Adeno-associated virus-mediated transfer of endothelial nitric oxide synthase gene inhibits protein synthesis of rat ventricular cardiomyocytes

We investigated whether nitric oxide (NO) synthase gene transfer could attenuate growth of cultured cardiac myocytes. First, we investigated the effects of exogenous NO and cGMP analog on protein synthesis of cultured neonatal rat cardiac myocytes. The NO donor 3-morpholino-sydnonimine-hydrochloride (SIN-1) and 8-bromo-cGMP caused concentration-dependent decreases in phenylephrine-stimulated incorporation of ³H-leucine into cardiac myocytes. We then transferred endothelial constitutive NO synthase (ecNOS) gene into cultured neonatal rat cardiac myocytes using adeno-associated virus (AAV) vectors. ecNOS gene transfer into cardiac myocytes induced 140 kD ecNOS protein expression and significantly increased cGMP contents of myocytes compared with control cells. ecNOS gene transfer inhibited ³H-leucine incorporation into cardiac myocytes in response to phenylephrine, which was significantly recovered in the presence of the NOS inhibitor N^G-monomethyl-L-arginine acetate. These results indicate that endogenously generated NO by ecNOS gene transfer using AAV vectors inhibits the -adrenergic agonist-induced cardiac protein synthesis at least partially via cGMP production.     

小凹蛋白与内皮型一氧化氮合成酶在大鼠肝硬化组织中的表达

目的探讨小凹蛋白Caveolin-1、内皮型一氧化氮合成酶eNOS在大鼠肝硬化组织中的异常表达及其意义。方法构建二甲基亚硝胺（DMN）致肝纤维化大鼠模型，在造模4周后观察肝纤维化程度。免疫组织化学染色检测30例大鼠肝硬化肝组织和30例正常大鼠肝组织中Caveolin-1和eNOS的细胞定位；Western Blot检测Caveolin-1和eNOS的蛋白表达水平变化。结果Caveolin-1和eNOS均主要分布于肝窦内皮细胞中，Caveolin-1在肝硬化组表达阳性率为90％，对照组为37％，两组比较差异有统计学意义（P〈0．05）；eNOS在肝硬化组表达阳性率为30％，对照组为66％，两组比较差异有统计学意义（P〈0．05）。Westem Blot检测Caveolin-1在肝硬化组织中较正常肝组织中表达明显增强；eNOS在肝硬化组织中呈低水平表达，较正常肝组织中表达明显减少。结论肝硬化肝窦内皮细胞中Caveolin-1的异常表达促进eNOS-Caveolin-1复合物的生成，结合形式的eNOS活性降低，导致NO合成减少，肝内血管阻力持续增加，从而导致了门静脉高压症的形成。     

Expression of nitric oxide synthase protein and gene in the splanchnic organsof liver cirrhosis and portal hypertensive rats

AIM To investigate the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS)protein and eNOS mRNA gene in the splanchnic organs of liver cirrhosis and portal hypertensive rats.METHODS In control and CCl4-induced liver cirrhotic rats, the expression of eNOS and iNOS proteins wasdetected by immunohistochemical method, and eNOS mRNA was detected by in situ hybridization.RESULTS The expression of eNOS protein and eNOS mRNA increased in most organs of the cirrhotic rats,including bronchial and alveolar epithelial cells, renal tubular epithelial cells and mesenchyma, endothelialand adventitial cells of aorta and superior mesenteric artery, whereas no significant increase of iNOS proteinwas found. In the hepatic tissue, NOS protein and eNOS mRNA were present in mesenchymal cells and vesseladventitial cells, no difference was observed in the expression between control and cirrhotic rats.CONCLUSION The expression of NOS varied in region. In splanchnic organs and vasculars there was anincreased expression of eNOS which induced aplanchnic vasodilation and increased the inflow of portal vein,while in the liver tissue and blood vessel showed no increased expression, which may be associated withincreased intrahepatic vascular resistance.     

