Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.13.39 (NO synthase)
 15,778 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the levels of nitrosyl hemoglobin (HbNO) in rat jugular blood by electron spin resonance (ESR) spectroscopy during and after middle cerebral artery occlusion. The levels of plasma nitric oxide (NO) end products, nitrate plus nitrate, were compared with the levels of HbNO. Small amounts of HbNO were detected in sham-operated rats (n=4) and those subjected to 2 h of occlusion (n=4), whereas nitrite plus nitrate was increased only in the latter (P<0.01; vs.sham). Upon reperfusion after 2 h of occlusion both HbNO and nitrite plus nitrate clearly increased after 15 min (n=4) and 30 min (n=6) reperfusion (P<0.01; vs.occlusion). Administration of superoxide dismutase (5 mg/kg) significantly increased HbNO (P<0.05) but not plasma nitrate plus nitrate (n=5). The increase in HbNO suppressed by administration of NG-nitro-L-arginine methyl ester (20mg/kg; n=4,P<0.01), and this suppression could be reversed by L-arginine (200 mg/kg) (n=4). The present study clearly showed that the L-arginine-NO synthase pathway was activated during reperfusion after focal cerebral ischemia and indicated the involvement of a reaction between NO and superoxide during early reperfusion.
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PMID:Generation of nitric oxide and superoxide during reperfusion after focal cerebral ischemia in rats. 863 53

Kupffer cells contribute to the important role of the liver defense mechanism through nitric oxide (NO) production. In this study, the effect of chronic ethanol administration on the ability of Kupffer cells to synthesize and release NO was investigated after stimulation with lipopolysaccharide (LPS). Male Wistar rats were chronically fed ethanol for 8 weeks according to the method described by DeCarli and Lieber et al. (J Nutr.91:331-336, 1967). Kupffer cells were isolated and cultured with LPS (1 micrograms/ml) for 24 hr. The levels of nitrite and nitrate, metabolites of NO, were determined in the culture medium, NO synthase (NOS) activity in Kupffer cells was determined by the method that measures conversion of [14C]arginine into [14C]citrulline. In control rats, a significant increase of nitrite and nitrate levels in culture medium was observed after LPS treatment. The magnitude of this increase was significantly smaller in chronic ethanol-fed rats. When the activity of NOS was determined, inducible NOS (iNOS) activity was higher than that of constitutive NOS, and LPS administration produced a significant elevation of iNOS activity in both control and chronic ethanol-fed rats. However, the elevation of iNOS activity by LPS stimulation was diminished by chronic ethanol administration. Distribution of iNOS in Kupffer cells as determined by an immunofluorescence method using a laser scanning confocal image system showed a lower expression of iNOS in chronic ethanol-fed rats even in the presence of LPS. These results demonstrate that the excessive production of NO by increased iNOS activity in Kupffer cells is diminished by chronic ethanol administration.
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PMID:Effect of chronic ethanol feeding on nitric oxide synthesis by rat Kupffer cells. 865 95

Inducible nitric oxide (NO) synthase produces a long-lasting NO flux which can exert cytotoxic effects on target cells. A prerequisite for the understanding of the molecular basis of NO action is quantitative data on the availability of this small neutral radical molecule at both the spatial and temporal levels. The limits of NO availability depend on the respective rates of NO production, diffusion and autoxidation by molecular oxygen. Kinetic modeling of these processes has been performed for a widely used experimental system consisting of a monolayer of adherent cells cultured in vitro for hours in unstirred culture medium. It appears that: (i) the maximal NO concentration in the culture is in the immediate vicinity of the monolayer, where target cells will sediment; (ii) the steady-state NO concentration in this area is lower than 4 to 5 microM; and (iii) measurements of nitrite/nitrate or citrulline accumulation in the bulk cell medium culture during a given time period significantly underestimate (by a factor of up to 3 to 4) the true rate of NO synthesis at the level of the producer cell. This rate can be, nevertheless, easily estimated from the rate of production of the stable NO synthase products.
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PMID:Kinetic modelling of the nitric oxide gradient generated in vitro by adherent cells expressing inducible nitric oxide synthase. 866 Feb 70

