神经型一氧化氮合酶羧基末端结合配体CAPON的研究进展

正内皮衍生小分子气体一氧化氮(nitric oxide,NO)因阐明了NO在心血管系统中是具有重要调节作用。随后的研究揭示了NO参与多种病理生理过程,包括血管舒张、神经传递、巨噬细胞街道的细胞毒性、胃肠道平滑肌舒张及支气管扩张~[1]。在生物体内,NO的生成过程需要关键酶一氧化氮合酶(nitric oxide synthase,NOS)的参与,将L-精氨酸(L-arginine,L-Arg)和分子氧作为底物,由还原型烟酰胺腺嘌呤二核苷酸     

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。     

内源性一氧化氮在急性高原病中的研究进展

1一氧化氮(nitric oxide,NO)与内源性一氧化氮(endogenous NO,eNO) NO是具有调节血管张力、血流等众多生物学作用的脂溶性气体信号分子,eNO是由L-精氨酸(L-arginine,L-Arg)经过体内一氧化氮合酶[nitric oxide synthase,NOS;主要有神经源型(neuronal NOS,nNOS)、诱导型(inducible NOS,iNOS)和内皮源型(endothelial NOS,eNOS)3种]催化合成的,广泛存在于全身组织[1].NO通过一些生物分子和细胞间相互作用参与机体的保护、调节及逆转等生理过程[2].近年来的研究发现NO在调节血管张力、抑制炎症以及抗动脉粥样硬化中发挥关键作用[1-2].     

一氧化氮、一氧化氮合酶与视网膜病变

1980年Furchgott和Zzwadzki^[1]发现血管内皮细胞能产生并释放内皮衍生舒张因子（endothelium-derived relaxing factor,EDRF)，又证实其中含有一氧化氮（nitric oxide,NO).Palmaer^[2]等进一步证实EDRF细胞学本质即为NO，Bredt(1991年）[3]首次成功地克隆了一氧化氮合酶（nitric oxide,NOS)，从而将NO的研究推进到细胞分子水平，有关NO及其在医学各领域的应用及研究迅速展开，目前研究已表明，NO是一种内源性血管扩张剂，炎症介质，血小板聚焦抑制因子和神经递质^[4]，本文就NO与眼部疾病的关系作一综述。     

内皮型一氧化氮合酶基因转染对血管损伤后新生内膜增生的影响

背景：一氧化氮能够抑制血管平滑肌细胞的迁移和增殖,而一氧化氮合酶是其合成的关键酶,有关一氧化氮合酶基因体内转染对平滑肌细胞及动脉粥样硬化血管损伤后内膜增生影响少有报道。 目的：观察内皮型一氧化氮合酶 (endothelial nitric oxide synthase,eNOS)基因体内局部转染对动脉粥样硬化大鼠血管损伤后新生内膜增生的抑制作用。 方法：建立动脉粥样硬化Wistar大鼠颈动脉球囊损伤模型,建模后随机分成空白对照组、AdCMV-lacz对照组和AdCMV-eNOS组,分别将PBS,AdCMV-lacz和AdCMV-eNOS体内转染至以上3组大鼠的损伤血管壁。转染2周后培养并鉴定损伤局部平滑肌细胞,并用RT-PCR法检测各组损伤及转染后血管平滑肌细胞eNOS mRNA的表达,同时观察转染后不同时期新生内膜增生的影响。 结果与结论：AdCMV-eNOS组的颈总动脉血管平滑肌细胞可表达eNOS mRNA。3组大鼠转染后1和3个月,AdCMV-eNOS组内膜/中膜面积比值低于空白对照组和AdCMV-lacz对照组(P < 0.01)。结果显示,eNOS基因体内转染损伤后血管可以抑制血管新生内膜增生,减少再狭窄发生率。     

一氧化氮在新生儿的临床应用

新生儿低氧血症是由多种原因引起,肺动脉高压在低氧血症起重要作用.肺血管阻力增加,心脏排出量减少,受损的组织释放氧,其结果是多系统器官功能障碍.肺血管阻力增加,部分原因是受损的血管内皮减少了内源性一氧化氮(nitric oxide,NO)合成,最终导致局部血管收缩.NO吸入(inhaled nitric oxide,iNO)代替缺乏的内源性NO[1],目前已应用于成人呼吸窘迫综合征,新生儿持续肺动脉高压(PPHN),早产儿呼吸窘迫综合征(RDS)和儿童急性呼吸窘迫综合征(ARDS).     

