Beneficial effects of pomegranate juice on oxidation-sensitive genes and endothelial nitric oxide synthase activity at sites of perturbed shear stress

Atherosclerosis is enhanced in arterial segments exposed to disturbed flow. Perturbed shear stress increases the expression of oxidation-sensitive responsive genes (such as ELK-1 and p-JUN) in the endothelium. Evidence suggests that polyphenolic antioxidants contained in the juice derived from the pomegranate can contribute to the reduction of oxidative stress and atherogenesis. The aim of the present study was to evaluate the effects of intervention with pomegranate juice (PJ) on oxidation-sensitive genes and endothelial NO synthase (eNOS) expression induced by high shear stress in vitro and in vivo. Cultured human coronary artery endothelial cells (EC) exposed to high shear stress in vitro and hypercholesterolemic mice were used in this study. PJ concentrate reduced the activation of redox-sensitive genes (ELK-1 and p-JUN) and increased eNOS expression (which was decreased by perturbed shear stress) in cultured EC and in atherosclerosis-prone areas of hypercholesterolemic mice. Moreover, oral administration of PJ to hypercholesterolemic mice at various stages of disease reduced significantly the progression of atherosclerosis. This experimental study indicates that the proatherogenic effects induced by perturbed shear stress can be reversed by chronic administration of PJ. This approach may have implications for the prevention or treatment of atherosclerosis and its clinical manifestations.     

一氧化氮缺乏鼠肾损害以及氟伐他汀保护作用

目的观察一氧化氮(nitricoxide,NO)缺乏性大鼠肾脏损害的机制以及氟伐他汀的保护作用。方法雄性SD大鼠40只,随机分成对照组和处理组。对照组16只大鼠自由进食及饮水;处理组24只大鼠加用左旋硝基精氨酸甲酯[N(omega)鄄nitro鄄L鄄argininemethylester,L鄄NAME]50mg·kg鄄1·d鄄1。4周后两组各取8只大鼠处死。处理组16只大鼠再随机分为:①L组:给予L鄄NAME50mg·kg鄄1·d鄄1;②L+S组:给予L鄄NAME50mg·kg鄄1·d鄄1和氟伐他汀5mg·kg鄄1·d鄄1。12周后处死所有大鼠。量血压,测定尿微白蛋白含量、血脂、血及肾皮质NO和血管紧张素Ⅱ(anginotensin鄄Ⅱ,AngⅡ)的水平;取肾皮质做病理检测;测定肾皮质转化生长因子β1(transforminggrowthfactorβ1,TGF鄄β1)的含量。结果给予L鄄NAME2周后血压开始持续升高,12周时,L组与对照组相比,尿微量白蛋白明显升高(P<0.001)。4周后给予氟伐他汀对尿微量白蛋白降低(P<0.05)。与对照组相比,L组大鼠血及肾皮质NO水平降低(P<0.001);AngⅡ水平升高(P<0.001)。与L组相比,L+S组大鼠血和肾皮质NO水平均增高(P<0.001);肾皮质中AngⅡ浓度降低(P<0.05)。病理检测L组大鼠的肾小球硬化。L组大鼠肾皮质中TGF鄄β1表达升高,氟伐他汀可减轻上述损害。结论高血压肾脏损害主要表现为肾小球硬化,与血及肾皮质NO水平降低,AngⅡ水平升高相关,TGF鄄β1在肾小球硬化中起重要作用,氟伐他汀能减轻上述损害。     

比索洛尔对一氧化氮和内皮型一氧化氮合酶昼夜节律的影响

目的探讨比索洛尔对大鼠一氧化氮和内皮型一氧化氮合酶(eNOS)及心肌组织eNOSmRNA表达水平昼夜节律的影响。方法健康雄性SD大鼠128只,体质量250～300g,随机分为4组:7:00灌药组(早灌药组)、19:00灌药组(晚灌药组)、7:00对照组(早对照组)、19:00对照组(晚对照组),每组32只。每日早灌药组与晚灌药组均给予比索洛尔3mg/kg灌服,两对照组分别于7:00与19:00给予相同剂量的安慰剂灌服。4周后,分别于同日内不同时间点(2:00,8:00,14:00,20:00)处死4大组大鼠中各8只大鼠,留取血清和心肌组织。分别采用比色法和硝酸还原法、逆转录多聚酶链反应法检测血和心肌组织中eNOS、一氧化氮的含量或活性以及eNOSmRNA的表达水平。结果两灌药组之间、两对照组之间血清及组织一氧化氮、eNOS含量或表达差异无统计学意义(均P>0.05),但灌药组和对照组之间血清及组织一氧化氮、eNOS含量或表达差异有统计学意义(均P<0.05),灌药组的一氧化氮、eNOS含量明显升高,eNOSmRNA的表达增强(P<0.05)。各组血清及组织一氧化氮、eNOS含量或表达均存在昼夜节律,灌药组部分节律振幅、峰值改变。灌药组和对照组各组的组织eNOSmRNA存在典型昼夜节律,节律振幅无差异。早、晚灌服比索洛尔对于一氧化氮、eNOS以及eNOSmRNA昼夜节律的影响有所不同。结论比索洛尔升高血清及组织一氧化氮、eNOS的含量,促进组织eNOSmRNA的表达。比索洛尔可对内皮源性血管活性物质的时间生物学特征产生影响,用药时间不同,对各参数的影响亦有所不同。     

