Role of p38 inhibition in cardiac ischemia/reperfusion injury

The p38 mitogen-activated protein kinases (p38s) are Ser/Thr kinases that are activated as a result of cellular stresses and various pathological conditions, including myocardial ischemia/reperfusion. p38 activation has been shown to accentuate myocardial injury and impair cardiac function. Inhibition of p38 activation and its activity has been proposed to be cardioprotective by slowing the rate of myocardial damage and improving cardiac function. The growing body of evidence on the use of p38 inhibitors as therapeutic means for responding to heart problems is controversial, since both beneficial as well as a lack of protective effects on the heart have been reported. In this review, the outcomes from studies investigating the effect of p38 inhibitors on the heart in a wide range of study models, including in vitro, ex vivo, and in vivo models, are discussed. The correlations of experimental models with practical clinical usefulness, as well as the need for future studies regarding the use of p38 inhibitors, are also addressed.     

Abnormalities in arachidonic acid metabolites in nephrotoxic glomerular injury

Arachidonic acid metabolites are suspected of contributing in various ways to major pathophysiological events that occur in toxic and immune glomerular injury. This paper focuses on the role of arachidonate metabolites in the experimental models of adriamycin nephrosis and cyclosporin A nephrotoxicity in rats as examples, respectively, of a toxic nephropathy characterized by increased glomerular permeability to proteins and a toxic nephropathy with macrophage accumulation and progressively deteriorating renal function. The important pathogenic contribution of thromboxane A2 to the impairment of renal function in these experimental models is discussed.     

缺血/再灌注过程中心肌细胞自噬研究进展

自噬是一种广泛存在于真核细胞中的生命现象,心肌细胞营养缺乏、缺血/再灌注损伤、心衰等均可诱发细胞自噬。缺血/再灌注过程中的心肌细胞自噬可以维持心肌细胞稳态、减少细胞缺失,但是自噬作用也可导致心肌细胞死亡。     

Role of cytochrome P450 metabolites of arachidonic acid in hypertension

Considerable evidence has accumulated over the last decade implicating a role of cytochrome P450 (CYP)-dependent metabolites of arachidonic acid (AA) in the pathogenesis of hypertension. Indeed, 20-hydroxyeicosatetraenoic acid (20-HETE) is produced by vascular smooth muscle (VSM) cells and is a potent vasoconstrictor that depolarizes VSM by blocking large conductance Ca+-activated K2+ channels. In contrast, epoxyeicosatrienoic acids (EETs) are synthesized by the vascular endothelium and have opposite effects on VSM (hyperpolarization and vasodilatation). Inhibition of the synthesis of 20-HETE attenuates myogenic tone and autoregulation of blood flow and modulates vascular responses to vasodilators (NO and CO) and vasoconstrictors (angiotensin II, endothelin). In the kidney, 20-HETE inhibits sodium transport in the proximal tubule by blocking Na+-K+-ATPase activity. In the thick ascending limb of the loop of Henle, 20-HETE inhibits Na+-K+-2Cl- transport, in part, by blocking a 70 pS apical K+ channel. EETs are produced in the proximal tubule where they inhibit Na+-H+ exchange and in the collecting duct where they inhibit sodium and water transport. Numerous studies have established that the formation of EETs and 20-HETE and the expression of CYP enzymes are altered in the kidney in many genetic and experimental animal models of hypertension and in some forms of human hypertension. However, the functional significance of these changes remains to be determined. Given the importance of this pathway in the control of renal function and vascular tone, it is likely that alterations in the renal formation of CYP-dependent metabolites of AA will be shown to participate in the development of hypertension in many of these models.     

