5-Aminoisoquinolinone, a novel inhibitor of poly(adenosine disphosphate-ribose) polymerase, reduces microvascular liver injury but not mortality rate after hepatic ischemia-reperfusion

OBJECTIVE: The aim of this study was to investigate the impact of the novel, potent, water-soluble inhibitor of poly(adenosine diphosphate-ribose) polymerase (PARP) 5-aminoisoquinolinone (5-AIQ) on hepatic microcirculation, hepatocellular injury, and survival in a murine model of hepatic ischemia-reperfusion. DESIGN: Randomized animal study. SETTING: Research laboratory. SUBJECTS: C57BL6 mice were subjected to warm either partial (90 mins) or total (75 mins) ischemia of the liver. INTERVENTIONS: Either PARP inhibitor 5-AIQ (3 mg/kg) or vehicle was administered to mice intravenously immediately before the start of reperfusion. Sham-operated animals served as controls. MEASUREMENTS AND MAIN RESULTS: As shown by intravital fluorescence microscopy after 30-60 mins of reperfusion, ischemia-reperfusion significantly enhanced platelet- and leukocyte-endothelial cell interactions in hepatic microvessels and impaired sinusoidal perfusion. Hepatocellular injury was characterized by an increase in the number of necrotic and apoptotic cells, dramatic elevation of aspartate aminotransferase/alanine aminotransferase serum activity, and lipid peroxidation in liver tissue. 5-AIQ treatment attenuated ischemia-reperfusion-induced increases in the numbers of adherent platelets and leukocytes as well as of necrotic and apoptotic cells and ameliorated perfusion failure. Furthermore, PARP inhibition prevented the increase in aspartate aminotransferase activity after ischemia-reperfusion but did not affect postischemic alanine aminotransferase release. However, no protective impact of 5-AIQ on postischemic oxidative stress was observed. Although PARP inhibition did not alter the survival percentage after ischemia-reperfusion (22% in both groups), this approach prolonged survival from 1 to 24 hrs (ischemia-reperfusion + vehicle) up to 48-72 hrs in the treated group. CONCLUSIONS: PARP inhibition with 5-AIQ during hepatic ischemia-reperfusion attenuates microvascular injury and reduces the extent of necrotic/apoptotic cell damage but does not protect from oxidative injury and does not improve postoperative survival rate.     

高渗盐水对缺血/再灌注损伤肝脏血红素加氧酶-1表达的影响

目的 探讨高渗盐水预处理对肝脏缺血／再灌注损伤的保护作用及其机制。方法 25只SD大鼠随机分为假手术组、血红素加氧酶-1（HO-1）抑制剂锌原卟啉（ZnPP）组、缺血／ig灌注组、高渗盐水预处理组及ZnPP干预组，每组5只。建立大鼠局部肝脏缺血／再灌注损伤模型，于缺血／再灌注后6h测定血清丙氨酸转氨酶（ALT）活性、肿瘤坏死因子-α（TNF-α）含量、肝组织髓过氧化物酶（MPO）活性及肝组织内皮素1（ET1）含量；采用逆转录-聚合酶链反应（RTPCR）和蛋白质免疫印迹法（Westernblot）检测肝组织HO-1mRNA和蛋白表达；光镜和电镜下观察肝脏病理学改变及肝窦情况。观察使用ZnPP后，高渗盐水预处理对肝脏缺血／再灌注损伤的保护作用。结果 肝脏缺血／再灌注后血清ALT活性、TNF-α含量及肝组织MPO活性、ET-1含量均明显升高（P均d0．01），HO-1mRNA和蛋白表达明显增强。高渗盐水预处理明显增强缺血／再灌注后肝脏HO-1mRNA及蛋白表达，降低血清ALT、TNF-α水平及肝组织MPO活性和ET-1含量，肝脏微循环明显改善；使用ZnPP以后，高渗盐水预处理的保护作用消失。结论 高渗盐水预处理通过增强HO-1表达，对肝脏缺血／再灌注损伤产生保护作用。     

Ischemia/reperfusion-induced increase in the hepatic level of prostacyclin is mainly mediated by activation of capsaicin-sensitive sensory neurons in rats

