Atherosclerosis suppression in the left anterior descending coronary artery by the presence of a myocardial bridge: an ultrastructural study

Ultrastructural changes of the left anterior descending coronary artery (LAD) by the presence of myocardial bridge (MB) were studied. In contrast with various atherosclerotic lesions in the intima both proximal to MB and in the whole length of the LAD having no MB, intimal thickness beneath MB was remarkably thin. Neither lipid deposition nor foam cells were present there even in the aged. The intima beneath MB consisted of only normal smooth muscle cells (SMCs) in some layers. Collagen fibrils loosely stuffed among SMCs showed a spiraled appearance. The intima distal to MB was thicker than that beneath MB. Modified SMCs were present along with normal SMCs, and foam cells were intermingled with them. By scanning electron microscopy, endothelial cells proximal to MB were arranged in a pavement-like appearance, and they were polygonal and flat. Endothelial cells beneath MB became spindle-shaped and regularly engorged along the direction of blood flow. Such regularity was lost in endothelial cells distal to MB. These endothelial changes indicate that the intima beneath MB is stressed by high shear and that intima proximal or distal to MB is stressed by low shear. It is, thus, suggested that alteration of hemodynamic factors that arise from contraction of MB greatly affects the evolution of atherosclerosis through the regulation of intimal lipid infiltration within the LAD.     

Endothelial expression of endothelial nitric oxide synthase and endothelin-1 in human coronary artery disease. Specific reference to underlying lesion.

Nitric oxide and endothelin-1 (ET-1) are two major endothelium-derived factors with opposing effects on the function and structure of the vessel wall. We investigated the endothelial expression of endothelial nitric oxide synthase (eNOS) and ET-1 in coronary artery disease (CAD) with special reference to the types of underlying lesions. Immunohistochemistry and in situ hybridization were performed in coronary arteries of heart transplant recipients with (n = 16) and without (n = 11) CAD. All coronary arteries from patients with CAD (n = 23) had concentric fibrous or advanced lesions, whereas most of the arteries (25 of 31) from patients with non-CAD showed normal appearance (myointimal thickening only) or eccentric lesions alone. Normal coronary segments consistently showed apparent endothelial immunoreactivity and mRNA signals for both eNOS and ET-1. In atherosclerotic coronary segments, endothelial expression of eNOS and ET-1 was reduced in most lesion sites, particularly in severe subendothelial lesions with dense fibrosis or macrophage accumulation, but not with smooth muscle cells only. Conversely apparent ET-1, compared with weak or focal eNOS signals, were more frequently seen in coronary segments with concentric severe lesions from CAD but not non-CAD patients. Immunoreactivity and mRNA signals for ET-1 were co-localized with those for ET converting enzyme-1 in the endothelium, as well as in the underlying macrophages and smooth muscle cells. These results indicate the presence of differential endothelial expression of eNOS and ET-1 in diseased human coronary arteries with severe concentric atherosclerotic lesions, a finding that was rare in atherosclerotic lesions of coronary arteries of non-CAD patients. Altered expression of endothelium-derived factors may contribute to abnormality of coronary vasomotor tone and the formation of subendothelial lesions in CAD.     

The effects of a myocardial bridge on coronary atherosclerosis and ischaemia

The term myocardial bridge (MB) describes the surprisingly common situation in which part of the left anterior descending coronary artery (LAD), running in epicardial adipose tissue, is covered by a bridge of myocardial tissue. The presence of an MB may influence arterial tissue through the alteration of haemodynamic forces by the myocardial contraction of the bridge itself. Histopathologically and ultrastructurally, any manifestations of atherosclerosis elsewhere in the LAD are suppressed in the intima beneath the MB. By scanning electron microscopy, abrupt changes in endothelial cell morphology indicate that the intima beneath the bridge is protected by haemodynamic factors. Furthermore, the closer the bridge to the left coronary ostium, the greater the extent of proximal intimal thickening. In parallel with this, considering the occurrence of myocardial infarction in cases of proximal MB together with previous reports on relationships between MB and coronary ischaemia, it appears that anatomical characteristics such as the location, length, and thickness of the MB have a bearing on the effects of this abnormality. When the pathologist examines the heart at autopsy, this quite common condition should be borne in mind, in view of its potential but complex relationship to atherosclerosis and ischaemic heart disease. © 1998 John Wiley & Sons, Ltd.     

