Nitric Oxide Donor Sodium Nitroprusside Research Articles

Endogenous nitric oxide contributes to chloride and sulphate salinity tolerance by modulation of ion transporter expression and reestablishment of redox balance in Brassica napus cultivars

Salinity is an adverse environmental stress for crop plants and the mechanism of salinity tolerance and its interaction with phytohormone like nitric oxide (NO) is still lacking, especially for Na2SO4 in B. napus. Therefore, in the present study, B. napus cultivars were grown under equimolar concentrations of NaCl/Na2SO4 and with their anions (KCl/K2SO4), to discriminate toxic responses of different types of salts on growth, oxidative stress, antioxidant defense, anion concentration and endogenous production of NO. Results showed that plant growth, photosynthetic rate and pigments productions were strongly inhibited under Na+ dominated salt treatments (NaCl/Na2SO4). As a result, production of oxidative stress (H2O2, O2.-, MDA, EL) related parameters were significantly induced under these treatments. The uptake of Na+ was high in B. napus cultivars irrespective of chloride/sulphate anions presence. However, Cl- and SO42- anions accumulation was only high in sensitive cultivars. The differential responses of B. napus cultivars against salinity treatments were associated with endogenous production of NO. The tolerant cultivar maintained higher level of NO, while sensitive cultivars experience a reduction in NO and inhibition of its biosynthesis enzymes, upon exposure to salinity treatments. To prove NO involvement, NO scavenger was applied on the leaves of B. napus cultivars, which significantly induced salt toxicity symptoms, oxidative stress and upregulated gene expression of ion transporters and uptake of Na+, Cl- and SO42-. Conversely, application of NO donor (sodium nitroprusside) reversed the salinity induce oxidative stress, ion accumulation and stimulated antioxidant defense in B. napus cultivars. Thus, the present study shows that endogenous NO level could act as an essential signaling molecule for triggering and activating the salinity adaptive response in rapeseed and Na+ toxicity plays a dominate role in growth inhibition, while the additive effect of chloride/sulphate anions may be cultivar dependent.

Nitric oxide inhibits endothelial cell apoptosis by inhibiting cysteine‐dependent SOD1 monomerization

Endothelial cell apoptosis is an important pathophysiology in many cardiovascular diseases. The gasotransmitter nitric oxide (NO) is known to regulate cell survival and apoptosis. However, the mechanism underlying the effect of NO remains unclear. In this research, by targeting cytosolic copper/zinc superoxide dismutase (SOD1) monomerization, we aimed to explore how NO inhibited endothelial cell apoptosis. We showed that treatment with the NO synthase (NOS) inhibitor nomega‐nitro‐l‐arginine methyl ester hydrochloride (L‐NAME) significantly decreased the endogenous NO content of endothelial cells, facilitated the formation of SOD1 monomers, inhibited dismutase activity, and promoted reactive oxygen species (ROS) accumulation in human umbilical vein endothelial cells (HUVECs); by contrast, supplementation with the NO donor sodium nitroprusside (SNP) upregulated NO content, prevented the formation of SOD1 monomers, enhanced dismutase activity, and reduced ROS accumulation in L‐NAME‐treated HUVECs. Mechanistically, tris(2‐carboxyethyl) phosphine hydrochloride (TCEP), a specific reducer of cysteine thiol, increased SOD1 monomer formation, thus preventing the NO‐induced increase in dismutase activity and the decrease in ROS. Furthermore, SNP inhibited HUVEC apoptosis caused by the decrease in endogenous NO, whereas TCEP abolished this protective effect of SNP. In summary, our data reveal that NO protects endothelial cells against apoptosis by inhibiting cysteine‐dependent SOD1 monomerization to enhance SOD1 activity and inhibit oxidative stress.

Nitric oxide is involved in hydrogen sulfide-induced adventitious rooting in tomato (Solanum lycopersicum).

