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Jose E Tanussantos - One of the best experts on this subject based on the ideXlab platform.
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oral nitrite circumvents antiseptic mouthwash induced disruption of enterosalivary circuit of nitrate and promotes nitrosation and blood pressure lowering effect
Free Radical Biology and Medicine, 2016Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Rafael L Portella, Sandra Conde O Tella, Madla A Passos, Jose E TanussantosAbstract:The nitric oxide (NO•) metabolites nitrite and nitrate exert antihypertensive effects by mechanisms that involve gastric formation of S-Nitrosothiols. However, while the use of antiseptic mouthwash (AM) is known to attenuate the responses to nitrate by disrupting its enterosalivary cycle, there is little information about whether AM attenuates the effects of orally administered nitrite. We hypothesized that the antihypertensive effects of orally administered nitrite would not be prevented by AM because, in contrast to oral nitrate, oral nitrite could promote S-Nitrosothiols formation in the stomach without intereference by AM. Chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats (and normotensive controls) treated with AM (or vehicle) once/day. We found that orally administered nitrite exerts antihypertensive effects that were not affected by AM. This finding contrasts with lack of antihypertensive responses to oral nitrate in 2K1C hypertensive rats treated with AM. Nitrite and nitrate treatments increased plasma nitrites, nitrates, and S-Nitrosothiols concentrations. However, while treatment with AM attenuated the increases in plasma nitrite concentrations after both nitrite and nitrate treatments, AM attenuated the increases in S-Nitrosothiols in nitrate-treated rats, but not in nitrite-treated rats. Moreover, AM attenuated vascular S-nitrosylation (detected by the SNO-RAC method) after nitrate, but not after nitrite treatment. Significant correlations were found between the hypotensive responses and S-Nitrosothiols, and vascular S-nitrosylation levels. These results show for the first time that oral nitrite exerts antihypertensive effects notwithstanding the fact that antiseptic mouthwash disrupts the enterosalivary circulation of nitrate. Our results support a major role for S-Nitrosothiols formation resulting in vascular S-nitrosylation as a key mechanism for the antihypertensive effects of both oral nitrite and nitrate.
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gastric s nitrosothiol formation drives the antihypertensive effects of oral sodium nitrite and nitrate in a rat model of renovascular hypertension
Free Radical Biology and Medicine, 2015Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Rafael L Portella, Carla S Ceron, Marcelo F Montenegro, Jose Carlos Toledo, Jose E TanussantosAbstract:Many effects of nitrite and nitrate are attributed to increased circulating concentrations of nitrite, ultimately converted into nitric oxide (NO•) in the circulation or in tissues by mechanisms associated with nitrite reductase activity. However, nitrite generates NO• , nitrous anhydride, and other nitrosating species at low pH, and these reactions promote S-nitrosothiol formation when nitrites are in the stomach. We hypothesized that the antihypertensive effects of orally administered nitrite or nitrate involve the formation of S-Nitrosothiols, and that those effects depend on gastric pH. The chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats treated with omeprazole (or vehicle). Oral nitrite lowered blood pressure and increased plasma S-nitrosothiol concentrations independently of circulating nitrite levels. Increasing gastric pH with omeprazole did not affect the increases in plasma nitrite and nitrate levels found after treatment with nitrite. However, treatment with omeprazole severely attenuated the increases in plasma S-nitrosothiol concentrations and completely blunted the antihypertensive effects of nitrite. Confirming these findings, very similar results were found with oral nitrate. To further confirm the role of gastric S-nitrosothiol formation, we studied the effects of oral nitrite in hypertensive rats treated with the glutathione synthase inhibitor buthionine sulfoximine (BSO) to induce partial thiol depletion. BSO treatment attenuated the increases in S-nitrosothiol concentrations and antihypertensive effects of oral nitrite. These data show that gastric S-nitrosothiol formation drives the antihypertensive effects of oral nitrite or nitrate and has major implications, particularly to patients taking proton pump inhibitors.
