Influence Of Nitric Oxide Donors Research Articles

Вплив донорів оксиду азоту на стан продихів рослин арабідопсису, дефектних за жасмонатним і саліцилатним сигналінгом

Вплив донорів оксиду азоту на стан продихів рослин арабідопсису, дефектних за жасмонатним і саліцилатним сигналінгом

Influence of nitric oxide donors on the intrinsic fluorescence of Na+,K+-ATPase and effects on the membrane lipids

Effects of the nitric oxide donors S-nitroso-glutathione (GSNO) and S-nitroso-N-acetylpenicillamine (SNAP) on Na+,K+-ATPase-rich membrane fragments purified from pig kidney outer medulla were studied using intrinsic fluorescence and ESR of spin-labeled membranes. These S-nitrosothiols differently affected the intrinsic fluorescence of Na+,K+-ATPase: GSNO induced a partial quenching, whereas SNAP produced no alteration. Quenching can be due to a direct modification of exposed tryptophan residues or to an indirect effect caused by reactions of nitrogen oxide reactive species with other residues or even with the membrane lipids. Pre-incubation of Na+,K+-ATPase with 0.4mM GSNO resulted in a modest inhibition of ATPase activity (about 24%) measured under optimal conditions. Stearic acid spin-labeled at the 14th carbon atom (14-SASL) was used to investigate membrane fluidity and the protein-lipid interface. SNAP slightly increased the mobility of bulk lipids from Na+,K+-ATPase-rich membranes, but did not change the fraction of bulk to protein-interacting lipids. Conversely, treatment with GSNO extinguished the ESR signals from 14-SASL, indicating generation of free radicals with high affinity for the lipid moiety. Our results demonstrated that membranes influence bioavailability of reactive nitrogen species and bias the activity of different S-nitrosothiols.

Characterization of the influence of nitric oxide donors on intestinal absorption of macromolecules

To characterize the influence of nitric oxide (NO) donors on the intestinal absorption of macromolecules, the relationship between the release rate of NO from NO donors and their absorption-enhancing effects and the effects of several scavengers and generators on the absorption-enhancing effects of NO donor were investigated. The t 1/2 values of the NO release rate from 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)-1-propanamine (NOC5), 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)- N-methyl-1-propanamine (NOC7) and N-ethyl-2-(1-ethyl-hydroxy-2-nitrosohydrazino)-ethanamine (NOC12) are 25, 5 and 100 min, respectively. The absorption-enhancing effects of NO donors on the absorption of fluorescein isothiocyanate dextrans with an average molecular weight of 4400 (FD-4) are NOC5 > NOC7 > NOC12 in the colon. The lowest enhancing effect of NOC12 may be due to the slow rate of NO release. The enhancing effect of NOC7 rapidly disappeared compared with the effect of NOC5. The results raise the possibility that the difference between NOC5 and NOC7 on enhancing effect is related to the t 1/2 of the NO release. The NOC7-induced enhancing effect was prevented by the co-administration of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl-3-oxide sodium salt (C-PTIO), an NO scavenger; tiron, an O 2 − scavenger; mannitol, an OH scavenger, and deferoxamine, peroxynitrate scavenger. Pyrogallol, an O 2 − generator, potentiated the NOC7-induced enhancing effect. These results support a role for peroxynitrate, and possibly OH , in the NO donor-induced intestinal enhancing effect.

Involvement of guanylate cyclase and potassium channels on the delayed phase of mouse carrageenan-induced paw oedema

Previous studies from this laboratory have shown that administration of nitric oxide (NO) donors reduces the early phase (which peaks at 4 h) of carrageenan-induced paw oedema. The aim of this study was to investigate the influence of NO donors on the delayed phase of the mouse paw oedema, which peaks 48 h after carrageenan injection. Treatment of animals with sodium nitroprusside (1.5, 5 and 10 μmol/kg, subcutaneously (s.c.)) 8 h after the subplantar carrageenan injection (300 μg/paw), reduced (∼50%) the delayed phase of paw oedema and the delayed increase in plasma leakage, as assessed by Evans Blue extravasation. Two other NO donors, S-nitroso- N-acetyl- dl-penicillamine (SNAP) or glyceril trinitrate (both at 28 μmol/kg) yielded an inhibition in paw oedema similar to that of sodium nitroprusside. NO-induced inhibition of the delayed phase of paw oedema was reversed when animals were treated with 1 H-[1,2,4]-oxadiazolo-[4,3- a]quinoxalin-1 (ODQ, a soluble guanylate cyclase inhibitor, 11 μmol/kg, s.c.) or with tetraethylammonium (TEA, a nonselective potassium channel blocker, 300 μmol/kg, s.c.), 30 min before the prophylactic dose of sodium nitroprusside. In conclusion, our results show that a brief exposure to NO donors, even when made several hours after the inflammatory reaction has been triggered, is still able to cause an important reduction on the delayed phase of carrageenan-induced mouse paw oedema and fluid leakage. Moreover, this long-lasting NO antiinflammatory effect appears to be dependent on guanylate cyclase and potassium channels.