西拉普利对缺氧大鼠肺血管内皮功能失调的改善作用

目的:进一步了解西拉普利(cilazapril)对缺氧大鼠肺血管内皮(EC)功能失调的改善作用。方法:采用生化、放射免疫、透射电镜和血流动力学技术研究缺氧肺血管EC结构和功能状况。结果:(1)缺氧大鼠肺血管EC超微结构发生变化, 细胞受损。(2)血管EC内皮依赖性舒缩功能失调, 表现为血浆NO、SOD和肺组织eNOS显著降低, 血浆ET－1、ACE和MDA显著增加, 这些舒缩因子与肺动脉平均压(mPAP)呈显著正相关或负相关。(3)cilazapril显著降低ET－1水平和ACE活性, 同时增加NO水平和eNOS及SOD活性, 减轻EC结构受损。结论:缺氧大鼠存在肺血管EC结构受损和功能失调是参与缺氧性肺动脉高压(PH)发病机理之一。Cilazapril能够减轻EC的损伤, 改善EC的分泌功能, 对PH防治有一定作用。     

肢体缺血预适应的小肠保护作用及与一氧化氮/内皮素-1的关系

目的：观察一氧化氮/内皮素-1(NO/ET-1)失衡与肢体缺血再灌注(I/R)后小肠损伤的关系，以及缺血预适应(IPC)对NO/ET-1系统的调节作用。 方法： 雄性Wistar大鼠18只，随机分为对照（control）组，缺血再灌注（IR）组和缺血预适应（IPC+IR）组，每组6只，分别测定血浆和小肠组织二氨氧化酶(DAO)、一氧化氮(NO)、内皮素-1(ET-1)、NO/ET-1比值的含量变化及小肠组织的髓过氧化物酶(MPO)、DNA双链百分率(ratio of DNA chain %)、总一氧化氮合酶（tNOS）、诱导型一氧化氮合酶（iNOS）、结构型一氧化氮合酶（cNOS）的水平；免疫组化法检测小肠组织的诱导型一氧化氮合酶（iNOS）、内皮型一氧化氮合酶（eNOS）的表达。 结果： IR组血浆和小肠组织NO、ET-1，血浆DAO及组织MPO均明显高于对照组，而 NO/ET-1的比值，组织DAO及DNA双链百分率明显少于对照组；小肠粘膜iNOS的表达及总NOS活性高于对照组，cNOS（主要为eNOS）的表达少于对照组。IPC+IR组血浆和小肠组织NO、ET-1，血浆DAO及组织MPO均明显少于IR组，而 NO/ET-1的比值，组织DAO及DNA双链百分率却明显高于IR组；小肠粘膜iNOS的表达及总NOS活性少于IR组，cNOS（主要为eNOS）的表达高于IR组。 结论： 肢体I/R后小肠损伤与NO/ET-1失衡有关，IPC对肢体IR继发的小肠粘膜损伤的拮抗作用可能通过对NO/ET-1系统的调节作用而介导，此时内皮源的NO产生增加，非内皮源的NO产生减少。     

