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.     

Globular adiponectin upregulates nitric oxide production in vascular endothelial cells

Aims/hypothesis Adiponectin, also called ACRP30, is a novel adipose tissue-specific protein that has been shown to improve insulin sensitivity and to exert anti-atherogenic effects. It is known that knockout mice lacking endothelial NO synthase (eNOS) develop hypertension, insulin resistance, hyperlipidaemia, and show augmented ischaemia-reperfusion damage. Thus, we examined whether globular adiponectin activates eNOS to produce NO.Methods To analyze NO production in bovine aortic endothelial cells (BAE), NOx (nitrite and nitrate) was measured in the medium with an automated NO detector/high-performance liquid chromatography system. eNOS activation was assessed by phosphorylation of the enzyme and its activity was evaluated by citrulline synthesis in human umbilical vein endothelial cells (HUVEC). eNOS mRNA and protein expressions in HUVEC were evaluated by Realtime PCR and Western blot analysis.Results Gobular adiponectin increased NO production in BAE. It also caused eNOS phosphorylation and potentiated eNOS activity in HUVEC. In addition, globular adiponectin up-regulated the eNOS gene to increase protein expression in HUVEC.Conclusion/interpretation Globular adiponectin increases NO production through two mechanisms, namely, by activation of eNOS enzyme activity and via an increase in eNOS expression. Activation and up-regulation of eNOS could explain some of the observed vasoprotective properties of globular adiponectin, as well as its beneficial effects on the cardiovascular system.Abbreviations NO nitric oxide - eNOS endothelial NO synthase - BAE bovine aortic endothelial cells - HUVEC human umbilical vein endothelial cells - ACRP30 adipocyte complement-related protein of 30 kDa - GAPDH glyceraldehyde-3-phosphate dehydrogenase     

银杏叶提取物对培养的人脐静脉内皮细胞结构型一氧化氮合酶的影响

目的 :观察银杏叶提取物 （EGB）对培养的人脐静脉内皮细胞结构型一氧化氮合酶 （ec NOS）活性的影响 ,并探讨 EGB防治 PTCA后再狭窄的意义。方法 :分别用 10 ,5 0 ,10 0 g· L- 1的 EGB作用于体外培养人脐静脉内皮细胞（HU VEC） ,行 ABC免疫酶染色 ,图像分析法观察 EGB对 NOS表达的影响。结果 :与对照组比较 ,各实验组 ec-NOS表达增强 （P<0 .0 5 ）。结论 :EGB增强了培养的内皮细胞的 c NOS表达。     

Possibility of the regression of atherosclerosis through the prevention of endothelial senescence by the regulation of nitric oxide and free radical scavengers

In the elderly, atherosclerotic diseases such as stroke and myocardial infarction occupy a major part of their causes of death and care. The elderly always have atherosclerosis in their aorta and other arteries and are exposed to risk of attacks. It is the elderly who should receive its safe, harmless and advanced treatment. Advanced stage of atherosclerosis in the elderly is progressed by complicated risk factors such as dyslipidemia and diabetes mellitus and specific risk factors for the elderly, aging (and menopause). Treatment of atherosclerotic disease may need special ones targeted for the elderly. Recent studies reported that frequencies of dyslipidemia were not decreased in the older oldest. In the elderly, impaired glucose tolerance occurrs and it progresses atherosclerosis. Endothelial dysfunction like impairment of nitric oxide (NO) bioavailability also progresses atherosclerosis. Although we tried to regress the high cholesterol diet‐induced atherosclerosis in rabbit aorta with a normal diet with or without statin, regression could not be achieved. NO targeting gene therapy (adenovirus endothelial nitric oxide synthase [eNOS] gene vector) regressed 20% of atherosclerotic lesions through reduction of lipid contents, however, a more integrated strategy is important for complete regression. We paid attention to NO bioavailability and developed two ways of increasing it in atherosclerosis: citrulline therapy and arginase II inhibition by estrogen. Further, we found a close relation between atherosclerosis and endothelial senescence and that NO can prevent it, especially in a diabetic model. Taken together, regression of atherosclerosis can be achieved by not only regulation of various risk factors but regulation of the cross‐talk of NO and free radicals.     