Influence of nitric oxide donors and peroxynitrite on the contractile effect and concentration of norepinephrine

Nitric oxide (NO) and peroxynitrite (ONOO) are said to destroy norepinephrine (NE). We studied the role of NE decomposition by NO donors and ONOO as they affect the contractile activity of NE in rat denuded thoracic aorta. First, we determined the relaxing effect of NO donors (SNAP, PROLI/NO, Sodium nitrite, SIN-1) and ONOO after precontraction by NE (1 μM). SNAP and SIN-1 (EC 50 50–110 nM) were more active than PROLI/NO, Sodium nitrite or ONOO (EC 50 19–30 μM). The relaxing effect of NO donors and ONOO were decreased by ODQ (10 μM), a guanylate cyclase inhibitor. Second, we compared the contractile activity of NE before and after preincubation with NO donors or ONOO in presence of ODQ. NE (1 μM) was incubated with NO donors or ONOO at the concentrations of 0.1 mM in both Krebs solution or phosphate buffer (pH 7.4; 0.1 M) for 10 minutes at 37°C. NE evoked the aorta contraction in the same concentrations before and after preincubation with NO donors. In contrast, ONOO decreased effect of NE, EC 50 was measured at 4.3±0.3 nM and 13.4±1.6 nM, before and after preincubation of NE with ONOO respectively. Third, we measured the NE concentration using the HPLC method. We revealed that the concentration of NE after preincubation with NO donors was unaltered. However HPLC measurement revealed that NE concentration after preincubation with ONOO was reduced 2-3-fold. Therefore, under these experimental conditions ONOO, but not NO donors, was capable of destroying NE.

Influence of nitric oxide donors on the sphingomyelinase activity,accumulation of lipid peroxidation products and DNA degradation in mice liver

Influence of nitric oxide donors on the sphingomyelinase activity,accumulation of lipid peroxidation products and DNA degradation in mice liver

The influence of nitric oxide donors on the responses to nitrergic nerve stimulation in the mouse duodenum

We investigated whether exogenous nitric oxide (NO) donors have a prejunctional and/or postjunctional inhibitory effect on the nitrergic responses and whether this inhibitory effect was mediated by NO itself and in part, by cyclic GMP in mouse duodenal strips. N ω-nitro- l-arginine inhibited relaxations induced by electrical field stimulation of nitrergic nerves, but not those with acidified NaNO 2. Furthermore, 1 H-[1,2,4]oxadiazolo[4,3- a]quinoxalin-1-one (ODQ) inhibited both types of relaxations while 2-amino-5,6-dihydro-6-methyl-4 H-1,3-thiazine (AMT) and N-ethylmaleimide were ineffective. NO donors, nitroglycerin and sodium nitroprusside, inhibited relaxations induced by nitrergic nerve stimulation, but not those with acidified NaNO 2. Hemoglobin, exogenous Cu 2+/Zn 2+ superoxide dismutase, diethyldithiocarbamic acid and pyrogallol did not influence the relaxation with nitrergic nerve stimulation. However, hemoglobin, diethyldithiocarbamic acid, pyrogallol and diethyldithiocarbamic acid plus pyrogallol attenuated the inhibitory effect of NO donors on relaxation with nitrergic nerve stimulation, and exogenous superoxide dismutase potentiated this inhibitory effect. Moreover, nitrergic nerve-mediated relaxations were inhibited by 8-bromo-cyclic GMP, but not by 8-bromo-cyclic AMP. These results suggest that exogenous NO donors have a prejunctional inhibitory effect on the nerve-mediated nitrergic relaxation and that the inhibitory effects of nitroglycerin and sodium nitroprusside are NO-dependent, but not related to NO metabolites such as peroxynitrite or a nitrosothiol intermediate. However, a contribution of S-nitrosothiol formed intracellularly cannot be entirely ruled out. Also, this prejunctional inhibition is mediated, at least in part, by the cyclic GMP, but not the cyclic AMP, pathway.

Influence of nitric oxide donors and of the α 2-agonist UK-14,304 on acetylcholine release in the pig gastric fundus

This study in circular muscle strips of the pig gastric fundus aimed to measure the release of acetylcholine directly and to investigate whether NO and α 2-adrenoceptor agonists can modulate acetylcholine release from cholinergic neurones. After incubation of the tissues with [ 3H]–choline, basal and electrically induced release of tritium and [ 3H]–acetylcholine were analyzed in a medium containing physostigmine (10 −5 M) as well as atropine (10 −6 M). The NO synthase inhibitor l-N G-nitroarginine methyl ester (3×10 −4 M), and the NO donors sodium nitroprusside (10 −5 M) and 3-morpholino-sydnonimine (10 −5 M) did not influence the basal release nor the electrically evoked release, indicating that NO does not modify [ 3H]–acetylcholine release. The α 2-adrenoceptor agonist UK-14,304 (10 −5 M) significantly inhibited the electrically evoked release of [ 3H]–acetylcholine, and this effect was prevented by the α 2-adrenoceptor antagonist rauwolscine (2×10 −6 M), suggesting that presynaptic α 2-adrenoceptors are present on cholinergic neurones of the pig gastric fundus.