N-乙酰-L-半胱氨酸对慢性间歇性缺氧大鼠血压变化及内皮功能的影响

 目的:观察N-乙酰-L-半胱氨酸(N-acetyl-L-cystein,NAC)对慢性间歇性缺氧（chronic intermittent hypoxia,CIH）大鼠的血压变化及其内皮功能变化,探讨CIH引起高血压的机制。方法:30只健康雄性Sprague-Dawley(SD)大鼠随机分成正常对照组、CIH组(缺氧55 s,复氧 55 s）及NAC干预CIH组（缺氧55 s,复氧55 s,NAC 300 mg·kg-1·d-1,灌胃）。尾套法测量大鼠尾动脉收缩压;实时荧光定量PCR测定胸主动脉内皮型一氧化氮合酶（endothelial nitric oxide synthase, eNOS）和内皮素1（endothelin-1, ET-1）mRNA的表达情况。使用Western blotting方法检测胸主动脉eNOS表达。胸主动脉及血清ET-1水平均采用放射免疫法测定。硝酸还原酶法测定血清中一氧化氮（nitric oxide,NO）含量。分别采用黄嘌呤氧化酶法和硫代巴比妥酸法测定外周血浆超氧化物歧化酶（superoxide dismutase, SOD）和丙二醛（malondialdehyde,MDA）水平。使用化学比色法测定胸主动脉组织匀浆中超氧阴离子(O-·2)含量。结果:CIH组大鼠尾动脉收缩压较对照组升高（P＜0.01）,NAC干预CIH组大鼠的尾动脉收缩压较CIH组显著降低（P＜0.05）。CIH组胸主动脉中eNOS mRNA和蛋白水平以及血清NO水平低于对照组（P＜0.01）,NAC干预组两者表达明显高于CIH组(P<0.05);CIH 组胸主动脉ET-1 mRNA和蛋白水平表达高于对照组（P＜0.01）,而NAC治疗使表达减低(P<0.05）。CIH组血清MDA和ET-1水平以及胸主动脉匀浆O-·2水平均高于对照组（P＜0.01）,而NAC干预组这些指标水平均低于CIH组（均P＜0.05）;CIH组血清SOD活性低于对照组（P＜0.01）,而NAC治疗组SOD活性增加（P＜0.05）。结论: NAC通过减少自由氧的产生,保护主动脉组织内皮功能,从而缓解血压升高,推测氧化应激参与CIH致高血压内皮功能障碍的发生机制。     

切应力通过Pim1/eNOS途径调节人脐静脉内皮细胞NO分泌

目的:探讨层流切应力是否可通过Pim1调节内皮型一氧化氮合酶(eNOS)活性,从而调节血管内皮细胞一氧化氮(NO)分泌。方法:体外原代培养人脐静脉内皮细胞(HUVECs),运用平行平板流动腔系统给HUVECs加载层流切应力(15 dyn/cm^2)。采用Western blot法检测Pim1蛋白表达及eNOS-Ser1177磷酸化水平;硝酸还原酶法检测NO分泌量;利用特异性小干扰RNA(siRNA)转染技术沉默Pim1基因后再检测上述指标的变化。结果:切应力作用HUVECs 15 min,可以显著上调Pim1蛋白表达(P<0.05),同时显著增强eNOS-Ser1177磷酸化水平(P<0.05),伴随HUVECs NO分泌显著增多(P<0.05)。转染siPim1可以抑制切应力诱导的Pim1表达(P<0.05),同时抑制eNOS-Ser1177磷酸化(P<0.05),NO分泌随之显著降低(P<0.05)。结论:流体切应力可能通过Pim1/eNOS途径调节血管内皮细胞NO分泌。     

当归、川芎、红花、人参萃取液对离体培养牛血管内皮细胞一氧化氮合酶的影响

目的：研究以当归、川芎、红花、人参为主要成份的CO2超临界萃取液对低切应力条件下培养的内皮细胞一氧化氮合酶(eNOS)表达的影响；探讨该萃取液改善血管功能、防止动脉粥样硬化的机理。方法：采用Westem blot印迹免疫检测，研究该萃取液对低切应力环境下体外培养的牛血管内皮细胞eNOS表达的影响。结果：低切应力水平下，内皮细胞eNOS表达降低，给予0.5％萃取液1ml(以萃取原液为100％)，eNOS的表达明显增加，并接近在高切应力水平下内皮细胞eNOS的正常表达水平。结论：当归、川芎、红花、人参萃取液可上调低切应力环境下内皮细胞eNOS的表达。     

Association of the endothelial nitric oxide synthase gene polymorphism with risk of coronary artery disease and myocardial infarction in middle-aged men

