川芎嗪后处理对大鼠心肌缺血再灌注损伤的保护作用

目的：观察川芎嗪后处理对大鼠心肌缺血再灌注损伤的保护作用及探讨其可能的作用机制。方法：采用结扎大鼠左冠状动脉前降支方法制备心肌缺血再灌注损伤模型,记录各组心律失常发生情况,测定肌酸激酶（CK）、超氧化物歧化酶（SOD）、丙二醛（MDA）、一氧化氮（NO）、一氧化氮合酶（NOS）含量,HE染色光镜下观察心肌组织形态学改变并秤重检测心肌梗死面积。结果：川芎嗪组的心律失常发生率明显降低,心肌细胞肿胀明显减轻,血中SoD、NO、NOS含量增加,MDA,CK的生成减少。（P〈0．05）。结论：川芎嗪后处理能降低心律失常发生、减少坏死面积,其作用可能与提高sOD、NO、NOs含量,减少MDA生成有关。     

非创伤性双下肢缺血后处理对大鼠心肌缺血再灌注损伤的保护作用

目的 观察双下肢缺血后处理(N-W IPTC)对大鼠心肌缺血再灌注损伤的保护作用及探讨其可能的作用机制.方法 采用结扎大鼠左冠状动脉前降支方法制备心肌缺血再灌注损伤模型,记录各组心律失常发生情况,测定肌酸激酶(CK)、超氧化物歧化酶(SOD)、丙二醛(MDA)、一氧化氮(NO)、一氧化氮合酶(NOS)含量,HE染色光镜下观察心肌组织形态学改变并称重检测心肌梗死面积.结果 N-W IPTC组的心律失常发生率明显降低,心肌细胞肿胀明显减轻,血中SOD、NO、NOS含量增加,MDA,CK的生成减少(P＜0.05).结论 N-W IPTC能降低心律失常发生、减少坏死面积,其作用可能与提高SOD、NO、NOS含量,减少MDA生成有关.     

红细胞生成素对大鼠心肌缺血-再灌注后抗氧化酶及NO等的影响

目的：探讨红细胞生成素（erythropoietin，EPO）对大鼠心肌缺血-再灌注损伤心肌组织中超氧化物岐化酶（SOD）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH-px）、过氧化氢酶（CAT）、一氧化氮（NO）及一氧化氮合酶（NOS）表达的影响。方法：以左冠脉穿线结扎法制备心肌缺血再灌注模型，造模前24h开始给药。在大鼠心肌缺血30min再灌注24h后分别检测心肌组织的MDA，GSHpx，SOD，CAT，NO及NOS。结果：EPO干预组的SOD活力有明显增高，MDA含量明显下降（P均〈0．05），GSHpx及CAT含量均显著提高（P〈0．05）。同时，EPO的预处理也降低了NO和NOS的含量（P〈0．01）。结论：对于大鼠心肌缺血再灌注损伤，EPO干预可以提高多种抗氧化酶活性，同时对NO产生增多有一定的抑制作用。     

辛伐他汀缺血后处理对大鼠心肌缺血再灌注损伤的保护作用

目的探讨辛伐他汀缺血后处理对大鼠心肌缺血再灌注（I/R）损伤的保护作用及机制。方法采用Langendorff离体心脏灌流模型,将32只大鼠随机分为四组各8只。对照组用改良K-H缓冲液持续灌流;I/R组用改良K-H缓冲液稳定灌注、停灌、再灌;治疗组用改良K-H缓冲液稳定灌注、停灌后,在K-H缓冲液中加入辛伐他汀20μmol/L再灌;K-H缓冲液再灌;N-硝基-L-精氨酸甲酯（L-NAME）组用改良K-H缓冲液稳定灌注、停灌后,在K-H缓冲液中加入辛伐他汀20μmol/L、L-NAME 100μmol/L再灌,K-H缓冲液再灌。观察各组再灌注心律失常发生情况,检测其冠脉流出液中的肌酸激酶（CK）、乳酸脱氢酶（LDH）、NO,心肌组织总超氧化物歧化酶（T-SOD）活性、丙二醛（MDA）及细胞凋亡指数（AI）。结果与I/R组比较,治疗组心律失常发生率下降,CK、LDH、MDA及细胞AI降低,T-SOD活性、NO升高（P均〈0.01）;与治疗组比较,L-NAME组心律失常发生率升高,CK、LDH、MDA及细胞AI升高,T-SOD活性、NO降低（P均〈0.01）。结论辛伐他汀缺血后处理能减轻大鼠心肌I/R损伤,其作用机制与清除氧自由基、增加NO含量、减少心肌细胞凋亡有关。     

