N-乙酰半胱氨酸对家兔缺血再灌注损伤心肌细胞凋亡的影响

目的观察N-乙酰半胱氨酸(NAC)对家兔缺血再灌注损伤心肌细胞凋亡的影响,并探讨其机制。方法 30只家兔随机等分为假手术组、心肌缺血再灌注(I/R)组和NAC组。NAC组和I/R组制作缺血再灌注模型,前者在血流灌注后阻断主动脉和肺动脉血管10 s,同时于心尖部注入NAC溶液0.5 mL;I/R组在再灌注开始即刻给予生理盐水0.5 mL。假手术组家兔开胸后只穿线,不结扎冠状动脉左前降支。再灌注3 h后,用黄嘌呤氧化酶法测定血清超氧化物歧化酶(SOD)活性,硫代巴比妥酸法测定血清丙二醛(MAD)水平。三组各取缺血区心肌组织,用原位末端标记法测定心肌细胞凋亡,并计算凋亡指数(AI)。用免疫组化SABC法检测缺血心肌组织中的Fas蛋白,计算Fas蛋白阳性表达指数(PI)。结果 I/R组的MDA水平高于、SOD活性低于NAC组和假手术组(P均<0.05);I/R组缺血区心肌细胞AI、心肌细胞中Fas蛋白PI明显高于NAC组和假手术组(P均<0.05)。结论 NAC可减少家兔缺血再灌注损伤心肌细胞的凋亡,可能是通过其抗氧化作用及下调Fas蛋白表达来实现的。     

心肌细胞凋亡与缺血/再灌注损伤

细胞凋亡（apoptosis）是细胞死亡的一种重要形式，即程序性细胞死亡，一般认为它是由基因控制的、有序化的主动死亡过程。自1972年Kerr等首次以形态学概念提出细胞凋亡这一术语以来，凋亡一直是医学界的研究热点。近年来，随着分子生物学技术的不断丰富及分子心血管病学的研究发展，已证实细胞凋亡现象存在于心血管系统的许多生理和病理变化中，与许多心血管疾病的发生发展密切相关。本文就心肌细胞凋亡与缺血再灌注损伤的关系综述如下。     

肿瘤坏死因子、缺血再灌注损伤和心肌细胞凋亡

肿瘤坏死因子在心脏疾病中的作用一直是研究热点。本文综述了肿瘤坏死因子在缺血再灌注损伤、心肌细胞凋亡方面的最新研究进展。     

缺血再灌注诱导心肌细胞凋亡及凋亡相关基因表达的研究

目的研究缺血再灌注诱导体外培养大鼠心肌细胞凋亡及凋亡相关基因表达.方法采用体外培养新生大鼠心肌细胞,随机分为正常对照组(Ⅰ组)、模拟缺血2h组(Ⅱ组)、缺血2h后再灌注1h组(Ⅲ组)以及持续缺血3h组(Ⅳ组).TUNEL法检测心肌细胞凋亡,荧光显微镜观察心肌细胞凋亡的形态学特征、免疫组织化学法检测Bcl-2/Bax基因表达.结果心肌细胞I/R后,TUNEL法检测到阳性凋亡细胞,且持续缺血3h组与再灌注组凋亡指数明显高于缺血2h组.荧光显微镜观察到典型的细胞凋亡超微结构;免疫组织化学检测发现Bcl-2蛋白表达下调,Bax蛋白表达上调.结论缺血和缺血再灌注均能诱导心肌细胞凋亡,且心肌细胞凋亡与Bcl-2/Bax基因表达有密切关系.     

微量去甲肾上腺素预处理对缺血再灌注大鼠心肌细胞凋亡及相关蛋白表达的影响

本实验复制缺血再灌注模型 ,应用微量去甲肾上腺素(ｎｏｒｅｐｉｎｅｐｈｒｉｎｅ ,ＮＥ)预处理 (ｐｒｅｃｏｎｄｉｔｉｏｎｉｎｇ ) ,观察缺血再灌注 (ｉｓｃｈｅｍｉａ ｒｅｐｅｒｆｕｓｉｏｎ ,Ｉ Ｒ)大鼠心肌细胞凋亡及Ｂｃｌ 2、Ｂａｘ基因表达情况 ,以探讨ＮＥ预处理防治     