Nitric oxide (NO), formed by endothelial constitutive nitric oxide synthase (eNOS) maintains endothelium-dependent vasodilatation and also mediates antithrombotic actions. The eNOS gene harbours a common polymorphism in intron 4 (4a/b), and some clinical studies have suggested an association of the rare a-allele with coronary artery disease (CAD) and myocardial infarction (MI). However, contradictory results have also been reported. We studied associations of eNOS polymorphism with CAD and MI in two prospective autopsy series comprising altogether 700 Caucasian Finnish men, who died suddenly. In ANCOVA, no significant differences in areas of atherosclerotic lesions and coronary stenosis percentages were found between men carrying the a-allele (ba+aa) compared with those homozygous for the b-allele. Subjects with the a-allele had significantly lower risk of MI (odds ratio 0.44, 95% confidence interval 0.25-0.77, P=0.004) compared with those carrying the bb genotype. Men with the a-allele also tended to have coronary thrombosis less often (odds ratio 0.43, 95% confidence interval 0.18-1.01, P=0.055). The eNOS gene 4a/b polymorphism was not associated with the extent of coronary atherosclerosis, but the a-allele of the variant seems to protect to some degree against the development of MI.     

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。     

Autophagy Regulates Vascular Endothelial Cell eNOS and ET-1 Expression Induced by Laminar Shear Stress in an Ex Vivo Perfused System

Vascular endothelial cell function responds to steady laminar shear stress; however, the underlying mechanisms are not fully elucidated. In the present study, we examined the effect of steady laminar shear stress on vascular endothelial cell autophagy and endothelial cell nitric oxide synthase (eNOS) and endothelin-1 (ET-1) expression using an ex vivo perfusion system. Human vascular endothelial cells and common arteries of New Zealand rabbits were pretreated with or without rapamycin or 3-MA for 30 min. These were then placed in an ex vivo cell perfusion system or an ex vivo organ perfusion system under static conditions (0 dynes/cm²) or steady laminar shear stress (5 or 15 dynes/cm²) for 1 h. In both ex vivo perfusion vascular endothelial cells and vascular vessel segment, steady laminar shear stress promoted autophagy and eNOS expression and inhibited ET-1 expression. Compared with steady laminar shear stress treatment alone, the pretreatment of autophagy inducer rapamycin obviously strengthened the expression of eNOS and decreased the expression of ET-1 in both the 5 and 15 dynes/cm² treatment groups. Moreover, when pretreated with the autophagy inhibitor 3-MA, the eNOS expression was obviously inhibited and the ET-1 expression was reversed. These findings demonstrate that autophagy is upregulated under steady laminar shear stress, improving endothelial cell maintenance of vascular tone function.     

Cerebroprotection by angiotensin-(1-7) in endothelin-1-induced ischaemic stroke

Activation of angiotensin-converting enzyme 2 (ACE2), production of angiotensin-(1-7) [Ang-(1-7)] and stimulation of the Ang-(1-7) receptor Mas exert beneficial actions in various peripheral cardiovascular diseases, largely through opposition of the deleterious effects of angiotensin II via its type 1 receptor. Here we considered the possibility that Ang-(1-7) may exert beneficial effects against CNS damage and neurological deficits produced by cerebral ischaemic stroke. We determined the effects of central administration of Ang-(1-7) or pharmacological activation of ACE2 on the cerebral damage and behavioural deficits elicited by endothelin-1 (ET-1)-induced middle cerebral artery occlusion (MCAO), a model of cerebral ischaemia. The results of the present study demonstrated that intracerebroventricular infusion of either Ang-(1-7) or an ACE2 activator, diminazine aceturate (DIZE), prior to and following ET-1-induced MCAO significantly attenuated the cerebral infarct size and neurological deficits measured 72 h after the insult. These beneficial actions of Ang-(1-7) and DIZE were reversed by co-intracerebroventricular administration of the Mas receptor inhibitor, A-779. Neither the Ang-(1-7) nor the DIZE treatments altered the reduction in cerebral blood flow elicited by ET-1. Lastly, intracerebroventricular administration of Ang-(1-7) significantly reduced the increase in inducible nitric oxide synthase mRNA expression within the cerebral infarct that occurs following ET-1-induced MCAO. This is the first demonstration of cerebroprotective properties of the ACE2-Ang-(1-7)-Mas axis during ischaemic stroke, and suggests that the mechanism of the Ang-(1-7) protective action includes blunting of inducible nitric oxide synthase expression.     