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increase in gastric ph reduces hypotensive effect of oral sodium nitrite in rats
Free Radical Biology and Medicine, 2012Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Marcelo F Montenegro, A Oliveira, Jose E TanussantosAbstract:Abstract The new pathway nitrate–nitrite–nitric oxide (NO) has emerged as a physiological alternative to the classical enzymatic pathway for NO formation from l -arginine. Nitrate is converted to nitrite by commensal bacteria in the oral cavity and the nitrite formed is then swallowed and reduced to NO under the acidic conditions of the stomach. In this study, we tested the hypothesis that increases in gastric pH caused by omeprazole could decrease the hypotensive effect of oral sodium nitrite. We assessed the effects of omeprazole treatment on the acute hypotensive effects produced by sodium nitrite in normotensive and L-NAME-hypertensive free-moving rats. In addition, we assessed the changes in gastric pH and plasma levels of nitrite, NO x (nitrate+nitrite), and S -Nitrosothiols caused by treatments. We found that the increases in gastric pH induced by omeprazole significantly reduced the hypotensive effects of sodium nitrite in both normotensive and L-NAME-hypertensive rats. This effect of omeprazole was associated with no significant differences in plasma nitrite, NO x , or S -nitrosothiol levels. Our results suggest that part of the hypotensive effects of oral sodium nitrite may be due to its conversion to NO in the acidified environment of the stomach. The increase in gastric pH induced by treatment with omeprazole blunts part of the beneficial cardiovascular effects of dietary nitrate and nitrite.
Neil Hogg - One of the best experts on this subject based on the ideXlab platform.
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Cytochrome c-mediated formation of S-nitrosothiol in cells
The Biochemical journal, 2012Co-Authors: Katarzyna A. Broniowska, Agnes Keszler, Swati Basu, Daniel B. Kim-shapiro, Neil HoggAbstract:S-Nitrosothiols are products of nitric oxide (NO) metabolism that have been implicated in a plethora of signalling processes. However, mechanisms of S-nitrosothiol formation in biological systems are uncertain, and no efficient protein-mediated process has been identified. Recently, we observed that ferric cytochrome c can promote S-nitrosoglutathione formation from NO and glutathione by acting as an electron acceptor under anaerobic conditions. In the present study, we show that this mechanism is also robust under oxygenated conditions, that cytochrome c can promote protein S-nitrosation via a transnitrosation reaction and that cell lysate depleted of cytochrome c exhibits a lower capacity to synthesize S-Nitrosothiols. Importantly, we also demonstrate that this mechanism is functional in living cells. Lower S-nitrosothiol synthesis activity, from donor and nitric oxide synthase-generated NO, was found in cytochrome c-deficient mouse embryonic cells as compared with wild-type controls. Taken together, these data point to cytochrome c as a biological mediator of protein S-nitrosation in cells. This is the most efficient and concerted mechanism of S-nitrosothiol formation reported so far.
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copper dependence of the biotin switch assay modified assay for measuring cellular and blood nitrosated proteins
Free Radical Biology and Medicine, 2008Co-Authors: Xunde Wang, Neil Hogg, Nicholas J Kettenhofen, Sruti Shiva, Mark T GladwinAbstract:Abstract Studies have shown that modification of critical cysteine residues in proteins leads to the regulation of protein function. These modifications include disulfide bond formation, glutathionylation, sulfenic and sulfinic acid formation, and S-nitrosation. The biotin switch assay was developed to specifically detect protein S-nitrosation (S. R. Jaffrey et al., Nat. Cell Biol. 3:193–197; 2001). In this assay, proteins are denatured with SDS in the presence of methyl methane thiosulfonate (MMTS) to block free thiols. After acetone precipitation or Sephadex G25 separation to remove excess MMTS, HPDP–biotin and 1 mM ascorbate are added to reduce the S-nitrosothiol bonds and label the reduced thiols with biotin. The proteins are then separated by nonreducing SDS PAGE and detected using either streptavidin–HRP or anti-biotin–HRP conjugate. Our examination of this labeling scheme has revealed that the extent of labeling depends on the buffer composition and, importantly, on the choice of metal-ion chelator (DTPA vs EDTA). Unexpectedly, using purified S-nitrosated albumin, we have found that “contaminating” copper is required for the ascorbate-dependent degradation of S-nitrosothiol; this is consistent with the fact that ascorbate itself does not rapidly reduce S-Nitrosothiols. Removal of copper from buffers by DTPA and other copper chelators preserves approximately 90% of the S-nitrosothiol, whereas the inclusion of copper and ascorbate completely eliminates the S-nitrosothiol in the preparation and increases the specific biotin labeling. These biotin switch experiments were confirmed using triiodide-based and copper-based reductive chemiluminescence. Additional modifications of the assay using N-ethylmaleimide for thiol blockade, ferricyanide pretreatment to stabilize S-nitrosated hemoglobin, and cyanine dye labeling instead of biotin are presented for the measurement of cellular and blood S-Nitrosothiols. These results indicate that degradation of S-nitrosothiol in the standard biotin switch assay is metal-ion dependent and that experimental variability in S-nitrosothiol yields using this assay occurs secondary to the inclusion of metal-ion chelators in reagents and variable metal-ion contamination of buffers and labware. The addition of copper to ascorbate allows for a simple assay modification that dramatically increases sensitivity while maintaining specificity.
