RGDS肽对胶元活化的大鼠血小板L-Arginine/NO途径的影响

本工作在胶原活化的大鼠血小板上,观察RGDS肽对血小板聚集、L一精氨酸（L－Arg）转运、一氧化氮合酶（NOS）活性和亚硝酸盐（NO2－）含量的影响。结果发现,4μg／mL胶原引起血小板聚集时,L－Arg转运增强、NOS活性增高和NO2-含量增加。血小板L－Arg转运的Vmax与NOS活性和NO2-生成呈明显正相关（r=0.8100和0.8343,p＜0．01）;血小板聚集与NO2-生成亦呈明显正相关（r=0.7660,P＜0.05）。RGDS肽200μmol／L凡与胶原共同孵育,可明显抑制胶原引起的血小板聚集、L－Arg转运增强、NOS活性增高和NO2-含量增加。提示,胶原激活的血小板L－Arg／NO途径增加是通过Ⅱb／Ⅲa复合物所介导,RGDS肽可括抗其增加作用。     

睾丸一氧化氮合酶与雄性生殖

一氧化氮合酶（nitric oxide synthase,NOS）在NADPH（还原型辅酶Ⅱ）存在下催化L－精氨酸分解生成一氧化氮（nitric oxide,NO）。NOS有以下几种形式：神经型NOS（nNOS），诱导型NOS（iNOS），内皮型NOS（eNOS）。NO是目前研究最多的体内信息分子和效应分子，广泛存在于人体的心血管系统、神经系统、消化系统、免疫系统、生殖系统等。NOS和NO对生殖活动的作用已被广泛研究，如对睾丸微循环的调解，参与睾酮分泌，调解精子活动等。本文对睾丸NOS／NO与雄性哺乳动物生殖关系的研究进展作一概述。     

睡眠剥夺对大鼠一氧化氮和一氧化氮合酶的影响

目的：探讨睡眠剥夺对大鼠脑组织一氧化氮（NO）及一氧化氮合酶（NOS）影响。方法：采用小平台水环境法（Flower Pot)制作大鼠睡眠剥夺模型，采用化学法和酶法观察不同时间睡眠剥夺后大鼠额叶、海马、中脑和下丘脑NO含量及NOS活性变化。结果：与正常对照组及大平台组比较，大鼠在SD后额叶和海马的NO含量及NOS活性增高，有显著性差异（P＜0．01－0．05），其余脑区无显著性差异（P＞0．05）。随着剥夺时间的延长，额叶和海马NO含量及NOS活性增高更加明显。结论：睡眠剥夺可致NO及NOS升高，可能与其学习障碍有关，NO可能参与大鼠的睡眠调节。     

低剂量γ射线辐照对血清一氧化氮及一氧化氮合酶水平的影响

目的：观察低剂量γ射线照射人离体外周血对血清中一氧化氮（NO）和一氧化氮合酶（NOS）水平的影响。方法：采集10份健康献血员全血，肝素抗凝，然后采用γ射线照射，照射剂量率为17Gy／min，总吸收剂量为1Gy，分别于照射前及照射后1h，2h采用分光光度法检测血清中NO含量和NOS活性。结果：经γ射线照射1h后，血清中NO及NOS水平与照射前比较明显升高（P〈0.01）；照射后2h，血清中NOS水平与照射后1h比较无统计学差异（P〉0、05），但是还明显高于照射前的水平（P〈0．01）；在照射后2h，血清中NO含量与照射后1h比较明显降低（P〈0.01），但仍明显高于照射前水平（P〈0．01）。结论：采用剂量为1Gy的γ射线照射外周血，可引起血清中NO水平及NOS活性的显著升高．从而为低剂量辐照自体血回输对肿瘤的辅助治疗提供了理论支持。     

夏至草醇提物对失血性休克大鼠器官一氧化氮及其合酶的影响

目的观察夏至草醇提物对失血性休克大鼠器官组织一氧化氮（NO）及其合酶（NOS）的影响。方法Wistar雄性大鼠18只，随机分为夏至草组、模型组和对照组（均n=6）。夏至草组和模型组复制失血性休克模型，维持90min，对照组仅手术。夏至草组自颈静脉缓慢推注夏至草醇提物（5g／ml，6g／kg．bw），其它两组以等量生理盐水代替。40min后，制备肝、肾、心肌、肺组织匀浆，检测各器官组织匀浆NO含量及NOS活性的变化。结果模型组肝、肾、心肌、肺组织匀浆NO含量及NOS活性均显著高于对照组（P〈0．01～0．05）；夏至草组各器官组织匀浆NO含量及NOS活性显著低于模型组（P〈0．01～0．05），且各指标与对照组无统计学意义（P〉0．05）。结论夏至草醇提物减轻大鼠重症失血性休克后器官损伤的机制与降低NO的生成和释放有关。     

