Spin trap (N-t-butyl-alpha-phenylnitrone)-mediated suprainduction of heme oxygenase-1 in kidney ischemia/reperfusion model: role of the oxygenase in protection against oxidative injury.

In mammals the rate-limiting step in heme catabolism is the heme oxygenase (HO) system. Two isozymes, HO-1 and HO-2, oxidatively cleave the substrate to form biliverdin, and the potential cellular messenger, CO; the chelated iron is released as the result of the tetrapyrrole ring opening. Biliverdin is subsequently reduced to bilirubin, an antioxidant, by biliverdin reductase. The aim of the present study was to investigate the involvement of HO-1, a heat shock/stress protein, in protection offered by the spin trap agent, N-tert-butyl-alpha-phenyl-nitrone (PBN), against kidney ischemia/reperfusion injury. For this, HO-1 expression and assessment of the parameters associated with tissue-oxidative injury were compared in the presence or absence of PBN pretreatment of rats (100 mg/kg i.p., 30 min) before the onset of 30-min ischemia. Twenty-four hours after reperfusion, Northern blot analysis showed an unprecedented approximately 37-fold increase in 1.8-kb HO-1 mRNA in PBN pretreated rat kidney; HO-2 mRNA levels did not increase. At 48 h, the levels of HO-1 mRNA remained nearly 14-fold higher than the control value. In the absence of PBN, the levels measured approximately 5- and 2-fold higher than control values at the 24- and 48-h intervals, respectively. PBN pretreatment also resulted in a most impressive increase in the levels of HO-1 protein as judged by Western blot analysis and measurement of enzyme activity at the 24-h time point. As detected by immunohistochemical analysis, PBN pretreatment caused an increase in HO-1 and biliverdin reductase-immunoreactive proteins in the cortex and in the outer stripe of the outer medulla. In the absence of PBN pretreatment, there was an intense immunostaining for HO-1 in the medullary rays, which corresponded with iron and lipid peroxidation staining of the region; these observations were not made with PBN-pretreated kidneys. Collectively, the findings are consistent with the likelihood that suprainduction of HO-1 gene expression protects the kidney from free radical-mediated injury by increasing the capacity to produce the potent cellular antioxidant bilirubin. We also suggest spin trap-mediated protection against ischemia/reperfusion injury is likely due to a sustained elevation of HO-1 gene expression by formation of stable radicals.     

Demonstration of free radical generation in "stunned" myocardium of intact dogs with the use of the spin trap alpha-phenyl N-tert-butyl nitrone

Recent studies suggest that oxygen free radicals may mediate postischemic myocardial dysfunction ("stunning"), but all the evidence for this hypothesis is indirect. Thus, we used electron paramagnetic resonance (EPR) spectroscopy and the spin trap, alpha-phenyl N-tert-butyl nitrone (PBN), to directly investigate whether free radicals are produced after a 15-min coronary artery occlusion and subsequent reperfusion in 30 open-chest dogs. After intracoronary infusion of PBN, EPR signals characteristic of oxygen- and carbon-centered radical adducts were detected in the venous blood draining from the ischemic/reperfused vascular bed. The myocardial release of PBN adducts began during coronary occlusion but increased dramatically in the first few minutes after reperfusion. After this initial burst, the production of radicals abated but did not cease, persisting up to 3 h after reflow. The EPR spectra (aH beta = 2.67-2.79 G, aN = 14.75-15.00 G) were consistent with the trapping by PBN of secondary oxygen- and carbon-centered radicals, such as alkoxy and alkyl radicals, which could be formed by reactions of primary oxygen radicals with membrane lipids. There was a linear, direct relationship between the magnitude of PBN adduct production and the degree of ischemic flow reduction. Recovery of contractile function (measured as systolic wall thickening) after reperfusion was greater (P less than 0.05) in dogs given PBN than in controls. This study demonstrates that reversible regional myocardial ischemia in the intact animal is associated with prolonged free radical generation, and that the intensity of such generation is related to the severity of ischemia. The results provide direct evidence to support the hypothesis that reactive oxygen metabolites contribute to the persistent contractile dysfunction (myocardial stunning) observed after brief ischemia in vivo.     