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requirement of transmembrane transport for s nitrosocysteine dependent modification of intracellular thiols
Journal of Biological Chemistry, 2006Co-Authors: Katarzyna A. Broniowska, Yanhong Zhang, Neil HoggAbstract:S-Nitrosothiols have been implicated as intermediary transducers of nitric oxide bioactivity; however, the mechanisms by which these compounds affect cellular functions have not been fully established. In this study, we have examined the effect of S-nitrosothiol transport on intracellular thiol status and upon the activity of a target protein (caspase-3), in bovine aortic endothelial cells. We have previously demonstrated that the specific transport of amino acid-based S-Nitrosothiols (S-nitroso-L-cysteine and S-nitrosohomocysteine) occurs via amino acid transport system L to generate high levels of intracellular protein S-Nitrosothiols (Zhang, Y., and Hogg, N. (2004) Proc. Natl. Acad. Sci. U. S. A. 101, 7891-7896). In this study, we demonstrate that the transport of S-Nitrosothiols is essential for these compounds to affect intracellular thiol levels and to modify intracellular protein activity. Importantly, the ability of these compounds to affect intracellular processes occurs independently of nitric oxide formation. These findings suggest that the major action of these compounds is not to liberate nitric oxide in the extracellular space but to be specifically transported into cells where they are able to modify cellular functions through nitric oxide-independent mechanisms.
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The mechanism of transmembrane S-nitrosothiol transport
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Yanhong Zhang, Neil HoggAbstract:S-Nitrosothiols have been suggested to play an important role in nitric oxide (NO)-mediated biological events. However, the mechanisms by which an S-nitrosothiol (or the S-nitroso functional group) is transferred across cell membrane are still poorly understood. We have demonstrated previously that the degradation of S-nitrosoglutathione (GSNO) by cells absolutely required the presence of cystine in the extracellular medium and proposed a mechanism that involved the reduction of cystine to cysteine, followed by the reaction of cysteine with GSNO to form S-nitrosocysteine (CysNO), mixed disulfides, and nitrosyl anion. In the present study we have assessed the effect of cystine on the transfer of the S-nitroso functional group from the extracellular to the intracellular space. Using RAW 264.7 cells, we found that the presence of l-cystine enhanced GSNO-dependent S-nitrosothiol uptake, increasing the intracellular S-nitrosothiol level from ≈60 pmol/mg of protein to ≈3 nmol/mg of protein. The uptake seems to depend on the reduction of l-cystine to l-cysteine, which involves the amino acid transport system, the transnitrosation between GSNO and l-cysteine to form l-CysNO, and uptake of l-CysNO via amino acid transport system L. Compared with GSNO, (Z)-1-[N-(3-ammoniopropyl)-N-[4-(3-aminopropylammonio)butyl]-amino]diazen-1-ium-1,2-diolate, an NO donor, is much less effective at intracellular S-nitrosothiol formation in the presence of l-cystine or l-cysteine, suggesting that the biochemical changes that occur after exposure of cells to S-nitrosothiol, with respect to thiol chemistry, are distinctly different from those observed with NO.
