Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expression in fulminant hepatic failure

BACKGROUND/AIMS: Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) have important functions in inflammation and vasoregulation but their role in fulminant hepatic failure (FHF) is not well understood. METHODS: Intrahepatic in situ staining and semi-quantification of iNOS and eNOS by immunohistochemistry in 25 patients with FHF, in 40 patients with chronic liver diseases (CLD) and in ten normal controls (NC). RESULTS: Expression patterns of iNOS and eNOS differed. While in NC only faint iNOS expression was found in some Kupffer cells/macrophages and hepatocytes, eNOS was expressed constitutively in sinusoidal and vascular endothelial cells. In CLD, iNOS expression was induced in Kupffer cells/macrophages and hepatocytes, representing the main iNOS expressing cell types. Additionally, bile ducts, vascular endothelial cells and lymphocytes also expressed iNOS (P = 0.001). In contrast, no differences were found between eNOS expression in CLD and NC (P = 0.64). The same cell types expressed eNOS and iNOS in FHF but numbers of both were significantly enhanced, exceeding the levels seen in CLD (P < 0.001, P = 0.017). CONCLUSIONS: Our data demonstrate that iNOS and eNOS are differently regulated in physiologic conditions and in liver disease. While eNOS seems to be involved in the physiological regulation of hepatic perfusion, strong upregulation of iNOS might contribute to inflammatory processes in FHF.     

cGMP-mediated negative-feedback regulation of endothelial nitric oxide synthase expression by nitric oxide

Earlier studies have demonstrated that nitric oxide (NO) exerts a fast-acting inhibitory influence on endothelial NO synthase (eNOS) enzymatic activity in isolated vascular tissue preparations. The present study was designed to examine the possible effect of NO on eNOS protein expression in cultured endothelial cells and intact animals. Human coronary endothelial cells were incubated with S-nitroso-N-acetyl-penicillamine (SNAP, an NO donor), oxyhemoglobin (HGB, an NO trapping agent), SNAP plus HGB, or inactive vehicle (control). In other experiments, cells were treated with 3-isobutyl-1-methylxanthine (a phosphodiesterase inhibitor), 1H-[1,2, 4]oxadiazolo-[4,3-2]quinoxalin-1-one (ODQ, a guanylate cyclase inhibitor), SNAP plus ODQ, 8-bromo-cGMP (8-Br-cGMP, a cell-permeable cGMP compound), 8-Br-cGMP plus HGB, or inactive vehicle in order to discern the effect of cGMP. The incubations were conducted for 24 hours, and total nitrate plus nitrite production and eNOS protein abundance (Western analysis) were measured. To determine the effect of NO on eNOS expression in vivo, rats were treated with either the NO donor isosorbide dinitrate or placebo by gastric gavage for 48 hours, and aortic eNOS protein expression was examined. The NO donor SNAP markedly depressed, whereas the NO scavenger HGB significantly raised, eNOS protein expression. The downregulatory action of SNAP was completely abrogated by HGB. Phosphodiesterase inhibitor and 8-Br-cGMP downregulated, whereas the guanylate cyclase inhibitor ODQ upregulated eNOS protein expression. The downregulatory action of SNAP was completely overcome by the guanylate cyclase inhibitor ODQ, and the upregulatory action of the NO scavenger HGB was abrogated by 8-Br-cGMP. Administration of NO donor resulted in a marked downregulation of aortic eNOS protein expression in intact animals, thus confirming the in vitro findings. NO serves as a negative-feedback regulator of eNOS expression via a cGMP-mediated process.     

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。     

Role of endoplasmic reticulum stress protein C / EBP homologous protein-10 in ischemia and hypoxia induced human aortic endothelial cells injury

<正>Objective To investigate the expression of endoplasmic reticulum stress(ESR)marker C/EBP homologous protein-10(CHOP-10)in the human aortic endothelial cells(HAEC)under the ischemia and hypoxia stress and to study the effects of atorvastatin on the process.Methods The cultured HAEC were divided into normal control group,ischemia/hypoxia model group,ischemia/hypoxia     

Reversal of endothelial nitric oxide synthase uncoupling and up-regulation of endothelial nitric oxide synthase expression lowers blood pressure in hypertensive rats.

