JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2006
TRI VUONG
ABSTRACT Serratia vaccinii, a novel bacterium isolated from blueberry microflora, increased the phenolic content of berry juices, and thus increased antioxidant activities. The fermentation capacity of Serratia was investigated with Saskatoon berries, cranberries, strawberries and grapes in both aerobic and anaerobic conditions. It was shown to be compatible with wine yeast in anaerobic fermentations, producing wine with high antioxidant activity. The effects of fermented berry juices were tested on lipopolysaccharide/inferon-gamma-activated macrophages 264.7 NO(,). Data indicated that fermented berry juices strongly inhibited activated-macrophage NO production but induced tumor necrosis factor-alpha production. [source]

INTERPLAY OF REACTIVE OXYGEN SPECIES AND NITRIC OXIDE IN THE PATHOGENESIS OF EXPERIMENTAL LEAD-INDUCED HYPERTENSION

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2007
ND Vaziri
SUMMARY 1Lead is a common environmental and industrial toxin that can cause a variety of acute and chronic illnesses. For example, chronic exposure to low levels of lead has been shown to raise arterial pressure and promote renal and cardiovascular complications. 2Several mechanisms have been identified by which chronic lead exposure can cause hypertension and cardiovascular disease. In recent years, increasing evidence has emerged pointing to the role of oxidative stress as a major mediator of lead-induced hypertension. 3The present article provides an overview of the published studies on this subject. [source]

DOES NITRIC OXIDE MODULATE TRANSMITTER RELEASE AT THE MAMMALIAN NEUROMUSCULAR JUNCTION?

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2007
Travis J Nickels
SUMMARY 1Application of the nitric oxide (NO) donor, sodium nitrite and the NO synthase substrate l -arginine had no effect on nerve-evoked transmitter release in the rat isolated phrenic nerve/hemidiaphragm preparation; however, when adenosine A1 receptors were blocked with the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) prior to application of sodium nitrate or l -arginine, a significant increase in transmitter release was observed. In addition, the NO donor s -nitroso- N -acetylpenicillamine (SNAP) significantly increased transmitter release in the presence of DPCPX. In the present study, we have made the assumption that these NO donors elevate the level of NO in the tissue. Future studies should test other NO-donating compounds and also monitor the NO concentrations in the tissue to ensure that these effects are, in fact, NO induced. 2Elevation of cGMP in this preparation with the guanylyl cyclase activator 3-(5,-hydroxymethyl-2,-furyl)-1-benzyl indazole (YC-1) significantly enhanced transmitter release. In the presence of DPCPX and the selective guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), which blocks the production of cGMP, the excitatory effects of sodium nitrite and l -arginine were abolished. 3These results suggest that NO serves to enhance transmitter release at the rat neuromuscular junction (NMJ) via a cGMP pathway and this facilitation of transmitter release can be blocked with adenosine. Previously, we demonstrated that adenosine inhibits N-type calcium channels. Because NO only affects transmitter release when adenosine A1 receptors are blocked, we suggest that NO enhances transmitter release by enhancing calcium influx via N-type calcium channels. Further studies are needed to confirm that NO alters transmitter release via cGMP and that this action involves the N-type calcium channel. 4The results of the present study are consistent with a model of NO neuromodulation that has been proposed for the mammalian vagal,atrial junction. This model suggests that NO acts on NO-sensitive guanylyl cyclase to increase the intracellular levels of cGMP. In turn, cGMP inhibits phosphodiesterase-3, increasing levels of cAMP, which then acts on the N-type calcium channels to enhance calcium influx, leading to an increase in transmitter release. Our only modification to this model for the NMJ is that adenosine serves to block the modulation of transmitter release by NO. [source]

IMPACT OF OBESITY AND INSULIN RESISTANCE ON VASOMOTOR TONE: NITRIC OXIDE AND BEYOND

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2006
David W Stepp
SUMMARY 1Obesity is rapidly increasing in Western populations, driving a parallel increase in hypertension, diabetes and vascular disease. Prior to the development of overt diabetes or hypertension, obese patients spend years in a state of progressive insulin resistance and metabolic disease. Mounting evidence suggests that this insulin-resistant state has deleterious effects on the control of blood flow, thus placing organ systems at a higher risk for end-organ damage and increasing cardiovascular mortality. 2The purpose of the present review is to examine the current literature on the effects of obesity and insulin resistance on the acute control of vascular tone. Effects on nitric oxide (NO)-mediated control of vascular tone are particularly examined with regard to proximal causes and distal mechanisms of the impaired NO-mediation of vasodilation. 3Finally, novel pathways of impaired control of perfusion are summarized from the recent literature to identify new avenues of exploring impaired vascular function in patients with metabolic disease. [source]