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reaction of s nitrosoglutathione with the heme group of deoxyhemoglobin
Journal of Biological Chemistry, 2000Co-Authors: Netanya Y Spencer, Rakesh P Patel, Hong Zeng, Neil HoggAbstract:The mechanism of interaction betweenS-nitrosoglutathione (GSNO) and hemoglobin is a crucial component of hypotheses concerning the role played byS-nitrosohemoglobin in vivo. We previously demonstrated (Patel, R. P., Hogg, N., Spencer, N. Y., Kalyanaraman, B., Matalon, S., and Darley-Usmar, V. M. (1999)J. Biol. Chem. 274, 15487–15492) that transnitrosation between oxygenated hemoglobin and GSNO is a slow, reversible process, and that the reaction between GSNO and deoxygenated hemoglobin (deoxyHb) did not conform to second order reversible kinetics. In this study we have reinvestigated this reaction and show that GSNO reacts with deoxyHb to form glutathione, nitric oxide, and ferric hemoglobin. Nitric oxide formed from this reaction is immediately autocaptured to form nitrosylated hemoglobin. GSNO reduction by deoxyHb is essentially irreversible. The kinetics of this reaction depended upon the conformation of the protein, with more rapid kinetics occurring in the high oxygen affinity state (i.e.modification of the Cysβ-93) than in the low oxygen affinity state (i.e. treatment with inositol hexaphosphate). A more rapid reaction occurred when deoxymyoglobin was used, further supporting the observation that the kinetics of reduction are directly proportional to oxygen affinity. This observation provides a mechanism for how deoxygenation of hemoglobin/myoglobin could facilitate nitric oxide release from S-Nitrosothiols and represents a potential physiological mechanism of S-nitrosothiol metabolism.
Lucas C Pinheiro - One of the best experts on this subject based on the ideXlab platform.
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oral nitrite circumvents antiseptic mouthwash induced disruption of enterosalivary circuit of nitrate and promotes nitrosation and blood pressure lowering effect
Free Radical Biology and Medicine, 2016Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Rafael L Portella, Sandra Conde O Tella, Madla A Passos, Jose E TanussantosAbstract:The nitric oxide (NO•) metabolites nitrite and nitrate exert antihypertensive effects by mechanisms that involve gastric formation of S-Nitrosothiols. However, while the use of antiseptic mouthwash (AM) is known to attenuate the responses to nitrate by disrupting its enterosalivary cycle, there is little information about whether AM attenuates the effects of orally administered nitrite. We hypothesized that the antihypertensive effects of orally administered nitrite would not be prevented by AM because, in contrast to oral nitrate, oral nitrite could promote S-Nitrosothiols formation in the stomach without intereference by AM. Chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats (and normotensive controls) treated with AM (or vehicle) once/day. We found that orally administered nitrite exerts antihypertensive effects that were not affected by AM. This finding contrasts with lack of antihypertensive responses to oral nitrate in 2K1C hypertensive rats treated with AM. Nitrite and nitrate treatments increased plasma nitrites, nitrates, and S-Nitrosothiols concentrations. However, while treatment with AM attenuated the increases in plasma nitrite concentrations after both nitrite and nitrate treatments, AM attenuated the increases in S-Nitrosothiols in nitrate-treated rats, but not in nitrite-treated rats. Moreover, AM attenuated vascular S-nitrosylation (detected by the SNO-RAC method) after nitrate, but not after nitrite treatment. Significant correlations were found between the hypotensive responses and S-Nitrosothiols, and vascular S-nitrosylation levels. These results show for the first time that oral nitrite exerts antihypertensive effects notwithstanding the fact that antiseptic mouthwash disrupts the enterosalivary circulation of nitrate. Our results support a major role for S-Nitrosothiols formation resulting in vascular S-nitrosylation as a key mechanism for the antihypertensive effects of both oral nitrite and nitrate.
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gastric s nitrosothiol formation drives the antihypertensive effects of oral sodium nitrite and nitrate in a rat model of renovascular hypertension
Free Radical Biology and Medicine, 2015Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Rafael L Portella, Carla S Ceron, Marcelo F Montenegro, Jose Carlos Toledo, Jose E TanussantosAbstract:Many effects of nitrite and nitrate are attributed to increased circulating concentrations of nitrite, ultimately converted into nitric oxide (NO•) in the circulation or in tissues by mechanisms associated with nitrite reductase activity. However, nitrite generates NO• , nitrous anhydride, and other nitrosating species at low pH, and these reactions promote S-nitrosothiol formation when nitrites are in the stomach. We hypothesized that the antihypertensive effects of orally administered nitrite or nitrate involve the formation of S-Nitrosothiols, and that those effects depend on gastric pH. The chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats treated with omeprazole (or vehicle). Oral nitrite lowered blood pressure and increased plasma S-nitrosothiol concentrations independently of circulating nitrite levels. Increasing gastric pH with omeprazole did not affect the increases in plasma nitrite and nitrate levels found after treatment with nitrite. However, treatment with omeprazole severely attenuated the increases in plasma S-nitrosothiol concentrations and completely blunted the antihypertensive effects of nitrite. Confirming these findings, very similar results were found with oral nitrate. To further confirm the role of gastric S-nitrosothiol formation, we studied the effects of oral nitrite in hypertensive rats treated with the glutathione synthase inhibitor buthionine sulfoximine (BSO) to induce partial thiol depletion. BSO treatment attenuated the increases in S-nitrosothiol concentrations and antihypertensive effects of oral nitrite. These data show that gastric S-nitrosothiol formation drives the antihypertensive effects of oral nitrite or nitrate and has major implications, particularly to patients taking proton pump inhibitors.