血红素加氧酶-1对心肌缺血再灌注损伤的保护作用

目的:探讨血红素加氧酶-1(HO-1)对心肌缺血再灌注损伤的保护作用及机制。方法:采用HO-1的诱导剂钴原卟啉(CoPP)和抑制剂锌原卟啉(ZnPP)分别进行干预处理后,建立大鼠的心肌缺血/再灌注损伤模型。观察大鼠再灌注后心肌形态变化,检测HO-1基因在大鼠心肌的表达情况,测定大鼠左心室心肌组织超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量。结果:再灌注前使用CoPP进行预处理,可以诱导HO-1蛋白的表达上调;HO-1蛋白表达上调可以减少缺血再灌注后的心肌细胞坏死,提高心肌组织中SOD含量并降低MDA的含量。结论:CoPP诱导的HO-1过表达可以抑制心肌缺血再灌注损伤后的细胞坏死,从而减轻心肌的再灌注损伤,其主要机制与抗氧自由基有关。     

肢体缺血-再灌注后大鼠心肌中的氧化应激及HO-1 mRNA表达

目的 探讨肢体缺血-再灌注损伤后心肌的氧化损伤机制及HO-1的保护作用,为研究肢体缺血-再灌注损伤所致的心肌损伤的预防提供实验依据.方法 应用止血带构造SD大鼠双后肢IR模型,实验动物随机(随机数字法)分为正常对照组和缺血4 h再灌注2 h,4 h,6 h,8 h,16 h,24 h共7组,分别取心肌和血液标本检测MDA,SOD,MPO,心肌形态学及心肌组织中HO-1 mRNA的表达.方差分析方法进行统计学处理.结果 (1)血浆及心肌IR各组MDA均较对照组明显升高(P<0.05),且于IR 4 h达高峰.血浆及心肌IR各组SOD均较对照组明显降低(P<0.05),且血清SOD于IR4 h达最低值,心肌SOD于IR 8 h达最低值.血浆及心肌IR各组MPO均较对照组明显升高(P<0.05),且血清MPO于IR 4 h达高峰,心肌MPO于IR 6 h达高峰.(2)在肢体缺血4 h再灌注4-6 h组,心肌形态学损伤最重.(3)与对照组比较,IR2 h组HO-1 mRNA表达差异无统计学意义(P>0.05),其余各组HO-1 mRNA表达均显著上调(P<0.05)且于IR 16 h达高峰.结论 心肌局部组织的自由基和中性粒细胞聚集活化是LIR心肌损伤的机制且能上调HO-1 mRNA的表达,HO-I在心肌组织的高表达能减轻心肌组织的损伤.     

纳洛酮对肺再灌注损伤诱导细胞凋亡的影响

目的 研究纳洛酮对大鼠肺缺血-再灌注(ischemia/reperfusion injury,I/R)损伤中细胞凋亡及血红素氧合酶-1(heme oxygenase-1,HO-1)表达的影响.方法 实验于南京医科大学附属南京第一医院动物实验中心进行,雄性SD大鼠42只,随机(随机数字法)均分为对照组(Sh组)、缺血-再灌注组(IR组)、纳洛酮组(Na组).I/R组钳夹肺门远心端,阻断肺门(以肺无舒缩为阻断标准),建立在体肺I/R损伤模型.Na组在该基础上予纳洛酮1 mg·kg-1腹腔注射,各组分别于3,6 h点取标本,用Annex-in-V-PI双染法检测肺组织凋亡细胞并计算凋亡率,测算肺湿于比(W/D),应用逆转录-聚合酶链反应(RT-PCR)法检测HO-1的mRNA表达,电镜观察肺超微结构改变.采用Stata 9.0统计软件行统计学分析.结果 IR组与Sh组相比,3,6 h点肺组织凋亡率明显增加,W/D显著升高,差异均有统计学意义(P<0.01);IR组3,6 h点,HO-1的mRNA表达与肺组织凋亡率、W/D呈显著负相关(P<0.01).与IR组相比,Na组3,6 h点肺组织凋亡率明显减少,W/D显著降低,差异均有统计学意义(P<0.01).肺组织HO-1表达显著增加(P<0.01),肺组织超微结构损害明显减轻.结论 在肺1/R损伤早期,纳洛酮可以诱导HO-1的mRNA表达大量表达从而抑制细胞凋亡的发生,起到保护作用.     