Nitric oxide (NO) and hydrogen sulfide (H2 S) are signalling molecules that regulate adventitious rooting in plants. However, little is known about the cross-talk between NO and H2 S during adventitious rooting. Tomato (Solanum lycopersicum L.) explants were used to investigate the roles of and relationships between NO and H2 S during rooting. Effects of the NO donor sodium nitroprusside (SNP) and the H2 S donor sodium hydrosulfide (NaHS) on adventitious rooting were dose-dependent, and the greatest biological responses were observed under 25μM SNP and 50μM NaHS. The positive effect of NaHS was reversed by the NO scavenger 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), indicating that the H2 S-induced response was partially NO-dependent. Peroxidase (POD), polyphenol oxidase (PPO), and superoxide dismutase (SOD) activities significantly increased by SNP and NaHS treatment, and indoleacetic acid oxidase (IAAO) activity and the O2 - and H2 O2 content significantly decreased by SNP and NaHS treatment. SNP and NaHS treatment also increased the content of soluble sugar and protein and indole-3-acetic acid (IAA). cPTIO significantly mitigated the increases in POD, PPO and SOD activity and soluble sugar, protein and IAA content induced by NaHS. SNP and NaHS upregulated the expression of auxin-related genes (ARF4 and ARF16 ), cell cycle-related genes (CYCD3 , CYCA3 and CDKA1 ), and antioxidant-related genes (TPX2 , SOD and POD ); whereas cPTIO significantly inhibited the increase in the expression of these genes induced by NaHS. Overall, these results show that NO may be involved in H2 S-induced adventitious rooting by regulating the activity of rooting-related enzymes, the expression of related genes, and the content of various nutrients.

Nitric Oxide Ameliorates Plant Metal Toxicity by Increasing Antioxidant Capacity and Reducing Pb and Cd Translocation.

Recently, nitric oxide (NO) has been reported to increase plant resistance to heavy metal stress. In this regard, an in vitro tissue culture experiment was conducted to evaluate the role of the NO donor sodium nitroprusside (SNP) in the alleviation of heavy metal toxicity in a bamboo species (Arundinaria pygmaea) under lead (Pb) and cadmium (Cd) toxicity. The treatment included 200 µmol of heavy metals (Pb and Cd) alone and in combination with 200 µM SNP: NO donor, 0.1% Hb, bovine hemoglobin (NO scavenger), and 50 µM L-NAME, N(G)-nitro-L-arginine methyl ester (NO synthase inhibitor) in four replications in comparison to controls. The results demonstrated that the addition of L-NAME and Hb as an NO synthase inhibitor and NO scavenger significantly increased oxidative stress and injured the cell membrane of the bamboo species. The addition of sodium nitroprusside (SNP) for NO synthesis increased antioxidant activity, protein content, photosynthetic properties, plant biomass, and plant growth under heavy metal (Pb and Cd) toxicity. It was concluded that NO can increase plant tolerance for metal toxicity with some key mechanisms, such as increasing antioxidant activities, limiting metal translocation from roots to shoots, and diminishing metal accumulation in the roots, shoots, and stems of bamboo species under heavy metal toxicity (Pb and Cd).

Spermine-Mediated Tolerance to Selenium Toxicity in Wheat (Triticum aestivum L.) Depends on Endogenous Nitric Oxide Synthesis

Excess selenium (Se) causes toxicity, and nitric oxide (NO)’s function in spermine (Spm)-induced tolerance to Se stress is unknown. Using wheat plants exposed to 1 mM sodium selenate—alone or in combination with either 1 mM Spm, 0.1 mM NO donor sodium nitroprusside (SNP) or 0.1 mM NO scavenger cPTIO—the potential beneficial effects of these compounds to palliate Se-induced stress were evaluated at physiological, biochemical and molecular levels. Se-treated plants accumulated Se in their roots (92%) and leaves (95%) more than control plants. Furthermore, Se diminished plant growth, photosynthetic traits and the relative water content and increased the levels of malondialdehyde, H2O2, osmolyte and endogenous NO. Exogenous Spm significantly decreased the levels of malondialdehyde by 28%, H2O2 by 37% and electrolyte leakage by 42%. Combined Spm/NO treatment reduced the Se content and triggered plant growth, photosynthetic traits, antioxidant enzymes and glyoxalase systems. Spm/NO also upregulated MTP1, MTPC3 and HSP70 and downregulated TaPCS1 and NRAMP1 (metal stress-related genes involved in selenium uptake, translocation and detoxification). However, the positive effects of Spm on Se-stressed plants were eliminated by the NO scavenger. Accordingly, data support the notion that Spm palliates selenium-induced oxidative stress since the induced NO elicits antioxidant defence upregulation but downregulates Se uptake and translocation. These findings pave the way for potential biotechnological approaches to supporting sustainable wheat crop production in selenium-contaminated areas.