Rosmarinic acid attenuates hepatic ischemia and reperfusion injury in rats

Rosmarinic acid (RosmA) demonstrates antioxidant and anti-inflammatory properties. We investigated the effect of RosmA on liver ischemia/reperfusion injury. Rats were submitted to 60 min of ischemia plus saline or RosmA treatment (150 mg/kg BW intraperitoneally) followed by 6 h of reperfusion. Hepatocellular injury was evaluated according to aminotransferase activity and histological damage. Hepatic neutrophil accumulation was also evaluated. Oxidative/nitrosative stress was estimated by measuring the reduced glutathione, lipid hydroperoxide and nitrotyrosine levels. Endothelial and inducible nitric oxide synthase (eNOS/iNOS) and nitric oxide (NO) were assessed with immunoblotting and chemiluminescence assays. Hepatic tumor necrosis factor-alpha (TNF-α) and interleukin-1beta mRNA were assessed using real-time PCR, and nuclear factor-kappaB (NF-κB) activation was estimated by immunostaining. RosmA treatment reduced hepatocellular damage, neutrophil infiltration and all oxidative/nitrosative stress parameters. RosmA decreased the liver content of eNOS/iNOS and NO, attenuated NF-κB activation, and down-regulated TNF-α and interleukin-1beta gene expression. These data indicate that RosmA exerts anti-inflammatory and antioxidant effects in the ischemic liver, thereby protecting hepatocytes against ischemia/reperfusion injury. The mechanisms underlying these effects may be related to the inhibitory potential of RosmA on the NF-κB signaling pathway and the reduction of iNOS and eNOS expressions and NO levels, in addition to its natural antioxidant capability.     

Rho激酶在远距缺血后处理抗心肌缺血/再灌注损伤中的作用

目的探讨Rho激酶在远距缺血后处理(remote ischemic postconditioning,RIPost C)中的作用及其可能的作用机制。方法 30只♂SD大鼠随机分为假手术组(Sham)、缺血/再灌注组(I/R)、远距缺血后处理组(RIPost C)、缺血/再灌注+Rho激酶阻断剂法舒地尔组(I/R+Fas),远距缺血后处理+Rho激酶激动剂溶血磷脂酸组(RIPost C+LPA),每组6只。全程监测动脉血压和Ⅱ导联心电图,实验结束后测定血浆肌酸激酶(CK)、乳酸脱氢酶(LDH)活性变化,HE染色观察心肌组织形态学变化,TTC染色法评价心肌梗死面积,Western blot测定磷酸化肌球蛋白轻链(p-MLC)蛋白表达。结果与Sham组相比,其余各组MAP、HR均下降,ST段增高;与I/R组相比,RIPost C和I/R+Fas组MAP、HR升高,ST段降低,心肌组织病理形态有明显改善,炎性细胞浸润减轻,心肌梗死面积降低,CK、LDH释放减少,p-MLC表达降低;与RIPost C组相比,RIPost C+LPA组减弱了RIPost C的作用,抑制了上述指标的恢复。结论 Rho激酶信号通路可能参与了远距缺血后处理抗心肌缺血/再灌注损伤的作用。     

Eicosapentaenoic acid reduces myocardial injury induced by ischemia and reperfusion in rabbit hearts

Intake of fish oil is known to have cardioprotective effects and reduce cardiovascular mortality. However, it is not widely recognized that eicosapentaenoic acid (EPA), one of the n-3 polyunsaturated fatty acids (PUFAs), exerts beneficial effects against myocardial ischemia/reperfusion injury. The purpose of this study is to investigate whether EPA attenuates the severity of myocardial ischemia/reperfusion injury and which cellular mechanism is involved. Rabbits were treated with or without EPA (600 mg/kg/day) for 2 weeks. Infarct size was measured in open-chest rabbits after 30-minute occlusion of the left anterior descending coronary artery (LAD) and after the subsequent 3-hour reperfusion. In several groups, NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase, or charybdotoxin, a blocker of calcium-activated potassium (K(Ca)) channels, was infused intravenously beginning 20 minutes before LAD occlusion and continuing during reperfusion. Infarct size was reduced in the group treated with EPA compared with the control group (7.2 +/- 1.0% vs 24.6 +/- 2.3%; P < 0.01). The occurrence of ventricular arrhythmias in the reperfusion period tended to decrease in the EPA group. Either L-NAME or charybdotoxin partially blunted or completely abolished the infarct size-limiting effect of EPA, respectively. Eicosapentaenoic acid significantly increased the n-3:n-6 ratio of PUFA. Eicosapentaenoic acid reduces myocardial infarct size, mainly via the opening of K(Ca) channel-mediated and partially NO-mediated mechanisms in rabbit hearts.     

