The nitric oxide pathway--evidence and mechanisms for protection against liver ischaemia reperfusion injury

Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMP- protein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.     

Blockade of the L-arginine/NO synthase pathway worsens hepatic apoptosis and liver transplant preservation injury

Organ graft preservation injury is a major problem complicating liver transplantation. The L-arginine/nitric oxide pathway has protective effects in several models of liver injury. The purpose of this study was to evaluate the role of the L-arginine/NO synthase (NOS) pathway on liver preservation injury and to characterize endogenous inducible NOS (iNOS) expression. Orthotopic liver transplantation was performed with 18-hour University of Wisconsin preservation solution in syngeneic rats. Recipient rats were either untreated or treated with L-arginine, D-arginine, nonspecific NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), or iNOS selective inhibitor L-N(6)-(1-imino-ethyl)lysine (L-NIL) after revascularization. As early as 1 hour following reperfusion, circulating arginine levels decreased 10-fold and ornithine levels increased 4-fold. A corresponding increase in arginase I protein was detected in serum. To address the profound arginine deficiency, we supplemented recipients with arginine after transplantation. L-arginine (but not D-arginine) supplementation significantly reduced preservation injury 12 hours after reperfusion, suggesting that the protective effect of L-arginine was mediated through the generation of NO. iNOS protein expression peaked in the liver 6 to 12 hours following reperfusion. Blockade of the L-arginine/NO pathway with L-NAME significantly increased necrotic and apoptotic cell death in the transplanted graft. Addition of the iNOS selective inhibitor L-NIL mildly increased liver transaminase levels and also increased apoptosis in the liver graft. In conclusion, transplant recipients are profoundly arginine deficient postreperfusion due to arginase release. L-Arginine supplementation and NO synthesis decrease necrotic and apoptotic cell death and ameliorate liver transplant preservation injury.     

大白兔肝缺血再灌注损伤时血浆内毒素的变化及对肝肾功能的影响

目的探讨肝缺血再灌注损伤过程中,肠源性内毒素的动态变化和继发性肝肾功能损害。方法取27只健康成年新西兰大白兔,体重1.4~2.3?,随机分为对照组7只,另外20只作为实验组。以缺血10min(I10min)、缺血20min(I20min)、缺血30min(I30min)和分别再灌注30min(R30min)随机分为3组。对照组取门、腔静脉血测肝肾功能及血浆内毒素,实验组阻断第一肝门造成不同的缺血时段,松开血管夹再灌注30min,其余实验同对照组。结果实验组中血浆谷草转氨酶、谷丙转氨酶、尿素氮、肌苷含量及内毒素浓度均有升高,在I10min/R30min组即有升高,但与对照组相比差异无显著性(P>0.05);而后随着缺血时间的延长这些指标继续明显升高,至I30min/R30min组达最高值,与对照组比差异有显著性(P<0.05~0.01)。肾组织电镜观察发现I10min/R30min组肾脏超微结构无明显改变,而I20min/R30min组和I30min/R30min组肾脏超微结构损害明显。结论肝门阻断后门静脉系统淤血,致肠源性内毒素产生和移位;肝门再开放造成肝缺血再灌注损伤,且随着缺血时间的延长,门、腔静脉血中内毒素水平进行性升高,肝功能进一步损害,最终引起肝肾综合征。     