Age Impairs Soluble Guanylyl Cyclase Function in Mouse Mesenteric Arteries.

Endothelial dysfunction (ED) comes with age, even without overt vessel damage such as that which occurs in atherosclerosis and diabetic vasculopathy. We hypothesized that aging would affect the downstream signalling of the endothelial nitric oxide (NO) system in the vascular smooth muscle (VSM). With this in mind, resistance mesenteric arteries were isolated from 13-week (juvenile) and 40-week-old (aged) mice and tested under isometric conditions using wire myography. Acetylcholine (ACh)-induced relaxation was reduced in aged as compared to juvenile vessels. Pretreatment with L-NAME, which inhibits nitrix oxide synthases (NOS), decreased ACh-mediated vasorelaxation, whereby differences in vasorelaxation between groups disappeared. Endothelium-independent vasorelaxation by the NO donor sodium nitroprusside (SNP) was similar in both groups; however, SNP bolus application (10−6 mol L−1) as well as soluble guanylyl cyclase (sGC) activation by runcaciguat (10−6 mol L−1) caused faster responses in juvenile vessels. This was accompanied by higher cGMP concentrations and a stronger response to the PDE5 inhibitor sildenafil in juvenile vessels. Mesenteric arteries and aortas did not reveal apparent histological differences between groups (van Gieson staining). The mRNA expression of the α1 and α2 subunits of sGC was lower in aged animals, as was PDE5 mRNA expression. In conclusion, vasorelaxation is compromised at an early age in mice even in the absence of histopathological alterations. Vascular smooth muscle sGC is a key element in aged vessel dysfunction.

Activation of Coronary Arteriolar PKCβ2 Impairs Endothelial NO-Mediated Vasodilation: Role of JNK/Rho Kinase Signaling and Xanthine Oxidase Activation.

Protein kinase C (PKC) activation can evoke vasoconstriction and contribute to coronary disease. However, it is unclear whether PKC activation, without activating the contractile machinery, can lead to coronary arteriolar dysfunction. The vasoconstriction induced by the PKC activator phorbol 12,13-dibutyrate (PDBu) was examined in isolated porcine coronary arterioles. The PDBu-evoked vasoconstriction was sensitive to a broad-spectrum PKC inhibitor but not affected by inhibiting PKCβ2 or Rho kinase. After exposure of the vessels to a sub-vasomotor concentration of PDBu (1 nmol/L, 60 min), the endothelium-dependent nitric oxide (NO)-mediated dilations in response to serotonin and adenosine were compromised but the dilation induced by the NO donor sodium nitroprusside was unaltered. PDBu elevated superoxide production, which was blocked by the superoxide scavenger Tempol. The impaired NO-mediated vasodilations were reversed by Tempol or inhibition of PKCβ2, xanthine oxidase, c-Jun N-terminal kinase (JNK) and Rho kinase but were not affected by a hydrogen peroxide scavenger or inhibitors of NAD(P)H oxidase and p38 kinase. The PKCβ2 protein was detected in the arteriolar wall and co-localized with endothelial NO synthase. In conclusion, activation of PKCβ2 appears to compromise NO-mediated vasodilation via Rho kinase-mediated JNK signaling and superoxide production from xanthine oxidase, independent of the activation of the smooth muscle contractile machinery.

Induction of Proline Iminopeptidase by Nitric Oxide May Result in the Proline Accumulation in the Pea Roots.

The nitric oxide (NO) donor sodium nitroprusside upregulated the proline iminopeptidase content in the pea seedling roots. It is assumed that NO activates deprolinization of the proline-rich proteins, as evidenced by an increase in the content of free proline, which is known to protect plants from the abiotic and biotic stressors.

Methyl Jasmonate and Sodium Nitroprusside Jointly Alleviate Cadmium Toxicity in Wheat (Triticum aestivum L.) Plants by Modifying Nitrogen Metabolism, Cadmium Detoxification, and AsA-GSH Cycle.

