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Nitric oxide released from luminal s-nitroso-N-acetylcysteine increases gastric mucosal blood flow.

ABSTRACT: Nitric oxide (NO)-mediated vasodilation plays a key role in gastric mucosal defense, and NO-donor drugs may protect against diseases associated with gastric mucosal blood flow (GMBF) deficiencies. In this study, we used the ex vivo gastric chamber method and Laser Doppler Flowmetry to characterize the effects of luminal aqueous NO-donor drug S-nitroso-N-acetylcysteine (SNAC) solution administration compared to aqueous NaNO2 and NaNO3 solutions (pH 7.4) on GMBF in Sprague-Dawley rats. SNAC solutions (600 ?M and 12 mM) led to a rapid threefold increase in GMBF, which was maintained during the incubation of the solutions with the gastric mucosa, while NaNO2 or NaNO3 solutions (12 mM) did not affect GMBF. SNAC solutions (600 ?M and 12 mM) spontaneously released NO at 37 °C at a constant rate of 0.3 or 14 nmol·mL-1·min-1, respectively, while NaNO2 (12 mM) released NO at a rate of 0.06 nmol·mL-1·min-1 and NaNO3 (12 mM) did not release NO. These results suggest that the SNAC-induced GMBF increase is due to their higher rates of spontaneous NO release compared to equimolar NaNO2 solutions. Taken together, our data indicate that oral SNAC administration is a potential approach for gastric acid-peptic disorder prevention and treatment.

SUBMITTER: de Souza GF

PROVIDER: S-EPMC6272716 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Nitric oxide released from luminal s-nitroso-N-acetylcysteine increases gastric mucosal blood flow.

de Souza Gabriela F P GF Taladriz-Blanco Patricia P Velloso Lício A LA de Oliveira Marcelo G MG

Molecules (Basel, Switzerland) 20150304 3

Nitric oxide (NO)-mediated vasodilation plays a key role in gastric mucosal defense, and NO-donor drugs may protect against diseases associated with gastric mucosal blood flow (GMBF) deficiencies. In this study, we used the ex vivo gastric chamber method and Laser Doppler Flowmetry to characterize the effects of luminal aqueous NO-donor drug S-nitroso-N-acetylcysteine (SNAC) solution administration compared to aqueous NaNO2 and NaNO3 solutions (pH 7.4) on GMBF in Sprague-Dawley rats. SNAC soluti ...[more]

PMID: 25749680

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Project description:Although sex differences in asthma severity are recognized, the mechanisms by which sex steroids such as estrogen influence the airway are still under investigation. Airway tone, a key aspect of asthma, represents a balance between bronchoconstriction and dilation. Nitric oxide (NO) from the bronchial epithelium is an endogenous bronchodilator. We hypothesized that estrogens facilitate bronchodilation by generating NO in bronchial epithelium. In acutely dissociated human bronchial epithelial cells from female patients exposure to 17?-estradiol (E(2); 10 pM-100 nM) resulted in rapid increase of diaminofluorescein fluorescence (NO indicator) within minutes, comparable with that induced by ATP (20 ?M). Estrogen receptor (ER) isoform-specific agonists (R,R)-5,11-diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol (THC) (ER?) and diaryl-propionitrile (DPN) (ER?) stimulated NO production to comparable levels and at comparable rates, whereas the ER antagonist 7?,17?-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol (ICI 182,780) (1 ?M) was inhibitory. Estrogen effects on NO were mediated via caveolin-1 (blocked using the caveolin-1 scaffolding domain peptide) and by increased intracellular calcium concentration [prevented by 20 ?M 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester but not by blocking Ca(2+) influx using LaCl(3)]. Estrogen increased endothelial NO synthase activation (inhibited by 100 ?M N(G)-nitro-l-arginine methyl ester) and phosphorylated Akt. In epithelium-intact human bronchial rings contracted with acetylcholine (1 ?M), E(2), THC, and DPN all produced acute bronchodilation in a dose-dependent fashion. Such bronchodilatory effects were substantially reduced by epithelial denudation. Overall, these data indicate that estrogens, acting via ER? or ER?, can acutely produce NO in airway epithelium (akin to vascular endothelium). Estrogen-induced NO and its impairment may contribute to altered bronchodilation in women with asthma.

Project description:Although nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results because of inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here, we show that temperature significantly modulates NO effects.To test the hypothesis that temperature profoundly affects nitroso-redox equilibrium, thereby affecting sarcoplasmic reticulum (SR) calcium (Ca(2+)) leak.We measured SR Ca(2+) leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (neuronal nitric oxide synthase-deficient mice-1 [NOS1(-/-)]), and hyper S-nitrosoglutathione reductase-deficient (GSNOR(-/-)) mice. In WT cardiomyocytes, SR Ca(2+) leak increased because temperature decreased from 37°C to 23°C, whereas in NOS1(-/-) cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR(-/-) cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1(-/-) cardiomyocytes; reducing leak at 37°C but increasing it at subphysiological temperatures. Oxypurinol and Tempol diminished the leak in NOS1(-/-) cardiomyocytes. Cooling from 37°C to 23°C increased reactive oxygen species generation in WT but decreased it in NOS1(-/-) cardiomyocytes. Oxypurinol further reduced reactive oxygen species generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca(2+) content in NOS1(-/-) cells but had no effect in WT or GSNOR(-/-).Ca(2+) leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating reactive oxygen species production because temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and reactive oxygen species which in turn has a major effect on SR Ca(2+).

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Dataset Information

Nitric oxide released from luminal s-nitroso-N-acetylcysteine increases gastric mucosal blood flow.

Publications

Nitric oxide released from luminal s-nitroso-N-acetylcysteine increases gastric mucosal blood flow.

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