The influence of nitric oxide on the regulation of plasminogen activator inhibitor type 1 and tissue-type plasminogen activator expression

Nitric oxide produced in various human tissues by nitric oxide synthase is involved in the regulation of many physiological processes. Mechanism of its action is diverse. The most important physiological activity of nitric oxide is guanylate cyclase activation and an increase of cGMP synthesis. At low concentrations NO plays a pivotal role in vessel relaxation and possesses antithrombotic, antiproliferative and anti-inflammatory features as well. An excessive production of nitric oxide can disturb vascular hemostasis and contribute to development of cardiovascular diseases. Studies provide that NO also participate in fibrynolysis regulation by the influence on the PAI-1 and t-PA expression, what may have important clinical implications. The aim of this review is to present current knowledge about the role of nitric oxide in the regulation of these plasminogen activation system factors.     

Role of eNOS in neovascularization: NO for endothelial progenitor cells

Nitric oxide (NO) is a gaseous molecule with an astonishingly wide range of physiological and pathophysiological activities, including the regulation of vessel tone and angiogenesis in wound healing, inflammation, ischaemic cardiovascular diseases and malignant diseases. Recent data have revealed the predominant role of endothelial nitric oxide synthase (eNOS), an endothelial-cell-specific isoform of NO producing enzyme, in both angiogenesis (the development of new blood vessels derived from existing vessels) and vasculogenesis (blood vessel formation de novo from progenitor cells). In addition, successes in gene therapy, together with the recent development of an eNOS-specific inhibitor, suggest that the modulation of eNOS might be a potent new strategy for the control of pathological neovascularization.     

Arginine-Modulated Receptor-Activated Calcium Influx via a NO/Cyclic GMP Pathway in Human SK-N-SH Neuroblastoma Cells

Abstract: The effects of arginine on calcium mobilization in human SK-N-SH neuroblastoma cells were examined. It was found that arginine potentiated an increase in carbachol-induced Ca²⁺ from the external Ca²⁺ influx as opposed to an internal Ca²⁺ release from intracellular pools. The potentiation effect of arginine on carbachol-induced calcium mobilization was mimicked by either 8-bromo cyclic GMP or sodium nitroprusside. In addition, it was found that arginine induced NO production and an increase in cyclic GMP. Moreover, arginine-induced potentiation, NO production, and cyclic GMP increases were all suppressed after the preincubation of cells with N -methyl- l -arginine or N -nitro- l -arginine, nitric oxide synthase inhibitor. It is suggested that the NO production and subsequent cyclic GMP elevation induced by arginine are responsible for the potentiation of carbachol-induced Ca²⁺ increase. Our results show the existence of a NO/cyclic GMP pathway and an interconnection of NO and Ca²⁺ signaling pathways in human SK-N-SH neuroblastoma cells. We also observed that NO, which is produced by endothelial CPAE cells, has a modulating effect on cyclic GMP elevation in human SK-N-SH neuroblastoma cells. The intercellular communication role of NO and its cell-diffusing character may also affect the regulation of nonneuronal cells in their interactions with neuronal cells.     

NO news is good news for plants

The organization of redox signaling and the use of nitric oxide (NO) to transmit information, modulate biological processes or create cellular damage are highly complex. Recent reports provide an exceptional picture of NO production, of the regulation of NO bioactivity through detoxification reactions and of biochemical events by which NO transduces signals into cellular responses, in particular during disease resistance. Furthermore, other exciting reports on NO function in germination, growth and reproduction support the view that NO is a 'do it all' molecule that plays a crucial role during the entire lifespan of the plant.     

Guanylate cyclase and the .NO/cGMP signaling pathway.

Signal transduction with the diatomic radical nitric oxide (NO) is involved in a number of important physiological processes, including smooth muscle relaxation and neurotransmission. Soluble guanylate cyclase (sGC), a heterodimeric enzyme that converts guanosine triphosphate to cyclic guanosine monophosphate, is a critical component of this signaling pathway. sGC is a hemoprotein; it is through the specific interaction of NO with the sGC heme that sGC is activated. Over the last decade, much has been learned about the unique heme environment of sGC and its interaction with ligands like NO and carbon monoxide. This review will focus on the role of sGC in signaling, its relationship to the other nucleotide cyclases, and on what is known about sGC genetics, heme environment and catalysis. The latest understanding in regard to sGC will be incorporated to build a model of sGC structure, activation, catalytic mechanism and deactivation.     