一氧化氮和内质网应激

一氧化氮(nitric oxide,NO)是一种重要的多功能内源性气体分子,能舒张血管、参与免疫反应和作为一种神经递质在神经元的信息传递中发挥重要作用,因而广泛参与机体心血管系统、神经系统和免疫系统等的生理和病理调节[1].     

一氧化氮及一氧化氮合酶在心血管系统中的研究进展

自1987年证实内皮细胞(endo thelial cell,EC)合成并释放一氧化氮(Nitric oxide,NO)以来,NO在心血管系统中的作用即倍受重视。目前的研究表明,一氧化氮及一氧化氮合酶(NO/nitric oxide sgnghase,NOS)不仅在心血管、免疫、神经系统中有着广泛的生理功能,而且参与多种疾病的发生和发展。     

氧化型低密度脂蛋白对人脐静脉内皮细胞ICAM-1及NO表达的影响

目的研究氧化型低密度脂蛋白(oxidized low density liprotein,ox-LDL)对脐静脉内皮细胞细胞间黏附分子-1(intercellular adhesion molecule-1,ICAM-1)及一氧化氮(nitric oxide,NO)表达的影响.方法采用细胞ELISA法测定细胞表面ICAM-l的含量,硝酸还原酶法测定细胞培养上清液中NO,免疫组化法结合图象分析测定细胞一氧化氮合酶(nitric oxide synthase,NOS)含量.结果 ox-LDL可明显增加脐静脉内皮细胞ICAM-l的表达,并减少NO及NOS的表达,且有浓度依赖性,但无明显的时间依赖性.结论 ox-LDL可损害内皮细胞的功能,减少内皮细胞NO、NOS的表达并增加内皮细胞ICAM-1的表达.这可能为ox-LDL促进动脉粥样硬化的机制之一.     

吸入一氧化氮对中枢神经系统的保护作用

<正>一氧化氮(nitric oxide,NO)在哺乳动物体内的作用最早由Furehgott和Zawadzki于1980年发现,后证实血管内皮细胞可合成NO引起血管扩张。外源性吸入NO(inhaled nitric oxide,iN O)于1999年被FDA批准作为新生儿肺动脉高压的治疗用药。目前公认NO为体内生物活性物质,并在中枢神经系统发挥重要的生理功能[1]。近年来iN O在神经损伤中的作用受到广泛关注,本文拟对iN O在中枢神经系统中作用的研究进展作一综述。     

低氧诱导肺血管平滑肌细胞诱生型一氧化氮合酶基因表达

本研究采用原位杂交、免疫组织化学、酶组织化学染色方法从三个层次分别证明低氧诱导大鼠肺血管中膜平滑肌细胞一氧化氮合酶（ＮｉｔｒｉｃＯｘｉｄｅＳｙｎｔｈａｓｅ，ＮＯＳ）的基因和蛋白表达，并使中膜平滑肌细胞具有ＮＯＳ活性；离体培养的肺动脉平滑肌细胞实验也证明低氧使肺动脉平滑肌细胞ＮＯＳ活性增加，ＮＯ生成增多。提示诱生型ＮＯＳ基因可能是一种低氧诱导基因，低氧诱导ＮＯＳ表达可能是细胞感受低氧的一种重要机制。     

Protective role of endothelial nitric oxide synthase

Nitric oxide is a versatile molecule, with its actions ranging from haemodynamic regulation to anti-proliferative effects on vascular smooth muscle cells. Nitric oxide is produced by the nitric oxide synthases, endothelial NOS (eNOS), neural NOS (nNOS), and inducible NOS (iNOS). Constitutively expressed eNOS produces low concentrations of NO, which is necessary for a good endothelial function and integrity. Endothelial derived NO is often seen as a protective agent in a variety of diseases.This review will focus on the potential protective role of eNOS. We will discuss recent data derived from studies in eNOS knockout mice and other experimental models. Furthermore, the role of eNOS in human diseases is described and possible therapeutic intervention strategies will be discussed.     

