8浓度降低,IL-10浓度升高,肝细胞c-fos和c-jun表达下调(P ＜0.05或0.01);与Ⅲ组及Ⅳ组比较,Ⅴ组上述指标差异无统计学意义(P＞0.05).Ⅲ组～Ⅴ组肝组织病理学损伤程度明显轻于Ⅱ组.结论 瑞芬太尼后处理可减轻大鼠肝脏缺血再灌注损伤,联合异丙酚后处理时其效应与单独一种方法的效应相似,其机制与抑制炎性反应和肝细胞凋亡有关.     

辛伐他汀后适应对血脂正常大鼠缺血再灌注心肌保护作用

【】 目的：探讨辛伐他汀药物后适应对缺血再灌注损伤大鼠髓过氧化物酶(MPO)、丙二醛(MDA)的影响,探讨其减少心肌损害的可能机制。方法：将30只SD大鼠随机分为假手术组(SH)、缺血/再灌注组(I/R组)、辛伐他汀后适应组(SIM组)。通过结扎大鼠冠状动脉前降支制作心肌梗死模型。SH组、I/R组：再灌注前经颈静脉注射生理盐水1ml;SIM组：再灌注前经颈静脉给予辛伐他汀(1mg.100g-1)注射。再灌注2小时后抽静脉血测定CK-mb、MPO、MDA及心肌梗死面积。结果：①各组大鼠血脂测定均在正常值范围内;②与SH组比较,I/R组、SIM组CK-mb、MPO、MDA均有增高(P<0.05);与I/R组比较,SIM组CK-mb、MPO、MDA下降(P<0.05);③与SH组比较,I/R组、SIM组心肌梗死面积明显(P<0.05);SIM组心肌梗死面积小于I/R组 (P<0.05)。结论：辛伐他汀后适应治疗可以减轻大鼠心肌炎症反应及心肌梗死面积,保护心肌并减轻缺血再灌注损伤的作用。     

Effects of Ischemic Postconditioning on the Hemodynamic Parameters and Heart Nitric Oxide Levels of Hypothyroid Rats

Background

Ischemic postconditioning (IPost) is a method of protecting the heart against ischemia-reperfusion (IR) injury. However, the effectiveness of IPost in cases of ischemic heart disease accompanied by co-morbidities such as hypothyroidism remains unclear.

Objective

The aim of this study was to determine the effect of IPost on myocardial IR injury in hypothyroid male rats.

Methods

Propylthiouracil in drinking water (500 mg/L) was administered to male rats for 21 days to induce hypothyroidism. The hearts from control and hypothyroid rats were perfused in a Langendorff apparatus and exposed to 30 min of global ischemia, followed by 120 min of reperfusion. IPost was induced immediately following ischemia.

Results

Hypothyroidism and IPost significantly improved the left ventricular developed pressure (LVDP) and peak rates of positive and negative changes in left ventricular pressure (±dp/dt) during reperfusion in control rats (p < 0.05). However, IPost had no add-on effect on the recovery of LVDP and ±dp/dt in hypothyroid rats. Furthermore, hypothyroidism significantly decreased the basal NO metabolite (NO_x) levels of the serum (72.5 ± 4.2 vs. 102.8 ± 3.7 μmol/L; p < 0.05) and heart (7.9 ± 1.6 vs. 18.8 ± 3.2 μmol/L; p < 0.05). Heart NO_x concentration in the hypothyroid groups did not change after IR and IPost, whereas these were significantly (p < 0.05) higher and lower after IR and IPost, respectively, in the control groups.

Conclusion

Hypothyroidism protects the heart from IR injury, which may be due to a decrease in basal nitric oxide (NO) levels in the serum and heart and a decrease in NO after IR. IPost did not decrease the NO level and did not provide further cardioprotection in the hypothyroid group.