急性应激时大鼠脑内一氧化氮及一氧化氮合酶的变化

目的：探讨急性应激状态下脑内一氧化氮（NO）含量和一氧化氮合酶（NOS）活性的变化及意义。方法：采用放免法测定强迫游泳应激后1、3小时的大鼠额叶、海马、中脑和下丘脑内NO含量和NOS活性。结果：应激结束后1小时，海马和下丘脑内NO含量和NOS活性均显著增高（t分别为2．32、2．61，P均＜0．05）。应激结束后3小时，额叶、海马、中脑和下丘脑内NO含量均显著增高（t分别为3．57、4．26、3．88、4．93，P均＜0．01），NOS活性均显著性增高（t分别为2．32、2．61，P均＜0．05）。结论：急性应激状态下，各脑区的NOS活性增加，产生的NO可能介导了神经毒性作用。     

一氧化氮合酶抑制剂对大鼠结肠炎损伤的影响

目的：了解一氧化氮合酶抑制剂L－精氨酸甲酯（L-NAME）对大鼠结肠炎损伤的影响。方法：将实验大鼠随机分为对照组、损伤组、NAME1、NAME2、NAME3（即N1、N2、N3）干预组。采用三硝基苯磺酸（TNB）30 mg+50%乙醇0.25 mL给大鼠灌肠复制结肠炎模型，并检测各组的溃疡指数（UI）、一氧化氮（NO）、MDA含量及GSH活性。结果：N1、N2、N3组的NO、UI、MDA值低于损伤组，GHS值高于损伤组，对照组的损伤不明显。相关分析表明，NO含量与MDA含量呈正相关，与GSH活性呈负相关。结论：在结肠炎症反应中，NO过量生成具有损伤作用，L－NAME通过抑制NOS活性，减少NO及自由基的生成，具一定的抗损伤作用。     

尿酸对ECV304细胞的NO-NOS通路及ADMA-DDAH系统的影响

目的：观察尿酸（uric acid，UA）对ECV304细胞的NO-NOS通路及ADMA-DDAH系统的影响。 方法： ①浓度依赖性分组：对照组、UA 200 μmol/L（UA2）组、UA 400 μmol/L（UA4）组、UA 600 μmol/L（UA6）组与ECV304细胞共同孵育24 h。②时间依赖性：UA6组分别观察1、3、5、7 d。检测培养液NO2-/NO3-浓度、NOS活性、非对称二甲基精氨酸（ADMA）浓度、二甲基精氨酸二甲胺水解酶（DDAH）活性以及SOD活性和Ang Ⅱ浓度，细胞裂解液DDAH表达。 结果： ① 3种浓度UA组NO2-/NO3-明显高于对照组，NOS、DDAH、SOD活性则在UA4、UA6两组明显高于对照组，而ADMA浓度在UA4、UA6两组降低，Ang Ⅱ浓度和DDAH表达则无显著差异。② UA6组各时段NO2-/NO3-浓度和NOS、DDAH、SOD活性均高于相应对照组，而ADMA浓度低于对照组；Ang Ⅱ浓度、DDAH表达则无明显差异。除NOS活性在第7 d明显下降外，其余指标在不同时段组没有明显的差异。 结论： ① 短期UA刺激使ECV304细胞分泌NO2-/NO3-增多，且呈浓度依赖，无时间依赖。② UA通过增加DDAH活性、加速ADMA的降解,使NOS活性增加而致NO2-/NO3-生成增多。③尿酸使SOD活性增加而不增加AngⅡ浓度。     