The principal intent of the investigation was to examine the influence of joint application of methyl jasmonate (MeJA, 10 μM) and a nitric oxide–donor sodium nitroprusside (SNP, 100 μM) to wheat plants grown under cadmium (Cd as CdCl2, 100 μM) stress. Cd stress suppressed plant growth, chlorophylls (Chl), and PSII maximum efficiency (Fv/Fm), but it elevated leaf and root Cd, and contents of leaf proline, phytochelatins, malondialdehyde, and hydrogen peroxide, as well as the activity of lipoxygenase. MeJA and SNP applied jointly or singly improved the concentrations of key antioxidant biomolecules, e.g., reduced glutathione and ascorbic acid and the activities of the key oxidative defense system enzymes such as catalase, superoxide dismutase, dehydroascorbate reductase, glutathione S-transferase, and glutathione reductase. Exogenously applied MeJA and SNP jointly or singly also improved nitrogen metabolism by activating the activities of glutamine synthetase, glutamate synthase, and nitrate and nitrite reductases. Compared with individual application of MeJA or SNP, the combined application of both showed better effect in terms of improving plant growth and key metabolic processes and reducing tissue Cd content, suggesting a putative interactive role of both compounds in alleviating Cd toxicity in wheat plants.Main findingsThe main findings are that exogenous application of methyl jasmonate and nitric oxide–donor sodium nitroprusside alleviated the cadmium (Cd)–induced adverse effects on growth of wheat plants grown under Cd by modulating key physiological processes and up-regulating enzymatic antioxidants and the ascorbic acid–glutathione cycle–related enzymes.

Intravascular Hemolysis Leads to Increased Esophagus Smooth Muscle Contractions in Mice: Implication for Dysphagia and Odynophagia

Introduction:The nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling pathway is well established as a regulatory pathway of smooth muscle relaxation and contraction. Intravascular hemolysis is a hallmark of some hemolytic anemia, such as paroxysmal nocturnal hemoglobinuria (PNH). NO scavenging by excess plasma hemoglobin (Hb) has been associated with clinical manifestation of intravascular hemolysis. PNH patients display odynophagia and dysphagia, particularly during hemolytic exacerbations, and appear to be due to esophageal spasm. In this study, since plasma Hb excess leads to lower NO bioavailability, we hypothesized that exaggerated intravascular hemolysis may impair the esophageal function. The aim of this study was to evaluate the esophageal function in phenylhydrazine (PHZ)-treated mice, a murine model of intravascular hemolysis. The magnitude of intravascular hemolysis in sickle cell disease (SCD) is a controversial issue. For comparative purpose, SCD mice were also studied. We have focused on the role of the NO signaling pathway and contractile mechanisms. Moreover, the effects of iron chelator deferoxamine treatment on esophagus contractile mechanisms in PHZ mice were also evaluated.Methods: C57BL/6 mice (control) and Berkeley SCD transgenic male mice (3-4 mo old) were used. Intravascular hemolysis was induced in C57BL/6 mice by intraperitoneal injection of 2 doses of PHZ at 50 mg/Kg 8h apart. Mice were euthanized in isoflurane chamber 4 days after the second PHZ injection. The esophagus smooth muscle rings were mounted in isolated organ baths. Concentration-response curves to muscarinic agonist carbachol (CCh; 10 nM -100 μM) and potassium chloride (KCl) were obtained in esophagus from control, PHZ and SCD mice. Control and PHZ mice were treated with deferoxamine (150 mg/kg/day) or vehicle (saline) from the second to the 4th day via i.p. injection.Results: Hematological parameters (RBC [x 10-6/μL], Hb [g/dL], HCT [%]) show that PHZ (2.8±0.2, 6±0.4 and 17±1) and SCD mice (5.6±0.5, 6.1±0.3 and 28±3) have severe anemia, compared to control mice (8.8±0.1, 12.4±0.1 and 45±1). Plasma Hb was higher in SCD and PHZ compared to control mice (2.1- and 3.3 fold, respectively, P<0.05). Moreover, plasma Hb was 57% higher (P<0.05) in PHZ compared to SCD mice. CCh induced concentration-dependent esophagus contractions in control, PHZ and SCD mice. The maximal responses (Emax) were higher (P<0.05) in the esophagus of PHZ (0.75±0.3 mN/mg) compared to control mice (0.50±0.03 mN/mg).In order to evaluate the esophagus contractions independently of receptor stimulation, a concentration-response curve to KCl was constructed. Again, Emax induced by KCl were greater (P<0.05) in PHZ esophagus (0.45±0.01 mN/mg) compared to control mice (0.28±0.02 mN/mg). In SCD mice esophagus, contractile responses induced by CCh and KCl remained unchanged. In vitro preincubation of esophagus with the NO-independent heme-dependent soluble guanylate cyclase (sGC) stimulator BAY 41-2272 (1 μM) fully reversed the higher Emax of CCh and KCl in PHZ mice to control values, without changing the responses in control mice. No changes in the contractile responses for CCh and KCl were observed with the preincubation with NO donor sodium nitroprusside (SNP; 300 μM) in the PHZ and control group. Treatment with deferoxamine did not prevent the elevation of contractile responses in PHZ mice esophagus.Conclusion: Our data show that exaggerated intravascular hemolysis can lead to enhanced esophagus contractions in PHZ mice. BAY 41-2272 is likely to counteract the elevation of contractile responses by stimulating sGC, elevating cGMP levels by stimulating the sGC mostly via NO-independent mechanisms. NO donor failed to modify the increased esophagus contractions in PHZ mice. It is likely that Hb or increased O2- production in esophagus of PHZ mice act to inactivate NO before it reaches sGC. Deferoxamine treatment failed to avoid the esophageal dysfunction, suggesting that excess iron may not be associated with this disorder. SCD mice do not display esophageal disorder, indicating that excess of plasma Hb is not abundant enough to cause esophagus damage in SCD. To the best of our knowledge this is the first study in an experimental model that supports the hypothesis that esophageal clinical symptoms in PNH are secondary to impairment of NO-cGMP pathway caused by intravascular hemolysis.Financial Support: FAPESP. DisclosuresFertrin:Alexion Pharmaceuticals: Consultancy.