Nitric oxide (NO) synthesis occurs during wound healing, but its role has not been defined. To study the effect of NO on wound repair, S-methyl isothiouronium (MITU, a competitive inhibitor of NO synthase) was administered at a dose of 10, 50, and 100 mg/kg body weight/day, using intraperitoneally implanted miniosmotic pumps. Groups of 10 male Balb/C mice underwent a dorsal skin incision and polyvinyl alcohol sponges were inserted subcutaneously. The animals were sacrificed 10 days postwounding and wound breaking strength and hydroxyproline content of sponges, an index of reparative collagen deposition, were determined. Some sponges were used to harvest wound fluid and infiltrating cells, which were then incubated overnight with or without 1 mM MITU. Nitrite and nitrate, stable end products of NO, were measured in wound fluid and in wound cell culture supernatants. Continuous intraperitoneal infusion of MITU significantly decreased wound fluid nitrite/nitrate concentrations in a dose dependent manner (P < 0.01). Inhibition of wound NO synthesis by 100 mg MITU/kg/day was paralleled by lowered wound collagen accumulation (P < 0.01) and wound breaking strength (P < 0.01). In vitro NO synthesis by wound cells obtained from animals treated with 100 mg MITU/kg/day was not significantly different from controls (12.6 +/- 1.2 vs 10.7 +/- 0.6 nmole NO2 + NO3/microgram DNA), reflecting the reversible inhibition of NO synthase by MITU. However, NO production was equally inhibited in wound infiltrating cells by the in vitro addition of MITU (83% vs 85%, respectively). These data suggest that nitric oxide synthesis is critical to wound collagen accumulation and acquisition of mechanical strength.
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PMID:Nitric oxide regulates wound healing. 866 Dec 4

MRL/MP-lpr/lpr (MRL/lpr) mice develop a spontaneous autoimmune disease. Serum from these mice contained significantly higher concentrations of nitrite/nitrate than serum from age-matched control MRL/MP-+/+ (MRL/+), BALB/c or CBA/6J mice. Spleen and peritoneal cells from MRL/lpr mice also produced significantly more nitric oxide (NO) than those from the control mice when cultured with interferon (IFN) gamma and lipopolysaccharide (LPS) in vitro. It is interesting to note that peritoneal cells from MRL/lpr mice also produced markedly higher concentrations of interleukin (IL) 12 than those from MRL/+ or BALB/c mice when cultured with same stimuli. It is striking that cells from MRL/lpr mice produced high concentrations of NO when cultured cells from MRL/+ or BALB/c mice. The enhanced NO synthesis induced by IFN-gamma/LPS was substantially inhibited by anti-IL-12 antibody. In addition, IL-12-induced NO production can also be markedly inhibited by anti-IFN-gamma antibody, but only weakly inhibited by anti-tumor necrosis factor alpha antibody. The effect of IL-12 on NO production was dependent on the presence of natural killer and possibly T cells. Serum from MRL/lpr mice contained significantly higher concentrations of IL-12 compared with those of MRL/+ or BALB/c control mice. Daily injection of recombinant IL-12 led to increased serum levels of IFN-gamma and NO metabolites, and accelerated glomerulonephritis in the young MRL/lpr mice (but not in the MRL/+ mice) compared with controls injected with phosphate-buffered saline alone. These data, together with previous finding that NO synthase inhibitors can ameliorate autoimmune disease in MRL/lpr mice, suggest that high capacity of such mice to produce IL-12 and their greater responsiveness to IL-12, leading to the production of high concentrations of NO, are important factors in this spontaneous model of autoimmune disease.
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PMID:The role of interleukin 12 and nitric oxide in the development of spontaneous autoimmune disease in MRL/MP-lpr/lpr mice. 866 3