Capsaicin-sensitive sensory neurons are nociceptive neurons that release calcitonin gene-related peptide (CGRP) on activation by various noxious stimuli. CGRP has been shown to increase the endothelial production of prostacyclin, which reduces ischemia/reperfusion (I/R)-induced liver injury. Therefore, if the sensory neurons can be activated by the pathologic process of hepatic I/R, they might help ameliorate I/R-induced liver injury by promoting the endothelial production of prostacyclin, also known as prostaglandin I(2). In this study, we examined these possibilities using a rat model of I/R-induced liver injury. Male Wistar rats were subjected to 60-minute hepatic ischemia and subsequent reperfusion. Hepatic levels of 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)), a stable metabolite of prostacyclin, were significantly increased after hepatic I/R, peaking 1 hour after reperfusion. Administration of capsaicin and CGRP significantly enhanced I/R-induced increases in hepatic levels of 6-keto-PGF(1alpha), increased hepatic-tissue blood flow after reperfusion, and inhibited the I/R-induced increase in tissue levels of both tumor necrosis factor-alpha (TNF-alpha) and myeloperoxidase. Capsazepine, a vanilloid receptor antagonist; CGRP(8-37), a CGRP-receptor antagonist; l-nitro-arginine-methyl-ester (L-NAME), a nonselective inhibitor of nitric oxide (NO) synthase (NOS); and indomethacin, a nonselective inhibitor of cyclooxygenase, inhibited the I/R-induced increases in hepatic tissue levels of 6-keto-PGF(1alpha) and decreased hepatic-tissue blood flow after reperfusion. These compounds significantly enhanced the I/R-induced increases in hepatic tissue levels of both TNF-alpha and myeloperoxidase. Although I/R-induced liver injury was significantly reduced by capsaicin and CGRP, it was exacerbated by capsazepine, CGRP(8-37), L-NAME, and indomethacin. Administration of aminoguanidine, a selective inhibitor of the inducible form of NOS, and NS-398, a selective inhibitor of cyclooxygenase-2, demonstrated no effects on the liver injury or the hepatic levels of 6-keto-PGF(1alpha). These findings strongly suggest that the activation of the sensory neurons helps ameliorate I/R-induced liver injury both by increasing hepatic-tissue blood flow and by limiting inflammatory response through the enhancement of endothelial production of prostacyclin. In the sensory neuron-mediated enhancement of endothelial production of prostacyclin, CGRP-induced activation of both endothelial NOS and cyclooxygenase-1 may be critically involved.     

Prevention of ischemia/reperfusion injury by hepatic targeting of nitric oxide in mice

Macromolecular nitric oxide (NO) donors possessing the ability to target a specific type of liver cells were developed for delivering NO to the liver. Six NO molecules were covalently bound to mannosylated (Man) or galactosylated (Gal) bovine serum albumin (BSA) through an S-nitrosothiol linkage to obtain Man-poly SNO-BSA and Gal-poly SNO-BSA, respectively. The carrier parts of Man-poly SNO-BSA and Gal-poly SNO-BSA predominantly accumulated in the liver after intravenous injection in mice. In an ischemia/reperfusion injury mouse model, in which hepatic injury was induced by occluding the portal vein for 15 min followed by a 6 h reperfusion, the elevation of plasma alanine aminotransferase and aspartate aminotransferase levels was significantly inhibited by a bolus intravenous injection of Man-poly SNO-BSA or Gal-poly SNO-BSA, just before the start of reperfusion. In marked contrast, S-nitroso-N-acetyl penicillamine and NO-conjugated BSA, two classical S-nitrosothiols, had no statistically significant effects on the serum levels of the markers. The released NO in mouse liver was detected by electron spin resonance spectrometry only in the liver of mice receiving Man-poly SNO-BSA or Gal-poly-SNO-BSA. These findings indicate that Man-poly SNO-BSA and Gal-poly SNO-BSA are promising compounds for preventing hepatic ischemia/reperfusion injury by delivering pharmacologically active NO to the liver.     