NANOMOLAR LEVEL OF OUABAIN INCREASES INTRACELLULAR CALCIUM TO PRODUCE NITRIC OXIDE IN RAT AORTIC ENDOTHELIAL CELLS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2004
Xian Hui Dong
Summary 1.,Changes in [Ca2+]i across the cell membrane and/or the sarcoplasmic reticulum regulate endothelial nitric oxide (NO) synthase activity. 2.,In the present study, we investigated the effect of ouabain, a specific inhibitor of Na+/K+ -ATPase, on NO release and [Ca2+]i movements in cultured rat aortic endothelial cells (RAEC) by monitoring NO production continuously using an NO-specific real-time sensor and by measuring the change in [Ca2+]i using a fluorescence microscopic imaging technique with high-speed wavelength switching. The t½ (half-time of the decline of [Ca2+]i to basal levels after stimulation with 10 µmol/L bradykinin) was used as an index of [Ca2+]i extrusion. 3.,A very low concentration of ouabain (10 nmol/L) did not increase the peak of NO production, but decreased the decay of NO release and, accordingly, increased integral NO production by the maximal dose,response concentration induced by bradykinin. The same dose of ouabain affected [Ca2+]i movements across the cell membrane and/or sarcoplasmic reticulum induced by bradykinin with a time-course similar to that of NO release. Moreover, the t½ was significantly increased. 4.,Pretreatment of RAEC with Na+ -free solution, an inhibitor of the Na+/Ca2+ exchanger, and nickel chloride hexahydrate prevented the effects induced by bradykinin and ouabain. 5.,These observations using real-time recording indicate that a small amount of ouabain contributes to the bradykinin-stimulated increase of NO production through inhibition of plasma membrane Na+/K+ -ATPase activity and an increase in intracellular Na+ concentrations. The membrane was then depolarized, leading to a decline in the bradykinin-stimulated increase in [Ca2+]i by forward mode Na+/Ca2+ exchange to prolong the Ca2+ signal time. 6.,From these results, we suggest that nanomolar levels of ouabain modulate [Ca2+]i movements and NO production in RAEC. [source]

Comment on "Endothelially Derived Nitric Oxide Affects the Severity of Early Acetaminophen-induced Hepatic Injury in Mice"

ACADEMIC EMERGENCY MEDICINE, Issue 9 2006
Kari Scantlebury MD
No abstract is available for this article. [source]

Endothelially Derived Nitric Oxide Affects the Severity of Early Acetaminophen-induced Hepatic Injury in Mice

ACADEMIC EMERGENCY MEDICINE, Issue 5 2006
Steven D. Salhanick MD
Abstract Objectives: The precise mechanism of hepatocellular toxicity following acetaminophen (APAP) poisoning remains unclear. Nitric oxide is implicated in APAP toxicity as an inflammatory signaling molecule and as a precursor to the free radical peroxynitrate. The effects of inducible nitric oxide synthase (iNOS)-derived NO in APAP toxicity are known; however, the role of endothelial nitric oxide synthase (eNOS)-derived NO is unknown. The authors sought to evaluate the effect of eNOS-derived NO during APAP toxicity. Methods: C57BL6/J mice deficient in eNOS (eNOS KO) or iNOS (iNOS KO) and wild-type mice (WT) were treated with 300 mg/kg APAP. Alanine aminotransferase levels and plasma nitrate and nitrite levels were measured. Hypoxia inducible factor (HIF)-1, and Glucose Transporter 1 (Glut-1) levels were determined by Western blot. Results: Alanine aminotransferase levels were significantly elevated in all treated animals. Alanine aminotransferase levels were significantly lower in eNOS KO and iNOS KO than in treated WT animals. Plasma nitrate/nitrite levels were significantly higher in WT animals than in iNOS KO and eNOS KO animals. HIF-1, expression was increased in WT mice and decreased in iNOS KO mice. Glut-1 is a downstream, indirect marker of HIF function. Glut-1 expression was increased in WT and eNOS KO mice. Conclusions: Deficiency of either iNOS or eNOS results in decreased NO production and is associated with reduced hepatocellular injury following APAP poisoning. HIF-1, and Glut-1 levels are increased following APAP poisoning, implying that HIF-1, is functional during the pathogenic response to APAP poisoning. [source]

A Comparison of Membrane Inlet Mass Spectrometry and Nitric Oxide (NO) Electrode Techniques to Detect NO in Aqueous Solution

ELECTROANALYSIS, Issue 4 2010
Chingkuang Tu
Abstract The NO electrode and membrane inlet mass spectrometry (MIMS) have the advantage of being sensitive, direct, and real time detectors of NO in aqueous solution. They do not require reacting NO with labels or purging of NO with an inert gas. We show that the NO electrode and MIMS are comparable in sensitivity detecting NO concentrations to 0.5,nM in aqueous solution, and both give identical results in a biological measurement, the reactions of deoxyhemoglobin with nitrite. [source]

Role of Nitric Oxide in Pentylenetetrazol-Induced Seizures: Age-Dependent Effects in the Immature Rat

EPILEPSIA, Issue 4 2000
Anne Pereira de Vasconcelos
Summary: Purpose: Seizure susceptibility and consequences are highly age dependent. To understand the pathophysiologic mechanisms involved in seizures and their consequences during development, we investigated the role of nitric oxide (NO) in severe pentylenetetrazol (PTZ)-induced seizures in immature rats. Methods: Four cortical electrodes were implanted in 10-day-old (P10) and 21-day-old (P21) rats, and seizures were induced on the following day by repetitive injections of subconvulsive doses of PTZ. The effects of NG -nitro- l -arginine methyl ester (l -NAME; 10 mg/kg) and 7-nitroindazole (7NI; 40 mg/kg), two NO synthase (NOS) inhibitors, and l -arginine (l -arg; 300 mg/kg), the NOS substrate, were evaluated regarding the mean PTZ dose, seizure type and duration, and mortality rate. Results: At P10, the postseizure mortality rate increased from 18,29% for the rats receiving PTZ only to 100% and 89% for the rats receiving l -NAME and 7NI, respectively; whereas l -arg had no effect. Conversely, at P21, NOS inhibitors did not affect the 82,89% mortality rate induced by PTZ alone, whereas l -arg decreased the mortality rate to 29%. In addition, all NO-related drugs increased the duration of ictal activity at P10, whereas at P21, L -arg and L -NAME affected the first seizure type, producing clonic seizures with L -arg and tonic seizures with L -NAME. Conclusions: The relative natural protection of very immature rats (P10) against PTZ-induced deaths could be linked to a high availability of L -arg and, hence, endogenous NO. At P21, the modulation of seizure type by NO-related compounds may be related to the maturation of the brain circuitry, in particular the forebrain, which is involved in the expression of clonic seizures. [source]