一氧化氮及一氧化氮合酶抑制剂对小鼠血吸虫病肝纤维化程度的影响

目的研究一氧化氮(NO)对小鼠日本血吸虫病肝纤维化程度的影响。方法昆明小鼠经腹部皮肤感染日本血吸虫,于感染后第4周末治疗组和抑制剂组分别给予NO前体-L-精氨酸(L-Arg)及一氧化氮合酶(NOS)抑制剂-NG-左旋-硝基精氨酸甲基乙酯(L-NAME),于第10周末处死小鼠,取血,分离血清,剖取肝脏。应用病理组织学方法及生物化学方法,观察各组小鼠血吸虫病肝纤维化程度,同时测定血清NO、层粘连蛋白(LN)、透明质酸(HA)、谷-草转氨酶(AST)及谷-丙转氨酶(ALT)活性和肝组织羟脯氨酸(Hyp)含量。结果小鼠感染血吸虫后,感染组肝脏有明显的纤维化,血清中HA、LN、AST、ALT等指标显著升高,肝组织内Hyp含量也明显增加。与感染组相比:L-Arg高、中剂量组肝纤维化程度评分降低显著,低剂量组虽有减轻但无统计学意义,同时,L-Arg高、中剂量组血清LN、HA、AST、ALT的水平和肝组织Hyp的含量有所降低;低剂量组HA、LN、AST、ALT的水平虽然降低,但无统计学意义,Hyp水平降低明显;抑制剂组血清LN、HA、AST、ALT含量和肝组织Hyp的水平均明显升高。血清NO的水平随着精氨酸剂量的增加而显著增加,而精氨酸抑制剂组NO的水平降低明显。结论NO能明显降低血吸虫病肝纤维化的程度和减轻肝纤维化所造成的损伤作用。     

NF-kB在大鼠肝缺血再灌注损伤中的活化及意义

目的探讨NFkB在肝缺血再灌注损伤过程中的作用。方法选择健康雌性Wistar大鼠24只,随机分为手术对照组,肝缺血90min组,肝缺血90min/再灌注120min组,每组8只。常规方法观察肝脏组织学改变,检测血清酶学水平和肝组织中髓过氧化物酶(MPO)含量,采用sABC免疫组织化学方法测定肝组织中NFkB的活化程度。结果手术对照组肝组织形态正常,无NFkB活化,肝功能酶学和MPO正常水平;缺血组动物肝细胞索排列紊乱,肝小叶变形,肝细胞和内皮细胞普遍水肿变性,NFkB呈中重度活化,血清酶学和MPO水平升高(P<0.01);肝缺血/再灌注组肝组织在缺血组改变基础上合并中央区局灶性肝细胞坏死,血窦内微血栓形成,汇管区中性粒细胞浸润,NFkB活化最为明显,血清酶学和MPO升高最为显著(P<0.01)。结论肝缺血再灌注时,NFkB被活化,使中性粒细胞组织浸润,对肝脏缺血再灌注损伤病理过程起到重要的作用。     

家兔肝缺血再灌注损伤中脂质过氧化反应及人参多糖的干预

目的 观察肝缺血再灌注损伤时脂质过氧化的变化以及人参多糖的干预作用,并探究其机制.方法 30只家兔随机均分为对照组、缺血再灌注组和人参多糖组.观察血浆及肝组织中丙二醛含量及超氧化物歧化酶、谷胱甘肽过氧化物酶、黄嘌呤氧化酶和丙氨酸氨基转移酶活力变化,光镜下观察肝组织结构变化,并观察人参多糖对上述指标的影响.结果 缺血再灌注组血浆超氧化物歧化酶和谷胱甘肽过氧化物酶活力在肝脏缺血45 min以及再灌注45 min逐步降低,丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量明显升高.人参多糖组血浆超氧化物歧化酶和谷胱甘肽过氧化物酶活力与缺血前比无明显下降,丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量无明显升高,尤其再灌注45 min血浆超氧化物歧化酶活力显著高于缺血再灌注组同期(P<0.01),丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量显著低于缺血再灌注组同期水平(P<0.01).肝组织超氧化物歧化酶、谷胱甘肽过氧化物酶活力缺血再灌注组明显低于对照组,人参多糖组则明显高于缺血再灌注组(P<0.01);黄嘌呤氧化酶活力和丙二醛含量缺血再灌注组明显高于对照组(P<0.05或P<0.01),而人参多糖组则明显低于缺血再灌注组(P<0.05或P<0.01).光镜下发现缺血再灌注组肝组织细胞形态学结构明显异常,人参多糖组肝组织损伤明显减轻.结论 人参多糖能降低黄嘌呤氧化酶活性,减少氧自由基的生成,并且能增强超氧化物歧化酶、谷胱甘肽过氧化物酶等抗氧化酶的活性,清除氧自由基,抑制脂质过氧化反应,从而有效减轻肝缺血再灌注损伤.     