Kupffer cells protect liver from ischemia-reperfusion injury by an inducible nitric oxide synthase-dependent mechanism

The aim of this study was to investigate the role of nitric oxide (NO) in rat hepatic ischemia-reperfusion (I/R) injury. Animals were divided into four groups: Group I, control; Group II, gadolinium chloride (GdCl3), a Kupffer cell depleting agent, pretreated; Group III, S-methylisothiourea (SMT), a potent inducible NO synthase (iNOS) inhibitor, pretreated; Group IV, pretreated with SMT, then treated with S-Nitroso-N-acetylpenicillamine (SNAP), a NO donor, after ischemia. Sprague-Dawley rats underwent left lateral and median lobe ischemia for 60 min and reperfusion for 120 min. The left lateral and median lobes were used as ischemic lobes, and the right lateral lobe in the same rat was used as a control lobe. The total NOS (tNOS), iNOS, constitutive NOS (cNOS) activity, and liver protein were determined. The liver tissue malonaldehyde (MDA) level was measured as an index of lipid peroxidation. Liver histology was also examined. The liver tNOS activity in ischemic lobes of Group I, II, III, and IV was increased by 214%, 86%, 61%, and 45%, respectively. The increase in tNOS activity is mainly due to the induction of iNOS activity in the ischemic lobes of rat liver. GdCl3 significantly decreased the tNOS by 66% in the ischemic lobes. GdCl3 significantly increased MDA by 39% in the ischemic lobes. SMT significantly decreased tNOS and iNOS activity by 66% and 85% in ischemic lobes. SMT increased MDA by 67% in the ischemic lobes. SMT + SNAP treatment increased iNOS activity by 117% in the ischemic lobes in comparison with the ischemic lobes of the SMT group. SMT + SNAP treatment decreased MDA by 39% in the ischemic lobes. SMT + SNAP treatment also decreased the sinusoidal congestion and spotty necrosis of hepatocytes in the ischemic lobes. iNOS immunostaining showed an obvious increase in sinusodial area of the ischemic lobes where most Kupffer cells were interspersed. In conclusion, in this model of liver I/R injury, I/R increased the activity of tNOS and iNOS, but not the cNOS activity. Kupffer cells might be the major source of the induction of iNOS activity. The iNOS specific inhibitor SMT increased the lipid peroxidation and the tissue damage in hepatic I/R injury. On the contrary, the NO donor SNAP increased the activity of iNOS and decreased the hepatic injury in this study. Kupffer cells could protect liver from I/R injury by an iNOS-dependent mechanism, thus NO production has a beneficial role in hepatic IR injury.     

二氮嗪预处理对大鼠肝窦内皮常温缺血再灌注损伤的影响

目的:通过观察二氮嗪(Diazoxide)预处理对大鼠肝窦内皮常温缺血再灌注损伤(I/RI)的影响,探讨线粒体ATP敏感性钾通道(MitoKATP)在其中的可能作用。方法:32只成年健康雄性SD大鼠,随机分为4组,每组8只:①假手术组(Sham组);②对照组(Control组),进腹后行部分肝脏缺血再灌注(I/R);③二氮嗪组(Dia组),在行肝I/R前10min,静注Diazoxide (5 mg·kg~(-1));④5-HD Dia组,在行肝I/R之前20min静注5-HD(10mg·kg~(-1)),10min后静注Diazoxide(5 mg·kg~(-1))。再灌注90min时测定各组血清谷丙转氨酶(ALT)、透明质酸(HA)水平和肝脏一氧化氮(NO)、内皮素(ET)含量;并进行肝组织病理形态学观察,包括光镜HE染色和透射电镜(TEM)超微结构检查;免疫组化检测细胞间粘附分子(ICAM-1)的表达。结果:与Sham组相比,Control组的血清ALT和HA水平,肝组织ET含量均明显升高(P<0.05);而肝组织NO含量明显降低(P<0.05)。与Control组相比,Dia组的ALT、HA及ET含量都降低(P<0.05)。肝组织中NO的含量升高。5-HD完全抵消了Dia的作用。HE染色和TEM检查提示Dia组较明显地减轻损伤,而5-HD Dia组则与Control组相似。Dia组肝窦内皮细胞膜ICAM-1表达比例明显减少,且染色较淡,组间比较有显著差异(P<0.05);5-HD可以抵消Diazoxide减少ICAM-1表达的效应。结论:线粒体ATP敏感性钾通道(MitoKATP)开放剂的预处理对后继的肝脏I/RI中肝窦内皮的损伤有较好的保护作用。     

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.     

Does upregulation of inducible nitric oxide synthase play a role in hepatic injury?