The Nitric Oxide (NO) Donor Sodium Nitroprusside (SNP) and Its Potential for the Schizophrenia Therapy: Lights and Shadows.

Schizophrenia is a severe psychiatric disorder affecting up to 1% of the worldwide population. Available therapy presents different limits comprising lack of efficiency in attenuating negative symptoms and cognitive deficits, typical features of schizophrenia and severe side effects. There is pressing requirement, therefore, to develop novel neuroleptics with higher efficacy and safety. Nitric oxide (NO), an intra- and inter-cellular messenger in the brain, appears to be implicated in the pathogenesis of schizophrenia. In particular, underproduction of this gaseous molecule is associated to this mental disease. The latter suggests that increment of nitrergic activity might be of utility for the medication of schizophrenia. Based on the above, molecules able to enhance NO production, as are NO donors, might represent a class of compounds candidates. Sodium nitroprusside (SNP) is a NO donor and is proposed as a promising novel compound for the treatment of schizophrenia. In the present review, we intended to critically assess advances in research of SNP for the therapy of schizophrenia and discuss its potential superiority over currently used neuroleptics.

Effects of nitric oxide treatment on lignin biosynthesis and texture properties at wound sites of muskmelons

Lignin is an important component of the healing tissue in fruits. In this study, we treated muskmelon (Cucumis melo L. cv. “Manao”) fruit with exogenous nitric oxide (NO) donor sodium nitroprusside (SNP) to observe and analyze its effect on lignin synthesis and accumulation during healing. Results showed that SNP treatment enhanced the contents of endogenous NO and H2O2, increased the activities of phenylalanine ammonia lyase, cinnamate 4 hydroxylase, cinnamyl alcohol dehydrogenase, and peroxidase, and raised the contents of sinapyl alcohol, coniferyl alcohol, coumaryl alcohol, and lignin. SNP augmented the hardness of the healing tissue and decreased its resilience, springiness, and cohesiveness. In addition, SNP treatment effectively reduced the weight loss and disease index of wounded muskmelons. All these results suggest that lignin metabolism mediated by NO play a crucial role in wound healing of muskmelons.

Nitric Oxide Alleviated High Salt-Induced Cardiomyocyte Apoptosis and Autophagy Independent of Blood Pressure in Rats.