Low-dose TNF-alpha protects against hepatic ischemia-reperfusion injury in mice: implications for preconditioning

Tumor necrosis factor alpha (TNF-alpha) is implicated in the pathogenesis of hepatic ischemia reperfusion injury but can also prime hepatocytes to enter the cell cycle. Ischemic preconditioning protects against ischemia-reperfusion (IR) liver injury and is associated with activation of nuclear factor kappaB (NF-kappaB) and cell cycle entry. We examined the pattern of TNF-alpha release during hepatic IR in the presence or absence of ischemic preconditioning, and we tested whether a single low-dose injection of TNF could mimic the biologic effects of ischemic preconditioning. In na?ve mice, hepatic and plasma levels of TNF-alpha rose during hepatic ischemia, reaching high levels after 90 minutes; values remained elevated during reperfusion until 44 hours. Following the ischemic preconditioning stimulus, there was an early rise in hepatic and serum TNF-alpha levels, but, during a second prolonged ischemic interval peak, TNF-alpha values were lower than in na?ve mice and declined to negligible levels by 2 hours reperfusion. An injection with 1 microg or 5 microg/kg body weight TNF-alpha 30 minutes prior to hepatic IR substantially reduced liver injury determined by liver histology and serum alanine aminotransferase (ALT) levels. As in ischemic preconditioning, TNF-alpha pretreatment activated NF-kappaB DNA binding, STAT3, cyclin D1, cyclin-dependent kinase 4 (cdk4) expression, and cell cycle entry, determined by proliferating cell nuclear antigen (PCNA) staining of hepatocyte nuclei. In conclusion, the hepatoprotective effects of "preconditioning" can be simulated by TNF-alpha injection, which has identical downstream effects on cell cycle entry. We propose that transient increases in TNF-alpha levels may substitute for, as well as, mediate the hepatoprotective effects of ischemic preconditioning against hepatic IR injury.     

Protective effect of curcumin against liver warm ischemia/reperfusion injury in rat model is associated with regulation of heat shock protein and antioxidant enzymes

AIM： To investigate the hypothesis that the protective effects of curcumin in hepatic warm ischemia/reperfusion （I/R） injury are associated with increasing heat shock protein 70 （Hsp70） expression and antioxidant enzyme activity. METHODS： Sixty Sprague-Dawley male rats were randomly divided into sham, I/R, C ＋ I/R groups. The model of reduced-size liver warm ischemia and reperfusion was used. Curcumin （50 mg/kg） was administered by injection through a branch of superior mesenteric vein at 30 min before ischemia in C ＋ I/R group. Five rats were used to investigate the survival during 1 wk after operation in each group. Blood samples and liver tissues were obtained in the remaining animals after 3, 12, and 24 h of reperfusion to assess serum alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, liver tissue NO2- ＋ NO3-, malondialdehyde （MDA） content, superoxide dismutase （SOD）, catalase （CAT）, nitricoxide synthase （NOS） and myeloperoxidase （MPO） activity, HspT0 expression and apoptosis ratio. RESULTS： Compared with I/R group, curcumin pretreatment group showed less ischemia/reperfusioninduced injury. CAT and SOD activity and Hsp70 expression increased significantly. A higher rate of apoptosis was observed in I/R group than in C ＋ I/R group, and a significant increase of MDA, NO2^- ＋ NO3^- and MPO level in liver tissues and serum transaminase concentration was also observed in I/R group compared to C ＋ I/R group. Curcumin also decreased the activity of inducible NO synthase （iNOS） in liver after reperfusion,but had no effect on the level of endothelial NO synthase （eNOS） after reperfusion in liver. The 7 d survival rate was significantly higher in C ＋ I/R group than in I/R group. CONCLUSION： Curcumin has protective effects against hepatic I/R injury. Its mechanism might be related to the overexpression of Hsp70 and antioxidant enzymes.     