Lipopolysaccharide (LPS) and gut ischemia/reperfusion (I/R) injury cause reversible liver injury. Because nitric oxide (NO) can have both beneficial and deleterious effects in the gastrointestinal tract, and because the role of NO in gut I/R-induced hepatic injury is unknown, this study examined its role in LPS and gut I/R-induced hepatic injury in the rat. Both LPS and gut I/R caused a similar increase in serum hepatocellular enzymes. LPS but not gut I/R caused a significant increase in upregulation of hepatic inducible NO synthase (iNOS) according to quantitative real-time RT-PCR and Western immunoblot analysis. Aminoguanidine, a selective iNOS inhibitor, attenuated LPS-induced hepatic injury and hypotension, but did not prevent gut I/R-induced hepatic injury. In contrast, the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester aggravated liver damage from both LPS and gut I/R. These data indicate that iNOS plays a role in mediating LPS-induced hepatic injury, but not gut I/R-induced hepatic injury. The data also suggest that the constitutive isoforms of NOS play a hepatoprotective role in both models of hepatic injury.     

异丙酚对兔肝缺血/再灌注损伤中一氧化氮和内皮素的干预

目的　探讨一氧化氮 (NO)和内皮素 (ET)在肝缺血 /再灌注损伤 (HIRI)中的作用及异丙酚对其的影响。方法　实验兔分为假手术对照组 (n =10 )、肝缺血 /再灌注组 (n =10 )及肝缺血 /再灌注 异丙酚治疗组 (n =10 ) ;分别检测缺血前、缺血 4 5min和再灌注 4 5min 3个时点的指标变化。用硝酸还原酶法检测血浆及肝组织一氧化氮代谢产物 (NOP)含量 ,放射免疫法测定ET水平 ,赖氏法测定谷丙转氨酶 (ALT)活性 ,并行肝组织电镜观察。结果　肝缺血 /再灌注期间 ,血浆NOP明显低于假手术对照组 ,而ET及ALT显著高于假手术对照组 ,尤以再灌注 4 5min变化显著 (P <0 0 5和P <0 0 1) ;肝组织NOP明显低于假手术对照组 ,而ET显著高于假手术对照组 (P <0 0 5和P <0 0 1) ;肝细胞形态学发生异常改变。异丙酚可逆转上述指标的异常变化。结论　缺血 /再灌注导致血管内皮功能紊乱 (即NO水平下降和ET水平升高 ) ,在HIRI发生发展中起介导作用 ;异丙酚通过保护肝窦内皮 ,提高机体内NO水平和降低机体内ET水平 ,从而减轻HIRI。     

阿托伐他汀钙预防大鼠肝缺血再灌注损伤的实验研究

目的探讨阿托伐他汀钙对肝缺血再灌注损伤的保护作用及其作用机制。方法采用在体大鼠肝原位缺血再灌注模型。21只健康雄性SD大鼠随机分成假手术组(N)、缺血再灌注组(I/R)、阿托伐他汀钙处理组(AT+I/R),每组7只。各组于再灌注90 min后经肝上下腔静脉取血,用于检测血清谷丙转氨酶(ALT)和谷草转氨酶(AST);取肝匀浆低温离心后采用试剂盒测定肝组织中总超氧化物歧化酶(TSOD)、丙二醛(MDA)、髓过氧化物酶(MPO)、一氧化氮(NO)、一氧化氮合酶(NOS)含量变化;同时取肝脏组织作病理切片观察。结果 AT+I/R组较I/R组:ALT分别为(928.43±96.17)、(1234.89±327.17)IU/L;AST分别为(1 222.91±249.85)、(1635.74±481.86)IU/L;MDA分别为(2.35±0.57)、(3.29±1.23)nmol/mg;MPO分别为(2.33±0.71)、(3.18±0.82)IU/mg;NO分别为(89.27±8.27)、(102.32±11.81)μmol/mg;iINOS分别为(0.25±0.14)、(0.45±0.21)U/mg,AT+I/R组明显降低(P<0.05),而SOD(20.86±2.49)、(14.58±2.04)IU/mg;cNOS(0.69±0.17)、(0.56±0.13)U/mg明显升高(P<0.05)。结论阿托伐他汀钙有保护肝缺血再灌注损伤的作用。其可能机制为激活了抗氧自由基、提高机体清除氧自由基、抗炎作用和减轻钙超载有关。     