非对称性二甲基精氨酸保护PCI2细胞拮抗谷氨酸兴奋性毒性的损伤作用

目的：探讨一氧化氮合酶（NOS）抑制剂-非对称性二甲基精氨酸（ADMA）对谷氨酸（Glu）兴奋性毒性损伤PCI2细胞的影响及其机制。方法：用不同浓度的谷氨酸处理PCI2细胞，建立谷氨酸兴奋性神经毒性损伤细胞的实验模型；应用四甲基偶氮唑蓝（MTF）比色法检测细胞存活率；乳酸脱氢酶（LDH）释放试验评价细胞的损伤程度；双氢罗丹明123（DHR）染色后流式细胞仪（FCM）检测细胞内活性氧（ROS）水平；应用试剂盒及分光光度计测定NOS活性和NO水平。结果：谷氨酸（1—6mmol／L）处理PC12细胞24h，可呈剂量依赖性地降低PC12细胞的存活率；在谷氨酸作用PCI2细胞前30min给予ADMA，可明显地抑制谷氨酸引起的细胞存活率降低及LDH释放增加，减少谷氨酸引起的细胞内ROS堆积，抑制谷氨酸过度激活NOS和增加NO的生成。结论：ADMA能显著地减弱谷氨酸对PC12细胞的兴奋性毒性损伤作用；其作用机制可能与抑制NOS活性，减少NO生成，进而减轻细胞内ROS的堆积有关。     

低糖诱导人脐静脉内皮细胞一氧化氮与活性氧变化的研究

目的观察低浓度葡萄糖对人脐静脉内皮细胞一氧化氮（NO）与活性氧（ROS）变化的影响。方法以体外培养人脐静脉内皮细胞株HUVEC-12为研究对象,将实验分为正常对照组（5.5mmol/L葡萄糖）、低糖组（2.8mmol/L葡萄糖）、无糖组（0mmol/L葡萄糖）。分别用2.8、0mmol/L葡萄糖干预HUVEC-12细胞,经过1、2、4、12h后,硝酸还原酶法测定NO产量,化学比色法测定一氧化氮合成酶（NOS）活性,Dihydroethidium荧光探针法测定细胞内ROS水平。结果与正常对照组相比,低糖组与无糖组NO水平降低（P〈0.01）,NOS活性下降（P〈0.01）,细胞内ROS水平升高（P〈0.01）,均呈剂量依赖关系。同一浓度组内随着时间的延长,内皮细胞NO水平、NOS活性进一步降低（P〈0.01）,ROS水平进一步升高（P〈0.05）,各指标都具有浓度和时间依赖性。结论低糖可导致内皮细胞功能障碍,NO水平降低,NOS活性下降,其机制可能与低糖导致内皮细胞氧化应激损伤有关。     

束缚应激对大鼠血小板-氧化氮释放的影响

目的 观察急性应激对大鼠血小板一氧化氮(NO)释放的影响及其机制.方法 大鼠浸水-束缚应激(WRS)2、4和8 h,以胃溃疡指数(UI)作为应激损伤的标识,采用Greiss法测定血小板孵育液中亚硝酸盐(NO2-)含量;同位素法测其一氧化氮合酶(NOS)活性和L精氨酸(L-Arg)转运量.结果 WRS 2 h血小板L-Arg转运量、NOS活性和孵育液NO2-含量较对照组显著增加,但随应激时间延长,其呈下降趋势,应激8 h时均显著低于对照组,胃溃疡逐渐加重.结论 WRS应激早期阶段可上调血小板L-Arg/NO通路,促进血小板NO生成;长时间应激下调L-Arg/NO通路,减少NO释放.     

GnRH agonist-suppressed expression of nitric oxide synthases and generation of peroxynitrite in adenomyosis

Because overproduction of nitric oxide (NO) and peroxynitrite is known to cause tissue injury, the expression of NO synthases (NOS) and generation of peroxynitrite were investigated in adenomyosis. Immunoreactivities to endothelial and inducible NOS demonstrated phase-dependent changes in normal endometrium, and in eutopic endometrium of adenomyosis. However, NOS were expressed throughout the menstrual cycle in ectopic endometrium from the majority of patients with adenomyosis. Nitrotyrosine, a footprint of peroxynitrite, was detected concomitantly with NOS protein. This suggested that high doses of NO and superoxide are produced in the ectopic endometrium, presumably by stimulation with bioactive molecules such as cytokines and growth factors. The expression of NOS and generation of peroxynitrite were markedly reduced by administration of gonadotrophin-releasing hormone agonists (GnRHa). The suppression of serum concentrations of nitrite/nitrate, stable metabolites of NO, by long-term administration of GnRHa was also demonstrated. The suppression of synthesis of NO and/or peroxynitrite may be part of both the therapeutic and adverse effects of GnRHa therapy.     