Endothelin-1 and endothelial nitric oxide synthase immunoreactivity in lymphatic vessels of the uterine broad ligament during the estrous cycle in the pig

Immunohistochemical localization and distribution of endothelin (ET-1) and nitric oxide synthase (eNOS) were investigated in precollector and collector lymphangions of lymphatic vessels leaving the ovary and were found in the vascular subovarian plexus (mesovarium) as well as in those emanating from the oviductal isthmus and uterine horn (mesosalpinx and mesometrium, respectively) forming the paraovarian lymphatic plexus in the broad ligament of the uterus during different phases of the estrous cycle in pigs. The polyclonal antibody for ET-1 and the monoclonal antibody for eNOS isoform were used for studies on the light-microscopic level. Immunoreactivities to both ET-1 and eNOS were observed in the endothelial cell cytoplasm of precollector and collector lymphangions and were not demonstrated in smooth muscle cells of the lymphatics examined. In the endothelium, the intensity of immunostaining for ET-1 and eNOS was found to be estrous phase-dependent and differed between precollector and collector lymphangions. In general, immunoreactivity to ET-1 was more intense in the endothelium of shrunken lymphangions, whereas that for eNOS was more intense in lymphangions with the large lumen. These results suggest that ET-1 and eNOS can play a role in mechanisms regulating the vascular contractile activity promoting lymph flow during the estrous cycle in the porcine broad ligament.     

Effects of pulsatile shear stress on signaling mechanisms controlling nitric oxide production, endothelial nitric oxide synthase phosphorylation, and expression in ovine fetoplacental artery endothelial cells.

During gestation, placental blood flow, endothelial nitric oxide (NO) production, and endothelial cell nitric oxide synthase (eNOS) expression are elevated dramatically. Shear stress can induce flow-mediated vasodilation, endothelial NO production, and eNOS expression. Both the activity and expression of eNOS are closely regulated because it is the rate-limiting enzyme essential for NO synthesis. The authors adapted CELLMAX artificial capillary modules to study the effects of pulsatile flow/shear stress on ovine fetoplacental artery endothelial (OFPAE) cell NO production, eNOS expression, and eNOS phosphorylation. This model allows for the adaptation of endothelial cells to low physiological flow environments and thus prolonged shear stresses. The cells were grown to confluence at 3 dynes/cm2, then were exposed to 10, 15, or 25 dynes/cm2 for up to 24 h and NO production, eNOS mRNA, and eNOS protein expression were elevated by shear stress in a graded fashion (p < .05). Production of NO by OFPAE cells exposed to pulsatile shear stress was de novo; i.e., inhibited by L-NMMA (N(G)-monomethyl-L-arginine) and reversed by excess NOS substrate L-arginine. Rises in NO production at 25 dynes/cm2 (8-fold) exceeded (p < .05) that seen for eNOS protein (3.6-fold) or eNOS mRNA (1.5-fold). Acute rises in NO production with shear stress occurred by eNOS activation, whereas prolonged NO rises were via elevations in both eNOS expression and enzyme activation. The authors therefore used Western analysis to investigate the signaling mechanisms underlying pulsatile shear stress-induced increases in eNOS phosphorylation and protein expression by "flow-adapted" OFPAE cells. Increasing shear stress from 3 to 15 dynes/cm2 very rapidly increased eNOS Ser1177, ERK1/2 (extracellular signal-regulated kinase 1 and 2) and Akt, but not p38 MAPK (p38 mitogen-activated protein kinase) phosphorylation by Western analysis. Phosphorylation of eNOS Ser1177 under shear stress was elevated by 20 min, a response that was blocked by PI-3K (phosphatidylinositol 3-kinase) inhibitors wortmannin and LY294002, but not the MEK (MAPK kinase) inhibitor UO126. Basic fibroblast growth factor (bFGF) enhanced eNOS protein levels in static culture via a MEK-mediated mechanism, but it could not further augment the elevated eNOS protein levels induced by 15 dynes/cm2 shear stress. Blocking of either signaling pathways or p38 MAPK did not change the shear stress-induced increase in eNOS protein levels. Therefore, shear stress induced rapid eNOS phosphorylation on Ser1177 in OFPAE cells through a PI-3K-dependent pathway. The bFGF-induced rise in eNOS protein levels in static culture was much less than those observed under flow and was blocked by inhibiting MEK. Prolonged shear stress-stimulated increases in eNOS protein levels were not affected by inhibition of MEK- or PI-3K-mediated pathways. In conclusion, pulsatile shear stress greatly induces NO production by OFPAE cells through the mechanisms of both PI-3K-mediated eNOS activation and elevations in eNOS protein levels; bFGF does not further stimulate eNOS expression under flow condition.     