甲状腺素对大鼠肝脏缺血再灌注后血红素加氧酶-1表达的影响

目的 探讨甲状腺素对大鼠肝脏缺血再灌注后血红素加氧酶-1(HO-1)表达的影响及其对肝脏的保护作用与机制.方法 建立70%大鼠肝脏缺血再灌注损伤模型(缺血1 h,再灌注6 h),将30 只雄性Sprague-Dawley 大鼠随机分为假手术组、对照组、处理组三组,每组10 只.处理方法为于缺血48 h 前0.1 mg/kg 的T3 腹腔注射.测定再灌注末血清ALT、AST 和肝脏组织丙二醛(MDA)、超氧化物歧化酶(SOD)的变化,HE 染色光镜下肝组织学观察.应用Western blot 及RT-PCR检测肝脏HO-1 的表达.结果 与假手术组相比,对照组细胞上清液中ALT、AST 和MDA 含量明显较高(P ＜0.05),SOD 明显较低(P ＜0.05);肝细胞坏死严重,排列紊乱.处理组的ALT、AST 和MDA 显著低于对照组(P ＜0.05),SOD 明显高于对照组(P ＜0.05);肝细胞坏死减轻,排列相对整齐.假手术组有少量HO-1 表达,处理组HO-1 表达高于对照组,差异有统计学意义(P ＜0.05).结论 甲状腺素能上调HO-1 的表达以减少肝细胞坏死,减轻大鼠肝脏缺血再灌注损伤,从而对肝脏有保护作用.     

The effect of hypoxia, reoxygenation, ischemia, and reperfusion on hydraulic permeability in rat mesenteric venules

Little is known regarding the effects of I/R on hydraulic permeability (Lp). We sought to compare the individual influences of hypoxia, ischemia, reoxygenation, and reperfusion on Lp. We hypothesized that (1) hypoxia increases Lp; (2) reoxygenation further increases Lp; (3) ischemia results in greater increases in Lp compared with hypoxia; (4) reperfusion causes additional increases in Lp compared with hypoxia, ischemia, and reoxygenation; and (5) xanthine oxidase (XO) and white blood cell adherence play important roles in hypoxia, ischemia, and reperfusion. Hydraulic permeability was measured by an in vivo microcannulation technique during hypoxia, reoxygenation, ischemia, and reperfusion in rat mesenteric postcapillary venules. Additional rats were fed a Tungsten-enriched diet to inhibit XO activity, and the studies were repeated. White blood cell adherence was also documented. Hypoxia and ischemia both increased Lp 2-fold from baseline levels (P < 0.001). Reoxygenation did not alter Lp compared with 15 min of hypoxia alone (P > 0.07). Reperfusion after hypoxia increased Lp 6-fold (P < 0.001). Reperfusion after ischemia also increased Lp 6-fold (P < 0.001). Inhibition of XO had no effect on the increase in Lp after both hypoxia and ischemia. However, inhibition of XO attenuated the 6-fold increase in Lp observed during reperfusion after both hypoxia and ischemia by approximately 50% (P < 0.001). White blood cell adherence increased during reperfusion but not hypoxia or ischemia. The complexity of I/R injury makes it a difficult clinical scenario to model for research. We have demonstrated in an in vivo model that hypoxia and ischemia increase Lp similarly, and that reperfusion has a profound deleterious effect on Lp. These changes in Lp seem to be XO and white blood cell dependent.     

Postischemic recovery and oxidative stress are independent of nitric-oxide synthases modulation in isolated rat heart