冠脑益嗪对大鼠心肌缺血/再灌注损伤保护作用的机制

目的 :观察冠脑益嗪对大鼠心肌缺血 /再灌注损伤的影响 ,探讨其保护作用的机制。方法 :采用在体大鼠心肌缺血 /再灌注模型 ,于结扎冠状动脉前 3m in iv冠脑益嗪 ,观察在心肌缺血 /再灌注状态下心电图、心肌丙二醛（MDA）、超氧化物歧化酶 （SOD）、Ca2 +、游离脂肪酸 （FFA）及血清中肌酸激酶 （CK）、乳酸脱氢酶 （L DH）的变化。结果 :冠脑益嗪能显著降低缺血 /再灌注损伤引起的室性心律失常发生率 ,缩短持续时间 ;升高 SOD活性 ,减少 MDA生成 ;减少 Ca2 +在心肌组织内的聚积 ;亦能明显降低心肌 CK、L DH和 FFA的释放。结论 :冠脑益嗪对大鼠心肌缺血 /再灌注损伤的保护作用可能与保护氧自由基清除酶的活性 ,防止膜脂质过氧化及阻断钙内流有关     

苯那普利后处理减轻离体心脏缺血再灌注损伤的观察

目的探讨苯那普利后处理对大鼠离体心脏缺血再灌注损伤的影响及其机制。方法应用Landendorff装置建立大鼠离体心脏缺血再灌注模型。将24只SD大鼠随机等分为3组：缺血再灌注组（I／R）、缺血后处理组和苯那普利后处理组。生化法检测各组稳灌20min和再灌60min肌酸激酶（CK）的水平,改良亮绿变色酸法观察心肌损害程度,硝基还原酶法测定各组再灌注末一氧化氮（NO）含量,测定心肌组织丙二醛（MDA）含量。结果与缺血再灌注组相比,苯那普利后处理组心肌梗死面积缩小[（14±7）％比（40±7）％,P〈0．01];再灌注流出液中CK含量减少[（100．8±31．8）U／ml比（188．5±49．1）U／ml,P〈0．01];心肌MDA含量降低[（2．5±0．7）nmol／mg prot比（4．4±0．6）nmol／mg prot,P〈0．01）;苯那普利后处理组再灌注流出液中NO含量明显高于缺血再灌注组[（101．7±8．7）μmol／L比（27．8±5．9）μmol／L,P〈0．01]。结论苯那普利后处理具有显著的心肌保护作用,这种心脏保护作用可能与增加NO浓度和抗脂质过氧化有关。     

心肌缺血预处理联合后处理在大鼠心肌缺血-再灌注损伤过程中的保护作用

目的 探讨心肌缺血预处理和缺血后处理联合作用对大鼠心肌缺血再灌注损伤的保护作用.方法 选择Wistar大鼠48只,建立大鼠心肌缺血再灌注模型,随机分为4组(每组12只):对照组(I/R)、缺血预处理组(IPC)、缺血后处理组(IPO)、缺血预处理后处理联合作用组(IPC+IPO).肢体Ⅱ导联心电图记录再灌注时的心律失常情况;测定再灌注末血清丙二醛(MDA)的含量;电镜观察心肌超微结构的变化;心肌含水量的测定.结果 IPC+IPO能明显减少再灌注时大鼠心律失常发生率,减轻再灌注损伤,降低MDA的含量,减少心肌含水量.结论 IPC+IPO对大鼠MIRI有明显的保护作用.     