参附注射液对兔肝脏缺血再灌注损伤保护作用的研究

目的研究参附注射液对兔肝脏缺血再灌注损伤的保护作用及其机理。方法 27只新西兰大白兔随机分为3组:对照组(A组)、缺血再灌注组(B组)、参附治疗组(C组)。分别在缺血前10min,缺血45min,再灌注45min取血检测肝功能、超氧化物歧化酶(SOD)、丙二醛(MDA)、肿瘤坏死因子(TNF-α)、白介素10(IL-10)、一氧化氮(NO)及肝组织标本行病理学观察。结果 C组与B组相比,再灌注45min肝酶指标、血浆MDA浓度、TNF-α浓度降低;血浆SOD活力、血浆IL-10浓度、血浆NO浓度升高,差异有统计学意义(t分别=-3.38～3.76,P均<0.05);病理检查提示C组肝脏变性坏死明显较B组减轻。结论参附注射液能增强兔血浆SOD活力,清除氧自由基,抑制脂质过氧化反应;抑制肝脏Kupffer细胞产生TNF-α,促进内源性IL-10的释放;促进肝脏合成释放NO,对兔肝脏缺血再灌注损伤有明显的保护作用。     

MMP-9抑制剂对大鼠肝脏缺血再灌注模型的影响分析

目的探讨基质金属蛋白酶-9(MMP-9)抑制剂对大鼠肝脏缺血再灌注模型的影响。方法选择36只健康雄性Wistar大鼠,将其随机分成3组,对照组(大鼠未进行任何处理不建立肝脏缺血再灌注模型)12只,模型组(肝脏缺血再灌注模型组建立前采用生理盐水处理)12只大鼠,实验组(肝脏缺血再灌注模型建立前采用盐酸多西环素处理)12只。检测各组大鼠肝脏缺血再灌注1 h、6 h、24 h血清天冬氨酸氨基转移酶(AST)与丙氨酸氨基转移酶(ALT)含量;观察评价肝脏组织损伤情况,肝脏组织的淤血、空泡样变、坏死程度以及MMP-9水平。结果模型组与实验组再灌注1 h、6 h、24 h的血清ALT与AST水平、肝组织病理评分均显著高于对照组(P <0.05)实验组低于模型组(P <0.05),模型组和实验组在肝脏缺血再灌注6 h时血清ALT与AST水平最高(P <0.05)。模型组与实验组再灌注1 h、6h、24 h的肝组织MMP-9相对表达水平均显著低于对照组(P <0.05),实验组高于模型组(P <0.05)。结论 MMP-9抑制剂能抑制大鼠肝脏缺血再灌注损伤,促进恢复大鼠的肝功能,缓解肝组织病变状况。     

PI3K/Akt信号通路在肝脏缺血再灌注损伤中的研究进展

肝脏缺血再灌注损伤是导致术后肝脏功能延迟恢复和功能障碍的重要原因。有研究表明,PI3K/Akt信号通路在缺血和再灌注的过程中被激活,通过抑制或增强下游相关靶蛋白的表达发挥对肝脏的保护作用。因此,PI3K/Akt信号成为预防和改善肝脏缺血再灌注损伤的重要靶向通路。本文就PI3K/Akt信号通路在肝脏缺血再灌注损伤中作用的研究进展进行综述。     

Inhibition of nitric oxide synthesis by L-name exacerbates acute lung injury induced by hepatic ischemia-reperfusion.