Evidence presented in this paper indicates that nitric oxide (NO), generated by a nonspecific "wound"-type of inflammation, is an important mediator of the early dysfunction of transplanted islets in rodents. Although allogeneic islets stimulate NO production to a greater degree than syngeneic islets, the amounts of NO produced after either are significantly elevated above baseline. Inhibition of NO production by N(G)-monomethyl-L-arginine (NMA), markedly decreases the time needed to restore euglycemia after intraportal transplantation of syngeneic islets in diabetic rats. The dose of NMA used was not observably toxic, with no significant changes in blood pressure, hepatic artery blood flow, serum hepatic enzyme levels, or in weight compared with control animals. In rat recipients of intraportal syngeneic transplants, evidence that NO is produced at the site of implantation includes (1) an early and transient increase in posttransplant hepatic vein nitrate levels (pretransplant, 90 microM; 24 hr, 230 microM; 48 hr, 250 microM; 72 hr, 170 microM; and 96 hr, 140 microM), (2) concurrent appearance of inducible NO synthase mRNA in liver extracts, and (3) immunohistochemical localization of inducible NO synthase within the transplanted islets. Suppression of NO production or inhibition of NO activity is a potential strategy to increase the early function and engraftment transplanted islets in the clinical setting.
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PMID:Nitric oxide mediates early dysfunction of rat and mouse islets after transplantation. 868 54

Ginsenosides (GS), saponins purified from Panax ginseng, increase renal blood flow in rats. Nitric oxide (NO) is thought to be the substance endogenously released by GS in preconstricted lungs and cultured endothelial cells. The present study aims to determine whether GS could stimulate endogenous release of NO in rat kidney and whether GS affected the activity of NO synthase in kidney tissues. The serum and urine levels of the stable NO metabolites, nitrite (NO2) and nitrate (NO3) and urinary cGMP levels were measured 8 hr after a single intraperitoneal injection of GS (200 mg/kg) into rats. The effects of the NO synthesis inhibitor, N omega-nitro-L-arginine methyl ester and the NO precursor, L-arginine, on the GS-induced changes were also determined. The activity of NO synthase, as determined by conversion of [14C]-L-arginine to [14C]-L-citrulline, in whole kidney, glomeruli and cortical tubules was also investigated. A single injection of GS resulted in endogenous production of NO as reflected by increase in serum and urine levels of NO2/NO3 and urinary cGMP levels, which were inhibited by the addition of N omega-nitro-L-arginine methyl ester and restored by L-arginine. GS also stimulated the activity of NO synthase in whole kidney as well as glomeruli and cortical tubules, and this increase was significantly prevented by N omega-nitro-L-arginine methyl ester. It was concluded that stimulation in endogenous production of NO by GS may contribute to its antinephritic action and may play a protective role in the kidney.
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PMID:Ginsenosides stimulate endogenous production of nitric oxide in rat kidney. 869 2

Treatment of cultured hepatocytes with a combination of cytokines, including tumour necrosis factor-alpha, interferon-gamma and interleukin-1 beta, plus lipopolysaccharide resulted in a time-dependent induction of nitric oxide (NO) synthase (as measured by NO2- (+) NO3- production) and inhibition of hepatic gluconeogenesis and glycogen breakdown. The inhibition of glucose release was comparable with the observed following treatment of rats with lipopolysaccharide or treatment of isolated hepatocytes with artificial NO donors. In addition, this effect was also evident with all substrates tested that enter the gluconeogenic pathway below the level of phosphoenolpyruvate carboxykinase, suggesting that this combination of cytokines may underlie the inhibition of gluconeogenesis observed in endotoxic shock. The maximal inhibition of glucose output required the presence of all the cytokines plus lipopolysaccharide, whereas the induction of NO synthase was independent of the lipopolysaccharide when the cytokines were employed. Inclusion of interferon-gamma was essential to obtain a maximal response for either parameter. Inclusion of 1 mM N(G)-monomethyl-L-arginine in the incubation abolished the increase in NO2- (+) NO3- observed with the complete cytokine mixture and various combinations; however, it failed to prevent the inhibition in glucose output, indicating that mechanisms other than NO underlie the cytokine-induced inhibition of glucose release.
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PMID:Effect of multiple cytokines plus bacterial endotoxin on glucose and nitric oxide production by cultured hepatocytes. 871 78