Relationship between the G894T polymorphism (Glu298Asp variant) in endothelial nitric oxide synthase and nitric oxide-mediated endothelial function in human atherosclerosis

Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), plays important roles in normal vascular homeostasis, and reduced endothelial NO bioactivity is an important feature of vascular disease states. The Glu298Asp (G894T) polymorphic variant of eNOS has been associated with vascular disease, but functional data are lacking. Accordingly, we examined the relationships between NO-mediated endothelial function, the presence of the eNOS Glu298Asp variant, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations to different agonists were determined in human saphenous veins obtained from patients with coronary artery disease and identified risk factors (n = 104). Patients were genotyped for the eNOS G894T polymorphism. Nitric oxide-mediated endothelial vasorelaxations were highly variable between patients. Reduced vasorelaxations were associated with increased number of clinical risk factors for atherosclerosis (r = - 0.54, P < 0.001), whereas the Glu298Asp variant was not associated with any differences in contractions to phenylephrine, NO-mediated vasorelaxations to acetylcholine, bradykinin or calcium ionophore, or relaxations to the NO donor sodium nitroprusside. Increased atherosclerotic risk factors, but not the presence of the eNOS Glu298Asp variant, are associated with impaired nitric oxide-mediated endothelial vasomotor function, suggesting that this polymorphism does not have a major direct functional effect on vascular eNOS activity in human atherosclerosis.     

Molecular mechanisms underlying the activation of eNOS

Endothelial cells situated at the interface between blood and the vessel wall play a crucial role in controlling vascular tone and homeostasis, particularly in determining the expression of pro- and anti-atherosclerotic genes. Many of these effects are mediated by changes in the generation and release of the vasodilator nitric oxide (NO) in response to hemodynamic stimuli exerted on the luminal surface of endothelial cells by the streaming blood (shear stress) and the cyclic strain of the vascular wall. The endothelial NO synthase (eNOS) is activated in response to fluid shear stress and numerous agonists via cellular events such as; increased intracellular Ca²⁺, interaction with substrate and co-factors, as well as adaptor and regulatory proteins, protein phosphorylation, and through shuttling between distinct sub-cellular domains. Dysregulation of these processes leads to attenuated eNOS activity and reduced NO output which is a characteristic feature of numerous patho-physiological disorders such as diabetes and atherosclerosis. This review summarizes some of the recent findings relating to the molecular events regulating eNOS activity.     