Role of nitric oxide in central sympathetic outflow

The gaseous molecule nitric oxide (NO) plays an important role in cardiovascular homeostasis. It plays this role by its action on both the central and peripheral autonomic nervous systems. In this review, the central role of NO in the regulation of sympathetic outflow and subsequent cardiovascular control is examined. After a brief introduction concerning the location of NO synthase (NOS) containing neurons in the central nervous system (CNS), studies that demonstrate the central effect of NO by systemic administration of NO modulators will be presented. The central effects of NO as assessed by intracerebroventricular, intracisternal, or direct injection within the specific central areas is also discussed. Our studies demonstrating specific medullary and hypothalamic sites involved in sympathetic outflow are summarized. The review will be concluded with a discussion of the role of central NO mechanisms in the altered sympathetic outflow in disease states such as hypertension and heart failure.     

Inducible NO synthase activity in blood vessels and heart: new insight into cell origin and consequences

Induction of the inducible form of nitric oxide synthase (iNOS) in the vascular and cardiac tissue by several inflammatory stimuli may result in the production of large amounts of nitric oxide (NO) for a sustained period. Recent data obtained in the rat aorta in which iNOS was induced by lipopolysaccharide (LPS) have demonstrated that adventitial cells represent the main site of NO production. Adventitial-derived NO can exert an immediate down-regulatory effect on smooth muscle contraction (via activation of the cyclic GMP pathway) but may also initiate longer lasting effects through the formation of NO stores within the medial layer. One candidate for such NO stores are dinitrosyl non-heme iron complexes. Low molecular weight thiols interact with preformed NO stores and promote vasorelaxation by a cyclic GMP-independent mechanism involving the activation of potassium channels. In the heart, the induction of iNOS is involved in delayed protection against ischemia-reperfusion-induced functional damages. Recent data obtained with monophosphoryl lipid A, a non-toxin derivative of LPS, strongly suggest that iNOS-derived NO in the rat heart does not act as an immediate mediator of the cardioprotection but rather as a trigger of long-term protective mechanisms. Thus, the present data reveal the important role of adventitial cells as a site of iNOS expression and activity in intact blood vessels. The induction of adaptive mechanisms in the heart and the formation of releasable NO stores in blood vessels are examples of long-term consequences of iNOS induction. These new information are relevant for a better understanding of the circumstances in which NO overproduction by iNOS may play either a beneficial or deleterious role in these tissues.     

胰岛素与血小板L- 精氨酸/ 一氧化氮系统

胰岛素抵抗在2型糖尿病和代谢综合征中占有核心地位。大多数研宄认为胰岛素有直接抑制血小板活化的作用,且主要是通过L-精氨酸／一氧化氮系统增加血小板内cGMP水平来抑制血小板聚集的。目前已经发现血小板也会发生胰岛素抵抗。而且血小板发生胰岛素抵抗可能存在多个环节。本文主要探讨胰岛素和血小板L-Arg／NO系统间的关系厦胰岛素抵抗时血小板L—ArGNO系统的改变。     

NO and ROS implications in the organization of root system architecture

Over the past decades the role of nitric oxide (NO) and reactive oxygen species (ROS) in signaling and cellular responses to stress has witnessed an exponential trend line. Despite advances in the subject, our knowledge of the role of NO and ROS as regulators of stress and plant growth and their implication in signaling pathways is still partial. The crosstalk between NO and ROS during root formation offers new domains to be explored, as it regulates several plant functions. Previous findings indicate that plants utilize these signaling molecules for regulating physiological responses and development. Depending upon cellular concentration, NO either can stimulate or impede root system architecture (RSA) by modulating enzymes through post-translational modifications. Similarly, the ROS signaling molecule network, in association with other hormonal signaling pathways, control the RSA. The spatial regulation of ROS controls cell growth and ROS determine primary root and act in concert with NO to promote lateral root primordia. NO and ROS are two central messenger molecules which act differentially to upregulate or downregulate the expression of genes pertaining to auxin synthesis and to the configuration of root architecture. The investigation concerning the contribution of donors and inhibitors of NO and ROS can further aid in deciphering their role in root development. With this background, this review provides comprehensive details about the effect and function of NO and ROS in the development of RSA.     