内皮型一氧化氮合酶基因G894T突变与肝硬化门脉高压的相关性研究

目的　探讨内皮型一氧化氮合酶 (endothelialnitricoxidesynthase ,eNOS)基因第 7外显子G894T点突变与肝硬化门脉高压症之间的关系。方法　采用病例对照和聚合酶链反应 限制性片段长度多态性 (PCR RFLP)方法 ,检测10 6例乙型肝炎后肝硬化患者和 10 8名健康对照者eNOS基因第 7外显子G894T点突变频率和外周血NO 2 /NO 3 含量 ,比较各组间基因型频率与等位基因频率。结果　①中国汉族正常人eNOS基因G894T突变GG、GT和TT基因型频率分别为 86.1%、11.1%和 2 .8%;G、T等位基因频率分别为 91.7%和 8.3 %。②乙型肝炎后肝硬化组GT TT基因型频率高于对照组 ( 2 4.5 %比 3 .9%) ,差异有显著性。③门脉高压症组T等位基因频率明显高于对照组 ,差异有显著性( 17.7%比 8.3 ,P <0 .0 5 ) ,相关分析呈正相关 (r =0 .2 )。携带T等位基因者发生门脉高压症的危险性高于非T等位基因携带者 1.76倍 (OR =2 .76)。结论　eNOS基因第 7外显子G894T突变与肝硬化门脉高压症形成相关 ,T等位基因可能是中国人群门脉高压症的遗传易感基因型     

Discrepant effects of inducible nitric oxide synthase modulation on systemic and splanchnic endothelial nitric oxide synthase activity and expression in cirrhotic rats

BACKGROUND: Arterial vasodilatation, which is a major factor in the pathogenesis of the hyperkinetic circulatory state and portal hypertension in cirrhosis, is due to arterial nitric oxide (NO) overproduction secondary to endothelial NO synthase (eNOS) and inducible NOS (iNOS) upregulation. However, in cirrhosis, the respective roles of eNOS and iNOS isoforms in NO overproduction are still unknown and the effect of iNOS modulation on eNOS activity and expression has not been evaluated in the systemic or splanchnic vessels. The aim of this study was to evaluate the effects of modulating aortic and superior mesenteric arteries (SMA) iNOS on arterial eNOS activity and expression in rats with cirrhosis. METHODS: eNOS and iNOS protein expression and eNOS activity (assessed by its phosphorylation at serine 1177) were measured in the aortas and SMA in untreated and treated cirrhotic rats with lipopolysaccharide (LPS), N-iminoethyl-L-lysine (L-NIL), a selective iNOS inhibitor, and LPS plus L-NIL. RESULTS: LPS administration significantly increased eNOS and iNOS protein expression and eNOS activity in the aortas of both sham-operated and cirrhotic rats. However, in SMA, LPS administration induced a decrease in eNOS protein expression and activity and an increase in iNOS protein expression. CONCLUSION: The results of this study may explain the worsening of the hyperdynamic state in cirrhosis during septic shock by direct LPS-induced eNOS activation in large systemic vessels, and its inhibition in concomitant small splanchnic vasculature by iNOS synthesized NO.     

雌激素对血管内皮细胞一氧化氮合酶活性调控的受体机制研究

目的　观察 17β 雌二醇对大鼠肺血管内皮细胞一氧化氮合酶 (NOS)活性的影响及雌激素受体在其中的作用。方法　用贴壁法和无酚红 16 40培养基培养大鼠肺血管内皮细胞 ,在不同浓度的 17β 雌二醇 (伴或不伴有雌激素受体拮抗剂代莫昔芬 )作用下 ,观察一定时间内内皮细胞的NOS活性及一氧化氮 (NO)的产量。放射配体结合分析技术检测内皮中的雌激素受体。结果　 (1) 1～ 10nmol的 17β 雌二醇作用 8～ 2 4h ,内皮细胞的NO产量显著增加 (vs对照 P<0 .0 5 ) ,10nmol的 17β 雌二醇作用 8～ 2 4hNOS活性显著增强 (与对照比 ,8h ,P<0 .0 5 ;16h ,2 4h ,P<0 .0 1)。 (2 )大鼠肺血管内皮细胞中存在雌激素受体。 (3)雌激素受体拮抗剂他莫昔芬能显著抑制雌激素的上述作用 (P <0 .0 1)。结论　 17β 雌二醇能增强大鼠血管内皮细胞的NOS活性和NO产量 ,该作用由雌激素受体介导 ,可能是雌激素降低血管阻力、抑制动脉粥样硬化作用的重要机理之一。     