Protective Effect of L-arginine Against Necrosis and Apoptosis Induced by Experimental Ischemic and Reperfusion in Rat Liver

Background/Aim:

To study the effect of L-arginine on apoptosis and necrosis induced by 1-h ischemia followed by 3-h reperfusion.

Materials and Methods:

Adult Wistar rats underwent 60 min of partial liver ischemia followed by 3-h reperfusion. Eighteen Wistar rats were divided into sham-operated control group (I) (n = 6), ischemia and reperfusion (I/R) group (0.9% saline (5 mL/kg, orally) for 7 days) (II) (n = 6), and L-arginine-treated group (10 mg/kg body weight daily orally for 7 days before inducing ischemia-reperfusion maneuver) (III) (n = 6). Apoptotic and necrotic hepatocytes, nitric oxide levels in hepatocytes, Bcl-2 mRNA, and Bcl-2 protein were measured. Liver injury was assessed by plasma alanine transaminases (ALT), aspartate transaminases (AST), liver histopathology, and electron microscopy.

Results:

An ischemic and reperfusion hepatocellular injury occurred as was indicated by increased serum ALT, AST, histopathology, and electron microscopy. Apoptosis and necrosis associated marker gene Bcl-2 mRNA and protein expression were decreased in I/R group. Pretreatment with L-arginine significantly decreased serum ALT and AST level and apoptotic and necrotic cells after 1 h ischemia followed by 3 h of reperfusion. Nitric oxide production in hepatocytes was increased twofold by L-arginine treatment when compared with I/R group. Histopathology and transmission electron microscopy (TEM) studies showed markedly diminished hepatocellular injury in L-arginine-pretreated rats during the hepatic I/R.

Conclusion:

Thus, it may be concluded that L-arginine afforded significant protection from necrosis and apoptosis in I/R injury by upregulated Bcl-2 gene and nitric oxide production.     

血红素氧合酶对大鼠肝脏缺血再灌注损伤细胞凋亡及相关基因的影响

目的通过应用血红素氧合酶（HO）的诱导剂氯高血红素和抑制剂锌原卟啉（ZnPP），探讨HO对大鼠肝脏缺血再灌注（IR）细胞凋亡及其相关基因的影响。方法将96只Sprague—Dawley大鼠采用钳夹法制备肝脏IR模型，随机分为假手术组、IR组、氯高血红素组和ZnPP组，检测再灌注0、1．5、4h和8h各个时间点大鼠肝脏功能以及病理学改变，流式细胞法测定肝细胞凋亡率、TUNEL法观察再灌注后4h大鼠肝细胞的凋亡情况，Western blot法检测再灌注后8h Bcl-2和Caspase-3的表达。结果在IR组各时间点均可见ALT和AST增高，病理学检查可见肝细胞肿胀，肝窦变窄，嗜中性粒细胞浸润和片状坏死等变化，肝组织中细胞凋亡率明显升高，Bcl-2的表达减少，而Caspase-3的表达增加。在氯高血红素组再灌注后1．5、4h和8h ALT和AST值明显降低，肝脏病理学改善，凋亡细胞减少及细胞凋亡率降低，肝脏Bcl-2的表达增加，Caspase-3的表达减少。ZnPP组则显示与之相反的结果。结论HO在肝脏IR损伤中具有保护作用，这种保护作用可能与抑制细胞凋亡有关。     

Splenectomy ameliorates hepatic ischemia and reperfusion injury mediated by heme oxygenase-1 induction in the rat