舒芬太尼后处理对大鼠心肌缺血再灌注损伤保护作用的实验研究

目的 观察不同剂量舒芬太尼(SFT)后处理的心肌保护作用.方法 健康SD雄性大鼠24只,体重250 g～300 g,随机分为假手术组、缺血再灌注组、舒芬太尼后处理低剂量组、舒芬太尼后处理高剂量组.采用结扎左冠状动脉前降支30 min再灌注120 min的方法制备心肌缺血再灌注模型.假手术组完成模型仅穿线,不结扎;假手术组穿线后腹腔注射生理盐水1 mL,缺血再灌注组缺血再灌注前2 min腹腔注射生理盐水1 mL,舒芬太尼后处理低、高剂量组分别腹腔注射舒芬太尼稀释液1 mL,2 μg/kg、10μg/kg.于实验结束时制作心肌组织匀浆,检测心肌组织中的超氧化物歧化酶(SOD)、丙二醛(MDA)含量;右心室采血常温离心分离检测血清心肌酶(CK)、血清乳酸脱氢酶(LDH)、血清一氧化氮(NO)含量,取左心室切5块,来用氯化硝基四氮唑蓝(N-BT)染色法区分正常和梗死区,用梗死区重量占左心室重量百分比观测梗死程度.结果 与假手术组比较,缺血再灌注组心肌组织SOD活性下降,MDA增高,血清CK及LDH水平增高,血清NO含量减少;与缺血再灌注模型组比较,舒芬太尼后处理组,心肌组织SOD活性升高,MDA降低,血清CK及LDH释放减少;血清NO含量增加;再灌注心律失常明显减少;心肌梗死程度降低;以舒芬太尼后处理高剂量组更为明显.结论 舒芬太尼后处理能够减轻大鼠心肌缺血再灌注损伤的程度,并且呈剂量依赖性.     

缺血预处理对肠缺血再灌注损伤的保护作用

目的观察肠缺血预处理（IPC）对缺血再灌注（I／R）损伤的保护作用．探讨IPC在肠I／R损伤中的作用机制。方法对大鼠肠系膜上动脉进行4次循环的5min夹闭／Smin开放（即IPC），24h后实施缺血30min再灌注24h，制作I／R损伤模型。检测IPC后肠组织一氧化氮（NO）含量（以NO2^-／NO3^-代表）、超氧化物歧化酶（SOD）、丙二醛（MDA）的含量及观察肠肌间神经丛一氧化氮合成酶（NOS）阳性神经元的变化，检测血清NO及血浆二氨氧化酶（DAO）．采用Chiu评分法观察肠组织损伤情况。结果IPC后肠组织NO、SOD含量下降．而MDA含量明显升高，肠肌间丛NOS阳性神经元数明显降低，DAO水平明显降低，肠组织损伤程度明显减轻。结论IPC对I／R损伤有明显保护作用，其机理与灭活了氧自由基，降低NO含量有关。     

ERK参与缺血后处理的心肌保护作用机制研究

目的 观察缺血后处理对大鼠心肌缺血-再灌注损伤的保护作用,并探讨其可能的机制.方法 选择Wistar大鼠24只,建立大鼠心肌缺血-再灌注损伤模型,随机分为3组:对照组(I/R组)、缺血后处理组(I-postC组 )、抑制剂组(I-postC+ERK抑制剂组).再灌注结束后腹主动脉插管取血测定血清生化指标,剖取左心室计算心肌梗死面积.结果 与I/R组相比,I-postC组心肌梗死面积减少,血清乳酸脱氢酶(LDH)、心肌肌酸激酶同工酶(CK-MB)活性及丙二醛(MDA)含量降低,血清超氧化物歧化酶(SOD)活性增加;抑制剂组与I-postC组相比,心肌梗死面积增大,血清LDH、CK-MB活性及MDA含量升高,血清SOD活性减弱.结论 心肌缺血后处理对实验性大鼠心肌缺血-再灌注损伤有明显的保护作用,该作用可能与细胞外调节蛋白激酶(ERK)信号传导通路有关.     