Inhibition of Neuronal Nitric Oxide Reduces Heart Rate Variability in the Anaesthetised Dog

EXPERIMENTAL PHYSIOLOGY, Issue 5 2001
F. Markos
In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1-(2-trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R-R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3-fold from a control of 790 ± 124 ms (mean ± S.D.; n = 5) to 666 ± 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart. [source]

The Contribution of Salvador Moncada to Our Understanding of the Biology of Nitric Oxide

IUBMB LIFE, Issue 10-11 2003
Emilio Clementi
Abstract The observation, by Furchgott and Zawadzki, that a factor of short average life, released by endothelial cells accounted for vasodilation was the beginning of one of the most fascinating adventures in the recent history of science. The discovery that this released factor was nitric oxide had tremendous implications for our understanding not only of the homeostasis of the vascular tissue, but also of a variety of other biological processes ranging from synaptic plasticity to regulation of immune responses. This review article will lead the reader through the landmark events in this adventure, highlighting the fundamental role played by Salvador Moncada and his team. IUBMB Life, 55: 563-565, 2003 [source]

The Anti-Parasitic Effects of Nitric Oxide

IUBMB LIFE, Issue 10-11 2003
Paolo Ascenzi
Abstract Endogenous and exogenous nitric oxide (NO) possesses anti-parasitic effects on both Protozoa and Metazoa. However, NO production requires a tight control to limit cytotoxic damage to the host's own cells. The best known parasitic macromolecular targets for NO(-donors) are cysteine proteases, which are relevant in several aspects of the parasite life cycle and parasite-host relationships, and appear as promising targets for anti-parasitic chemotherapy. IUBMB Life, 55: 573-578, 2003 [source]

Nitric Oxide, Mitochondria, and Cell Death

IUBMB LIFE, Issue 3-5 2001
Guy C. Brown
Abstract NO or its derivatives (reactive nitrogen species: RNS) have three types of actions on mitochondria: 1) reversible inhibition of mitochondrial respiration at cytochrome oxidase by NO, and irreversible inhibition at multiple sites by RNS; 2) stimulation of mitochondrial production of superoxide, hydrogen peroxide, and peroxynitrite by NO; and 3) induction of mitochondrial permeability transition (MPT) by RNS. Similarly there are three main roles of mitochondria in NO-induced cell death: a) NO inhibition of respiration can induce necrosis (or excitotoxicity in neurons) and inhibit apoptosis if glycolysis is insufficient to compensate, b) RNS- or oxidant-induced signal transduction or DNA damage may activate the mitochondrial pathway to apoptosis, and c) RNS-induced MPT may induce apoptosis or necrosis. [source]

Mitochondrial Production of Hydrogen Peroxide Regulation by Nitric Oxide and the Role of Ubisemiquinone

IUBMB LIFE, Issue 4-5 2000
Alberto Boveris
Abstract Mitochondria are considered the major cellular site for hydrogen peroxide production, a process that is kinetically controlled by the availability of oxygen and nitric oxide to cytochrome oxidase and of ADP to F1-ATPase. The multisite regulation of mi1 tochondrial respiration and energy-transducing pathways support a critical regulatory role of mitochondrion in cell signaling pathways. The cellular steady-state levels of hydrogen peroxide and the role of mitochondria in maintaining these levels are reviewed. [source]

Nitric Oxide: The "Second Messenger" of Insulin

IUBMB LIFE, Issue 5 2000
Nighat N. Kahn
Abstract Incubation of various tissues, including heart, liver, kidney, muscle, and intestine from mice and erythrocytes or their membrane fractions from humans, with physiologic concentration of insulin resulted in the activation of a membrane-bound nitric oxide synthase (NOS). Activation of NOS and synthesis of NO were stimulated by the binding of insulin to specific receptors on the cell surface. A Lineweaver-Burk plot of the enzymatic activity demonstrated that the stimulation of NOS by insulin was related to the decrease in the Km for L-arginine, the substrate for NOS, with a simultaneous increase of Vmax. Addition of NG-nitro-L-arginine methyl ester (LNAME), a competitive inhibitor of NOS, to the reaction mixture completely inhibited the hormone-stimulated NO synthesis in all tissues. Furthermore, NO had an insulin-like effect in stimulating glucose transport and glucose oxidation in muscle, a major site for insulin action. Addition of NAME to the reaction mixture completely blocked the stimulatory effect of insulin by inhibiting both NO production and glucose metabolism, without affecting the hormone-stimulated tyrosine or phosphatidylinositol 3-kinases of the membrane preparation. Injection of NO in alloxan-induced diabetic mice mimicked the effect of insulin in the control of hyperglycemia (i.e., lowered the glucose content in plasma). However, injection of NAME before the administration of insulin to diabetic-induced and nondiabetic mice inhibited not only the insulin-stimulated increase of NO in plasma but also the glucose-lowering effect of insulin. [source]

Exogenously Applied Nitric Oxide Enhances the Drought Tolerance in Fine Grain Aromatic Rice (Oryza sativa L.)