N-乙酰半胱氨酸对大鼠肺缺血再灌注损伤的保护作用

目的探讨N-乙酰半胱氨酸(NAC)对大鼠在体肺缺血再灌注(I/R)损伤的保护作用。方法建立大鼠在体肺缺血再灌注模型,将30只SD大鼠随机分成假手术对照组,缺血再灌注组(I/R组)和N-乙酰半胱氨酸组(NAC组),NAC组缺血前1 h给予腹腔注射N-乙酰半胱氨酸200 mg/kg。再灌注2 h后摘取左肺,分别对各组进行以下检测:肺湿/干比(W/D)、超氧化物歧化酶(SOD)活力、髓过氧化物酶(MPO)活性、丙二醛(MDA)含量并进行病理学检查及肺组织损伤定量评价(IQA)。结果I/R组肺W/D和IQA显著高于假手术组(P0.01),NAC组上述指标明显降低(P0.01)。病理学结果显示三组动物肺组织结构基本正常,假手术组无充血;与NAC组比较,I/R组肺组织充血明显、白细胞浸润更严重及肺间质高度淤血水肿。I/R组MDA含量和MPO活性较假手术组明显升高(P0.01),SOD活性显著下降(P0.01)。NAC能明显减少MDA含量和降低MPO活性,提高SOD活性(P0.01)。结论N-乙酰半胱氨酸对肺缺血再灌注损伤具有保护作用,可能与其抗氧化作用和抑制中性粒细胞激活有关。     

凋亡抑制基因bel-2与缺血再灌注损伤后神经细胞凋亡

脑缺血后，缺血中心区周围的神经细胞，要经过一个潜伏期才出现细胞凋亡。这种缺血后的细胞凋亡，不仅在神经细胞，在胶质细胞、小胶质细胞、内皮细胞和血管壁中也出现bcl-2的表达，说明非致死性的损伤导致细胞产生bcl-2，以抵抗细胞的凋亡。     

肝缺血再灌注损伤与细胞凋亡关系的临床研究

目的 通过检测肝缺血再灌注前后肝组织的细胞凋亡情况,探讨临床手术中肝缺血再灌注与细胞凋亡之间的关系,为更好地预防或减轻临床肝脏手术中造成的缺血再灌注损伤(HIRI)提供理论基础.方法 以细胞凋亡测定法(TUNEL 法)测定肝缺血再灌注前后肝细胞的凋亡情况.结果 肝门阻断前与肝门开放时和关腹前肝细胞的凋亡指数各组间的差异有统计学意义(P＜0.01),肝门阻断前肝细胞的凋亡指数高于肝门开放时和关腹前肝细胞的凋亡指数(P＜0.01);肝门开放时肝细胞的凋亡指数高于关腹前肝细胞的凋亡指数(P＜0.01).结论 研究表明肝脏手术中,在肝细胞短时间(15 min左右)缺血后的再灌注损伤中,肝细胞凋亡和缺血再灌注损伤呈负相关,它并不是术后早期肝细胞损伤的一种主要方式.     

抗氧化剂抑制缺血后再灌注损伤相关的心肌细胞凋亡

目的 探讨老年急性胰腺炎（ＡＰ）患者血清一氧化氮（ＮＯ）和肿瘤坏死因子α（ＴＮＦ－α）的变化及临床意义。方法 对３２例老年ＡＰ患者及２０例健康老年人血清中ＮＯ和ＴＮＦ－α水平进行检测。结果 老年ＡＰ患者血清中ＮＯ浓度明显低于正常对照组,且随病情加重降低更为明显（Ｐ〈０．０１）;而血清ＴＮＦ－α浓度明显高于正常对照组,且随病情加重升高更为明显（Ｐ〈０．０１）,ＮＯ和ＴＮＦ－α呈显著负相关（Ｐ〈０．０     