The present study aimed to explore whether high-salt diet (HSD) could cause cardiac damage independent of blood pressure, and whether nitric oxide (NO) could alleviate high-salt–induced cardiomyocyte apoptosis and autophagy in rats. The rats received 8% HSD in vivo. H9C2 cells or primary neonatal rat cardiomyocytes (NRCM) were treated with sodium chloride (NaCl) in vitro. The levels of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1 and autophagy related 7 (ATG7) were increased in the heart of HSD rats with hypertension (HTN), and in hypertension-prone (HP) and hypertension-resistant (HR) rats. Middle and high doses (50 and 100 mM) of NaCl increased the level of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in H9C2 cells and NRCM. The endothelial NO synthase (eNOS) level was increased, but p-eNOS level was reduced in the heart of HSD rats and H9C2 cells treated with 100 mM NaCl. The level of NO was reduced in the serum and heart of HSD rats. NO donor sodium nitroprusside (SNP) reversed the increases of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2 induced by NaCl (100 mM) in H9C2 cells and NRCM. SNP treatment attenuated the increases of cleaved-caspase 3/caspase 3, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in the heart, but had no effect on the blood pressure of HSD rats with HR. These results demonstrated that HSD enhanced cardiac damage independently of blood pressure. Exogenous NO supplementarity could alleviate the high salt–induced apoptosis and autophagy in cardiomyocytes.

Interaction between reactive oxygen species and hormones during the breaking of embryo dormancy in Sorbus pohuashanensis by exogenous nitric oxide

The breaking of dormancy mediated by reactive nitrogen species (RNS) is related to the accumulation of reactive oxygen species (ROS) in germinating embryos but the underlying mechanism is unclear. The objectives of this study were: (1) to explore the relationship between RNS-mediated dormancy release and ROS accumulation in germinating embryos of Sorbus pohuashanensis; and, (2) to investigate the relationships among germination time, ROS metabolism, and endogenous hormone synthesis. We studied the effects of exogenous nitric oxide (NO) donor sodium nitroprusside (SNP), the NO scavenger (4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), abscisic acid (ABA), the exogenous ethylene donor ethrel, and the ethylene receptor inhibitor 2,5-norbornadien (NBD) on embryo germination and seedling growth. Embryos were released from dormancy by pretreatment with NO or ethylene, which was related to increased ethylene biosynthesis and decreased ABA levels. Breaking of dormancy by SNP was related to increased levels of ethylene, hydrogen peroxide, and glutathione, increased activities of superoxide dismutase and glutathione peroxidase, and decreased levels of ABA, superoxide anions, and malondialdehyde. These effects of nitric oxide were especially significant in seedling hypocotyls and radicles. These results demonstrate that NO can break S. pohuashanensis embryo dormancy by inducing ethylene biosynthesis, and that this signalling pathway is closely related to ROS accumulation and the antioxidant defence response.

The Effects of Nitric Oxide and Inhibitor, and Combination of Albendazole and Praziquantel On Liver in Mice Injected with Echinococcus granulosus Larvae

In this study, the role of nitric oxide (NO) in the pathogenesis of hydatidosis and the interaction with effects of anthelmintic drugs, albendazole and praziquantel, were examined in larval infection caused by protoscolices obtained from hydatid cysts of sheep liver in Albino Balb/c mice.Animals were divided into ten groups including controls and infected groups. Larval infection was established with intraperitoneal injection of protoscolices. Eight months after infection with protoscolices, the infected animals were divided into 6 groups. The infected animals were given a selective inhibitor of inducible nitric oxide synthase (iNOS) L-N6-(1-Iminoethyl) lysine-hydrochloride (L-NIL), NO donor sodium nitroprusside (SNP), albendazole and praziquantel as anthelmintic drugs for 7 days. In addition, control groups were composed of intact group, control, anthelmintic drugs + L-NIL, and anthelmintic drugs + SNP. The liver and blood samples were taken for cytological, histological, immunohistochemical and biochemical analyses 7 days after treatments at the end of experiment.The animals injected with protoscolices showed histopathological changes including inflammation areas, infiltration and accumulation of leukocytes, dilation of sinusoids, and damage in endothelial cells and hepatocytes at light microscopy. Electron microscopy were revealed severe damage in sinusoidal endothelial cells, leukocytes especially eosinophils in sinusoid lumens and disorganization in endoplasmic reticulum and nuclear membrane. Endothelial nitric oxide synthase (eNOS) and iNOS reactions were increased in the tissue. Anthelmintic drugs decreased inflammation areas and damages; however, it did not change NOS reactions in the animals given protoscolices. L-NIL and SNP diminished both iNOS and eNOS reactions. Unlike the group administered the inhibitor, SNP treated group exhibited less inflammation areas. Combination of these substances and drugs resulted in decreased inflammation areas. eNOS and iNOS reactions decreased in the drugs and SNP administered group, while only iNOS reaction was decreased in L-NIL given infection group. In addition, the infected groups which received SNP displayed expanded sinusoids and hepatocytes with vacuoles, intriguingly. While levels of serum nitrite/nitrate elevated only in the infection group given drugs and SNP, it decreased in the L-NIL administered group. Tissue level of malondialdehyde increased in infection groups with drugs and SNP.In conclusion, the results indicated that NO plays an important role in the pathogenesis of hydatidosis.