Beneficial effects of low-dose benidipine in acute autoimmune myocarditis: suppressive effects on inflammatory cytokines and inducible nitric oxide synthase.

Excessive production of nitric oxide (NO) by inducible NO synthase (iNOS) contributes to the progression of myocardial damage in myocarditis. Some dihydropyridine calcium channel blockers reportedly inhibit NO production and proinflammatory cytokines and the present study sought to clarify if a low dose of benidipine, a novel dihydropyridine calcium channel blocker, would ameliorate experimental autoimmune myocarditis (EAM). Rats with or without myocarditis were administered oral benidipine at a dose of 3 mg. kg(-1). day(-1) for 3 weeks. Low-dose benidipine did not decrease blood pressure significantly compared with the untreated group, but markedly reduced the severity of myocarditis. Myocardial interleukin-1beta (IL-1beta) expression and IL-1beta-positive cells were significantly less in rats with EAM that were treated with low-dose benidipine compared with untreated rats. Also, myocardial iNOS expression and iNOS-positive cells were markedly reduced in in the treated rats compared with the untreated group. Furthermore, myocardial NO production and nitrotyrosine expression were suppressed by the treatment in rats with EAM. The cardioprotection of low-dose benidipine may be caused by suppression of inflammatory cytokines and inhibition of NO production.     

Discrepant effects of inducible nitric oxide synthase modulation on systemic and splanchnic endothelial nitric oxide synthase activity and expression in cirrhotic rats

BACKGROUND: Arterial vasodilatation, which is a major factor in the pathogenesis of the hyperkinetic circulatory state and portal hypertension in cirrhosis, is due to arterial nitric oxide (NO) overproduction secondary to endothelial NO synthase (eNOS) and inducible NOS (iNOS) upregulation. However, in cirrhosis, the respective roles of eNOS and iNOS isoforms in NO overproduction are still unknown and the effect of iNOS modulation on eNOS activity and expression has not been evaluated in the systemic or splanchnic vessels. The aim of this study was to evaluate the effects of modulating aortic and superior mesenteric arteries (SMA) iNOS on arterial eNOS activity and expression in rats with cirrhosis. METHODS: eNOS and iNOS protein expression and eNOS activity (assessed by its phosphorylation at serine 1177) were measured in the aortas and SMA in untreated and treated cirrhotic rats with lipopolysaccharide (LPS), N-iminoethyl-L-lysine (L-NIL), a selective iNOS inhibitor, and LPS plus L-NIL. RESULTS: LPS administration significantly increased eNOS and iNOS protein expression and eNOS activity in the aortas of both sham-operated and cirrhotic rats. However, in SMA, LPS administration induced a decrease in eNOS protein expression and activity and an increase in iNOS protein expression. CONCLUSION: The results of this study may explain the worsening of the hyperdynamic state in cirrhosis during septic shock by direct LPS-induced eNOS activation in large systemic vessels, and its inhibition in concomitant small splanchnic vasculature by iNOS synthesized NO.     

Beneficial effects of statins on endothelial progenitor cells

ABSTRACT:: In recent years, endothelial progenitor cells (EPCs) have been demonstrated to play an important role during tissue vascularization and endothelium homeostasis in adults. In addition, EPCs have been implicated in the pathophysiology of cardiovascular and cerebrovascular disease, such that a decreased number of EPCs may not only be a risk indicator but also a potential therapeutic target. Of the many agents that have been examined to increase EPCs and enhance their function, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or statins are one of the most intriguing. Accumulated evidence has demonstrated that statins promote EPC mobilization, proliferation, migration, adhesion, differentiation and reduce senescence and apoptosis independent of their serum lipid-lowering effect. This review summarizes the understanding of current mechanisms explaining the myriad of beneficial effects of statins on EPCs and discusses future challenges for studies involving statins and subpopulations of EPCs. However, the pharmacologic mechanisms of action of statins on EPCs remain at the cellular level, whereas the putative molecular mechanisms await further studies.     