1. Endothelium-derived nitric oxide (NO), a major modulator of vascular tone, is synthesized from the terminal guanidino nitrogen of L-arginine. This reaction is inhibited by analogues of L-arginine, such as N-nitro-L-arginine methyl ester (L-NAME). Many of the biological effects of NO are mediated by the second messenger cGMP. NO is rapidly oxidized to NO3-, which, like cGMP, is eliminated via excretion into the urine. In a placebo controlled study, we investigated whether oral bolus administration of L-arginine and L-NAME affects the urinary excretion rates of NO3- and cGMP in Munich Wistar Frommter (MWF) rats. 2. Twenty MWF rats were kept in metabolic cages and received L-arginine (3 g/kg bodyweight), L-NAME (50 mg/kg), or placebo (0.9% saline) in randomized order. Urine samples were sequentially collected for 10 h and analysed for creatinine, NO3- and cGMP. 3. L-Arginine inducted a slight, but prolonged increase in urine flow, whereas L-NAME induced an early, transient increase in urine flow which was followed by a decrease. Creatinine clearance decreased by 65% after L-NAME, but was not affected by L-arginine or placebo. 4. Urinary NO3- and cGMP excretion rates transiently increased after L-arginine (NO3-: + 29%; cGMP: +16%) for 4-5 h, whereas L-NAME induced an immediate, pronounced and lasting inhibition of urinary NO3- and cGMP excretion (NO3-: -76%; cGMP: -46%). Urinary NO3- and cGMP excretions were significantly correlated (r = 0.755; P < 0.001). 5. Urinary excretion rates of NO3- and cGMP, expressed as mu mol/h, were correlated to urine flow (mL/h; r = 0.617 and 0.649, respectively; both P < 0.05), whereas after correction by urinary creatinine (mu mol/mmol creatinine) no correlation with urine flow was observed, indicating that these excretion rates were independent of renal excretory function. Thus we conclude that changes in the urinary excretion rates of NO3- and cGMP represent changes in NO production rates in vivo when expressed in relation to urinary creatinine. Urinary NO3- and cGMP excretion is modulated by acute NO synthase inhibition or substrate provision.
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PMID:Urinary NO3- excretion as an indicator of nitric oxide formation in vivo during oral administration of L-arginine or L-name in rats. 871 90

There is controversy regarding the evidence for the production of nitric oxide (NO) by neutrophils (PMNs). The present study investigates NO production, as assessed by the biosynthesis of the end products, nitrite and nitrate, in the pellets and supernatants of rat and mouse peripheral blood neutrophils obtained during endotoxemia and of peritoneal carrageenin-elicited PMNs stimulated in vitro with E. coli lipopolysaccharide (LPS). We also investigated the induction of NO synthase by rat and mouse peritoneal cells. The intraperitoneal (ip) administration of LPS to mice (10 mg/kg) and rats (5 mg/kg) significantly increased plasma nitrate concentration by six and 23-fold, respectively. In vivo pretreatment with L-NGmonomethyl arginine (L-NMMA) significantly inhibited this production. Compared to animals injected with PBS, the cell pellets of blood PMNs obtained from mice, but not rats, 2 or 6 h after LPS administration produced significant amounts of nitrite (14 +/- 3 and 18 +/- 2 nmol/mg protein, respectively). Little or no nitrite was found in the incubating medium. In contrast, 6 h after a carrageenin challenge (700 micrograms) peritoneal neutrophils obtained from rats, but not mice, released high concentrations of nitrite into the supernatant during a 24-h period of incubation (34 +/- 0.8 microM). The nitrite concentration of the pellet of these cells was negligible. In contrast to the lack of increase in the amount of nitrite released into the supernatants, the in vitro stimulation of rat PMNs with LPS (10 micrograms/ml) for 24 h did increase intracellular nitrite concentration (from 0.8 +/- 0.07 to 8 +/- 0.3 nmol/mg protein). In mouse PMNs, LPS treatment caused only a small release of nitrite into the incubation medium (14 +/- 1 microM). There was no significant change in nitrite concentration in the cell pellets. These data suggest that rat and mouse neutrophils differ in their ability to produce nitric oxide following stimulation with endotoxin.
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PMID:Differential production of nitric oxide by endotoxin-stimulated rat and mouse neutrophils. 873 34


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