A novel model of occlusive thrombus formation in mice

A novel model to induce occlusive thrombus formation was developed in mice in vivo. Mice were simultaneously treated with ligation and cuff placement at the left carotid artery. At 7 days after the treatment, occlusive thrombus was observed at the intracuff region, but not in the distal and proximal regions of the cuff, and not induced by a single treatment of ligation or cuff placement. The plasma levels of von Willebrand factor (vWF), which represent the endothelial status, were significantly increased in combined treatment of ligation and cuff placement 1 day after the operation. Whereas no significant changes in plasma vWF were observed in either single treatment of ligation or cuff placement. The expression of vWF, considered to be the endothelial marker, was detected on the luminal surface distal and proximal to the cuff and the carotid artery in the single treatment groups treated with either ligation or cuff placement, but was not detected in the intracuff region. Furthermore, the binding of Griffolia Simplicifolia Lectin-I (GSL-I) and endothelial nitric oxide synthase (eNOS) expression indicating the endothelial integrity was not detected in the intracuff region. Intermittent injections of ancrod, which decreases the plasma fibrinogen, inhibited occlusive thrombus formation in the intracuff region. The expression of eNOS was detected at the distal and proximal but not the intracuff region of the carotid artery treated with ancrod. Daily administration of aspirin significantly suppressed the thrombus formation in this model. These results indicate that occlusive thrombus formation accompanied by endothelial damage or dysfunction is induced by the combined application of ligation and cuff placement at the carotid artery, and suggest that this endothelial damage or dysfunction may be one pathogenesis of thrombogenesis in this model.     

The Glu-298→Asp (894G→T) mutation at exon 7 of the endothelial nitric oxide synthase gene and coronary artery disease

We examined associations between the endothelial nitric oxide synthase (eNOS) gene Glu-298-->Asp (894G-->T) mutation and the occurrence and severity of angiographically defined coronary artery disease (CAD). eNOS mediates basal vascular wall nitric oxide production, and altered nitric oxide production has been implicated in atherosclerosis. The newly identified eNOS Glu-298-->Asp mutation in exon 7 is common and likely to be functional. It was found to be associated with myocardial infarction (MI) in Japanese but not in whites. We genotyped 763 white Australians undergoing coronary angiography for the eNOS Glu-298-->Asp mutation. The frequencies of the eNOS GG, TG and TT genotypes were 47.8%, 41.2% and 11.0% in men and 45.2%, 41.1% and 13.7% in women with CAD, and were not significantly different from those without CAD (43.2%, 40.7% and 16.0%, P=0.423 in men; 40.2%, 48.1% and 11.7%, P=0.582 in women). The mutation was also not associated with MI (P=0.469 in males; P=0.389 in females) or with the number of significantly stenosed vessels (P=0.954; P=0.734). The "T" allele frequency (32.5%) was much greater than that reported for the Japanese population (7.8% in controls and 10.0% in MI patients). In conclusion, the eNOS Glu-298-->Asp mutation is common, occurring with an allele frequency of 32.5%, but is not associated with either the occurrence or severity of CAD in the Australian population or with other established coronary risk factors assessed in our study. The mutation is significantly more frequent in the Australian than in the Japanese.     

Relationship between the G894T polymorphism (Glu298Asp variant) in endothelial nitric oxide synthase and nitric oxide‐mediated endothelial function in human atherosclerosis

Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), plays important roles in normal vascular homeostasis, and reduced endothelial NO bioactivity is an important feature of vascular disease states. The Glu298Asp (G894T) polymorphic variant of eNOS has been associated with vascular disease, but functional data are lacking. Accordingly, we examined the relationships between NO‐mediated endothelial function, the presence of the eNOS Glu298Asp variant, and clinical risk factors for atherosclerosis. Endothelium‐dependent vasorelaxations to different agonists were determined in human saphenous veins obtained from patients with coronary artery disease and identified risk factors (n = 104). Patients were genotyped for the eNOS G894T polymorphism. Nitric oxide‐mediated endothelial vasorelaxations were highly variable between patients. Reduced vasorelaxations were associated with increased number of clinical risk factors for atherosclerosis (r = ? 0.54, P < 0.001), whereas the Glu298Asp variant was not associated with any differences in contractions to phenylephrine, NO‐mediated vasorelaxations to acetylcholine, bradykinin or calcium ionophore, or relaxations to the NO donor sodium nitroprusside. Increased atherosclerotic risk factors, but not the presence of the eNOS Glu298Asp variant, are associated with impaired nitric oxide‐mediated endothelial vasomotor function, suggesting that this polymorphism does not have a major direct functional effect on vascular eNOS activity in human atherosclerosis. © 2001 Wiley‐Liss, Inc.