肝癌组织中一氧化氮合酶及其基因表达的研究

目的研究肝癌组织中一氧化氮合酶(iNOS)及其基因表达与肝癌发生发展的关系。方法用免疫组化和原位杂交的方法对21例肝癌及癌旁组织中的诱导型一氯化氮合酶(iNOS)及其基因表达进行原位检测和观察。结果:NOS 阳性反应物质呈黄色或棕黄色,位于细胞浆中。非癌殖织(肉眼观距癌组织边缘>1.5)多呈阴性或弥漫弱阳性,但部分非癌组织中可见 iNOS 呈阳性的细胞呈点状分布;癌旁组织多呈阳性,提示 iNOS 表达与肝组织癌变有关。癌组织核心多呈阴性或弥漫弱阳性,但分化中和差的癌组织核心也分别有一例 NOS 呈强阳性;周边癌组织呈局灶阳性,侵入纤维组织中的弥敢癌细胞星强阳性,提示 NOS 的表达与肝癌组织的侵润能力有关。肝癌组织 iNOSmRNA 阳性细胞的分布与 iN-OS 蛋白的表达基本相似。结论 iNOS 蛋白及其基因表达与肝组织癌变及肝癌侵润能力有关。     

eNOS基因第7外显子894G→T多态与糖尿病肾病合并高血压的相关性研究

目的　探讨内皮细胞型一氧化氮合酶 (eNOS)基因第 7外显子 894位点多态性与糖尿病肾病合并高血压的相关性。方法　随机选择研究对象为单纯糖尿病 (DM )患者 5 2例 ,平均年龄 (6 6 .3± 7.9)岁 ,单纯糖尿病肾病 (DN)患者 4 5例 ,平均年龄 (6 5 .9± 6 .7)岁 ,糖尿病肾病合并高血压 (DN +HP)患者 5 0例 ,平均年龄 (6 5 .9± 6 .8)岁。运用聚合酶链反应限制性片段长度多态性 (PCR RFLP)技术扩增eNOS基因第 7外显子的DNA片段 (2 4 8bp) ,以限制性内切酶BanⅡ进行酶切消化 ,2 %的琼脂糖电泳分离PCR产物。各组间等位基因频率及基因型频率的比较用 χ2 检验 ,危险因素分析用Logistic回归分析。结果　DN组T等位基因和TG基因型频率显著高于单纯DM组 (χ2 =7.2 0 ,P <0 .0 5 ;χ2 =9.17,P <0 .0 5 ) ,DN合并高血压组T等位基因及TG基因型频率高于DN组 ,但差异无显著性 (χ2 =0 .4 4 ,P >0 .0 5 ;χ2 =0 .6 1,P >0 .0 5 )。多因素Logistic回归分析发现 :收缩压 (SBP)、糖化血红蛋白 (HbA1c)、甘油三酯 (TG)、总胆固醇 (TC)、eNOS基因第 7外显子 894G→T突变是DN的独立危险因素。结论　eNOS基因第 7外显子 894G→T多态与糖尿病肾病有关。T等位基因可能是中国人 2型糖尿病患者易患DN的独立危险因素。eNOS基因第 7外显     

Elevated expression of caveolin-1 at protein and mRNA level in human cirrhotic liver: relation with nitric oxide

Background. Caveolin, the principal structural protein of caveolae, binds with endothelial nitric oxide synthase (eNOS) leading to enzyme inhibition. This study examined the expression of caveolin and eNOS at the protein and mRNA levels in patients with hepatocellular carcinoma and hepatitis C-related cirrhosis, and in control noncirrhotic liver specimens obtained from patients with metastatic liver carcinoma. Methods. Anti-eNOS, anti-caveoin-1, and anti-calmodulin antibodies were used for Western blotting. For in situ hybridization (ISH), human eNOS and caveolin-1 peptide nucleic acid probes were used with a catalyzed signal amplification system. Results. Western blotting showed marked overexpression of caveolin-1 protein in cirrhotic liver, while caveolin-1 was almost undetectable in control liver tissue. Endothelial NOS was expressed at a slightly higher level in cirrhotic liver than in control liver tissue. Calmodulin was expressed abundantly in control liver tissue and at a low level in cirrhotic liver tissue. By ISH, eNOS mRNA was localized on portal vein and hepatic lining cells, and caveolin-1 mRNA was almost undetectable in normal liver tissue. In cirrhotic liver tissue, caveolin-1 mRNA was overexpressed on hepatic sinusoidal lining cells, while eNOS mRNA expression was similar to that in normal liver. Conclusions. Enhanced caveolin-1 expression may be associated with a significant reduction in NO catalytic activity in cirrhosis.     