CYB5R3 BIASES SOLUBLE GUANYLYL CYCLASE ACTIVATION IN RESISTANCE ARTERIES

Objective: Nitric oxide (NO) regulates blood pressure by binding the reduced heme iron on soluble guanylyl cyclase (sGC) in vascular smooth muscle cells (SMC) which leads to the production of cyclic guanosine 3’,5’-monophosphate (cGMP) and vasodilation. In cardiovascular disease, oxidative stress causes oxidation or loss (apo-) of the sGC heme, impairing NO binding and causing vasoconstriction. Subsequently, new therapeutic compounds termed sGC activators have been developed for use in cardiovascular disease to target oxidized heme, and to a greater extent apo-sGC, to cause irreversible, NO-independent reactivation of cGMP production and vasodilation. However, few studies have defined the impact of NO-independent sGC activation on vascular physiology in non-stressed conditions. Design and method: To address this, we performed vasoreactivity studies on resistance and aortic arteries under non-stressed, physiological conditions and telemetry for in vivo blood pressure recordings. Results: Interestingly, we found that resistance arteries are log-orders more sensitive to sGC activator BAY 58–2667 than conduit aortic arteries in non-stressed conditions. This suggests that resistance arteries may contain a previously unknown, physiologically activatable pool of heme oxidized and/or apo-sGC that can be activated independent of NO and disease. We have previously published that cytochrome b5 reductase 3 (CYB5R3) reduces the oxidized heme sGC to its NO-sensitive, reduced state which confers resilience from systemic hypertension. We hypothesized that CYB5R3 may serve as a rheostat in physiological blood pressure and sGC activator function. In transgenic CYB5R3 overexpression (CYB5R3 OE) mice, we found that resistance arteries, but not aorta have a blunted response to sGC activator induced vasodilation and blood pressure lowering in unstressed conditions (n = 4–8/group). OE CYB5R3 mice also exhibit a ∼7 mmHg decreases in pulse pressure and impaired blood pressure reduction in response to an acute injection of BAY 58–2667 when compared to controls (n = 5/group). Consistent with this, no difference in vasodilation response to NO donor sodium nitroprusside (SNP) was observed between CYB5R3 OE and littermate controls irrespective of vessel type (n = 2–6/group). Conclusions: These data suggest that CYB5R3 is important in regulating resistance artery sensitivity to sGC activator BAY 58–2667 likely via governing sGC redox state in non-stressed, physiological conditions.

Nitric oxide and abscisic acid regulate osmoprotective and antioxidative mechanisms related to water stress tolerance of grapevines

Background and Aims Exogenously applied nitric oxide (NO) and abscisic acid (ABA) are known to improve the tolerance of plants to abiotic stress. The effects of NO and ABA applications on physiological and metabolic responses associated with vine protection against water stress were analysed. Methods and Results The responses to the NO donor sodium nitroprusside (hereinafter referred to as NO treatment) and ABA were assessed on metabolic profiling, the activity of antioxidant enzymes, and physiological parameters in leaves of water-stressed Malbec vines. Application of NO and ABA partially closed stomata, thus increasing water potential and reducing vine growth. As well, NO and ABA increased guaiacol peroxidase activity and the concentration of specific sugars and anthocyanins in leaves, whereas the accumulation of amino acids was reduced, in turn associated with less protein degradation. Differential responses triggered by NO in stimulating ascorbate peroxidase activity and in incrementing tricarboxylic acid cycle intermediates and terpenes that stabilise membranes, suggest differential mechanisms for NO and ABA in counteracting water stress effects in leaves of grapevines. Conclusions Nitric oxide and ABA differentially regulate osmoprotective and antioxidative mechanisms related to water stress tolerance in grapevines. Significance of the Study Spray application of NO and ABA to whole plants promoted leaf metabolic responses known to be associated with water stress tolerance mechanisms in grapevines. This approach may provide the basis for improving viticulture in grapegrowing regions affected by water scarcity due to climate change.