姜黄素对大鼠肝缺血再灌注早期肝组织一氧化氮表达的影响

目的:探讨姜黄素对大鼠肝脏缺血再灌注早期损伤微循环的影响.方法:将大鼠随机分为假手术组、对照组和实验组(姜黄素40 mg/kg,2次给药).通过检测再灌注早期1、3 h血清转氨酶水平、肝组织中一氧化氮(nitricoxide,NO)、一氧化氮合酶(nitricoxide synthase,NOS),诱导型一氧化氮合酶(inducible nitricoxide synthase,iNOS)mRNA及内皮型一氧化氮合酶(endothelium nitricoxide synthase,eNOS)mRNA水平,以及肝组织病理学检查来评价姜黄素对大鼠肝脏缺血再灌注早期损伤微循环的影响.结果:相对于对照组,姜黄素可降低大鼠肝脏缺血再灌注早期损伤1、3 h血清谷丙转氨酶(ALT)的水平(603.8 U/L±64.5 U/L vs 758.1 U/L±114.7U/L,837.1 U/L±33.3 U/L vs 1012.7 U/L±119.8 U/L,均P<0.01)和谷草转氨酶(AST)的水平(605.7 U/L±65.7 U/L vs 779.5 U/L±124.3 U/L,849.6 U/L±36.0 U/L vs 1027.8 U/L±139.8 U/L,均P<0.01);改善肝组织病理学损害;减少肝脏缺血再灌注早期损伤1、3 h肝组织由iNOS产生的NO蛋白水平(0.455±0.056 vs 0.594±0.087.0.492±0.040 vs 0.671±0.079,均P<0.01);降低肝脏缺血再灌注早期损伤1、3 h肝组织iNOS mRNA的表达强度(0.426±0.075 vs 0.569±0.073,0.527±0.066vs 0.702±0.089,均P<0.01).结论:姜黄素可通过减轻肝组织中由iNOS产生的NO生成,来改善肝缺血再灌注早期损伤中微循环的紊乱,从而减少对肝缺血再灌注肝实质细胞的损伤.     

Reduced susceptibility to epinephrine-induced arrhythmias in cirrhotic rats: the roles of nitric oxide and endogenous opioid peptides

BACKGROUND/AIMS: The clinical relevance of QT prolongation, the most widely recognized cardiac electrophysiological abnormality of cirrhosis, is still undefined. The aim of this study is to examine the susceptibility of chronic (4-week) bile duct-ligated rats to epinephrine-induced arrhythmias. The roles of nitric oxide and endogenous opioids were also evaluated. METHODS: Sham-operated and cirrhotic rats were treated with daily subcutaneous administrations of normal saline (1 ml/kg/day), L-NAME (a non-selective nitric oxide synthase inhibitor, 3mg/kg/day), and naltrexone (20mg/kg/day) during the fourth week after operation. In order to evaluate the effects of acute nitric oxide synthesis inhibition, additional groups of animals were treated by acute intraperitoneal L-NAME injections (3mg/kg). Arrhythmias were induced by intravenous injections of 10 microg/kg epinephrine. RESULTS: Despite QT prolongation (P<0.001), epinephrine induced fewer arrhythmias in cirrhotic rats compared to sham-operated animals (P<0.05). Chronic, but not acute, L-NAME administration corrected the QT prolongation in cirrhotic rats (P<0.001), and restored the susceptibility of cirrhotic rats to arrhythmias (P<0.05). Naltrexone injection without a significant effect on epinephrine-induced arrhythmias corrected QT interval in cirrhotic rats (P<0.001). CONCLUSIONS: This study shows that despite QT prolongation, cirrhotic animals are resistant against epinephrine-induced arrhythmias. This resistance is mediated by chronic nitric oxide overproduction.     

Nitric Oxide Contributes to Multiorgan Oxidative Stress in Acute Experimental Pancreatitis

Dabrowski A, Gabryelewicz A. Nitric oxide contributes to multiorgan oxidative stress in acute experimental pancreatitis. Scand J Gasteroenterol 1994;29:943-948.