Intervention by nitric oxide, NO, and its oxide derivatives particularly in mammals

Nitric oxide (NO) is a natural and stable free radical produced in soil and water by the bacteriological reduction of nitrites and nitrates and in animals by the enzyme oxidation of L-arginine. NO is biosynthesised by finely regulated enzymatic systems called NO-synthases and readily diffuses through tissues. It reacts rapidly with hemoproteins and iron-sulphur centers to form nitrosylated compounds. It oxidises more slowly to form nitrogen oxides that nitrosate thiols into thionitrite. NO is transported in these various forms and released spontaneously or through yet unclear mechanisms into most cells; it also regulates oxygen consumption at the mitochondrial respiratory chain level through interaction with cytochrome oxidase. In the cardiovascular system, NO lowers blood pressure by activating a hemoprotein, the guanylate cyclase present in muscle cells; through such interaction it acts also as a neuromediator and neuromodulator in the nervous system. However, many of NO's roles result from rapid coupling to other radicals; for example, it reacts with the superoxide anion (O2-) to form oxoperoxinitrate (ONOO-, also known as peroxynitrite). This strong oxidant of metallic centers, thiols, and antioxidants is also able to convert tyrosine to 3-nitrotyrosine and to act upon tyrosine residues contained in proteins. The biological aspects of the roles of NO are presented with particular respect to the rapid interactions of NO with hemoproteins' iron and other radicals. Concurrently, NO oxidation enables nitrosation reactions primarily of thiols but ultimately of nucleic bases. The thionitrite function (R-S-NO) thus formed and the dimerisation and nitration of tyrosine residues are protein post-translational modifications that are being investigated in animals.     

A cell-based nitric oxide reporter assay useful for the identification and characterization of modulators of the nitric oxide/guanosine 3',5'-cyclic monophosphate pathway

Nitric oxide (NO) plays an important role in protection against the onset and progression of various cardiovascular disorders. Therefore, the NO/guanosine 3',5'-cyclic monophosphate (cGMP) pathway has gained considerable attention and has become a target for new drug development. We have established a rapid, homogeneous, cell-based, and highly sensitive reporter assay for NO generated by endothelial nitric oxide synthase (eNOS). In a coculture system, NO production is indirectly monitored in living cells via soluble guanylyl cyclase (sGC) activation and calcium influx mediated by the olfactory cyclic nucleotide-gated (CNG) cation channel CNGA2, acting as the intracellular cGMP sensor. Using this NO reporter assay, we performed a fully automated high-throughput screening campaign for stimulators of NO synthesis. The coculture system reflects most aspects of the natural NO/cGMP pathway, namely, Ca(2+)-dependent and Ca(2+)-independent regulation of eNOS activity by G protein-coupled receptor agonists, oxidative stress, phosphorylation, and cofactor availability as well as NO-mediated stimulation of cGMP synthesis by sGC activation. The NO reporter assay allows the real-time detection of NO synthesis within living cells and makes it possible to identify and characterize activators and inhibitors of enzymes involved in the NO/cGMP signaling pathway.     

Role of nitric oxide in larval and juvenile fish

Fish are known to express the three isoforms of nitric oxide synthase (NOS), the constitutive forms endothelial or eNOS, neuronal or nNOS and the inducible form iNOS. Most studies in fish have focussed on possible roles for NO in cardiovascular physiology although there has been recent attention on the role of nNOS in embryonic development. However compared to mammalian studies there have been relatively few studies on effects of nitric oxide (NO) on fish. Studies on heart and blood vessel preparations from various fish species appear to show results specific to the species or to the particular preparation. Possible roles of NO in the in vivo biology of adult fish or larval fish have received little attention. This article reviews effects of nitric oxide on cardiovascular physiology in fish with special emphasis on larval fish. It introduces some experimental work on possible signaling pathways in larval fish and introduces the possibility that NO could be an important environmental influence for some aquatic organisms. In higher vertebrates LPS (lipopolysaccharide) is known to activate the cytokine signaling system and stimulate increased expression of iNOS and increased production of NO, but this remains less investigated in fish. The effects of LPS on cardiovascular and osmoregulatory physiology of larval and juvenile salmonids are discussed and a possible role of NO in stress-induced drinking is suggested.     