Status of myocardial antioxidants in ischemia-reperfusion injury

BACKGROUND: Myocardial ischemia-reperfusion represents a clinically relevant problem associated with thrombolysis, angioplasty and coronary bypass surgery. Injury of myocardium due to ischemia-reperfusion includes cardiac contractile dysfunction, arrhythmias as well as irreversible myocyte damage. These changes are considered to be the consequence of imbalance between the formation of oxidants and the availability of endogenous antioxidants in the heart. OBSERVATIONS: An increase in the formation of reactive oxygen species during ischemia-reperfusion and the adverse effects of oxyradicals on myocardium have now been well established by both direct and indirect measurements. Although several experimental studies as well as clinical trials have demonstrated the cardioprotective effects of antioxidants, some studies have failed to substantiate the results. Nonetheless, it is becoming evident that some of the endogenous antioxidants such as glutathione peroxidase, superoxide dismutase, and catalase act as a primary defense mechanism whereas the others including vitamin E may play a secondary role for attenuating the ischemia-reperfusion injury. The importance of various endogenous antioxidants in suppressing oxidative stress is evident from the depression in their activities and the inhibition of cardiac alterations which they produce during ischemia-reperfusion injury. The effects of an antioxidant thiol containing compound, N-acetylcysteine, and ischemic preconditioning were shown to be similar in preventing changes in the ischemic-reperfused hearts. CONCLUSIONS: The available evidence support the role of oxidative stress in ischemia-reperfusion injury and emphasize the importance of antioxidant mechanisms in cardioprotection.     

心肌缺血-再灌注损伤钙超载及其防治策略

缺血-再灌注(I-R)可引起肌膜损伤、Na+/Ca2+交换逆转以及肌(内)质网钙泵(SERCA)含量或活性下降从而导致心肌钙超载.钙超载诱导心肌Calpain活化与线粒体膜通透性转换孔(mPTP)开放进而引起心肌细胞收缩功能障碍、凋亡甚至坏死.通过抑制Na+/Ca2+交换蛋白、Na+/H+交换蛋白、Calpain活性、...     

Rapamycin confers preconditioning-like protection against ischemia-reperfusion injury in isolated mouse heart and cardiomyocytes

Rapamycin (sirolimus) is an antibiotic that inhibits protein synthesis through mammalian target of rapamycin (mTOR) signaling and is used as an immunosuppressant in the treatment of organ rejection in transplant recipients. Recently, the antigrowth properties of rapamycin have been utilized for cardiovascular benefit as stents impregnated with rapamycin effectively reduce coronary restenosis. We report here a novel role of this drug in protection against ischemia/reperfusion (I/R) injury. Adult male ICR mice were treated with rapamycin (0.25 mg/kg, IP) or volume-matched DMSO (solvent for rapamycin). The hearts were subjected to 20 min of global ischemia and 30 min of reperfusion in Langendorff mode. The blocker of mitochondrial KATP channel, 5-hydroxydecanoate (5-HD, 100 microM) was given 10 min before ischemia. Infarct size in the DMSO treated group was 28.2 +/- 1.3% and was reduced to 10.1 +/- 2.8% in the rapamycin-treated mice (64% decrease, P < 0.001). 5-HD blocked the protective effect (infarct area 32.2 +/- 1.8%, P < 0.001 vs. rapamycin). The infarct limiting effect of rapamycin was not associated with improved recovery of ventricular function. We further examined the effect of rapamycin in protection against necrosis and apoptosis in adult cardiomyocytes subjected to simulated ischemia and reoxygenation. Myocytes treated with rapamycin in doses from 25-100 nM demonstrated significantly lower trypan blue-positive necrotic cells and TUNEL-positive apoptotic nuclei, supporting the protective role of drug in the intact heart. These data suggest that rapamycin induces potent preconditioning-like effect against myocardial infarction through opening of mitochondrial KATP channels. We propose that rapamycin may be a novel therapeutic strategy to limit infarction, apoptosis, and remodeling following I/R injury in the heart.     