Activation of endothelial nitric oxide synthase is dependent on its interaction with globular actin in human umbilical vein endothelial cells

Endothelial nitric oxide synthase (eNOS) has been reported to associate with globular actin, and this association increases eNOS activity. Adenosine, histamine, salbutamol and thrombin cause activation of eNOS through widely different mechanisms. Whether these eNOS agonists can regulate eNOS activity through affecting its association with actin is unknown. As previously reported, we confirmed in cultured human umbilical vein endothelial cells (HUVEC) that histamine and thrombin increased intracellular Ca²⁺ whereas adenosine and salbutamol did not, and that these four agonists caused different effects on actin filament structure. Nevertheless, despite their divergent effects on intracellular Ca²⁺ and on actin filament structure, we found by immunoprecipitation that adenosine, histamine, salbutamol and thrombin all caused an increase in association between eNOS and globular actin. This increase of association was inhibited by pre-treatment with phalloidin, an actin filament stabilizer. All of these agonists also increased phosphorylation of eNOS on serine residue 1177, eNOS activity, and cyclic guanosine-3′, 5′-monophosphate, and these increases were all attenuated by phalloidin. Agonist-induced phosphorylation of eNOS on serine 1177 was attenuated by Akt inhibition, whereas association of eNOS with actin was not. We also found, in HEK-293 cells transfected with the eNOS mutants eNOS-S1177A or eNOS-S1177D, that the association between eNOS and globular actin was decreased as compared to cells transfected with wild-type eNOS. We conclude that association of globular actin with eNOS plays an essential and necessary role in agonist-induced eNOS activation, through enabling its phosphorylation by Akt at serine residue 1177.     

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。     

非诺贝特促进人内皮细胞内皮一氧化氮合酶复偶联的作用研究

目的探讨非诺贝特能否对脂多糖（LPS）诱导的血管内皮一氧化氮合酶（eNOS）脱偶联发挥保护作用。方法体外培养人脐静脉内皮细胞（HUVECs）,用非诺贝特预处理HUVECs 2 h,再与LPS共孵育24 h,采用高效液相色谱法检测细胞四氢生物蝶呤（BH4）的表达水平,ELISA检测细胞eNOS表达水平和细胞上清一氧化氮（NO）浓度,利用Confocal方法检测细胞内活性氧（ROS）产生水平。结果与对照组比较,单纯LPS刺激组内皮细胞BH4表达水平降低,伴有eNOS表达下调和NO水平降低,而内皮细胞内ROS产生增加（P均〈0.05）。与单纯LPS刺激组比较,非诺贝特预处理组内皮细胞BH4表达水平升高,同时伴有eNOS表达上调和NO水平增加,而内皮细胞内ROS产生降低（P均〈0.05）。结论非诺贝特通过上调BH4水平,对LPS诱导的血管内皮细胞eNOS脱偶联有逆转作用,这可能是其发挥血管内皮保护作用的机制之一。     

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。     

TSB2通过减少脱偶联内皮型一氧化氮合酶氧自由基生成抑制动脉粥样硬化形成

目的]观察TSB2抑制热休克蛋白90(HSP90)与内皮型一氧化氮合酶(eNOS)的结合对动脉粥样硬化形成的影响。 [方法]用TSB2处理人脐静脉内皮细胞,用免疫共沉淀法检测HSP90与eNOS的结合情况。利用C57BL/6小鼠和低密度脂蛋白受体敲除(LDLR－/－)小鼠,普通饮食(ND)或高脂饮食(HFD)喂养12周,同时腹腔注射PBS或TSB2,分为4组:C57BL/6＋ND＋PBS组、LDLR－/－＋ND＋PBS组、LDLR－/－＋HFD＋PBS组、LDLR－/－＋HFD＋TSB2组。提取主动脉检测HSP90与eNOS的结合情况,检测主动脉和主动脉窦的粥样硬化斑块情况、一氧化氮(NO)和氧自由基(O₂·－)生成情况,同时使用左旋精氨酸的竞争性底物L-单甲基-精氨酸(L-NMMA)明确NO的生成和一氧化氮合酶抑制剂左旋硝基精氨酸甲酯(L-NAME)明确O₂·－的生成。 [结果]与对照组相比,加入TSB2处理的人脐静脉内皮细胞后,HSP90与eNOS的结合水平减少41.06%(P＜0.05)。与LDLR－/－＋HFD＋PBS组相比,LDLR－/－＋HFD＋TSB2组小鼠主动脉中HSP90与eNOS的结合水平减少40.95%(P＜0.05),主动脉内皮细胞O₂·－生成水平减少63.73%(P＜0.05)(L-NAME明显抑制LDLR－/－＋HFD＋PBS组O₂·－的生成),但NO生成量未见明显变化(L-NMMA抑制所有组NO的生成),同时主动脉及主动脉窦的斑块形成水平分别减少59.39%和68.86%(P＜0.05)。 [结论]TSB2通过抑制主动脉血管内皮细胞HSP90与eNOS的结合,减少血管内皮细胞脱偶联eNOS的O₂·－生成,最终抑制动脉粥样硬化形成。     