Background: Nitric oxide is a highly reactive free radical gas. The study was undertaken to determine the nitric oxide contribution to oxidative stress in acute experimental pancreatitis induced in Wistar rats. Methods: Acute haemorrhagic pancreatitis was induced in male Wistar rats by means of a retrograde intraductal injection of 5% Na-taurocholate. The rats were treated with the nitric oxide donor, sodium nitroprusside (SNP) (0.25mg/kg), or with JVtu-nitro-L-arginine methyl ester (l-NAME) (10mg/kg), which is an inhibitor of nitric oxide synthase. We measured malondialdehyde and sulphhydryl group concentrations in pancreatic, lung, and liver tissue. Results: In rats with acute pancreatitis treated with SNP, oxidative stress, expressed by malondialdehyde increase and sulphhydryl group depletion, was much more pronounced than in the other groups. In contrast, intensity of the oxidative stress was significantly reduced in rats treated with l-NAME. Conclusion: The data suggest that nitric oxide is partly responsible for oxidative stress in acute haemorrhagic pancreatitis.     

Oral Administration of Inducible Nitric Oxide Synthase Inhibitors Reduces Nitric Oxide Synthesis but Has No Effect on the Severity of Experimental Colitis

Background: Increased concentrations of nitrate and nitrite (the breakdown products of nitric oxide) in the serum and faeces of patients with inflammatory bowel disease (IBD) suggests that increased synthesis of nitric oxide occurs in IBD. The aim of this study was to assess aminoguanidine (AMG), a selective inhibitor of inducible nitric oxide synthase, with regard to its effectiveness as a nitric oxide inhibitor and as a modulator of inflammation in trinitrobenzene sulfonic acid (TNBS)-induced colitis. Materials and Methods: Colitis was induced in Wistar rats. Selective (AMG) and non-selective (1-nitroso-arginine methyl ester (1-NAME)) inhibitors of nitric oxide synthase were given in the drinking water. Colonic citrulline and arginine concentrations were assessed using high-performance liquid chromatography. The severity of colitis was assessed by a macroscopic scoring system. Results: Both l-NAME and AMG successfully reduced nitric oxide synthesis. There was no evidence of substrate depletion in the colonic wall. Neither of the agents reduced the severity of colonic inflammation. Conclusions: Oral administration of nitric oxide synthase inhibitors reduced nitric oxide synthesis in the colonic wall. This study does not provide evidence to support a role for nitric oxide in the pathogenesis of colonic inflammation in TNBS colitis.     

Oral administration of inducible nitric oxide synthase inhibitors reduces nitric oxide synthesis but has no effect on the severity of experimental colitis

BACKGROUND: Increased concentrations of nitrate and nitrite (the breakdown products of nitric oxide) in the serum and faeces of patients with inflammatory bowel disease (IBD) suggests that increased synthesis of nitric oxide occurs in IBD. The aim of this study was to assess aminoguanidine (AMG), a selective inhibitor of inducible nitric oxide synthase, with regard to its effectiveness as a nitric oxide inhibitor and as a modulator of inflammation in trinitrobenzene sulfonic acid (TNBS)-induced colitis. MATERIALS AND METHODS: Colitis was induced in Wistar rats. Selective (AMG) and non-selective (1-nitroso-arginine methyl ester (1-NAME)) inhibitors of nitric oxide synthase were given in the drinking water. Colonic citrulline and arginine concentrations were assessed using high-performance liquid chromatography. The severity of colitis was assessed by a macroscopic scoring system. RESULTS: Both 1-NAME and AMG successfully reduced nitric oxide synthesis. There was no evidence of substrate depletion in the colonic wall. Neither of the agents reduced the severity of colonic inflammation. CONCLUSIONS: Oral administration of nitric oxide synthase inhibitors reduced nitric oxide synthesis in the colonic wall. This study does not provide evidence to support a role for nitric oxide in the pathogenesis of colonic inflammation in TNBS colitis.     

An enhancement of nitric oxide production regulates energy metabolism in rat hepatocytes after a partial hepatectomy.