Expression of nitric oxide synthase and effect of substrate manipulation of the nitric oxide pathway in mouse ovarian follicles

BACKGROUND: Nitric oxide (NO) is a cell messenger with multiple actions in different biological systems, implicated in the control of follicle and oocyte function. NO is formed from L-arginine by isoforms of nitric oxide synthase (NOS) via NG-hydroxy-L-arginine, with L-citrulline as a byproduct. This study aimed to show how modulation of NO by manipulating NOS substrates would affect mouse follicle growth and ovulation in vitro, where vascular effects of NO are attenuated. METHODS: Immunohistochemistry [endothelial (eNOS) and inducible (iNOS)] and in situ hybridization (iNOS) were applied on mouse ovaries. Cultured follicles were also stained for iNOS by immunohistochemistry. For follicles cultured in the presence or absence of L-arginine, the ability of L-citrulline or NG-hydroxy-L-arginine to substitute for L-arginine was assessed in terms of follicle growth and ovulation. RESULTS: iNOS and eNOS were localized in oocytes and theca, with some staining in granulosa. iNOS mRNA occurred predominantly in granulosa and oocyte. Omission of L-arginine significantly reduced follicle survival and ovulation. Partial compensation for L-arginine withdrawal was achieved with L-citrulline and NG-hydroxy-L- arginine. Specific abnormalities of follicle growth were noted. CONCLUSIONS: NOS is present in mouse follicles, and its action is necessary at a local level for normal follicle development in vitro. Reduced growth, persistent basement membranes and reduced ovulation were associated with in vitro disruption of NO.     

Nitric oxide generation from hydroxylamine in the presence of neutrophils and in the cell-free system

Conversion of hydroxylamine (HA) to nitric oxide (NO) has been studied in the presence or absence of human neutrophils with or without myristate acetate phorbol (PMA), catalase (CAT), hydrogen peroxide (H2O2), and superoxide dismutase (SOD) and nitric oxide synthase (NOS) inhibitors. The generation of NO from HA in the presence of neutrophils was higher than in the cell-free system. We found that catalase did not influence the nitrite generation from HA in the cell-free system and in the presence of neutrophils. The H2O2 enhanced the NO generation from HA in the presence of neutrophils only. When catalase and H2O2 were added together, a high increase of NO generation from HA in both systems was observed. The addition of SOD decreased whereas addition of PMA enhanced the NO generation from HA in the presence of neutrophils. The presented data show the possible role of oxygen radicals in the decomposition of HA to NO. The addition of NOS inhibitors to the culture of neutrophils decreased the generation of nitrite from HA. Our results suggest that NO generation from HA, which is an intermediate in NO production from L-arginine, may be supported by an enzymatic pathway in which cellular NO synthase is involved.     

Differential regulation of nitric oxide synthase isoforms in experimental acute chagasic cardiomyopathy

We have previously demonstrated induction and high level expression of IL-1beta, IL-6 and tumour necrosis factor-alpha in the myocardium during the acute stage of experimental Trypanosoma cruzi infection (Chagas' disease). The myocardial depressive effects of these cytokines are mediated in part by the induction of nitric oxide synthase (NOS), production of nitric oxide (NO) and formation of peroxynitrite. In this study we investigated the expression, activity and localization of NOS isoforms, and the levels of NO, malondialdehyde (a measure of oxidative stress), and peroxynitrite in rats at 1.5, 5, 10 and 15 days after infection with T. cruzi trypomastigotes. The myocardial inflammatory infiltrate and number of amastigote nests increased over the course of infection. A significant increase in tissue nitrate + nitrite levels, NOS2 mRNA, and NOS2 enzyme activity was observed at all time points in the infected compared with uninfected animals. The enzyme activity of constitutive NOS, tissue malondialdehyde levels, and NOS3 mRNA levels was only transiently increased after infection. The protein levels of the NOS isoforms paralleled their mRNA expression. While no positive nitrotyrosine immunoreactivity was detected in control myocardium, its levels increased in infected animals over time. Thus, by 1.5 days post-infection, when no parasite or immune cell infiltration could be detected, the myocardium expressed high levels of NOS and NO metabolites. Nevertheless, the early production of NO in the myocardium was not sufficient to clear the parasites.     