BACKGROUND/AIMS: Ischemia/reperfusion (I/R) induces severe organic injury. I/R injury seems to be mainly caused by oxidative stress. The aim of this study was to determine the role of the spleen in experimental hepatic I/R injury in the rat. Stress protein heme oxygenase (HO)-1 plays a protective role against the oxidative injury. In normal state, HO-1 is highly expressed in the spleen. METHODS: Liver HO-1 expression was assessed by Western blot before and after splenects. Liver injury was assessed by measurement of ALT and AST and by histopathology. RESULTS: Although HO-1 was not detected in normal liver, levels of HO-1 protein gradually increased and peaked on 3 days after splenectomy. When splenectomy was performed 3 days prior to the hepatic (45-min) ischemia followed by (2-h) reperfusion, the levels of serum aspartate transaminase (AST) and alanine transaminase (ALT), as markers for hepatic injury, were improved compared to the rats with I/R alone. In addition, prior administration of zinc-protoporphyrin IX, a specific inhibitor of HO, suppressed the protective effect of the splenectomy on the subsequent hepatic I/R injury. Histopathological examination also confirmed these results. CONCLUSIONS: Our findings suggest that the elevated HO-1 levels by splenectomy play a protective role against hepatic I/R injury.     

川芎嗪对老龄鼠再灌注肾损伤中一氧化氮的作用研究

目的 观察川芎嗪对老龄鼠肾缺血再主中一氧化氮合酶（ＮＯＳ）和一氧化氮（ＮＯ）的影响及对肾脏的保护作用。方法 制做老龄鼠肾缺血再灌注模型,分为用川芎嗪组和未用川芎嗪组,检测缺血６０ｍｉｎ,再灌注１５ｍｉｎ和２４ｈ的肾组织ＮＯＳ、ＮＯ及丙二醛（ＭＤＡ）浓度。结果 缺血再灌注后肾组织中ＮＯＳ明显升高（Ｐ〈０．０１）,ＮＯ明显升高（Ｐ〈０．０１）,ＭＤＡ明显升高（Ｐ〈０．０１）,与此结果相比,用川芎嗪组Ｎ     

葛根素对再灌注损伤肝能量代谢的保护作用及机制

[目的]研究葛根素对兔缺血再灌注损伤中肝脏能量代谢的改善作用及其机制。[方法]将30只家兔随机均分为对照组(C组)、缺血/再灌注组(IR组)和葛根素组(Pur组)。测定血浆中谷丙转氨酶(ALT)浓度和肝组织内一磷酸腺苷(AMP)、二磷酸腺苷(ADP)、三磷酸腺苷(ATP)、总腺苷酸量(TAN)、肝脏的细胞能荷(EC)、丙二醛(MDA)、超氧化物歧化酶(SOD)、一氧化氮(NO)、内皮素(ET)、NO/ET、血栓素B2(TXB2)、前列腺素F1α(PGF1α)、TXB2/PGF1α水平,并观察肝细胞形态学的改变。[结果]与C组比较,IR组血浆ALT浓度、肝组织AMP、ADP、MDA、ET含量显著升高(P0.01),TXB2、TXB2/PGF1α亦明显升高(P0.05),肝组织ATP、EC、SOD、NO/ET显著下降(P0.01),NO、PGF1α亦明显降低(P0.05),TAN差异无统计学意义(P0.05),肝细胞形态学异常改变;与IR组比较,Pur组血浆ALT浓度、肝组织AMP、MDA、ET含量显著降低(P0.01),肝组织ADP、TXB2/PGF1α亦明显减少(P0.05),TXB2略低于IR组(P0.05),肝组织ATP、EC、SOD、NO/ET显著升高(P0.01),肝组织NO、PGF1α亦明显增高(P0.05),TAN差异无统计学意义(P0.05),肝细胞形态学异常改变较大程度减轻。[结论]葛根素(60mg/kg)预处理可通过拮抗氧化损伤、调节NO/ET和前列腺素I2/血栓素A2(PGI2/TXA2)失衡而改善肝细胞的能量代谢,有效防治兔肝再灌注损伤。     

Preconditioning protects liver and lung damage in rat liver transplantation: role of xanthine/xanthine oxidase