Blood pressure control in eNOS knock‐out mice: comparison with other species under NO blockade

Changes in arterial blood pressure (ABP) lead to changes in vascular shear stress. This mechanical stimulus increases cytosolic Ca²⁺ in endothelial cells, which in turn activates the endothelial isoform of the nitric oxide synthase. The subsequently formed NO reaches the adjacent vascular smooth muscle cells, where it reduces vascular resistance in order to maintain ABP at its initial level. Thus, NO may play an important role as a physiological blood pressure buffer. Previous data on the importance of eNOS for blood pressure control are reviewed with special emphasis on the fact that endogenous nitric oxide can buffer blood pressure variability (BPV) in dogs, rats and mice. In previous studies where all isoforms of the nitric oxide synthase were blocked pharmacologically, increases in blood pressure and variability were observed. Thus, we set out to clarify which isoform of the nitric oxide synthase is responsible for this BPV controlling effect. Hence, blood pressure control was studied in knock‐out mice lacking specifically the gene for endothelial nitric oxide synthase with their respective wild‐type controls. One day after surgery, under resting conditions, blood pressure was increased by 47 mmHg (P < 0.05), heart rate was lower (?77 beats min^?1, P < 0.05), and BPV doubled (P < 0.05). Based on these results, we conclude that chronic blood pressure levels are influenced by eNOS and that there is a blood pressure buffering effect of endogenous nitric oxide which is mediated by the endothelial isoform of the nitric oxide synthase.     

Endothelial dysfunction and vascular disease – a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best‐characterized endothelium‐derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium‐dependent hyperpolarizations, EDH‐mediated responses). As regards the latter, hydrogen peroxide (H₂O₂) now appears to play a dominant role. Endothelium‐dependent relaxations involve both pertussis toxin‐sensitive G_i (e.g. responses to α₂‐adrenergic agonists, serotonin, and thrombin) and pertussis toxin‐insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low‐density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin‐sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂O₂), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium‐derived contracting factors. Recent evidence confirms that most endothelium‐dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium‐dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium‐dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin‐1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.     

Learning from vascular remodelling

The positioning of a hollow silicone collar around the carotid artery of a rabbit induces many changes of early atherosclerosis including intimal proliferation of smooth muscle cells. This occurs below an intact endothelium indicating that endothelial damage is not necessary for smooth muscle cell proliferation. The endothelium may in fact produce substances that control processes occurring in the intima. Vascular endothelial growth factor (VEGF) is an angiogenic agent that is produced by cultured vascular smooth muscle cells. The combination of hypoxia and factors such as platelet-derived growth factor, tumour necrosis factor alpha, basic fibroblast growth factor, and interleukin-1β lead to synergistic production of VEGF by cultured smooth muscle cells. VEGF receptors are present predominantly on the endothelium and may be an important target for modulating the response to damage, hypoxia and inflammation. Transfection of the gene for VEGF resulted in inhibition or regression of intimal hyperplasia induced by the silicone collar in the rabbit. Studies suggest that the two mediators responsible for this inhibition of smooth muscle cell proliferation are nitric oxide and prostacyclin, which are produced by cultured endothelial cells incubated with VEGF. Thus, VEGF produced by smooth muscle cells in response to hypoxia, damage or inflammation, acts on specific endothelial receptors to produce nitric oxide and prostacyclin, which inhibit smooth muscle cell proliferation. Failure of this process could give rise to intimal hyperplasia. Early clinical studies of VEGF transfection from the outside of human arteries using a biodegradable collar are in progress.     

Endothelium-dependent vascular smooth muscle relaxation activated by electrical field stimulation

Electrical field stimulation (EFS) produced relaxation of contracted arteries in the presence of tetrodotoxin. In the present study the contributions of vascular smooth muscle repolarization and endothelial release of nitric oxide to the relaxation response were investigated using isolated rat tail arteries and bovine aortic endothelial cells (BAEC). Intact and endothelium-denuded rings or intact, pressurized artery segments were contracted with either phenylephrine or KCl prior to EFS. Electrical field stimulation induced a small relaxation in denuded, phenylephrine contracted rings that was inhibited by the K⁺ channel blockers glibenclamide and BaCl₂ In intact, phenylephrine-contracted rings, EFS induced significantly larger relaxations that were inhibited by BaCl₂ as well as by _LNAME, an inhibitor of nitric oxide (NO) synthase, and methylene blue. EFS-induced relaxations were completely inhibited when BaCl₂ and _L-NAME or methylene blue were combined. Exposure to Ca2^+- free buffer or diltiazem also inhibited the relaxation while ascorbic acid had no effect. Effluent from electrically stimulated BAEC caused denuded, phenylephrine contracted rings to relax. The ability of the effluent to cause relaxation was almost completely blocked by exposure of the BAEC to _L-NAME or exposure of the recipient vascular smooth muscle to methylene blue; glibenclamide caused partial blockade. Simultaneous measurements of membrane potential and intraluminal pressure showed that EFS-induced membrane repolarization preceded changes in steady-state pressure. It is concluded that (1) the smooth muscle cells possess an endothelium-independent repolarization mechanism, (2) EFS causes endothelial cells of intact arteries to release NO and possibly a hyperpolarizing factor, (3) EFS of BAEC causes release of NO, and (4) EFS-induced relaxation depends on vascular smooth muscle cell membrane repolarization and endothelial cell release of vasoactive substances.     