Caffeic acid phenethyl ester prevents ovary ischemia/reperfusion injury in rabbits

Protective effect of caffeic acid phenethyl ester (CAPE) on ovary ischemia/reperfusion (IR) injury was investigated in this study. Twenty four New Zealand rabbits were divided into 4 groups as follows: group S served as sham. Group C was intraperitoneally injected with CAPE (8.5 mg/kg). In groups E + IR and C + IR, 1% ethanol and CAPE was given intraperitoneally before torsion, respectively. Then, the ovaries were subjected to IR in both groups. Ovary reduced glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity in group E + IR were significantly reduced compared to that of group S. GSH level and GSH-Px activity was significantly increased in group C + I/R. Thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity in group E + I/R was significantly higher than in group S. CAT activity was decreased to normal levels by CAPE treatment in group C + I/R, while TBARS in group C + IR was significantly reduced compared to that of E + IR. According to histopathological examination, severe congestion, hemorrhage, edema and leukocyte infiltration were observed in E + I/R group. CAPE prominently reduced degenerative effects of IR injury thus it alleviates free radical damage.     

The effect of Allium sativum on ischemic preconditioning and ischemia reperfusion induced cardiac injury

In the present study, the effect of garlic (Allium sativum) extract on ischemic preconditioning and ischemia-reperfusion induced cardiac injury has been studied. Hearts from adult albino rats of Wistar strain were isolated and immediately mounted on Langendorff's apparatus for retrograde perfusion. After 15 minutes of stabilization, the hearts were subjected to four episodes of 5 min ischemia, interspersed with 5 min reperfusion (to complete the protocol of ischemic preconditioning), 30 min global ischemia, followed by 120 min of reperfusion. In the control and treated groups, respective interventions were given instead of ischemic preconditioning. The magnitude of cardiac injury was quantified by measuring Lactate Dehydrogenase and creatine kinase concentration in the coronary effluent and myocardial infarct size by macroscopic volume method. Our study demonstrates that garlic extract exaggerates the cardio protection offered by ischemic preconditioning and per se treatment with garlic extract also protects the myocardium against ischemia reperfusion induced cardiac injury.     

肿瘤坏死因子在肝缺血-再灌注损伤中的作用及左旋精氨酸的干预

目的 :探讨肿瘤坏死因子 (TNF)在肝缺血 -再灌注损伤 (HIRI)中的作用及左旋精氨酸 (L Arg)对其影响。方法 :选择HIRI实验兔及肝癌手术患者 ,观察血浆TNF含量、谷丙转氨酶 (ALT)活性、肝形态学的变化及L Arg对上述指标的影响。结果 :HIRI期间 ,TNF和ALT明显升高 (P <0 .0 1) ,两者呈显著正相关 (实验兔r =0 .912 ,P <0 .0 1;患者r =0 .5 35 ,P <0 .0 1) ,肝形态学发生异常变化。使用L Arg后 ,上述指标的异常变化显著减轻 (P <0 .0 5和P <0 .0 1)。结论 :TNF是HIRI的重要发病因素 ,L Arg可通过降低TNF减轻HIRI。     

Gene therapy in liver ischemia and reperfusion injury

Ischemia and reperfusion injury (IRI) is a prime antigen-independent inflammatory factor in the dysfunction of liver transplants. Despite improved allograft preservation and surgical techniques, IRI can still cause up to 10% of early orthotopic liver transplant failure, and can lead to a higher incidence of both acute and chronic graft rejection. Recent advances in gene transfer have resulted in a reduction or inhibition of liver IRI in several experimental models. This review summarizes the development of existing and potential approaches to human gene therapy. These studies aimed at ameliorating I/R injury are focused on the cytoprotective effects in transplant recipients by induction of anti-apoptotic or protective genes, immunoregulation of cytokines or blockade of signaling transduction pathway in graft cells. Although this review focuses on the application of viral mediated gene therapy, new non-viral gene transfer techniques, such as RNA interference (RNAi) application, are discussed. Future advances in gene therapy technology should result in fewer side effects, and thus more acceptable for clinical application, and more successful for organ transplantation.     