OBJECTIVES: We sought to examine the hypothesis that a pharmacologic up-regulation of endothelial nitric oxide synthase (eNOS) combined with a reversal of eNOS uncoupling provides a protective effect against cardiovascular disease. BACKGROUND: Many cardiovascular diseases are associated with oxidant stress involving protein kinase C (PKC) and uncoupling of eNOS. METHODS: Messenger ribonucleic acid (mRNA) expression was analyzed with RNase protection assay or quantitative real-time polymerase chain reaction, vascular nitric oxide (NO) with spin trapping, and reactive oxygen species (ROS) with dihydroethidium fluorescence. RESULTS: Aortas of spontaneously hypertensive rats (SHR) showed an elevated production of ROS when compared with aortas of Wistar-Kyoto rats (WKY). The aortic expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits (Nox1, Nox2, Nox4, and p22phox) was higher in SHR compared with WKY. In SHR, aortic production of ROS was reduced by the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), indicating eNOS "uncoupling" in hypertension. Oral treatment with the PKC inhibitor midostaurin reduced aortic Nox1 expression, diminished ROS production, and reversed eNOS uncoupling in SHR. Aortic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH4) were significantly reduced in SHR compared with WKY. Midostaurin normalized BH4 levels in SHR. In both WKY and SHR, midostaurin increased aortic expression of eNOS mRNA and protein, stimulated bioactive NO production, and enhanced relaxation of the aorta to acetylcholine. Midostaurin lowered blood pressure in SHR and, to a lesser extent, in WKY; the compound did not change blood pressure in WKY made hypertensive with L-NAME. CONCLUSIONS: Pharmacologic interventions that combine eNOS up-regulation and reversal of eNOS uncoupling can markedly increase bioactive NO in the vasculature and produce beneficial hemodynamic effects such as a reduction of blood pressure.     

Retinal pericytes control expression of nitric oxide synthase and endothelin-1 in microvascular endothelial cells

Pericytes are known to communicate with endothelial cells by direct contact and by releasing cytokines such as TGF-beta. There is also strong evidence that pericytes act as regulators of endothelial cell proliferation and differentiation. We have investigated the effect of pericyte-conditioned medium (PCM) on proliferation of human microvascular endothelial cells in vitro, together with the expression of the vasoregulatory molecules, constitutive and inducible nitric oxide synthases (ecNOS and iNOS), and endothelin-1 (ET-1). Expression was measured at the mRNA level using semiquantitative RT-PCR for all three genes and at the protein level for ecNOS and iNOS using Western blotting. Growth curves for HMECs showed that PCM inhibits proliferation, eventually leading to cell death. Exposure to PCM repressed iNOS mRNA expression fivefold after 6 h. A similar, though delayed, reduction in protein levels was observed. ecNOS mRNA was slightly induced at 6 h, though there was no significant change in ecNOS protein. By contrast, ET-1 mRNA was induced 2.3-fold after 6 h exposure to PCM. We conclude that pericytes release a soluble factor or factors that are potent inhibitors of endothelial cell growth and promote vasoconstriction by up-regulating endothelin-1 and down-regulating iNOS.     

Functional implications of polymorphisms of endothelial nitric oxide synthase gene.

Gorchakova et al. have published a very interesting articleaddressing the increase in risk of death or myocardial infarctionin Caucasian patients that carry the TT genotype for the     

内皮细胞型一氧化氮合酶基因多态性与糖尿病肾病的相关性

糖尿病肾病是糖尿病 (ＤＭ )致死致残的主要原因之一。近年来流行病学调查显示 ,有些ＤＭ患者虽血糖长期控制不良 ,但并不发生ＤＮ ,而有些患者虽代谢控制良好 ,最终仍发生ＤＮ〔1,2〕,提示遗传因素在ＤＮ的发生发展中可能起关键作用。分子水平的研究发现 ,内皮细胞型一氧化氮合酶(ｅＮＯＳ)基因第 7外显子的Ｇｌｕ2 98Ａｓｐ(894Ｇ→Ｔ)基因点突变及第 4内含子一个 2 7ｂｐ的插入 /缺失 (ａ/ｂ)多态与糖尿病微血管并发症及冠心病、心肌梗死的发生有明显相关性〔1 5〕,但该点突变及多态与糖尿病肾病的相关性各家报道不一〔6,7〕,特别是该突…     