Hepatic Kupffer cells and pulmonary alveolar macrophages together constitute a macrophage-axis involved in the regulation of regional and systemic inflammatory responses. Systemic inflammatory response syndrome induced by overproduced pro-inflammatory mediators is the major cause of adult respiratory distress syndrome. In the present study, we examined the anti-inflammatory role of nitric oxide (NO) in a rat model of acute lung injury induced by hepatic ischemia-reperfusion (HI/R). The left and median lobes of the liver were subjected to 30 min of ischemia by clamping the relevant branches of hepatic artery and portal vein, followed by a 4-h reperfusion achieved by removal of the vascular clamp. Four groups of animals were studied: sham control + saline; sham control + N(omega)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg, i.v., 10 min before reperfusion); HI/R + saline; HI/R + L-NAME. Results show that (1) administration of L-NAME to rats subjected to HI/R decreased plasma NO levels; however, the attenuation of NO increased plasma alanine aminotransferase (ALT) activity and superoxide generation in the ischemic lobes of liver, compared to HI/R alone. (2) Inhibition of NO synthesis with L-NAME in rats subjected to HI/R also enhanced systemic inflammatory response as assessed by the increase in the number of circulating leukocytes and levels of plasma tumor necrosis factor-alpha (TNFalpha) and interleukin 1-beta (IL-1beta). (3) The overwhelming systemic inflammatory response induced by administration of L-NAME in rats subjected to HI/R also augmented pulmonary vascular permeability and superoxide generation in the lung tissue. (4) Pulmonary alveolar macrophages isolated from rats subjected to HI/R + L-NAME produced higher levels of TNFalpha and IL-1beta in the supernatant of culture medium than that of rats subjected to HI/R alone. (5) There were no differences between the groups of sham + saline and sham + L-NAME in terms of plasma NO levels and ALT activity, circulating leukocytes, superoxide generation in the liver and lung, lavage protein levels, and TNFalpha and IL-1beta levels in plasma and bronchoalveolar lavage fluid. Our results suggest that inhibition of NO synthesis by L-NAME in rats subjected to HI/R not only augments ischemic liver injury, but also enhances the systemic inflammatory response and exacerbates remote lung injury. The increase in TNFalpha and IL-1beta production by alveolar macrophages may, in part, account for L-NAME-induced enhancement of acute lung injury.     

The effect of nitric oxide on ischemia-reperfusion injury in rat liver.

A dual role for nitric oxide (NO) in ischemia-reperfusion (I/R) injury is still controversial. This study aims to investigate the role of NO in rat hepatic reperfusion injury. Ischemia was induced by total occlusion of hepatic artery and portal vein for 30 min, then the tissue was reperfused for 30 min. The animals in the L-NAME group (n=10) received N(G)nitro-L-arginine methyl ester (L-NAME) (15 mg/kg) intraperitoneally 60 min before ischemia. The ischemia group (n=10) was given an equal volume of saline solution. The control group comprised eight healthy rats which were not exposed to ischemia or reperfusion. An indicator of hepatic injury, plasma alanine amino transferase (ALT) enzyme activities, were increased in the L-NAME group as compared with the ischemia group (p<0.001). The level of serum nitrite, an index of NO production, and hepatic reduced glutathione (GSH) concentration were lower in the L-NAME group than in the ischemia group (p<0.001, p<0.01, respectively). Hepatic levels of malondialdehyde (MDA) and conjugated dienes (CD) were significantly increased in the L-NAME group as compared to the ischemia group (p<0.05, p<0.001, respectively). Our results confirm that L-NAME, an inhibitor of the enzyme NO synthase, increased the lipid peroxidation and possibly tissue injury, due to the inhibition of cytoprotective effects of NO in a rat hepatic I/R model.     

Hepatocyte apoptosis is enhanced after ischemia/reperfusion in the steatotic liver

Liver steatosis is associated with organ dysfunction after hepatic resection and transplantation which may be caused by hepatic ischemia/reperfusion injury. The aim of the current study was to determine the precise mechanism leading to hepatocyte apoptosis after steatotic liver ischemia/reperfusion. Using a murine model of partial hepatic ischemia for 90 min, we examined the levels and pathway of apoptosis, and the peroxynitrite expression, serum alanine aminotransferase levels, and liver histology 1 and 4 h after reperfusion. In the steatotic liver, the peroxynitrite expression increased after ischemia/reperfusion. Significant hepatocyte apoptosis in the steatotic liver was seen after reperfusion, caused by upregulation of cleaved caspases 9 and 3, but not caspase 8. Serum alanine aminotransferase levels were elevated and histological examination revealed severe liver injury in the steatotic liver 4 h after reperfusion. In mice treated with aminoguanidine, ischemia/reperfusion-induced increases in serum alanine aminotransferase levels and apoptosis were significantly reduced in steatotic liver compared with mice treated with phosphate buffered saline. Survival of mice with steatotic livers significantly improved by treatment with aminoguanidine. Our data suggested that the steatotic liver is vulnerable to hepatic ischemia/reperfusion, leading to significant hepatocyte apoptosis by the mitochondrial permeability transition, and thereby resulting in organ dysfunction.     