原儿茶酸对大鼠心肌缺血/再灌注损伤的保护作用

目的研究原儿茶酸对大鼠心肌缺血/再灌注(myocardial ischemia/reperfusion,MI/R)损伤的保护作用。方法采用结扎SD大鼠冠状动脉建立MI/R(30min/3h)损伤模型,将动物随机分为假手术组、模型组、原儿茶酸组(低、中、高剂量)、丹参多酚酸盐6组。除模型组于再灌注时给予生理盐水外,原儿茶酸低、中、高剂量组及丹参多酚酸盐组于再灌注即刻给予原儿茶酸(5,10和20mg·kg-1)及丹参多酚酸盐(20mg·kg-1)。实验过程中监测心功能,实验末测定心肌梗死面积,并检测血清中肌酸激酶同工酶(CK-MB)、肌钙蛋白(cTnI)水平。结果与模型组相比,原儿茶酸中、高剂量组大鼠心功能得以改善(P<0.05),心肌梗死面积显著减少(P<0.05),血清中心肌损伤酶CK-MB、cTnI的水平显著下降(P<0.05)。结论原儿茶酸对大鼠MI/R损伤具有一定的保护作用。     

Effect of ursodeoxycholic acid on ischemia/reperfusion injury in isolated rat heart

In this study, the effects of ursodeoxycholic acid (UDCA) on ischemia/reperfusion injury were investigated on isolated heart perfusion model. Hearts were perfused with oxygenated Krebs-Henseleit solution (pH 7.4, 37 degrees C) on a Langendorff apparatus. After equilibration, isolated hearts were treated with UDCA 20 to 160 microM or vehicle (0.04% DMSO) for 10 min before the onset of ischemia. After global ischemia (30 min), ischemic hearts were reperfused and allowed to recover for 30 min. The physiological (i.e. heart rate, left ventricular developed pressure, coronary flow, double product and time to contracture formation) and biochemical (lactate dehydrogenase; LDH) parameters were evaluated. In vehicle-treated group, time to contracture formation was 21.4 min during ischemia, LVDP was 18.5 mmHg at the endpoint of reperfusion and LDH activity in total reperfusion effluent was 54.0 U/L. Cardioprotective effects of UDCA against ischemia/reperfusion consisted of a reduced TTC (EC25=97.3 microM), reduced LDH release and enhanced recovery of cardiac contractile function during reperfusion. Especially, the treatments of UDCA 80 and 160 microM significantly increased LVDP and reduced LDH release. Our findings suggest that UDCA ameliorates ischemia/reperfusion-induced myocardial damage.     

Role of polyamines in myocardial ischemia/reperfusion injury and their interactions with nitric oxide

Polyamines (putrescine, spermidine, and spermine) are present in all higher eukaryotic cells and are essential for cell growth, differentiation and apoptosis. Sharing common precursor with polyamines, nitric oxide (NO) is associated with myocardial ischemia/reperfusion injury by the generation of peroxynitrite. Although polyamines have been implicated in tissue ischemia injury, their metabolism and interactions with NO in myocardial ischemia/reperfusion injury have not been fully understood. In our experiment, when Langendorff perfused rat hearts were subjected to 40 min ischemia without reperfusion, both ornithine decarboxylase (ODC) and Spermidine/spermine N(1)-acetyltransferase (SSAT) activities were up-regulated and putrescine accumulated. While after reperfusion, ODC activity decreased and SSAT activity increased, resulting in putrescine accumulation and decreased spermidine and spermine. Meanwhile NO content was increased. In addition, sodium nitroprusside (SNP, a NO donor) decreased ODC activity in cardiac tissue homogenate but increased SSAT activity in a dose-dependent manner. Pre-treatment of isolated heart with N(omega)-nitro-L-arginine methyl ester hydrochloride (L-NAME, an inhibitor of NO synthase) increased ODC activity. Exogenous spermine (1 mM) administration prior to ischemia prevented spermine decrease, reduced cardiac myocyte necrosis and apoptosis, and promoted the recovery of cardiac function after ischemia/reperfusion. These results suggest that acute heart ischemia activates myocardial polyamine stress response characterized by increased ODC and SSAT activities and accumulation of putrescine. Ischemia/reperfusion disturbs polyamine metabolism, and the loss of spermine might be associated with NO increase and thereby influences myocardial cell viability. Exogenous spermine may protect the hearts from myocardial ischemia/reperfusion injury.     