This study was designed to evaluate whether ischemic preconditioning could confer protection against liver and lung damage associated with liver transplantation. The effect of preconditioning on the xanthine/xanthine oxidase (XOD) system in liver grafts subjected to 8 and 16 hours of cold ischemia was also evaluated. Increased xanthine levels and marked conversion of xanthine dehydrogenase (XDH) to XOD were observed after hepatic cold ischemia. Xanthine/XOD could play a role in the liver and lung damage associated with liver transplantation. This assumption is based on the observation that inhibition of XOD reduced postischemic reactive oxygen species (ROS) generation and hepatic injury as well as ensuing lung inflammatory damage, including neutrophil accumulation, oxidative stress, and edema formation. Ischemic preconditioning reduced xanthine accumulation and conversion of XDH to XOD in liver grafts during cold ischemia. This could diminish liver and lung damage following liver transplantation. In the liver, preconditioning prevented postischemic ROS generation and hepatic injury as well as the injurious effects in the lung following liver transplantation. Administration of xanthine and XOD to preconditioned rats led to hepatic ROS and transaminase levels similar to those found after reperfusion and abolished the protective effect of preconditioning on the lung inflammatory damage. In conclusion, ischemic preconditioning reduces both liver and lung damage following liver transplantation. This endogenous protective mechanism is capable of blocking xanthine/XOD generation in liver grafts during cold ischemia.     

Protective effect of N2-mercaptopropionylglycine on rats and dogs liver during ischemia/reperfusion process

BACKGROUND: N2-mercaptopropionylglycine is a powerful super oxide synthesis inhibitor and has been tested as a preventive agent of metabolic and structural hepatic damage in the ischemia/reperfusion process. AIM: To analyze some effects of N2-mercaptopropionylglycine administration to animals of two species submitted to normothermic liver ischemia/reperfusion. MATERIAL AND METHODS: Twenty-two rats and 22 dogs were divided into four groups: group I: rats that received intravenous saline 0.9%; group II: rats that received 100 mg/kg of N2-mercaptopropionylglycine; group III: dogs that received saline intravenous 0.9% and group IV: dogs that received 100 mg/kg N2-mercaptopropionylglycine. RESULTS: Ten minutes after the saline or drug administration, each group was submitted to left lobe liver ischemia for 25 minutes followed by reperfusion. Biochemical studies 24 hours after reperfusion revealed a significantly lower elevation of transaminases in animals of groups II (AST = 271 +/- 182; ALT = 261 +/- 161 ) and IV (AST = 101 +/- 45; ALT = 123 +/- 89) when compared to the controls group: I (AST = 2144 +/- 966; ALT = 1869 +/- 1040 00) and III (AST = 182 +/- 76.51; ALT = 277 +/- 219), respectively. Histology study demonstrated a significantly minor aggression to animals of groups II and IV when compared to groups I and III, respectively. CONCLUSION: These results suggest a significant release of free radicals of oxygen in the process and that N2-mercaptopropionylglycine may have a significant protective effect on liver parenchyma when submitted to ischemia/reperfusion.     

一氧化氮在ConA诱发小鼠急性肝损害中的作用

目的：观察一氧化氮（NO）在刀豆素（ConA）诱发急性小鼠肝损害中的作用。方法：25只昆明小鼠随机分为5组，ConA(40mg/kg)自小鼠尾静脉注入复制急性肝损害，为ConA组；应用ConA前半小时，给予NO合成的抑制剂（L-NAME，5mg/只），为LN组；应用ConA前半小时，给予NO合成底物（L-精氮酸），为L-精氮酸组；单独给予L-NAME(5mg/只)者为L-NAME组；对照组只给予尾静脉注射生理盐水。各组8小时后取血分别测定丙氮酸转氮酶（ALT），取肝组织测定亚硝酸盐（NO2^-）和丙二醛（MDA）含量。结果：ConA造成肝损害后，肝组织中亚硝酸盐（NO2^-）较对照组显著升高；以L-NAME抑制NO合成，肝组织中NO2^-含量下降，肝细胞损害反而加重，且肝组织MDA增加，肝窦内血细胞淤集加重；L-精氮酸组未见明显的肝脏保护作用。结论：在ConA性肝损害中，NO通过消除氧自由基和抑制血细胞在肝窦内淤而发挥一定的保护作用。     