流体切应力对内皮祖细胞内皮型一氧化氮合酶基因表达和一氧化氮分泌的影响

目的本研究旨在观察不同切应力对内皮祖细胞内皮型一氧化氮合酶（eNOS）基因表达和一氧化氮（NO）分泌的影响,以探讨流体切应力对内皮祖细胞功能的调节作用。方法诱导健康成人外周血的单个核细胞分化为内皮祖细胞,分为静态组、低切应力组（5dyn／cm^2,1dyn／cm^2=0．1Pa）、中切应力组（15dyn／cm^2）和高切应力组（25dyn／cm^2）4个不同处理组,观察不同切应力对内皮祖细胞eNOS基因表达和NO分泌的影响。结果外周血单个核细胞分化成为内皮祖细胞,倒置荧光显微镜下呈典形的“纺锤样”梭形细胞,ac-LDL吞噬及lectin抗体荧光标记双阳性,FLK-1和vWF免疫荧光抗体染色均为阳性。切应力处理4h,低、中和高切应力组内皮祖细胞eNOS／β-肌动蛋白基因表达比值分别为0．364、0．505和0．548,较静态组（0．183）明显高（P〈0．05）。在切应力处理的各时间点,低、中和高切应力组内皮祖细胞NO分泌也较静态组明显升高（P〈0．05）。结论流体切应力提高明显上调内皮祖细胞eNOS基因表达和促进其NO分泌,提示流体切应力可改善内皮祖细胞的功能活性,是提高内皮祖细胞修复血管内皮损伤能力的有效方法之一。     

血管内皮生长因子对培养内皮细胞合成一氧化氮的影响

目的 :探讨血管内皮生长因子 （VEGF） /血管渗透因子 （VPF）对内皮细胞 （EC）分泌一氧化氮 （NO）的影响。方法 :将培养的人脐静脉内皮细胞 （HUVEC）随机分为 6组 （n=6 /组 ） :1正常对照组 ;2 VEGF 1ng/ m l;3VEGF 10ng/ m l;4VEGF 10 0 ng/ m l;5低氧组 ;6低氧组 +VEGF 10 0 ng/ m l。采用硝酸还原酶法测定培养液中的 NO2 - ,NO3 -的含量以反映 NO水平。结果 :VEGF促进正常 EC分泌 NO,在一定浓度范围内呈剂量依赖性 ;低氧损伤 EC,使其分泌 NO减少 ;VEGF 10 0 ng/ ml预处理可保护 EC免受低氧损害 ,保持正常分泌 NO的功能。结论 :VEGF能够调节 EC的功能 ,为其促血管形成作用中 EC分裂、增殖、迁移奠定物质基础     

Effect of IBD sera on expression of inducible and endothelial nitric oxide synthase in human umbilical vein endothelial cells

AIM: To study the expression of endothelial and inducible nitric oxide synthases (eNOS and iNOS) and their role in inflammatory bowel disease (IBD). METHODS: We examined the effect of sera obtained from patients with active Crohn's disease (CD) and ulcerative colitis (UC) on the function and viability of human umbilical vein endothelial cells (HUVEC). HUVECs were cultured for 0-48 h in the presence of a medium containing pooled serum of healthy controls, or serum from patients with active CD or UC. Expression of eNOS and iNOS was visualized by immunofluorescence, and quantified by the densitometry of Western blots. Proliferation activity was assessed by computerized image analyses of Ki-67 immunoreactive cells, and also tested in the presence of the NOS inhibitor, 10-4 mol/ L L-NAME. Apoptosis and necrosis was examined by the annexin-V-biotin method and by propidium iodide staining, respectively. RESULTS: In HUVEC immediately after exposure to UC, serum eNOS was markedly induced, reaching a peak at 12 h. In contrast, a decrease in eNOS was observed after incubation with CD sera and the eNOS level was minimal at 20 h compared to control (18%±16% vs 23%±15% P<0.01). UC or CD serum caused a significant increase in iNOS compared to control (UC: 300%±1%; CD: 275%±7% vs 108%±4%, P<0.01). Apoptosis/ne-crosis characteristics did not differ significantly in either experiment. Increased proliferation activity was detected in the presence of CD serum or after treatment with L-NAME. Cultures showed tube-like formations after 24 h treatment with CD serum. CONCLUSION: IBD sera evoked changes in the ratio of eNOS/iNOS, whereas did not influence the viability of HUVEC. These involved down-regulation of eNOS and up-regulation of iNOS simultaneously, leading to increased proliferation activity and possibly a reduced anti-inflammatory protection of endothelial cells.     