During myocardial ischemia and reperfusion, nitric oxide ((.)NO) was shown to exert either beneficial or detrimental effects. Uncoupled (.)NO synthases (NOS) can generate superoxide anion under suboptimal concentrations of substrate and cofactors. The aim of our study was to investigate the role of NOS modulation on 1) the evolution of functional parameters and 2) the amount of free radicals released during an ischemia-reperfusion sequence. Isolated perfused rat hearts underwent 30 min of total ischemia, followed by 30 min of reperfusion in the presence of N(G)-nitro-D- or L-arginine methyl ester (NAME, 100 microM) or of D- or L-arginine (3 mM). Functional parameters were recorded and coronary effluents were analyzed with electron spin resonance to identify and quantify the amount of alpha-phenyl-N-tert-butylnitrone spin adducts produced during reperfusion. The antioxidant capacities of the compounds were determined with the oxygen radical absorbance capacity test. L-NAME-treated hearts showed a reduction of coronary flow and contractile performance, although neither L-NAME nor L-arginine improved the recovery of coronary flow, left end diastolic ventricular pressure, rate pressure product, and duration of reperfusion arrhythmia, compared with their D-specific enantiomers. A large and long-lasting release of alkyl/alkoxyl radicals was detected upon reperfusion, but no differences of free radical release were observed between D- and L-NAME or D- and L-arginine treatment. These results may indicate that, in our experimental conditions, cardiac NOS might not be a major factor implicated in the oxidative burst that follows a global myocardial ischemia.     

Upregulation of heme oxygenase-1 protects genetically fat Zucker rat livers from ischemia/reperfusion injury

We examined the effects of upregulation of heme oxygenase-1 (HO-1) in steatotic rat liver models of ex vivo cold ischemia/reperfusion (I/R) injury. In the model of ischemia/isolated perfusion, treatment of genetically obese Zucker rats with the HO-1 inducer cobalt protoporphyrin (CoPP) or with adenoviral HO-1 (Ad-HO-1) significantly improved portal venous blood flow, increased bile production, and decreased hepatocyte injury. Unlike in untreated rats or those pretreated with the HO-1 inhibitor zinc protoporphyrin (ZnPP), upregulation of HO-1 by Western blots correlated with amelioration of histologic features of I/R injury. Adjunctive infusion of ZnPP abrogated the beneficial effects of Ad-HO-1 gene transfer, documenting the direct involvement of HO-1 in protection against I/R injury. Following cold ischemia/isotransplantation, HO-1 overexpression extended animal survival from 40% in untreated controls to about 80% after CoPP or Ad-HO-1 therapy. This effect correlated with preserved hepatic architecture, improved liver function, and depressed infiltration by T cells and macrophages. Hence, CoPP- or gene therapy-induced HO-1 prevented I/R injury in steatotic rat livers. These findings provide the rationale for refined new treatments that should increase the supply of usable donor livers and ultimately improve the overall success of liver transplantation.     

Pharmacological preconditioning protects lung injury induced by intestinal ischemia/reperfusion in rat

Intestinal ischemia/reperfusion (IIR) is a critical and triggering event in the development of distal organ dysfunction, frequently involving the lungs. Respiratory failure is a common cause of death and complications after intestinal I/R. Stress protein heme oxygenase-1 (HO-1) confers the protection against a variety of oxidant-induced cell and tissue injuries. The aim of this study was to investigate the hypothesis that the induced HO-1 expression by pharmacological preconditioning with anticancer drug doxorubicin (Dox) could protect the lung injury induced by intestinal I/R. Intravenous administration of Dox induced HO-1 expression in the lungs and high levels of the expression were sustained at least to 48 h after the injection. Therefore, as pharmacological preconditioning, a low dose of Dox was injected intravenously into rats at 48 h before the start of intestinal ischemia. Rats underwent intestinal I/R by superior mesenteric artery occlusion for 120 min followed by 120 min of reperfusion. Preconditioning with Dox significantly ameliorated the lung injury induced by the intestinal I/R. Administration of a specific inhibitor of HO activity reduced the efficacy of the preconditioning. Our results suggest that this improvement may be mediated at least in part by the HO-1 induction. These findings may offer interesting perspectives for patient management In Intestinal surgical operation and intestine transplantation.     