Bleeding duodenal ulcer and association with polymorphism of endothelial constitutive nitric oxide synthase gene

Nitric oxide (NO) exerts both protective and proinflammatory actions in the gastrointestinal tract. Enhanced gastric NO synthase (NOS) activity has been shown in duodenal ulcer patients. Recently, intron-4 polymorphism of the endothelial constitutive (ec) NOS gene has been associated with some pathological conditions. Our aim was to determine the genotype and allele frequencies of the ecNOS4 polymorphism in peptic ulcer patients. The distribution of the polymorphism ecNOS4a/b was studied in 188 ulcer patients and 120 healthy controls, from genomic DNA. Genotypes ab, bb, and aa and allele frequency were similar in both peptic ulcer patients and controls, and no differences were found when patients and controls were analyzed according to the presence of several etiological factors. However, alelle a carrier status was associated with decreased risk of bleeding in duodenal ulcer patients (OR = 0.49; 95% CI = 0.25–0.95; P = 0.03). In conclusion, this ecNOS4 polymorphism gene could be related to susceptibility of duodenal ulcer patients to bleeding.     

高同型半胱氨酸血症诱导eNOS脱偶联损害冠状动脉内皮功能

目的探讨高同型半胱氨酸血症（HHcy）患者冠状动脉内皮功能是否被损伤,以及这种损伤是否通过内皮型一氧化氮合酶（eNOS）脱偶联实现的。方法 71例参与者被分成健康对照组（n=50）和HHcy组（n=21）,利用多普勒超声心动测定腺苷诱导下冠状动脉左前降支的舒张功能的改变,冠脉血流速度储备（CFVR）由最大血流速度与基线水平的比值计算得出。采用ELISA以及高效液相色谱法测定血浆一氧化氮（NO）、四氢生物蝶呤（BH4）的水平。结果与健康对照组相比,HHcy组患者血浆NO、BH4的水平降低（P〈0.05）;HHcy组CFVR低于健康对照组（P〈0.05）;血浆Hcy水平与NO及CFVR呈负相关（P〈0.05）。结论 HHcy可能通过降低BH4生物利用度,诱导eNOS脱偶联,而导致冠状动脉内皮功能损伤,进而促进不良冠脉事件的发生。     

High nitric oxide synthase activity in endothelial cells in ulcerative colitis

Endothelial nitric oxide (NO) synthase, a unique NO synthase (NOS) isoform that is expressed constitutively by the vascular endothelium both in vivo and in vitro, is believed to be essential to systemic and/or local vascular integrity. NOS expression by endothelial cells may indicate vascular activation. We successfully established a simple method for the culture of microvascular endothelial cells from a small amount of tissue and investigated ulcerative colitis (UC), in which condition vascular factors have not been studied extensively. We cultured endothelial cells from the mesenteries of surgical patients with UC and assayed NOS activity by reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry. Strong NOS activity was demonstrated in the cells from all UC patients (5/5), whereas no activity was detected in the cells from human umbilical veins and the mesenteries of colon cancer patients (0/10 and 0/5, respectively). This strong NOS activity was not diminished by incubation with a high concentration of glucocorticoid, suggesting that it was constitutive. These results indicate a close relationship of vascular activation (high NOS activity) with the pathogenesis of UC.     

C-reactive protein decreases endothelial nitric oxide synthase activity via uncoupling