Short-term intestinal ischemia-reperfusion alters intestinal motility that can be preserved by xanthine oxidase inhibition

While the effects of transient intestinal ischemia on mucosa have been well investigated, less is known about its effect on motor function. An experimental study was designed to investigate the effects of ischemia–reperfusion (I/R) on intestinal motility and intestinal muscular microcirculation. Wistar albino rats were divided into four groups: (1) baseline, (2) sham operation, (3) I/R, and (4) I/R with allopurinol pretreatment. Ischemia was induced by clamping the superior mesenteric artery (SMA) for 10 min. Gastroanal transit time (GATT) was measured with serial x-rays after instillation of barium sulfate to the stomach. Intestinal muscular microcirculation was evaluated by determining the number of carbon-perfused intestinal muscular microvessels (CPIMM). I/R prolonged GATT and decreased CPIMM significantly (P < 0.01). Pretreatment with allopurinol prevented prolongation of GATT and returned the number of CPIMM to the level of sham treatment (P < 0.01). In conclusion, reperfusion after 10 min of SMA ischemia alters intestinal motility. The no-reflow phenomenon plays an important role in this alteration of motility. Administration of allopurinol before reperfusion preserves intestinal motility by preventing the occurrence of no-reflow phenomenon.     

Microvascular changes in liver after ischemia-reperfusion injury

Morphological changes in the hepatic microvasculature were studied in experimentally induced ischemia-reperfusion injury in the rat using a vascular casting technique. Partial hepatic ischemia was induced for 90 min followed by 24 hr of reperfusion. Microvascular casting was performed after 24 hr reperfusion by either intraarterial or intravenous infusion of acrylic resin (Mercox). After corrosion of the tissue, the cast was examined by scanning electron microscopy. Casts of normal livers showed good patency with no evidence of unfilled areas. The mean diameter of sinusoids was 14±3 µm with those in zone 1 slightly smaller than those in zone 3. Liver casts from rats subjected to ischemia and reperfusion resulted in gross disruption of normal architecture. The common characteristics seen in both prograde and retrograde casts were clusters of closed sinusoids around zones 2 and 3 of the liver acini, which resulted in cavities of various sizes. Varicosities were observed in some areas. The mean diameter of sinusoids in areas of patent microvascular structure (10±2 µm) was significantly smaller compared to those in normal livers (P<0.001). Misoprostol given at 1 min before reperfusion markedly reduced the microvascular injury. The hepatic microvasculature was generally intact with mild focal unfilled areas. The majority of the sinusoids were of normal size and no clusters of blind ending sinusoids were detected. The present study shows that hepatic ischemia-reperfusion results in extensive microvascular injury in the liver. The protective effects of misoprostol against this injury may occur at the vascular level.This study is supported by the Australian National Health and Medical Research Council Grant No. 91/0662 and Alfred Hospital, Victoria, Australia.     

Genetically induced moderate inhibition of the proteasome in cardiomyocytes exacerbates myocardial ischemia-reperfusion injury in mice

Rationale: Both cardiomyocyte-restricted proteasome functional enhancement and pharmacological proteasome inhibition (PSMI) were shown to attenuate myocardial ischemia/reperfusion (I/R) injury. The role of cardiac proteasome dysfunction during I/R and the perspective to diminish I/R injury by manipulating proteasome function remain unclear. Objectives: We sought to determine proteasome adequacy in I/R hearts, create a mouse model of cardiomyocyte-restricted PSMI (CR-PSMI), and test CR-PSMI impact on I/R injury. Methods and Results: Myocardial I/R were modeled by ligation (30 minutes) and subsequent release of the left anterior descending artery in mice overexpressing GFPdgn, a validated surrogate proteasome substrate. At 24 hours of reperfusion, myocardial proteasome activities were significantly lower whereas total ubiquitin conjugates and GFPdgn protein levels were markedly higher in all regions of the I/R hearts than the sham controls, indicative of proteasome functional insufficiency. CR-PSMI in intact mice was achieved by transgenic (tg) overexpression of a peptidase-disabled mouse β5 subunit (T60A-β5) driven by an attenuated mouse mhc6 promoter. Overexpressed T60A-β5 can replace endogenous β5 and inhibits proteasome chymotrypsin-like activities in the heart. Mice with moderate CR-PSMI showed no abnormalities at the baseline but displayed markedly more pronounced structural and functional damage during I/R, compared with non-tg littermates. The exacerbation of I/R injury by moderate CR-PSMI was associated with significant increases in the protein level of PTEN and protein kinase Cδ (PKCδ), decreased Akt activation, and reduced PKCε. Conclusions: Myocardial I/R causes proteasome functional insufficiency in cardiomyocytes and moderate CR-PSMI augments PTEN and PKCδ, suppresses Akt and PKCε, increases cardiomyocyte apoptosis, and aggravates I/R injury in mice.