Protective effect of S-nitrosylated alpha(1)-protease inhibitor on hepatic ischemia-reperfusion injury

S-Nitrosylated compounds (nitrosothiols; RS-NOs) function as nitric oxide (NO) reservoirs and preserve the antioxidant activities of NO. We found remarkable cytoprotection by an S-nitrosylated protease inhibitor from human plasma, S-nitroso-alpha(1)-protease inhibitor (S-NO-alpha(1)-PI) that possesses a completely nitrosylated SH group, in hepatic ischemia-reperfusion injuries in rats. Liver ischemia was induced in rats by occluding both the portal vein and hepatic artery for 30 min and was followed by reperfusion. S-NO-alpha(1)-PI and control compounds such as native alpha(1)-PI, an NO synthase (NOS) inhibitor, and standard RS-NOs were given via the portal vein just after reperfusion was initiated. Liver injury was evaluated by measuring the extracellular release of liver enzymes (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase). Infiltration of neutrophils and induction of apoptosis and heme oxygenase-1 (HO-1) in the liver were also examined. Maximal liver injury occurred at 3 h after reperfusion and then decreased gradually. Not only did S-NO-alpha(1)-PI treatment (0.1 micromol; 5.3 mg/rat) greatly reduce elevation of liver enzymes in plasma, as well as neutrophil accumulation and apoptotic change in liver, it also improved the impaired hepatic blood flow as assessed by laser Doppler flowmetry and potentiated the induction of HO-1 in the liver. Although native alpha(1)-PI moderately reduced liver injury, low molecular weight RS-NOs such as S-nitrosoglutathione and S-nitroso-N-acetyl penicillamine produced no obvious protective effect. An NOS inhibitor exacerbated the hepatic ischemia-reperfusion injuries. These results suggest that S-NO-alpha(1)-PI exerts a potent cytoprotective effect on ischemia-reperfusion liver injury by maintaining tissue blood flow, inducing HO-1, and suppressing neutrophil-induced liver damage and apoptosis.     

Protective effect of heme oxygenase induction in ischemic acute renal failure

OBJECTIVE: To examine the role of heme oxygenase-1 (HO-1) induction in the recovery of renal function in rats with ischemic acute renal failure. DESIGN: Randomized, masked, controlled animal study. SETTING: University-based animal research facility. SUBJECTS: Sprague-Dawley male rats, weighing 200-250 g. INTERVENTIONS: Anesthetized rats were subjected to bilateral flank incisions, and the right kidney was removed. Renal ischemia was performed by left renal microvascular clamping, followed by reflow of the blood. MEASUREMENTS AND MAIN RESULTS: Ischemia of the kidney in the uninephrectomized rat significantly induced HO-1 messenger RNA, protein, and enzyme activity, reaching a maximum at 6 hrs, which was mediated in part through an increase in microsomal heme concentration. Heat shock protein 70 was induced extremely rapidly, reaching a maximum at 1 hr, suggesting that HO-1 and heat shock protein 70 gene expression are regulated separately. Inhibition of HO activity by tin mesoporphyrin, which resulted in an increase in microsomal heme concentration, significantly exacerbated renal function, as judged by the sustained increase in serum creatinine concentration and extensive tubular epithelial cell injuries. In contrast, animals that did not receive tin mesoporphyrin showed normal creatinine concentration and microsomal heme concentration 24 hrs after reperfusion, as well as restoration of abnormal renal histology. CONCLUSION: These findings indicate that the expression of HO-1 in the ischemic kidney may be critical in the recovery of renal cell function in this animal model. These findings also suggest that H0-1 induction may play an important role in conferring protection on renal cells from oxidative damage caused by heme.     

高压氧对大鼠脑缺血后NOS阳性神经元的影响

目的　探讨一氧化氮合酶 (NOS)阳性细胞在大鼠急性局灶性脑缺血 /再灌注损伤和高压氧 (HBO)治疗后表达的变化。方法　应用血管内细丝栓堵大脑中动脉 (MCA)的局灶性脑缺血大鼠模型 ,利用黄递酶 -NADPH组织化学方法 ,观察MCA缺血 1h ,再灌注 4、11、2 3、71hNOS阳性细胞在视交叉平面梗死区皮层、视前区、纹状体外侧区和纹状体内侧区域分布的变化 ,在以上期间应用 0 2 5MPaHBO于开始缺血后 2、9、2 1、4 5和 6 9h分别治疗 1次 (1h)。结果　脑缺血后 ,在上述区域形态改变的NOS阳性细胞数随着再灌注时间的延长逐渐增多。HBO治疗后 ,各时间点在皮层、视前区和纹状体内侧区 ,形态改变的NOS阳性细胞数明显减少 (P <0 0 5 ) ,而纹状体外侧区无明显变化 (P >0 0 5 )。结论　HBO可明显抑制大鼠急性局灶性脑缺血 /再灌注损伤区NOS阳性细胞的变性     