NO and NOS isoforms in the development of apoptosis in renal ischemia/reperfusion

Nitric oxide (NO) and the expression of endothelial (eNOS) and inducible (iNOS) isoforms of nitric oxide synthase (NOS) are recognized as important mediators of physiological and pathological processes of renal ischemia/reperfusion (I/R) injury, but little is known about their role in apoptosis. The ability of the eNOS/NO system to regulate the iNOS/NO system and thus promote apoptosis was assessed during experimental renal I/R. Renal caspase-3 activity and the number of TUNEL-positive cells increased with I/R, but decreased when NOS/NO systems were blocked with L-NIO (eNOS), 1400W (iNOS), and N-nitro-l-arginine methyl ester (L-NAME; a nonselective NOS inhibitor). I/R increased renal eNOS and iNOS expression as well as NO production. The NO increase was eNOS- and iNOS-dependent. Blockage of NOS/NO systems with L-NIO or L-NAME also resulted in a lower renal expression of iNOS and iNOS mRNA; in contrast, eNOS expression was not affected by iNOS-specific blockage. In conclusion, two pathways define the role of NOS/NO systems in the development of apoptosis during experimental renal I/R: a direct route, through eNOS overexpression and NO production, and an indirect route, through expression/activation of the iNOS/NO system, induced by eNOS.     

Differential biological effects of products of nitric oxide (NO) synthase: it is not enough to say NO

The radical gas nitric oxide (NO) is implicated in an enormous number of biological function both in physiological and pathological conditions. Often it is not clear if it plays a deleterious or beneficial role. Here briefly, are analyzed some of the reasons of this multitude of effects. Emphasis is given to factors influencing NO formation and to the type and quantity of radicals formed by nitric oxide synthase. In particular, a comparison between the biological effects of nitroxyl anion (HNO/NO(-)) and nitric oxide NO(.) is considered. These redox siblings often exhibit orthogonal behavior in physiological and pathological conditions. In the light of the multitude of effects of NO, the role of this gas, their siblings and their derivatives in cardiac ischemic preconditioning scenario is more extensively analyzed.     

Simultaneous in situ monitoring of intracellular Ca2+ and NO in endothelium of coronary arteries

We developed an in situ assay system to simultaneously monitor intracellular Ca(2+) concentration ([Ca(2+)](i), fura 2 as indicator) and nitric oxide (NO) levels [4,5-diaminofluorescein as probe] in the intact endothelium of small bovine coronary arteries by using a fluorescent microscopic imaging technique with high-speed wavelength switching. Bradykinin (BK; 1 microM) stimulated a rapid increase in [Ca(2+)](i) followed by an increase in NO production in the endothelial cells. The protein tyrosine phosphatase inhibitor phenylarsine oxide (PAO; 10 microM) induced a gradual, small increase in [Ca(2+)](i) and a slow increase in intracellular NO levels. Removal of extracellular Ca(2+) and depletion of Ca(2+) stores completely blocked BK-induced increase in NO production but had no effect on PAO-induced NO production. However, a further reduction of [Ca(2+)](i) by application of BAPTA-AM or EGTA with ionomycin abolished the PAO-induced NO increase. These results indicate that a simultaneous monitoring of [Ca(2+)](i) and intracellular NO production in the intact endothelium is a powerful tool to study Ca(2+)-dependent regulation of endothelial nitric oxide synthase, which provides the first direct evidence for a permissive role of Ca(2+) in tyrosine phosphorylation-induced NO production.     