一氧化氮合酶抑制物对大鼠离体乳头肌收缩力的影响及其机制

目的:探讨一氧化氮合酶(NOS)抑制物对电刺激大鼠离体左心室乳头肌收缩力的影响及其机制。方法:制备大鼠离体左心室乳头肌条,用Muscle Research System记录电刺激(频率1 Hz、波宽5 ms)诱导心肌收缩张力。结果:与正常对照组比较,用30μmol/L内源性NOS抑制物非对称二甲基精氨酸(asymmetric dimethylarginine,ADMA)孵育乳头肌60 min后,肌条对电刺激收缩张力明显降低;用相同浓度的外源性NOS抑制物NG-硝基-L-精氨酸孵育60 min,均可产生与ADMA相似的抑制作用。用1 mmol/L一氧化氮(NO)合成前体L-精氨酸或10μmol/L NO供体硝普钠预孵育肌条15 min,再与ADMA共孵育60 min,均可逆转ADMA对心肌收缩的抑制作用。用10μmol/L蛋白激酶C抑制剂chelerythrine或抗氧化剂N-乙酰半胱氨酸预处理,亦可逆转ADMA的抑制作用。结论:NOS抑制物对电刺激大鼠离体左心室乳头肌收缩具有抑制作用,可能是由于减少NO生成、活化蛋白激酶C、使氧化应激增加所致。     

一氧化氮途径在大鼠肝移植缺血再灌注损伤中的作用

本实验应用三袖套法大鼠原位肝移植模型,探讨一氧化氮途径在大鼠原位肝移植缺血再灌注损伤中对移植肝的功能作用及可能机制。加强一氧化氮途径能显著延长受体的存活率,改善肝功能及抑制肿瘤坏死因子（Ｔｈ卜ａ）的合成与表达;而抑制ＮＯ合成则能明显降低术后受体存活率、加剧肝功能恶化,上调ＴＮＦ－ａ及Ⅰ型细胞间粘附分子（ＩＣＡＭ－１）的表达。提示：ＮＯ途径很可能是肝移植缺血再灌注损伤的关键因素。     

一氧化氮、一氧化氮合酶和心脏功能

一氧化氮合酶(nitric　oxide synthase,NOS)催化L-精氨酸的氧化反应生成L-胍氨酸和一氧化氮(nitric oxide,NO)。其产物NO可通过依赖cGMP(环磷酸鸟苷)途径与非依赖cGMP途径发挥其复杂的生理学功能,如在心血管系统具有维持血管张力、调节血压,抑制血管平滑肌细胞迁移、增生,抑制血小板聚集与白细胞对血管壁的粘附以及调节影响心肌收缩与舒张功能的作用,并参与心率变异调节功能。本文就3种NOS同工酶的基因及其基因表达调节及影响因素进行简要综述。着重介绍nNOS1的心脏自主神经调节机制,iNOS对心脏收缩抑制以及心脏保护与损伤的双重作用,并对eNOS参与心功能调节的机制及其它生理、病理学等方面研究进展进行综述。     

败血症休克大鼠血管L-精氨酸/一氧化氮途径的变化

目的:观察败血症休克大鼠主动脉内膜、中膜和外膜一氧化氮合成途径的改变。方法:雄性Wistar大鼠盲肠结扎并穿孔复制败血症休克模型,分别测定假手术组、早期休克组和晚期休克组大鼠主动脉内膜、中膜和外膜的亚硝酸盐(NO^-₂)含量、一氧化氮合酶(NOS)活性及L-精氨酸(L-Arg)转运;免疫组化染色检测诱导型一氧化氮合酶(iNOS)在主动脉各层的分布。结果:早期及晚期败血症休克大鼠主动脉内膜产生的NO^-₂含量、NOS活性及L-Arg转运速率均低于假手术组,而中膜和外膜的NO^-₂、NOS活性及L-Arg转运速率则显著高于假手术组,外膜增加的程度尤为显著。免疫组织化学染色显示,败血症休克时血管中膜和外膜尤其是外膜iNOS阳性染色明显较强。结论:败血症休克时血管内膜NO合成受到抑制,而中膜和外膜NO合成显著增强,这一改变与休克状态下血管中L-Arg转运、iNOS表达及其活性的变化有关。