内毒素对正常大鼠和肝硬化大鼠肝脏一氧化氮合酶活性及局部一氧化氮水平的影响

观察内毒素血症时肝硬化大鼠和正常大鼠肝脏一氧化氨台酶(NOS)活性以及NO水平的变化．探讨两者在肝硬化大鼠对内毒素高敏感性中的作用。方法：肝硬化大鼠模型由四氯化碳台并乙醇诱导．内毒素4mg／kg体重经尾静脉注射。分别于注射后2、6、12小时测定血清咎丙转氨酶(ALT)、谷草转氨酸(AST）肝脏组织中NOS活性以及N0代谢产物NO^-／NO^-水平。结果：肝硬化大鼠对内毒素损伤敏感性增高。正常大鼠在内毒素作用2小时后NOS活性和NO水平均显著增高．并持续至12d,时,但肝硬化大鼠肝脏NOS活性则未见显著变化,NO水平在12小时才开始增高。结论：肝硬化时肝脏NOS对内毒素刺激的敏感性降低,NO产生减少,可能是导致肝硬化肝脏对内毒素损伤高敏感性的原因之一。     

Effects of propofol on early phase of warm hepatic ischemia/reperfusion injury

BACKGROUND/AIMS: It is still unclear whether propofol may protect the liver against ischemia/ reperfusion injury (IRI) in vivo. METHODOLOGY: The livers of male Sprague-Dawley rats were subjected to 60 minutes of partial normothermic ischemia allowing perfusion to right and caudate lobes and subsequent 45 minutes of reperfusion. Either propofol (Propofol group, n = 11, 10 mg/ kg/h) or saline (Control group, n = 11) was continuously administered. At the end of reperfusion blood and liver samples were taken to analyze malondialdehyde, hepatic injury score, palmitate oxidation rate, serum AST and ALT concentrations. RESULTS: The malondialdehyde concentration (micromol/g tissue, mean +/- SD) was decreased in the Propofol group (1.39 +/- 0.21, perfused lobes and 1.85 +/- 0.27, ischemic reperfused lobes) compared with Control group (1.97 +/- 0.20, perfused lobes and 2.39 +/- 0.28, ischemic reperfused lobes) (P < 0.01). Hepatic injury scores were decreased in Propofol group compared with Control group (P < 0.01), but with mild hepatic injury in both groups. There were no differences of serum AST and ALT concentrations, and palmitate oxidation rate between groups. CONCLUSIONS: Propofol might be effective mainly in attenuation of lipid peroxidation with only minimal hepatocellular protection during the early phase of warm hepatic IRI in vivo.     

Protective effect of prednisolone on ischemia-induced liver injury in rats

AIM： To investigate the effects of prednisolone on cell membrane bleb formation, calpain μ activation and talin degradation during hepatic ischemia-reperfusion injury in rats. METHODS： The hilar area of the left lateral and median lobes of rat liver （68%） was clamped for 60 min and followed by 120 min reperfusion. Prednisolone was administered at 1.0, 3.0, or 10 mg/kg at 30 min before ischemia. In addition to biochemical and microscopic analyses, activation of calpain μ was determined using specific antibodies against the intermediate （activated） form of calpain μ. Degradation of talin was also studied by Western blotting. RESULTS： In the control and prednisolone （1.0 mg/kg） groups, serum aspartate transaminase （AST） and alanine transaminase （ALT） level were elevated, and cell membrane bleb formation was observed after 120 min of reperfusion. Moreover, calpain μ activation and talin degradation were detected. Infusion of prednisolone at 3.0 or 10 mg/kg significantly suppressed serum AST and ALT, and prevented cell membrane bleb formation. At 10 mg/kg, prednisolone markedly suppressed calpain μ activation and talin degradation. CONCLUSION： Prednisolone can suppress ischemia- reperfusion injury of the rat liver. Its cytoprotective effect is closely associated with the suppression of calpain μ activation and talin degradation.