肢体缺血预适应的肝保护作用与一氧化氮／内皮素-1系统关系的研究

目的：观察肢体缺血／再灌注（I／R）后一氧化氮／内皮素-1（NO／ET-1）失衡与肝损伤的关系以及缺血预适应（1pc）对NO／ET-1系统的调节作用。方法：实验用雄性Wistar大鼠18只,随机分为3组（n=6）：对照组（control）、缺血／再灌注组（I／R）和缺血预适应组（IPC＋I／R）,分别测定血浆谷草转氨酶（ALT）、谷丙转氨酶（AST）;血浆和肝组织一氧化氮（NO）、内皮素-1（ET-I）的含量变化,一氧化氮／内皮素-1（NO／ET-1）比值及肝组织的总一氧化氮合酶（tNOS）、诱导型一氧化氮合酶（iNOS）、结构型一氧化氮合酶（cNOS）的水平;免疫组化法检测肝组织的诱导型一氧化氮舍酶（iNOS）、内皮型一氧化氮合酶（eNOS）的表达;HE染色,在光学显微镜下观察肝组织的形态学改变。结果：发现肢体再灌注期血浆和肝组织NO、ET-1均明显增加,而NO／ET-1的比值却明显降低,同时血浆ALT、AST升高,光学显微镜下肝细胞、内皮细胞肿胀,肝细胞变性及肝窦淤血,炎性细胞浸润,肝损伤加重,肢体I／R后肝组织iNOS的表达增强,而eNOS（主要为eNOS）的表达减少,伴有总NOS活性增强。说明肢体缺血再灌注后肝组织内皮源的NO产生减少,而非内皮源的NO产生增多;IPC减轻了肢体I／R后引起的NO／ET-1失衡。结论：肢体I／R后肝组织损伤与NO／ET-1失衡有关,IPC对肢体I／R继发的肝组织损伤的保护作用可能是通过对NO／ET-1系统的调节作用而介导的,此时内皮源的NO产生增加,非内皮源的NO产生减少。     

Changes occurring in cortical NO release and brain NO-synthases during a paradoxical sleep deprivation and subsequent recovery in the rat

Variations occurring in cortical nitric oxide (NO) release were analysed with a voltametric method in rats (i) placed in control conditions, (ii) while being paradoxical sleep deprived (PSD), or (iii) recovering from a PSD. Activities of neuronal (nNOS) and inducible (iNOS) NO-synthases as well as nNOS expression were also determined in several brain regions. In baseline conditions, circadian variations in nNOS expression and activity were maximal during the dark period and minimal during the light one for all the structures analysed (frontal cortex, pons and medulla). In the same way, cortical NO release occurred through a circadian rhythm exhibiting maxima and minima during dark and light periods, respectively. In the same experimental conditions, iNOS activity did not exhibit time-dependent changes. The correlative changes observed in baseline conditions between NO release, nNOS expression and activity within the frontal cortex were disrupted during PSD and subsequent recovery. Still again, iNOS activity remained unchanged. Results obtained point out that the tight coupling existing in control conditions between nNOS expression-activity and NO release is disrupted by a PSD and remains affected during the subsequent 24 h recovery. Their significance is discussed.     

Role of DDAH-1 in lipid peroxidation product-mediated inhibition of endothelial NO generation

Altered nitric oxide (NO) biosynthesis is thought to play a role in the initiation and progression of atherosclerosis and may contribute to increased risk seen in other cardiovascular diseases. It is hypothesized that altered NO bioavailability may result from an increase in endogenous NO synthase (NOS) inhibitors, asymmetric dimethly araginine (ADMA), and N(G)-monomethyl arginine, which are normally metabolized by dimethyarginine dimethylamine hydrolase (DDAH). Lipid hydroperoxides and their degradation products are generated during inflammation and oxidative stress and have been implicated in the pathogenesis of cardiovascular disorders. Here, we show that the lipid hydroperoxide degradation product 4-hydroxy-2-nonenal (4-HNE) causes a dose-dependent decrease in NO generation from bovine aortic endothelial cells, accompanied by a decrease in DDAH enzyme activity. The inhibitory effects of 4-HNE (50 microM) on endothelial NO production were partially reversed with L-Arg supplementation (1 mM). Overexpression of human DDAH-1 along with antioxidant supplementation completely restored endothelial NO production following exposure to 4-HNE (50 microM). These results demonstrate a critical role for the endogenous methylarginines in the pathogenesis of endothelial dysfunction. Because lipid hydroperoxides and their degradation products are known to be involved in atherosclerosis, modulation of DDAH and methylarginines may serve as a novel therapeutic target in the treatment of cardiovascular disorders associated with oxidative stress.     

Nitric oxide in plants. To NO or not to NO

The current knowledge on the occurrence and activity of NO in plants is reviewed. The multiplicity of nitrogen monoxide species and implications for differentiated reactivity are indicated. Possible sources of NO are evaluated, and the evidence for the presence of nitric oxide synthase in plants is summarised. The regulatory role of NO. in plant development and in plant interactions with microorganisms, involving an interplay with other molecules, like ethylene or reactive oxygen species is demonstrated. Finally, some other suggestions on potential functions of NO. in plants are indicated.