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2009
M. Farooq
Abstract Drought stress is a severe threat to the sustainable rice production, which causes oxidative damage and disturbs plant water relations, while exogenously applied nitric oxide (NO) may have the potential to alleviate these effects in rice plants. In this study, the role of NO to improve drought tolerance in fine grain aromatic rice (Oryza sativa L. cv. Basmati 2000) was evaluated. Sodium nitroprusside, a NO donor, was used at 50, 100 and 150 ,mol l,1 both as seed priming and foliar spray. To prime, the seeds were soaked in aerated NO solution of respective solution for 48 h and dried back to original weight. Primed and non-primed seeds were sown in plastic pots with normal irrigation in a greenhouse. At four leaf stage, plants were subjected to drought stress except the controls, which were kept at full field capacity. Drought was maintained at 50 % of field capacity by watering when needed. Two controls were maintained; both receiving no NO treatments as foliar application or seed treatment, one under drought conditions and the other under well-watered conditions. Drought stress seriously reduced the rice growth, but both methods of NO application alleviated the stress effects. Drought tolerance in rice was strongly related to the maintenance of tissue water potential and enhanced capacity of antioxidants, improved stability of cellular membranes and enhanced photosynthetic capacity, plausibly by signalling action of NO. Foliar treatments proved more effective than the seed treatments. Among NO treatment, 100 ,mol l,1 foliar spray was more effective. [source]

Aging Increases the Interleukin-1,,Induced INOS Gene Expression and Nitric Oxide (NO) Production in Vascular Smooth Muscle Cells

JOURNAL OF CARDIAC SURGERY, Issue 6 2002
Gabriel HH Chan
Objectives: Inducible form of nitric oxide synthase (iNOS) is induced by cytokines (e.g. interleukin-1, (IL-1,)) during pathological conditions, such as sepsis. Excessive NO synthesis in blood vessels during sepsis can result in massive vasodilation and life-threatening hypotension. In addition, chronic expression of iNOS contributes to onset of diabetes, autoimmune diseases, arthritis, renal toxicity, and neurodegenerative disorders. The purpose of the present study was to examine the effect of aging on the levels of expression of iNOS induced by a low concentration (5 ng/ml) of IL-1, in VSMCs. Methods: Gene expression of iNOS was determined by RT-PCR and analysis of the PCR products by both agarose gel electrophoresis and capillary electrophoresis with laser-induced fluorescence detector (CE-LIF). This new CE-LIF technique, just developed in our laboratory, provides greater than 1,000 fold better sensitivity compared to agarose gels. The production of nitrite, the stable metabolite of NO, was measured (by a modified Griess reaction) in the media of cultured VSMCs isolated from young and elderly rats (3-month and 20-months old, respectively) of both genders following the exposure to IL-1, (5 ng/ml). VSMCs were used in their 1st passage to avoid phenotypic changes that typically occur in cultures of VSMCs after 3-10 passages. Results: IL-1, (5 ng/ml) caused a much larger increase in iNOS mRNA in VSMCs of elderly rats as compared to young rats. Furthermore, IL-1, (5 ng/ml) had no significant effect on nitrite levels in VSMCs of young, but significantly increased nitrite levels by 7.9 fold in VSMCs from elderly male rats and by 2.6 fold in VSMCs from elderly female rats, as compared to young rats. A report had previously shown that the neuropeptide CGRP could synergistically enhance the expression of iNOS caused by IL-1, in later passages (10-15 passages) of rat aortic VSMCs (i.e. phenotypically modulated VSMCs). We found that IL-1, and CGRP together did not act synergistically to increase production of nitrite in our phenotypically normal (1st passage) VSMCs. Conclusion: IL-1,, at a low concentration (5 ng/ml), preferentially induces iNOS expression and increases production of NO in VSMCs of elderly rats as compared to young rats. The data suggest that aging enhances the responsiveness of VSMCs to the iNOS-inducing actions of the cytokine IL-1,. This may be a contributing factor in the increased risk of developing severe hypotension in elderly patients with sepsis. (Supported by a Direct Grant for Research). [source]

Interaction Between Norepinephrine, Oxytocin, and Nitric Oxide in the Stimulation of Gonadotropin-Releasing Hormone Release From Proestrous Rat Basal Hypothalamus Explants

JOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2004
D. J. Selvage
Abstract In the proestrous female rat, norepinephrine, oxytocin and nitric oxide (NO) all participate in the regulation of the preovulatory gonadotropin-releasing hormone (GnRH) surge. Recent studies from our laboratory have demonstrated that oxytocin induces dose-dependent release of GnRH from proestrous basal hypothalamus explants. The present studies were undertaken to determine whether norepinephrine could also stimulate GnRH release from similar explants, to identify the receptors responsible for this effect and to investigate interactions between norepinephrine, oxytocin and NO. Norepinephrine significantly stimulated GnRH release from proestrous basal hypothalamus explants, and coadministration of the ,1 -adrenergic antagonist prazosin blocked this effect. Combined administration of oxytocin and norepinephrine stimulated significantly more GnRH release than either drug alone, and this stimulation was blocked by inhibition of NO synthase, or by an oxytocin receptor antagonist. NO production was measured from the same samples using a modified Griess reaction. Oxytocin, but not norepinephrine, significantly increased NO production, as did norepinephrine and oxytocin in combination. Oxytocin receptor antagonist administration attenuated the stimulation of NO production by norepinephrine/oxytocin. These results demonstrate for the first time that oxytocin and norepinephrine dramatically stimulate GnRH release from basal hypothalamus explants harvested on the afternoon of proestrus, and indicate that this involves oxytocin receptor and NO-dependent mechanisms. [source]

Nitric Oxide Mediates Inhibitory Effect of Interleukin-1, on Estrogen Production in Human Granulosa-Luteal Cells

JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 1 2001
Hisako Tobai
Abstract Objective: To investigate the effect of IL-1, on NO production and steroidogenesis in human granulosa-luteal cells obtained from women undergoing in vitro fertilization procedures. Subjects and Methods:To investigate the effect of IL-1,, granulosa-luteal cells were cultured with various doses of IL-1, (0, 0.05, 0.5, 5, 50, 100 ng/ml), IL-1, (5 ng/ml) with NG -nitro-L-arginine-methyl ester (l-NAME), selective inhibitors of NOS, sodium nitroprusside (SNP), NO donors and Genistain, a tyrosine kinase inhibitor. Results:IL-1, induced a dose-dependent stimulation of NO production and inhibited the production of estradiol in a significant way in a dose-dependent manner. l-NAME significantly decreased NO production and increased the production of estradiol and progesterone. SNP significantly increased NO production and caused decreases in the production of both estradiol and progesterone. Genistain decreased NO production and significantly increased the production of estradiol and progesterone. Inducible NOS (iNOS) messenger RNA was present in granulosa-luteal cells before treatment with IL-1,. Conclusions:IL-1, stimulated NO production, and NO inhibited the production of estradiol. [source]

Nitric Oxide Plays a Crucial Role in the Development/Progression of Nonalcoholic Steatohepatitis in the Choline-Deficient, l-Amino Acid-Defined Diet-Fed Rat Model

ALCOHOLISM, Issue 2010
Koji Fujita
Background:, The pathogenesis of nonalcoholic steatohepatitis (NASH) is still unclear. Recently, the 2-hit hypothesis was proposed, in which nitric oxide production, representing oxidative stress, was proposed as a very important candidate for the second hit. Methods:, The total study period was 10 weeks. A total of 20 rats were randomly divided into 2 groups. Group 1 was administered the Choline-Deficient, l-Amino Acid-Defined diet to produce a NASH model, and Group 2 as control received the Choline-Sufficient, l-Amino Acid-defined diet. The blood and tissue concentrations of nitrate + nitrite were measured using the Griess reagent and the expression levels of inducible nitric oxide synthase (iNOS) proteins and mRNA was determined by Western blotting. Results:, In regard to nitric oxide (NO) and NO metabolites, there were significant differences in the blood (especially portal venous blood) as well as tissue (liver and visceral fat) concentrations between the 2 animal groups; the amounts of NO metabolites in the tissues were much higher in the NASH models. The level of nitrotyrosine was much markedly higher in the NASH models than in the controls. In regard to the tissue expression of iNOS a significant difference between the 2 groups was found in the visceral fat, especially in the mesenterium. Conclusions:, Based on these results, we hypothesize that the iNOS expression and NO levels in the visceral fat increase, with increased diffusion of NO and its metabolites into the liver, resulting in increased nitrotyrosine formation in the liver; this, in turn, induces inflammation, apoptosis, and fibrosis in the liver, which are one of the characteristic features of NASH. [source]

Alcohol Stimulates Ciliary Motility of Isolated Airway Axonemes Through a Nitric Oxide, Cyclase, and Cyclic Nucleotide-Dependent Kinase Mechanism

ALCOHOLISM, Issue 4 2009
Joseph H. Sisson
Background:, Lung mucociliary clearance provides the first line of defense from lung infections and is impaired in individuals who consume heavy amounts of alcohol. Previous studies have demonstrated that this alcohol-induced ciliary dysfunction occurs through impairment of nitric oxide (NO) and cyclic nucleotide-dependent kinase-signaling pathways in lung airway ciliated epithelial cells. Recent studies have established that all key elements of this alcohol-driven signaling pathway co-localize to the apical surface of the ciliated cells with the basal bodies. These findings led us to hypothesize that alcohol activates the cilia stimulation pathway at the organelle level. To test this hypothesis we performed experiments exposing isolated demembranated cilia (isolated axonemes) to alcohol and studied the effect of alcohol-stimulated ciliary motility on the pathways involved with isolated axoneme activation. Methods:, Isolated demembranated cilia were prepared from bovine trachea and activated with adenosine triphosphate. Ciliary beat frequency, NO production, adenylyl and guanylyl cyclase activities, cAMP- and cGMP-dependent kinase activities were measured following exposure to biologically relevant concentrations of alcohol. Results:, Alcohol rapidly stimulated axoneme beating 40% above baseline at very low concentrations of alcohol (1 to 10 mM). This activation was specific to ethanol, required the synthesis of NO, the activation of soluble adenylyl cyclase (sAC), and the activation of both cAMP- and cGMP-dependent kinases (PKA and PKG), all of which were present in the isolated organelle preparation. Conclusions:, Alcohol rapidly and sequentially activates the eNOS,NO,GC,cGMP,PKG and sAC,cAMP, PKA dual signaling pathways in isolated airway axonemes. These findings indicate a direct effect of alcohol on airway cilia organelle function and fully recapitulate the alcohol-driven activation of cilia known to exist in vivo and in intact lung ciliated cells in vitro following brief moderate alcohol exposure. Furthermore, these findings indicate that airway cilia are exquisitely sensitive to the effects of alcohol and substantiate a key role for alcohol in the alterations of mucociliary clearance associated with even low levels of alcohol intake. We speculate that this same axoneme-based alcohol activation pathway is down regulated following long-term high alcohol exposure and that the isolated axoneme preparation provides an excellent model for studying the mechanism of alcohol-mediated cilia dysfunction. [source]

The Receptors and Role of Angiotensin II in Knee Joint Blood Flow Regulation and Role of Nitric Oxide in Modulation of Their Function