C-reactive protein (CRP), a cardiovascular risk marker, induces endothelial dysfunction. We have previously shown that CRP decreases endothelial nitric oxide synthase (eNOS) expression and bioactivity in human aortic endothelial cells (HAECs). In this study, we examined the mechanisms by which CRP decreases eNOS activity in HAECs. To this end, we explored different strategies such as availability of tetrahydrobiopterin (BH4)-a critical cofactor for eNOS, superoxide (O(2)(-)) production resulting in uncoupling of eNOS and phosphorylation/dephosphorylation of eNOS. CRP treatment significantly decreased levels of BH4 thereby promoting eNOS uncoupling. Pretreatment with sepiapterin, a BH4 precursor, prevented CRP-mediated effects on BH(4) levels, superoxide production as well as eNOS activity. The gene expression and enzymatic activity of GTPCH1, the first enzyme in the de novo biosynthesis of BH(4), were significantly inhibited by CRP. Importantly, GTPCH1 is known to be regulated by cAMP-mediated pathway. In the present study, CRP-mediated inhibition of GTPCH1 activity was reversed by pretreatment with cAMP analogues. Furthermore, CRP-induced O(2)(-) production was reversed by pharmacologic inhibition and siRNAs to p47 phox and p22 phox. Additionally, CRP treatment significantly decreased the eNOS dimer: monomer ratio confirming CRP-mediated eNOS uncoupling. The pretreatment of cells with NO synthase inhibitor (N-nitro-l-arginine methyl ester [l-NAME]) also prevented CRP-mediated O(2)(-) production further strengthening CRP-mediated eNOS uncoupling. Additionally, CRP decreased eNOS phosphorylation at Ser1177 as well as increased phosphorylation at Thr495. CRP appears to mediate these effects through the Fcgamma receptors, CD32 and CD64. To conclude, CRP uncouples eNOS resulting in increased superoxide production, decreased NO production and altered eNOS phosphorylation.     

Conservation of whole body nitric oxide metabolism in human alcoholic liver disease: Implications for nitric oxide production

Objective. Patients with advanced liver diseases tend to develop a hyperdynamic circulation which complicates cirrhosis. Impairment of nitric oxide (NO) metabolism has been implicated in the pathogenesis of portal hypertension. The aim of this study was to determine nitric oxide synthase (NOS)-dependent whole body NO production in patients with decompensated liver cirrhosis and portal hypertension. Material and methods. Ten patients with decompensated alcoholic liver disease and portal hypertension (Child-Pugh Classifications B and C with no signs of infection) and 10 age- and gender-matched control subjects received an intravenous infusion of L-[¹⁵N]₂-arginine (50 µmol/min for 30 min). Urine and serum nitrite and nitrate concentrations were determined using ion chromatography-mass spectrometry. Results. NOS-dependent whole body NO synthesis was estimated by the conversion of [¹⁵N]guanidino nitrogen of arginine to urine ¹⁵N-nitrite and ¹⁵N-nitrate. The amount of ¹⁵N-nitrite and ¹⁵N-nitrate in the urine of patients and control subjects was significantly correlated with the amount of urine nitrite and nitrate over 36 h (r=0.91 and 0.77, respectively, p<0.0001). However, neither a median of 12 h ¹⁵N-nitrite and ¹⁵N-nitrate nor nitrite and nitrate excretion in the urine was different between patients and control subjects, 46.4 (9.4–152.2) versus 98.7 (29.9–146.5) nmol/mmol creatinine and 20.6 (2.1–69.0) versus 40.0 (27.0–70.1) µmol/mmol creatinine, respectively. No differences were found in serum nitrite and nitrate concentrations and glomerular filtration rates between patients and control subjects, 111.4 (73.2–158.8) versus 109.3 (83.5–176.4) µmol/l. Conclusion. Our results contraindicate a greater basal NOS-dependent whole body NO production in patients with decompensated liver disease and portal hypertension.     

内皮型一氧化氮合酶基因4b/a和T786C多态性与颈动脉粥样硬化的关联分析

目的:在汉族老年群体中探讨内皮型一氧化氮合酶(eNOS)基因4b/a和T786C多态性与颈动脉粥样硬化(CAS)的关联性。方法:选择接受颈动脉超声检查的汉族老年患者521例,根据超声检查结果分为CAS组266例和对照组255例。分别用PCR和PCR-RFLP方法分析4b/a和T786C多态性的基因型,同时对所有对象检验血脂等危险因素。结果:两个多态性处于连锁不平衡(LD)。两个多态性的基因型和等位基因分布在CAS组和对照组间均差异无统计学意义(均P>0.05)。在调整性别和年龄等多个CAS常见危险因素的前后,两个多态性各基因型与CAS的关联均差异无统计学意义(均P>0.05)。单体型分析发现,对常见危险因素进行调整后,单体型4a-T与CAS的关联差异有统计学意义(OR=2.86,95%CI=1.11～7.40,P=0.030)。结论:在所研究的汉族老年人群中未发现eNOS基因4b/a或T786C多态性单独与CAS相关联,但二者构成的单体型4a-T可能是汉族老年群体发生CAS的独立易感遗传标记。