内皮型一氧化氮合酶基因rs3918181位点多态性与原发性高血压的关系研究

目的 探讨天津市汉族人群内皮型一氧化氮合酶(eNOS)基因第14内含子rs3918181位点多态性与原发性高血压(EH)的关系.方法 采用聚合酶链反应-限制性内切酶片段长度多态分析法(PCR-RFLP)对290例EH患者和161名健康对照者的eNOS基因rs3918181位点进行基因多态性分型,同时检测所有研究对象的血脂等危险因素,分析不同基因型与EH发病的关系.结果 两组年龄、体质指数的差异有统计学意义(均为P＜0.05).EH组患者的AA、AG和GG基因型分布频率分别为0.293、0.393和0.314,对照组分别为0.180、0.472和0.348,两组相比差异有统计学意义(均为P ＜0.05);EH组A与G等位基因频率分别为0.490和0.510,对照组分别为0.416和0.584,两组相比差异有统计学意义(均为P ＜0.05).影响EH的危险因素有年龄、体质指数.结论 eNOS基因rs3918181位点多态性与EH相关.     

eNOS/NO 信号通路与心血管疾病关系的研究进展

一氧化氮（nitric oxide,NO）作为一种信号分子,在生理活动中起着重要作用,包括血压调节、血管张力维持、免疫系统调控等,尤其在心血管系统中发挥重要作用。NO产生异常是多种心血管疾病的诱因。内皮型一氧化氮合酶（endothelial nitric oxide synthase,eNOS）作为诱导合成NO的限速酶,主要在血管壁的调节中发挥重要作用,因此,其与心血管的正常生理活动密切相关。本文综述了eNOS的基本结构与功能、NO的理化性质,以及eNOS/NO信号通路与心血管系统疾病的关系。     

Association of (-)786T-C mutation of endothelial nitric oxide synthase gene with insulin resistance

AIMS/HYPOTHESIS: Endothelial derived nitric oxide synthase ( eNOS) gene polymorphisms affect eNOS activity and are associated with abnormal vasomotility and impaired local blood flow. A decrease in local blood flow has been reported to cause insulin resistance. The aim of this study was to examine a possible association of two eNOS polymorphisms, Glu298Asp (G894T) in exon 7 and (-)786T-C mutation with insulin resistance. METHODS: Genotypes of both Glu298Asp and (-)786T-C mutation were examined by the PCR-RFLP method. Plasma nitrate and nitrite concentrations were also measured. RESULTS: The allele frequencies of both polymorphisms showed no considerable differences in 233 non-diabetic subjects and 301 patients with Type II (non-insulin-dependent) diabetes mellitus. Non-diabetic subjects with the (-)786C allele had (p<0.05) higher fasting plasma insulin and homeostasis model assessment of insulin resistance than those with the (-)786T/ (-)786T genotype. Diabetic subjects with (-)786C allele showed higher HbA(1c) than those with the (-)786T/(-)786T genotype. A euglycaemic hyperinsulinemic clamp study done on 71 of the 301 patients showed a lower glucose infusion rate in diabetic patients with the (-)786C allele than those without it. In diabetic patients with the (-)786C allele, plasma nitrate and nitrite concentrations were lower than in subjects without it (p=0.026). No differences were observed between mutant carriers of Glu298Asp and non-carriers among both non-diabetic subjects and Type II diabetic patients. CONCLUSIONS/INTERPRETATION: The (-)786T-C mutation of the eNOS gene is associated with insulin resistance in both Japanese non-diabetic subjects and Type II diabetic patients.