MICROCIRCULATION, Issue 5 2003
H. NAJAFIPOUR
ABSTRACT Objectives: Angiotensin-converting enzyme (ACE) upregulation in the stroma cells of arthritis rheumatoid joints may produce a higher tissue concentration of angiotensin II (angII), which is a vasoconstrictor and mitogen factor that causes local hypoxia and synovial proliferation. No study in the literature has examined the role of angII in joint blood flow (JBF) regulation and the potential effect of ACE inhibitors on JBF. Methods: The study was performed on 20 Dutch white rabbits to examine the JBF response to angII, angII receptor subtypes, and the role of nitric oxide (NO) in angII effects in knee joint blood vessels. Drugs were administered locally through retrograde saphenous artery cannulation. Joint vascular resistance (JVR) was calculated by dividing the arterial blood pressure by the JBF. Results: AngII increased JVR dose dependently. The angII type 1 (AT1) receptor antagonist losartan did not change the basal JVR but completely blocked the effect of angII on JVR. N, -nitro-L-arginin methyl ester (L-NAME) increased JVR by a mean (±SEM) of 25.8 ± 8.7% (p < 0.05) but did not affect the joint vessel response to angII and losartan. Conclusions: AngII receptors are from the AT1 subtype in normal joint blood vessels, but angII plays no significant role in JBF regulation. The basal release of NO plays a role in resting JBF regulation, but NO does not affect the AT1 receptor-mediated vasoconstriction of joint blood vessels. [source]

Self-sensitized Photodegradation of Membrane-bound Protoporphyrin Mediated by Chain Lipid Peroxidation: Inhibition by Nitric Oxide with Sustained Singlet Oxygen Damage

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005
Magdalena Niziolek
ABSTRACT In the presence of exciting light, iron and reductants, the singlet oxygen (1O2)-generating sensitizer protoporphyrin IX (PpIX) induces free radical lipid peroxidation in membranes, but gradually degrades in the process. We postulated that NO, acting as a chain-breaking antioxidant, would protect PpIX against degradation and consequently prolong its ability to produce 1O2. This idea was tested by irradiating PpIX-containing liposomes (LUVs) in the presence of iron and ascorbate, and monitoring the cholesterol hydroperoxides 5,-OOH and 7,/,-OOH as respective 1O2 and free radical reporters. 5,-OOH accumulation, initially linear with light fluence, slowed progressively after prolonged irradiation, whereas 7,/,-OOH accumulation only accelerated after an initial lag. The active, but not spent, NO donor spermine NONOate (0.4 mM) virtually abolished 7,/,-OOH buildup as well as 5,-OOH slowdown. Increasing membrane phospholipid unsaturation hastened the onset of rapid chain peroxidation and 5,-OOH slowdown. Accompanying the 5,-OOH effect was a steady decrease in 1O2 quantum yield and PpIX fluorescence at 632 nm, both of which were inhibited by NO. An NO-inhibitable decay of PpIX fluorescence was also observed during dark incubation of 5,-OOH-bearing LUVs with iron and ascorbate, confirming a link between chain peroxidation and PpIX loss. By protecting PpIX in irradiated membranes, NO might select for and prolong purely 1O2 -mediated damage. Supporting this was our observation that 1O2 -mediated photoinactivation of a nonmembrane target, lactate dehydrogenase, slowed concurrently with 5,-OOH accumulation and that spermine NONOate prevented this. Thus, NO not only protected membrane lipids against PpIX-sensitized free radical damage, but PpIX itself, thereby extending its 1O2 -generating lifetime. Consistent findings were obtained using porphyrin-sensitized COH-BR1 cells. These previously unrecognized effects of NO could have important bearing on 5-aminolevulinate-based photodynamic therapy in which PpIX is metabolically deposited in tumor cells. [source]

Effects of Melanogenesis-Inducing Nitric Oxide and Histamine on the Production of Eumelanin and Pheomelanin in Cultured Human Melanocytes

PIGMENT CELL & MELANOMA RESEARCH, Issue 1 2003
Michael W. Lassalle
Melanin pigments produced in human melanocytes are classified into two categories; black coloured eumelanin and reddish-yellow pheomelanin. Stimulation of melanocytes with ,-melanocyte-stimulating hormone (,-MSH), one of several melanogenic factors, has been reported to enhance eumelanogenesis to a greater degree than pheomelanogenesis, which contributes to hyperpigmentation in skin. Nitric oxide (NO) and histamine are also melanogenesis-stimulating factors that are released from cells surrounding melanocytes following ultraviolet (UV) irradiation. In this study, the effects of NO and histamine on the ratio of eumelanin and pheomelanin were examined in human melanocytes, and then compared with that of ,-MSH. The amounts of eumelanin and pheomelanin were quantified using high-performance liquid chromatography analysis after oxidation and hydrolysis of melanin. Melanogenesis was induced by the addition of ,-MSH, NO, or histamine to melanocytes. The amount of eumelanin production significantly increased with independent stimulation by these melanogenic factors, especially histamine, while that of pheomelanin significantly increased with ,-MSH and NO, but only slightly with histamine. As a result, the ratio of eumelanin and pheomelanin increased significantly with the addition of NO or histamine. These results suggest that NO and histamine, as in the case of ,-MSH, may contribute to UV-induced hyperpigmentation by enhancing eumelanogenesis. [source]

Spontaneous Ca2+ Waves in Rabbit Corpus Cavernosum: Modulation by Nitric Oxide and cGMP