人胃癌组织中一氧化氮合酶的表达

目的探讨NOS与胃癌的关系.方法用NADPH-d组织化学法测定了正常胃组织、癌旁组织和癌组织中一氧化氮合酶(NOS)表达水平.结果正常胃组织中粘膜上皮细胞、各种有分泌功能的细胞及肌层神经纤维中均有NOS表达,测一个视野NOS阳性细胞的平均灰度,正常胃组织为112、癌旁组织为120、胃癌组织为145.各组间差异有显著意义.表明正常胃组织NOS活性最高,胃癌组织NOS活性最低.结论①正常胃组织有广泛的NOS分布,提示NO对维持正常胃功能具有重要作用;②胃粘膜细胞癌变过程中,NOS活性明显降低,提示NOS活性与胃粘膜细胞癌变有高度相关性.     

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.     

Increased salt-sensitivity in endothelial nitric oxide synthase-knockout mice

BACKGROUND: Although impaired nitric oxide production contributes importantly to salt-sensitivity, the role of the endothelial isoform of nitric oxide synthase (eNOS) has received little attention. In the present study we compared the effects of a high-salt diet on the blood pressure response of eNOS knockout (eNOS-/-) and control (eNOS+/+) mice. METHODS: Mean arterial pressure (MAP), heart rate, pulse pressure, and activity levels were recorded by telemetry in mice fed a regular-salt diet (0.7% NaCl) followed by 6 weeks on either a high-salt (8% NaCl) or regular-salt diet. RESULTS: The eNOS-/- mice exhibited a 15% increase in MAP and a 2- to 2.5-fold increase in salt-sensitivity relative to the control strain. Salt-induced increases in MAP were well sustained in eNOS-/-, whereas in eNOS+/+ the initial increase was biphasic. The effects of salt on MAP were particularly pronounced during locomotor activity, during the dark phase, and at the peak levels of MAP recorded over the course of the day. The high-salt diet also led to a transient increase in the proportion of time spent active. Levels of heart rate and pulse pressure were relatively unaffected by the high-salt diet. CONCLUSION: The eNOS-/- mice exhibit an increased blood pressure response to a high-salt diet. This finding suggests that eNOS normally provides an important contribution to the body's adaptation to a salt load and that reduced production of NO by eNOS may promote salt-sensitivity and salt-induced hypertension.     

Enhanced expression of endothelial nitric oxide synthase and caveolin‐1 in human cirrhosis

Abstract: Background/aims: Nitric oxide is synthesized in diverse mammalian tissues by a family of calmodulin‐dependent nitric oxide synthases (NOS). Caveolin, the principal structural protein in caveolae, interacts with endothelial NOS (eNOS) leading to enzyme inhibition by a reversible process modulated by Ca⁺⁺ ‐calmodulin. The aim of the present study was to examine the localizations of eNOS and caveolin‐1 at protein level in normal human liver tissue, and how the expressions are altered in cirrhotic liver. Methods: Fresh liver specimens were obtained from hepatic surgeries. Normal portions resected from cases of carcinoma metastasized to the liver were used as control specimens, and cirrhotic portions resected from cases of hepatocellular carcinoma with hepatitis C‐related cirrhosis were used as cirrhotic specimens. Anti‐eNOS and anticaveolin‐1 antibodies were used for immunohistochemistry and Western blotting. Immunoelectron microscopy was conducted on ultra thin sections using immunoglobulin–gold combined with silver staining. Results: Immunohistochemistry revealed that both eNOS and caveolin‐1 were sparsely expressed on hepatic sinusoidal lining in normal liver specimens, and these findings were confirmed by Western blot. Both immunohistochemistry and Western blotting demonstrated over‐expression of eNOS and caveolin‐1 in cirrhotic liver specimens. Morphometric analysis of immunogold particle labeling for eNOS and caveolin‐1 was performed on immunoelectron micrographs. In normal liver tissue, hepatic stellate cells and sinusoidal endothelial cells (SEC) expressed low levels of caveolin‐1, and SEC expressed a very low level of eNOS. In cirrhotic liver, both caveolin‐1 and eNOS expressions were significantly increased by approximately four‐fold on SEC compared to normal liver. Conclusion: In cirrhotic human liver, marked increase of caveolin‐1 in perisinusoidal cells may promote caveolin‐eNOS binding and reduce the activity of eNOS despite an increased eNOS expression, leading to impaired NO production and increased hepatic microvascular tone.