内源性硫化氢参与缺血后处理减轻离体大鼠心脏缺血/再灌注损伤

目的探讨内源性硫化氢是否参与缺血后处理减轻大鼠心肌缺血/再灌注损伤。方法Sprague Dawley(SD)大鼠离体心脏Langendorff灌流,平衡20min,全心缺血30min,复氧灌注60min,在复灌即刻给与短暂停灌15s/复灌15 s循环4次造成心肌缺血后处理模型。预先给予胱硫醚-γ-裂解酶(cystanthionine-γ-lysase,CSE)抑制剂炔丙基甘氨酸(L-propargylglycine,PAG),以及给予PAG后加用外源性硫化氢供体NaHS后处理,观察它们对缺血后处理的影响。记录心率(HR)、左室发展压(LVDP)、冠脉流出量(CF);检测灌流液中乳酸脱氢酶(LDH)活性、心肌组织CSE活性、硫化氢的含量以及心肌梗死面积。结果缺血/再灌注组LVDP下降、冠脉灌流液中LDH活性明显增加、心肌梗死面积增加(vsControl组,P<0.05)。缺血后处理组LVDP升高、冠脉灌流液中LDH活性下降、心肌梗死面积缩小(vsIR组,P<0.05)。PAG加缺血后处理组心肌CSE活性及H2S生成下降、并且逆转了缺血后处理的作用,而外源性硫化氢供体NaHS后处理组H2S生成回升、LVDP升高、心肌梗死面积缩小(vsIR组,P<0.05)。结论内源性硫化氢参与大鼠心肌缺血后处理减轻缺血/再灌注损伤。     

Susceptibility to cardiac ischemia/reperfusion injury is modulated by chronic estrogen status

The purpose of this study was to test whether the susceptibility of the heart to ischemia/reperfusion injury is modulated by the chronic estrogen status, i.e., increased with estrogen deficiency and attenuated by pharmacologic estrogen supplementation. In addition, the study tested whether estrogen-dependent changes in mechanical function are associated with alterations of cardiac high-energy phosphate metabolism. Rats were ovariectomized, not ovariectomized, or ovariectomized and treated with subcutaneous estrogen pellets (1.5 mg/21 d) (n = 8-11 per group). Three weeks later, hearts were isolated and perfused isovolumically under constant perfusion pressure conditions. Hearts were subjected to 15 min of total global ischemia (37 degrees C) and 30 min of reperfusion. Simultaneous [31P] nuclear magnetic resonance spectra were recorded throughout this protocol to monitor changes in ATP, phosphocreatine, and inorganic phosphate content. Whereas preischemic values for heart rate, end-diastolic pressure, and coronary flow were not different among groups, left ventricular developed pressure was slightly but significantly decreased in the estrogen-treated group (p < 0.05). However, treated hearts showed improved recovery of left ventricular developed pressure on reperfusion (89 +/- 4% in control rats, 70 +/- 8% in ovariectomized hearts, and 114 +/- 9% of preischemic values in estrogen-treated rats). However, changes in ATP, phosphocreatine, and inorganic phosphate during ischemia were as previously described and were unaffected by chronic estrogen status. In conclusion, in the isolated buffer-perfused rat heart, estradiol treatment caused improved functional recovery after ischemia/reperfusion injury. This improvement, however, did not include preservation of high-energy phosphate metabolism. Other potential mechanisms include an anti-oxidant activity of 17beta-estradiol-and estrogen-induced alterations in glucose metabolism.     