THE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009
Gerard P. Sergeant PhD
ABSTRACT Introduction., Detumescent tone and subsequent relaxation by nitric oxide (NO) are essential processes that determine the erectile state of the penis. Despite this, the mechanisms involved are incompletely understood. It is often assumed that the tone is associated with a sustained high cytosolic Ca2+ level in the corpus cavernosum smooth muscle cells, however, an alternative possibility is that oscillatory Ca2+ signals regulate tone, and erection occurs as a result of inhibition of Ca2+ oscillations by NO. Aims., The aim of this study is to determine if smooth muscle cells displayed spontaneous Ca2+ oscillations and, if so, whether these were regulated by NO. Methods., Male New Zealand white rabbits were euthanized and smooth muscle cells were isolated by enzymatic dispersal for confocal imaging of intracellular Ca2+ (using fluo-4AM) and patch clamp recording of spontaneous membrane currents. Thin tissue slices were also loaded with fluo-4AM for live imaging of Ca2+. Main Outcome Measure., Cytosolic Ca2+ was measured in isolated smooth muscle cells and tissue slices. Results., Isolated rabbit corpus cavernosum smooth muscle cells developed spontaneous Ca2+ waves that spread at a mean velocity of 65 µm/s. Dual voltage clamp/confocal recordings revealed that each of the Ca2+ waves was associated with an inward current typical of the Ca2+ -activated Cl - currents developed by these cells. The waves depended on an intact sarcoplasmic reticulum Ca2+ store, as they were blocked by cyclopiazonic acid (Calbiochem, San Diego, CA, USA) and agents that interfere with ryanodine receptors and IP3 -mediated Ca2+ release. The waves were also inhibited by an NO donor (diethylamine NO; Tocris Bioscience, Bristol, Avon, UK), 3-(5-hydroxymethyl-2-furyl)-1-benzyl indazole (YC-1) (Alexis Biochemicals, Bingham, Notts, UK), 8-bromo-cyclic guanosine mono-phosphate (Tocris), and sildenafil (Viagra, Pfizer, Sandwich, Kent, UK). Regular Ca2+ oscillations were also observed in whole tissue slices where they were clearly seen to precede contraction. This activity was also markedly inhibited by sildenafil, suggesting that it was under NO regulation. Conclusions., These results provide a new basis for understanding detumescent tone in the corpus cavernosum and its inhibition by NO. Sergeant GP, Craven M, Hollywood MA, McHale NG, and Thornbury KD. Spontaneous Ca2+ waves in rabbit corpus cavernosum: Modulation by nitric oxide and cGMP. J Sex Med **;**:**,**. [source]

ORIGINAL RESEARCH,BASIC SCIENCE: A Nitric Oxide-Releasing PDE5 Inhibitor Relaxes Human Corpus Cavernosum in the Absence of Endogenous Nitric Oxide

THE JOURNAL OF SEXUAL MEDICINE, Issue 1 2005
Jasjit S. Kalsi BSc, MRCS
ABSTRACT Introduction., In conditions with severe deficiency of endogenous nitric oxide (NO), such as long-term diabetes and cavernosal nerve injury, phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in the treatment of erectile dysfunction. NO-releasing PDE5 inhibitors could be an alternative therapeutic approach in such cases. Aim., We therefore aimed to compare sildenafil and NO-releasing sildenafil (NCX-911) in relaxing human corpus cavernosum in the absence or presence of endogenous NO. Methods., The two compounds were compared in reducing the phenylephrine-induced tone of human corpus cavernosum in the presence or absence of an inhibitor of NO synthase (L-NAME; 500 µM) or an inhibitor of soluble guanylate cyclase (ODQ, 10 µM). Results., NCX-911 was as potent as sildenafil in control conditions (EC50 = 733.1 ± 94.4 nM and 800.7 ± 155.8 nM, respectively). The potency of NCX-911 was not altered but that of sildenafil decreased significantly in the presence of L-NAME (EC50 = 980.4 ± 106.7 nM and 2446.7 ± 256.8 nM, respectively; P < 0.001 for sildenafil vs. control). Both compounds below 1 µM failed to induce relaxation in the presence of ODQ (EC50 = 6578 ± 1150 nM and 6488 ± 938 nM for NCX-911 and sildenafil, respectively). Conclusion., These results show that the potency of NCX-911 was maintained unlike sildenafil in the absence of endogenous NO confirming the potential use of NO-releasing PDE5 inhibitors in NO-deficient conditions. [source]

Vaginal Nitric Oxide in Pregnant Women with Bacterial Vaginosis

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2006
Mehmet R. Genç
Problem To evaluate vaginal nitric oxide (NO) production in response to alterations in the vaginal microbial flora. Method of study Cervicovaginal lavage samples from 206 women at 18,22 weeks of gestation were tested for NO, interleukin-1, (IL-1,), IL-1 receptor antagonist (IL-1ra), tumor necrosis factor- , and the inducible 70 kDa heat shock protein (hsp70). Bacterial vaginosis (BV) was diagnosed based on gram staining of vaginal smears. Results and conclusions Elevated NO (>2.14 mmol/L) was associated with a diagnosis of BV (38% versus 11%, P < 0.008) as well as an increased median vaginal IL-1ra concentration (72.5 ng/ml versus 36.6 ng/ml, P = 0.041). Elevated vaginal NO was also associated with vaginal hsp70 and this relationship was independent of BV status or IL-1ra concentrations (P < 0.026). We conclude that vaginal hsp70 release in response to abnormal vaginal microflora may trigger NO production in an attempt to minimize the pathological consequences of this altered milieu. [source]

Role of Nitric Oxide in the Development of Distant Metastasis From Squamous Cell Carcinoma,