BACKGROUND/AIMS: Infection after a liver resection often results in hepatic failure. Nitric oxide is one of the candidates which has been suspected to cause cellular dysfunction during infection in the liver. We have previously reported that the inflammatory cytokine interleukin-1beta (IL-1beta) induced the expression of the inducible nitric oxide synthase gene in primary cultured rat hepatocytes. We hypothesized that an enhancement of nitric oxide production after the resection was implicated in a change in liver energy metabolism, thus resulting in liver dysfunction. METHODS: In this study, we performed a 70% hepatectomy or a sham operation in rats, and then isolated hepatocytes from the remnant liver by collagenase perfusion. The cultured hepatocytes were treated with cytokines including IL-1beta. The effects on nitric oxide induction, the ATP content and ketone body ratio (acetoacetate/beta-hydroxybutyrate) were then compared between the partial hepatectomized (PH) and sham-operated (control) rats. RESULTS: IL-1beta augmented the induction of nitric oxide production two-fold in hepatocytes from the PH rats as compared to the control rats. IL-1beta markedly decreased the ATP content in the PH rats, although IL-1beta also decreased the ATP content in the control rats, but to a lesser extent. IL-1beta also decreased the ketone body ratio in both groups. The addition of L-arginine further stimulated the inhibition of the ATP levels and the ketone body ratio concomitantly with increased nitric oxide production in the PH rats. N(G)-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, abolished the effects of IL-1beta on the ATP levels and ketone body ratio, as well as on the nitric oxide production. CONCLUSIONS: These results demonstrate that the decreased ATP content observed in PH rats resulted from an increase in nitric oxide production. The decrease in ketone body ratio indicates that nitric oxide-induced mitochondrial dysfunction contributes significantly to ATP attenuation in hepatocytes. Therefore, the regulation of nitric oxide induction may be crucial for preventing liver failure after a hepatic resection.     

Effect of L—NAME on nitric oxide and gastrointestinal motility alterations in cirrhotic rats

AIM: To invsstigare the effect of L-NAME on nitric oxide andgastriubtestubal motility alterations in cirrhotic ratsMETHODS: Rats with cirrhosis induced by carbontetrachloride were randomly divided into two groups, one( n= 13) receiving 0. 5 mg@ kg-1 per clay of NG-nitro-L-argininemethyl ester (L-NAME), a nitric oxide synthase inhibitor,for 10 days, whereas the other group ( n = 13) and control( n = 10) rats were administrated the same volume of 9 g@ L-1saline.Half gastric emptying time and 2 h residual rate weremeasured by SPECT, using 99m Tc-DTPA-labeled bariumsuifate as test meal. Gastrointestinal transition time wasrecorded simultaneously. Serum concentration of nitrcoxide (NO) was determined by the kinetic cadmiunreduction and colorimetric methods. ImmunohistochemicalSABC method was used to observe the expression anddistribution of three types of nitric oxide synthase (NOS)isoforms in the mt gastrointestinal tract. Western blot wasused to detect expression of gastrointestinal NOS isoforms.RESULTS: Half gastric emptying time and trans-gastrointestinal time were significantly prolonged( 124.0 ± 26.4min; 33.7± 8.9min;72.1 ± 15.3 min; P＜0.01), (12.4±0.5h; 9.5±0.3 h; 8.2±0.8 h; P＜0.01), 2h residual rate wasraised in cirrhotic rots than in controls and cirrhotic ratstreated with L-NAME(54.9± 7.6 % ,13.7 ± 3.2 %, 34.9± 10.3%, P＜ 0.01). Serum concentration of NO was significantlyincreased in cirrhotic rots than in the other groups (8.20 ± 2.48)μmol@L-1, (5.94± 1.07) μmol@L-1 ,and control (5.66± 1.60) tμmol@L-1, P＜ 0.01. NOS staining intensities which weremainly located in the gastrointestinal tissues were markedlylower in cirrhotic rats than in the controls and cirrhotic ratsafter treated with L- NAME.CONCLUSION: Gastrointestinal motility was remarkablyinhibited in cirrhotic rats, which could he alleviated by L-NAME. Nitric oxide may play an important role in theinhibition of gastrointestinal motility in cirrhotic rats.     