迟发缺血预处理低温保存肾移植供体中血红素加氧酶1的表达

背景:缺血预适应延迟反应通过诱导保护性蛋白增强组织对缺血再灌注损伤的耐受能力;血红素加氧酶1参与缺血预适应延迟保护作用。迟发缺血预处理对低温保存肾脏的作用及血红素加氧酶1是否参与其中尚不清楚。目的:观察缺血预处理诱导血红素加氧酶1的迟发缺血预处理反应对低温保存肾脏移植供体的作用。方法:雄性SD大鼠随机分入5组:空白对照组、低温保存组、缺血预处理组、缺血+低温组(n=12);缺血+给药+低温组。各组大鼠均行右肾切除,预处理或假手术操作处理后24h采用大鼠肾脏非循环离体灌注模型获取肾脏,分别于保存24,48,72h取样。缺血+给药+低温组除上述处理外,还于原位低温灌注术前1h接受1次血红素加氧化酶1抑制剂锡原卟啉腹腔注射。低温保存肾脏于各保存终点留取保存液,测定pH值和乳酸脱氢酶含量;切取1/2肾脏按照光镜要求制备标本送检;剩余1/2肾脏用于免疫印迹法测定血红素加氧酶1表达,比色法测定皮质Na-K-ATP酶活性、丙二醛和还原型谷胱甘肽含量;未保存肾脏仅通过免疫印迹法测定血红素加氧酶1的基础表达情况。结果与结论:迟发缺血预处理诱导了肾组织血红素加氧酶1的表达,与单纯低温保存组相比保存24,48h后,缺血+低温组保存液pH值、乳酸脱氢酶活性降低;肾脏组织Na-K-ATP酶活性、谷胱甘肽含量增加,丙二醛含量降低;同时点预处理组肾组织光镜形态学改变稍好于单纯低温保存组。给予血红素加氧酶1抑制剂后,这种保护作用消失。提示,迟发缺血预处理延长了肾脏低温保存时限,这可能与诱导血红素加氧酶1,增加组织抗氧化能力,减轻低温保存氧应激有关。     

下肢缺血再灌注损伤模型大鼠接受依达拉奉干预后的超微结构变化

背景：肢体缺血再灌注损伤中,氧自由基及细胞凋亡发挥重要的作用,通过抑制氧自由基生成及细胞凋亡,可减轻肢体缺血再灌注损伤。 目的：验证依达拉奉在大鼠肢体缺血再灌注损伤方面的应用及疗效。 方法：30只雌性SD大鼠,随机取20只,分别用自制气囊袖带环扎大鼠右后肢根部加压至40 kPa达到阻断血流,4h后松解形成再灌注,制作肢体缺血再灌注损伤模型。造模成功后随机分为2组,依达拉奉灌注组于再灌注前5 min由左股静脉注射依达拉奉3 mg/kg,模型组及剩余10只（正常组）于相同时间点给予等量的生理盐水。于再灌注24 h,取每组大鼠右胫前肌,用透射电镜观察其超微结构变化,并采用RT-PCR对每组大鼠胫前肌中bcl-2 mRNA、bax mRNA进行半定量检测并计算bcl-2/bax比值。 结果与结论：①电镜结果显示：依达拉奉灌注组与模型组相比肌纤维较整齐,M 线、Z 线较清晰,线粒体肿胀减轻、其数量及嵴稍增多。②RT-PCR结果显示,缺血再灌注24 h后,右胫前肌bcl-2 mRNA的相对表达量以及bcl-2 mRNA与bax mRNA的比值：模型组显著低于依达拉奉灌注组（P＜0.05）,而bax mRNA的相对表达量模型组高于依达拉奉灌注组,且两组均高于正常组（P＜0.05）。结果提示自由基清除剂依达拉奉可能通过改善线粒体等超微结构及促进bcl-2 mRNA、抑制bax mRNA的表达来减轻肢体缺血再灌注损伤,这可为肢体缺血再灌注损伤的治疗提供新的选择。