THE LARYNGOSCOPE, Issue 2 2007
Richard L. Scher MD
Abstract Background: Metastasis, the dissemination of malignant cells to distant sites, remains one of the most significant factors responsible for death from cancer. Recent studies have shown some improvement in the rate of distant metastasis (DM) with the addition of chemotherapy to surgery and radiation for treatment of head and neck squamous cell carcinoma (HNSCC). However, diagnosis and treatment at an early stage ultimately leads to a better prognosis. The prediction of which patients will develop metastasis and the selection of treatment most effective at preventing and treating metastasis remains dependent on an incomplete understanding of prognostic factors and the biological and molecular basis for metastatic development. This study was undertaken using an in vivo model to investigate the possible role of nitric oxide (NO) in the development of metastasis from HNSCC. The findings will result in better understanding of the metastatic process for HNSCC, with the potential to develop and implement therapies that could prevent and treat metastasis in patients. Objectives/Hypothesis: 1) To analyze whether in vivo videomicroscopy (IVVM) is useful for the study of DM from squamous cell carcinoma of the head and neck; 2) with use of IVVM, investigate the effect of the biological mediators NO and interleukin (IL)-1 on the adhesion of circulating human HNSCC cells in the hepatic microcirculation. Study Design: Prospective study using an animal model. Methods: Phase 1: athymic nude rats and mice were used for IVVM experiments. The cremaster muscle and liver, used as arterial and venous flow models, were tested to determine whether IVVM was useful for the study of human HNSCC interactions with the microcirculation. A human squamous cell carcinoma cell line (FaDu) labeled with the intracytoplasmic fluorescent marker BCECF-am. was used for all experiments. Videomicroscopic images of FaDu cells in the microcirculation were analyzed for cell adhesion, morphology, deformation, circulation, location of adhesion within the microcirculation, and alteration of microvascular circulation. Phase 2: the effect of IL-1, NO, and NO inhibitors on HNSCC cell adhesion in the hepatic microcirculation of nude mice was analyzed by IVVM. This was followed by histologic determination of the ratio of FaDu cells present for liver area analyzed. Nude mice were treated with 1) IL-1; 2) L-arginine (an NO substrate); or 3) L-N-monomethyl-L-arginine (an NO synthase inhibitor) alone or in combination. These data were analyzed statistically to determine the effect on cell adhesion in the liver. Results: IVVM provided a method for the study of circulating HNSCC with the microcirculation in both the cremaster and liver models. FaDu cells were arrested at the inflow side of the circulation, with maintenance of cell integrity. L-arginine and IL-1 both increased FaDu cell arrest in the liver above baseline (P = .00008 and P = .03), and the combination of these agents potentiated the effect (P = .000009). Conclusions: IVVM allows direct assessment of circulating HNSCC with the microcirculation and is a powerful model for the study of DM. NO and IL-1 play a role in increasing the arrest of HNSCC in the liver and are important in the generation of DM in patients with HNSCC. [source]

Nasal Nitric Oxide in Children: A Novel Measurement Technique and Normal Values,,

THE LARYNGOSCOPE, Issue 10 2002
Hamid Daya FRCS (ORL)
Abstract Objectives To develop and standardize a technique for measuring nasal nitric oxide (NO) output in children and to determine normal values in this population. Study Design Prospective study evaluating a new technique for measuring nasal nitric oxide in a cohort of normal patients and a cohort of patients with nasal disease. Methods Nasal NO was measured using an aspiration technique, aspirating room air through the nasal cavities by means of a Teflon nozzle placed in one nasal vestibule while maintaining velopharyngeal closure using a party "blow-out" toy Results Nasal NO measurements were performed in 45 children (mean age, 11.0 y; age range, 3.2,17.6 y) There were 20 girls and 25 boys. All children were able to perform the maneuvers necessary for measurement of nasal NO output. Among the subgroup of normal healthy children (30), there was considerable variation in NO output between subjects, with a mean NO output of 481 nL/min and an SD of 283 nL/min. Conclusions Nasal NO can be readily measured in children using the presented technique. There is considerable variability in the values for nasal NO output in normal children. [source]

l -Arginine Inhibits Isoproterenol-Induced Cardiac Hypertrophy through Nitric Oxide and Polyamine Pathways

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2008
Yan Lin
Nitric oxide exhibits antihypertrophic functions and inhibits cardiac remodelling. However, the metabolism of polyamines and the potential interactions with nitric oxide in cardiac hypertrophy remain unclear. We randomly divided Wistar rats into four treatment groups: controls, isoproterenol (ISO), ISO and l -arginine, and l -arginine. Isoproterenol (5 mg/kg/day, subcutaneously) and/or l -arginine (800 mg/kg/day, intraperitoneally) was administered once daily for 7 days. The expression of atrial natriuretic peptide mRNA was determined by reverse transcription,polymerase chain reaction, and fibrogenesis of heart was assessed by Van Gieson staining. Polyamines were measured with high-performance liquid chromatography, and plasma nitric oxide content and lactate dehydrogenase (LDH) activity were determined with a spectrophotometer. The expression levels of ornithine decarboxylase, spermidine/spermine N1-acetyltransferase (SSAT), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) were analysed by Western blot. Heart-to-body weight ratio, left ventricle-to-body weight ratio, atrial natriuretic peptide mRNA expression, collagen fibres and LDH activity were elevated, both ornithine decarboxylase and SSAT proteins were up-regulated, and total polyamines were increased in the group treated with ISO. Additionally, the expression of iNOS was up-regulated, eNOS was down-regulated, and nitric oxide levels were low. Notably, cotreatment with l -arginine reversed most of these changes except for SSAT expression, which was further up-regulated. We propose that increased polyamines and decreased nitric oxide are involved in cardiac hypertrophy induced by ISO and suggest that l -arginine pre-treatment can attenuate cardiac hypertrophy through the regulation of key enzymes of the polyamine and nitric oxide pathways. [source]