丹参对大鼠移植肝血红素氧合酶1表达的影响

背景：器官移植前使用丹参预处理能够保护组织缺血-再灌注损伤,改善移植器官存活率。目的：观察含丹参的冷灌注液对同种异体大鼠移植肝脏中血红素氧合酶1表达的影响,以及对供体肝脏缺血-再灌注损伤的保护作用。方法：将SD雄性大鼠随机分成UW液组（术中使用UW液灌注保存）、丹参＋UW液组（术中使用丹参＋UW液灌注保存）、ZnPP预处理组（移植前24h腹腔内注射ZnPP,术中使用丹参＋UW液灌注保存）,建立稳定的大鼠同种异体肝移植模型。同时取10只正常大鼠作为正常对照。结果与结论：丹参＋UW液组和UW液组血清总胆红素、谷丙转氨酶、谷草转氨酶水平明显低于ZnPP预处理组（P〈0.01）。血红素氧合酶1mRNA及其蛋白在丹参＋UW液组中较UW组表达更明显,在ZnPP预处理组中表达明显受到抑制（P〈0.05）。丹参＋UW液组肝脏Suzuki标准评分明显低于ZnPP预处理组及UW液组（P〈0.05）。表明丹参能上调同种异体的大鼠移植肝脏中血红素氧合酶1mRNA及其蛋白的表达,减轻供肝缺血-再灌注损伤,保护移植大鼠肝脏。     

肝细胞内糖原拮抗肝脏缺血——再灌注损伤的临床初步研究

目的：探讨临床上施行复杂的肝脏手术前增加肝细胞内糖原含量能否减轻术中因阻断肝血流所带来的肝脏缺血一再灌注损伤。方法：将近3年我院收治的临床基本情况相近的17例患者分为实验组及对照组。实验组患者于术前24h内静脉滴注25％葡萄糖250ml,共4次（1次／6h）,对照组不作特殊处理。两组患者均采用阻断第一肝门方法行病变肝脏切除术。术中分别于肝脏缺血前、缺血后及再灌注1h获取相对正常的肝组织测定组织中ATP含量,此外于术前及术后第1、5d,抽取血液标本,检测患者肝功能情况。结果：两组患者于缺血后及再灌注1h,实验组肝组织ATP含量显著高于对照组（P＜0.01）;术后第1、5d,实验组肝功能改善程度均显著优于对照组（P＜0.01）,而术前组间则差异不显著。结论：临床上在阻断肝脏血流施行复杂的肝脏手术之前,增加肝细胞内糖原含量可有效地减轻肝脏缺血一再灌注损伤程度,降低手术风险。     

微波照射预处理对兔肝MDA、SOD、NO和NOS的影响

目的探讨微波照射预处理对兔肝缺血再灌注(I/R)损伤的影响及机制。方法选择新西兰大白兔32只随机分为假手术组、微波照射组、微波照射后再灌注组、单纯再灌注组4组,每组各8例。均于术后2、4 h抽血查丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、乳酸脱氢酶(LDH),后处死并获取肝脏标本,检测各组肝组织匀浆脂质过氧化物丙二醛(ma-londi-aldehyde,MDA)和超氧化物歧化酶(superoxide dismutase,SOD)、一氧化氮(NO)、一氧化氮合酶(NOS)水平,并通过HE染色观察组织学变化。结果术后2、4 h微波照射组、微波照射后再灌注组、单纯再灌注组ALT、AST、LDH显著高于假手术组,其中单纯再灌注组高于微波照射后再灌注组,差异均有统计学意义(P<0.01);微波照射后再灌注组MDA浓度低于单纯再灌注组,SOD浓度高于单纯再灌注组,差异均有统计学意义(P<0.01);微波照射后再灌注组、单纯再灌注组NO、NOS浓度显著低于假手术组、微波照射组,其中单纯再灌注组又显著低于微波照射后再灌注组,差异亦均有统计学意义(P<0.01)。微波照射后再灌注组肝组织病理改变明显轻于单纯再灌注组。结论微波照射预处理通过减少MDA生成,提高SOD活性及NO、NOS含量,改善肝脏I/R损伤。