Large arterioles in the control of blood flow: role of endothelium‐dependent dilation

Although it is generally assumed that small arterioles form the major site of vascular resistance, microcirculatory studies revealed that 40–55% of the total network resistance can reside in large arterioles and small arteries. Thus, the mechanisms that control smooth muscle tone in these vessels have a major impact on the overall conductance of the vascular network. These control mechanisms are different from those in small arterioles: Aside from an apparently reduced sensitivity to metabolites, the large resistance vessels are normally too far away from the capillary areas which they feed to be reached by diffusing metabolites from dependent cells within a reasonable period of time. Rather, recent intravital microscopic studies suggest that large resistance vessels are under tight control of endothelial factors such as nitric oxide and endothelium‐derived hyperpolarising factor (EDHF). Nitric oxide opposes myogenic constrictions of large arterioles that potentially would impair tissue perfusion and oxygenation. Moreover, nitric oxide and EDHF play an important role in the co‐ordination of large and small resistance vessel behaviour that is pivotal for the adaptation of blood flow to altered tissue oxygen demands.     

Endothelial dysfunction and vascular disease

The endothelium can evoke relaxations (dilatations) of the underlying vascular smooth muscle, by releasing vasodilator substances. The best characterized endothelium‐derived relaxing factor (EDRF) is nitric oxide (NO). The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium‐dependent hyperpolarizations, EDHF‐mediated responses). Endothelium‐dependent relaxations involve both pertussis toxin‐sensitive G_i (e.g. responses to serotonin and thrombin) and pertussis toxin‐insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. The release of NO by the endothelial cell can be up‐regulated (e.g. by oestrogens, exercise and dietary factors) and down‐regulated (e.g. oxidative stress, smoking and oxidized low‐density lipoproteins). It is reduced in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively loose the pertussis toxin‐sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and causing endothelium‐dependent hyperpolarizations), endothelial cells also can evoke contraction (constriction) of the underlying vascular smooth muscle cells by releasing endothelium‐derived contracting factor (EDCF). Most endothelium‐dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells. EDCF‐mediated responses are exacerbated when the production of NO is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium‐dependent vasodilatations in aged subjects and essential hypertensive patients.     

阿司匹林对高糖和高胰岛素诱导的血管平滑肌细胞增殖的影响

目的：探讨阿司匹林对高糖和高胰岛素诱导的大鼠血管平滑肌细胞(VSMCs)增殖的影响及相关机制。方法：组织贴块法培养原代大鼠胸主动脉平滑肌细胞, 用高糖和高胰岛素诱导细胞增殖。实验设对照组、高糖和高胰岛素组(HGI)、HGI +阿司匹林（0.5,1.25,2.50 mmol/L）组。采用四甲基偶氮唑盐(MTT)比色法测定VSMCs增殖;一氧化氮(NO)试剂盒检测培养基上清液NO含量;流式细胞仪检测细胞周期。结果：阿司匹林呈剂量依赖性地抑制高糖和高胰岛素诱导的动脉VSMCs增殖,最大抑制作用出现在2.50 mmol/L阿司匹林培养5 d时(P<0.01);阿司匹林（2.50 mmol／L）干预可使高糖和高胰岛素导致下降的NO含量上升 (P<0.01);与高糖和高胰岛素组比较,阿司匹林(2.50 mmol/L)可使细胞静止期/DNA合成前期(G0/G1期)的VSMCs所占比例显著升高(P<0.05),而DNA合成期(S 期)细胞所占比例显著降低(P<0.05)。结论：阿司匹林能呈剂量依赖性地抑制高糖和高胰岛素诱导的动脉VSMCs的增殖,抑制细胞在G0/G1期,促进动脉平滑肌细胞NO的产生。