Nitric oxide synthase inhibitor increases hepatic injury with formation of oxidative DNA damage and microcirculatory disturbance in endotoxemic rats

BACKGROUND/AIMS: Nitric oxide plays important roles in the pathogenesis of endotoxin shock and multiple organ failure. Nitric oxide synthase inhibitors are used in patients to improve hemodynamics in endotoxin shock. However, the role of nitric oxide is controversial in hepatic injury with oxidative DNA damage in endotoxemia. This report investigated the role of nitric oxide on hepatic blood flow and liver injury in endotoxemic rats. METHODOLOGY: Under light ether anesthesia, male Wistar rats were given lipopolysaccharide (10 mg/kg) intravenously. Several hours (0-24 hr) later, the animals were used for experiments. In some experiments, NG-[1-iminoethyl]-L-ornithine, a potent inhibitor of nitric oxide synthase, was administered 5 mg/kg intraperitoneally every 3 hour after lipopolysaccharide injection. Hemodynamic changes, biochemical and histological analysis were determined. RESULTS: Lipopolysaccharide increased the activity of inducible nitric oxide synthase in the liver, lungs and spleen. Significant amounts of nitric oxide-hemoglobin complexes and nitrite plus nitrate appearing in the blood peaked at 8 hr after treatment. NG-[1-iminoethyl]-L-ornithine completely inhibited the generation of nitric oxide metabolites, but hardly affected formation of urinary 8-hydroxydeoxyguanosine and the systemic blood pressure in normal rats. NG-[1-iminoethyl]-L-ornithine increased 8-hydroxydeoxyguanosine formation and decreased the blood flow more in the superior mesenteric artery and hepatic microvascular blood flow in endotoxemic rats. Inhibition of nitric oxide synthase markedly caused deterioration of the lipopolysaccharide-induced liver injury indicated by hepatic enzymes and histological findings. CONCLUSIONS: These results suggested that suppresion of endogenous nitric oxide might aggravate hepatic injury, partly caused by decrease in hepatic blood flow accompanied with oxidative stress in endotoxemia.     

Treatment with the arginase inhibitor N(omega)-hydroxy-nor-L-arginine improves vascular function and lowers blood pressure in adult spontaneously hypertensive rat

OBJECTIVE: High vascular arginase activity and subsequent reduction in vascular nitric oxide production were recently reported in animal models of hypertension. The present study investigated the effects of in-vivo arginase inhibition on blood pressure and vascular function in adult spontaneously hypertensive rats. METHODS: Ten-week-old spontaneously hypertensive rats and normotensive age-matched Wistar-Kyoto rats were treated with or without the selective arginase inhibitor N-hydroxy-nor-L-arginine for 3 weeks (10 or 40 mg/kg per day, intraperitoneally). Systolic blood pressure and cardiac rate were measured before and during treatment. Flow and pressure-dependent reactivity as well as remodeling of mesenteric arteries, acetylcholine-dependent vasodilation of aortic rings, cardiac hypertrophy, arginase activity and nitric oxide production were investigated in 13-week-old spontaneously hypertensive rats. RESULTS: In spontaneously hypertensive rats, N-hydroxy-nor-L-arginine treatment decreased arginase activity (30-40%), reduced blood pressure ( approximately 35 mmHg) and improved the reactivity of mesenteric vessels. However, vascular and cardiac remodeling was not different between treated and untreated spontaneously hypertensive rats. In Wistar-Kyoto rats, N-hydroxy-nor-L-arginine did not affect blood pressure. Finally, arginase inhibition was associated with increased nitric oxide production. Consistent with this, the response of aortic rings to acetylcholine was fully restored by N-hydroxy-nor-L-arginine, and the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester significantly reduced the effect of N-hydroxy-nor-L-arginine on flow-dependent vasodilation. CONCLUSION: Pharmacological inhibition of arginase in adult spontaneously hypertensive rats decreases blood pressure and improves the reactivity of resistance vessels. These data represent in-vivo argument in favor of selective arginase inhibition as a new therapeutic strategy against hypertension.