NOSTRIN: a protein modulating nitric oxide release and subcellular distribution of endothelial nitric oxide synthase

Activity and localization of endothelial nitric oxide synthase (eNOS) is regulated in a remarkably complex fashion, yet the complex molecular machinery mastering stimulus-induced eNOS translocation and trafficking is poorly understood. In a search by the yeast two-hybrid system using the eNOS oxygenase domain as bait, we have identified a previously uncharacterized eNOS-interacting protein, dubbed NOSTRIN (for eNOS traffic inducer). NOSTRIN contains a single polypeptide chain of 506-aa residues of 58 kDa with an N-terminal cdc15 domain and a C-terminal SH3 domain. NOSTRIN mRNA is abundant in highly vascularized tissues such as placenta, kidney, lung, and heart, and NOSTRIN protein is expressed in vascular endothelial cells. Coimmunoprecipitation experiments demonstrated the eNOS-NOSTRIN interaction in vitro and in vivo, and NOSTRIN's SH3 domain was essential and sufficient for eNOS binding. NOSTRIN colocalized extensively with eNOS at the plasma membrane of confluent human umbilical venous endothelial cells and in punctate cytosolic structures of CHO-eNOS cells. NOSTRIN overexpression induced a profound redistribution of eNOS from the plasma membrane to vesicle-like structures matching the NOSTRIN pattern and at the same time led to a significant inhibition of NO release. We conclude that NOSTRIN contributes to the intricate protein network controlling activity, trafficking, and targeting of eNOS.     

Novel features of nitric oxide,endothelial nitric oxide synthase,and atherosclerosis

There is a complex pathophysiologic scenario involving nitric oxide (NO), endothelial nitric oxide synthase (_eNOS), and the development of atherosclerosis and unstable atheroma. Endothelial damage induced by atherosclerosis leads to the reduction in bioactivity of _eNOS with subsequent impaired release of NO. An important mechanism is local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals, with subsequent cascade of oxidationsensitive mechanisms in the arterial wall. Novel molecular approaches have resulted in the development of new strains of mice lacking _eNOS. These experimental models will help to understand how to implement NO-based therapies against atherosclerosis. L-arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. The target or goal for new drugs should be the complete restoration of NOmediated signaling pathways in atherosclerotic arteries.     

Novel features of nitric oxide,endothelial nitric oxide synthase,and atherosclerosis

There is a complex pathophysiologic scenario involving nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and the development of atherosclerosis and unstable atheroma. Endothelial damage induced by atherosclerosis leads to the reduction in bioactivity of ENOS with subsequent impaired release of NO. An important mechanism is local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals, with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Novel molecular approaches have resulted in the development of new strains of mice lacking eNOS. These experimental models will help to understand how to implement NO-based therapies against atherosclerosis. L-arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. The target or goal for new drugs should be the complete restoration of NO-mediated signaling pathways in atherosclerotic arteries.     

Nitric oxide: inhibitory effects on endothelial cell calcium signaling, prostaglandin I2 production and nitric oxide synthase expression

OBJECTIVE: Nitric oxide (NO) produced in large amounts by inducible nitric oxide synthase exerts many harmful effects such as stimulation of inflammation and induction of apoptosis. The effects of excessive NO production on functions of endothelial cells, the major physiological source of NO, are not completely known. The aim of this study was to investigate the role of NO on the regulation of endothelial cell Ca2+ signaling and endothelial cell function. METHODS: Primary porcine aortic endothelial cells (PAECs) were used for all these studies. Intracellular Ca2+ concentrations ([Ca2+]i) were measured using fura-2/AM. Production of prostaglandin I2 (PGI2) and cyclic GMP were assessed using enzyme immunoassays, and endothelial NO synthase protein expression was evaluated by Western blotting. RESULTS: Bradykinin (BK, 10 nM) and thapsigargin (TG, 1 microM) provoked large increases in [Ca2+]i. The NO donor NOC12 reduced these responses, respectively, by 21% and 31% at 100 microM, 60% and 55% at 300 microM, and 74% and 78% at 500 microM. These effects were also observed with other NO donors including spermine NONOate and NOC18, and were completely prevented by carboxy-PTIO (200 microM), an NO scavenger. 8-Bromo-cGMP, however, had no effects on BK- and TG-stimulated Ca2+ responses. A 30-fold increase in PGI2 production was observed in cells stimulated with BK. NOC12 again reduced this response by 12%, 54%, 83% and 95% at 10, 100, 300 and 500 microM, respectively. Endothelial NO synthase protein level was reduced by 2%, 15%, 36 and 47% after 2, 6, 12 and 24 h, respectively, of incubation with NOC18, a NO donor with long half-life. CONCLUSIONS: NO, when produced in large amounts, can inhibit agonist-induced Ca2+ responses independently of cyclic GMP, reduce the production of endothelium-derived relaxing factors (EDRFs) and interfere with endothelial NO synthase protein expression.