尼可地尔对心脏瓣膜置换术患者心肌缺血再灌注损伤的保护作用

目的：观察尼可地尔对心脏瓣膜置换术患者心肌缺血再灌损伤的保护作用。方法：60例心脏瓣膜置换术患者分为对照组（Ⅰ组）、尼可地尔延迟处理组（Ⅱ组）、尼可地尔早期处理组（Ⅲ组）,每组20例。Ⅱ组在术前24h用尼可地尔20mg静滴。Ⅲ组在麻醉诱导后用尼可地尔20mg静滴。在阻断主动脉即刻（T0）、开放主动脉15min（T1）、30min（T2）、60min（T3）、90min（T4）取冠状静脉窦血测定心肌肌钙蛋白（cTnI）、TNF-α、IL-6,并记录心脏复跳方式和心脏复跳后的心律失常发生率。在阻断主动脉即刻和开放主动脉后30min取右房肌肉组织行电镜观察。结果：Ⅱ、Ⅲ组cTnI、TNF—α、IL-6含量明显低于Ⅰ组,电镜下心肌超微结构受损程度小于Ⅰ组。Ⅱ组患者在T3、T4时刻与Ⅲ组患者同时值比较：cTnI、TNF—α、IL-6含量降低,心肌超微结构受损程度小于Ⅲ组。结论：尼可地尔可明显减轻心脏瓣膜置换术患者心肌缺血再灌注损伤,延迟处理方式的保护作用优于早期处理方式。     

缺血后适应减轻急性下肢缺血再灌注损伤的实验研究

目的 观察缺血后适应(IPC)减轻急性下肢缺血(AU)再灌注损伤的疗效并探讨其机制.方法 将45只新西兰大白兔采用高脂饮食与动脉内膜球囊损伤结合的方式建立下肢动脉粥样硬化狭窄动物模型,随机分为对照组、缺血再灌注组(IR组)、缺血后适应组(IPC组),每组各15只.检测三组大白兔阻断股动脉前、持续再灌注2h后血液中肌酸激酶(CK)、丙二醛(MDA)、超氧化物岐化酶(SOD)水平,观察再灌注后下肢骨骼肌组织学改变,并采用原位末端标记法(TUNEL)分析三组大白兔下肢再灌注后骨骼肌细胞凋亡情况.结果 与IR组比较,IPC组兔血浆CK、MDA明显降低[(7.49±0.84) U/L与(8.19±1.06) U/L,P＜0.05],[(3.67±0.36) nmol/L与(4.06±0.55) nmol/L,P＜0.05],而SOD则显著升高[(420.40±30.94)μmol/L与(384.73±44.12) μmol/L,P＜0.05],骨骼肌细胞凋亡指数降低[(12.27±2.11)％与(16.62±1.44)％,P＜0.01],差异有统计学意义,并且组织形态学观察IPC组兔骨骼肌损伤、坏死程度较IR组减轻.结论 急性下肢缺血应用IPC能显著减轻下肢缺血再灌注损伤,其机制与减少自由基生成、增强抗氧化及减轻缺血再灌注诱导的骨骼肌细胞凋亡有关.     

黄连素对心肌缺血家兔再灌注损伤后心功能的影响

目的 探讨黄连素对家兔心肌缺血再灌注损伤后心功能的影响.方法 采用在体兔心肌缺血再灌注损伤模型,将35只新西兰大白兔随机分为5组:假手术组,模型组,黄连素小(3mg/kg)、中(6mg/kg)、大(12mg/kg)3个剂量组,每组7只.用BL-420生物系统记录各组动物左室收缩压(INSP)、左室内压上升/下降的最大速率(±dp/dt<,max>)和左室舒张末压(INEDP),并记录心电图.结果 与假手术组相比较,模型组大鼠LVSP、+dp/dt、-dp/dt水平明显降低,LVEDP水平明显升高,差异均有统计学意义(P<0.01).与模型组比较,黄连素各组可升高缺血再灌注家兔LVSP、+dp/dt、-dp/dt水平,降低INEDP水平,大剂量组作用最明显(P<0.05).与假手术组比较,模型组大鼠心律失常发生只数明显增多,评分增高(P<0.01).与模型组比较,黄连素各组可使缺血再灌注后心律失常发生只数有减少的趋势,但黄连素各组心律失常发生只数及评分差异无统计学意义(P>0.05).结论 黄连素可在一定程度上改善心肌缺血大鼠再灌注后损伤的心功能,在一定程度上减少缺血再灌注后心律失常的发生.