Determination of Hydrogen Sulfide in Endoplasmic Reticulum by Two-Photon Fluorescence

An endoplasmic reticulum (ER) targetable two-photon fluorescent probe termed ER-N3 is presented for the determination of hydrogen sulfide (H2S) in living cells and mice. The results demonstrate that ER-N3 was highly selective and sensitive to H2S. Confocal fluorescence imaging in living cells indicated that ER-N3 was accumulated in the endoplasmic reticulum and visualized exogenous and endogenous H2S production. Moreover, a burst of H2S upregulated by the nitric oxide donor sodium nitroprusside was monitored. Meanwhile, the increase of H2S ended following the addition of DL-propargylglycine, an inhibitor for cystathionine β-synthase and cystathionine γ-lyase that are the main sources of H2S. Importantly, the exogenous H2S was visualized in abdominal tissue of mice by utilizing two-photon fluorescence microscopy. The ER-N3 fluorescent probe may be an excellent tool to image H2S fluctuations in the endoplasmic reticulum and characterize the relationship between H2S and disease in vivo.

Effects of hypoxic acclimation, muscle strain, and contraction frequency on nitric oxide-mediated myocardial performance in steelhead trout (Oncorhynchus mykiss)

Whether hypoxic acclimation influences nitric oxide (NO)-mediated control of fish cardiac function is not known. Thus, we measured the function/performance of myocardial strips from normoxic- and hypoxic-acclimated (40% air saturation; ∼8 kPa O2) trout at several frequencies (20–80 contractions·min−1) and two muscle strain amplitudes (8% and 14%) when exposed to increasing concentrations of the NO donor sodium nitroprusside (SNP) (10−9 to 10−4 M). Further, we examined the influence of 1) nitric oxide synthase (NOS) produced NO [by blocking NOS with 10−4 M NG-monomethyl-l-arginine (l-NMMA)] and 2) soluble guanylyl cyclase mediated, NOS-independent, NO effects (i.e., after blockade with 10−4 M ODQ), on myocardial contractility. Hypoxic acclimation increased twitch duration by 8%–10% and decreased mass-specific net power by ∼35%. However, hypoxic acclimation only had minor impacts on the effects of SNP and the two blockers on myocardial function. The most surprising finding of the current study was the degree to which contraction frequency and strain amplitude influenced NO-mediated effects on myocardial power. For example, at 8% strain, 10−4 SNP resulted in a decrease in net power of ∼30% at 20 min−1 but an increase of ∼20% at 80 min−1, and this effect was magnified at 14% strain. This research suggests that hypoxic acclimation has only minor effects on NO-mediated myocardial contractility in salmonids, is the first to report the high frequency- and strain-dependent nature of NO effects on myocardial contractility in fishes, and supports previous work showing that NO effects on the heart (myocardium) are finely tuned spatiotemporally.

Improvement of Postharvest Anthracnose Resistance in Mango Fruit by Nitric Oxide and the Possible Mechanisms Involved.

The anthracnose rot of postharvest mango fruit is a devastating fungal disease often resulting in tremendous quality deterioration and postharvest losses. Nitric oxide (NO), as an important signaling molecule, is involved in the responses to postharvest fruit diseases. In the present study, the effectiveness of NO donor sodium nitroprusside (SNP) to prevent anthracnose of "Tainong" mango fruit caused by Colletotrichum gloeosporioides was evaluated through in vivo and in vitro tests. Results from in vivo test showed that SNP treatment effectively inhibited the lesion diameter and disease incidence on inoculated mango fruit during storage. SNP treatment could regulate hydrogen peroxide levels by reinforcing the activities of catalase, peroxidase, superoxide dismutase, and ascorbate peroxidase. Furthermore, SNP elevated the accumulation of lignin, total phenolics, anthocyanin, and flavonoids and the activities of chitinase and β-1,3-glucanase. In addition, in vitro tests indicated that SNP markedly suppressed mycelial growth and spore germination of C. gloeosporioides through damaging plasma membrane integrity and increasing the leakage of soluble sugar and protein. Our results suggested that SNP could suppress anthracnose decay in postharvest mango fruit, possibly by directly suppressing pathogen growth and indirectly triggering host defense responses.