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increase in gastric ph reduces hypotensive effect of oral sodium nitrite in rats
Free Radical Biology and Medicine, 2012Co-Authors: Lucas C Pinheiro, Jefferson H Amaral, Graziele C Ferreira, Marcelo F Montenegro, A Oliveira, Jose E TanussantosAbstract:Abstract The new pathway nitrate–nitrite–nitric oxide (NO) has emerged as a physiological alternative to the classical enzymatic pathway for NO formation from l -arginine. Nitrate is converted to nitrite by commensal bacteria in the oral cavity and the nitrite formed is then swallowed and reduced to NO under the acidic conditions of the stomach. In this study, we tested the hypothesis that increases in gastric pH caused by omeprazole could decrease the hypotensive effect of oral sodium nitrite. We assessed the effects of omeprazole treatment on the acute hypotensive effects produced by sodium nitrite in normotensive and L-NAME-hypertensive free-moving rats. In addition, we assessed the changes in gastric pH and plasma levels of nitrite, NO x (nitrate+nitrite), and S -Nitrosothiols caused by treatments. We found that the increases in gastric pH induced by omeprazole significantly reduced the hypotensive effects of sodium nitrite in both normotensive and L-NAME-hypertensive rats. This effect of omeprazole was associated with no significant differences in plasma nitrite, NO x , or S -nitrosothiol levels. Our results suggest that part of the hypotensive effects of oral sodium nitrite may be due to its conversion to NO in the acidified environment of the stomach. The increase in gastric pH induced by treatment with omeprazole blunts part of the beneficial cardiovascular effects of dietary nitrate and nitrite.
Mark H. Schoenfisch - One of the best experts on this subject based on the ideXlab platform.
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s nitrosothiol analysis via photolysis and amperometric nitric oxide detection in a microfluidic device
Analytical Chemistry, 2015Co-Authors: Rebecca A. Hunter, Mark H. SchoenfischAbstract:A 530 nm light emitting diode was coupled to a microfluidic sensor to facilitate photolysis of Nitrosothiols (i.e., S-nitrosoglutathione, S-nitrosocysteine, and S-nitrosoalbumin) and amperometric detection of the resulting nitric oxide (NO). This configuration allowed for maximum sensitivity and versatility, while limiting potential interference from nitrate decomposition caused by ultraviolet light. Compared to similar measurements of total S-nitrosothiol content in bulk solution, use of the microfluidic platform permitted significantly enhanced analytical performance in both phosphate-buffered saline and plasma (6-20× improvement in sensitivity depending on nitrosothiol type). Additionally, the ability to reduce sample volumes from milliliters to microliters provides increased clinical utility. To demonstrate its potential for biological analysis, this device was used to measure basal nitrosothiol levels from the vasculature of a healthy porcine model.
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S‑Nitrosothiol Analysis via Photolysis and Amperometric Nitric Oxide Detection in a Microfluidic Device
2015Co-Authors: Rebecca A. Hunter, Mark H. SchoenfischAbstract:A 530 nm light emitting diode was coupled to a microfluidic sensor to facilitate photolysis of Nitrosothiols (i.e., S-nitrosoglutathione, S-nitrosocysteine, and S-nitrosoalbumin) and amperometric detection of the resulting nitric oxide (NO). This configuration allowed for maximum sensitivity and versatility, while limiting potential interference from nitrate decomposition caused by ultraviolet light. Compared to similar measurements of total S-nitrosothiol content in bulk solution, use of the microfluidic platform permitted significantly enhanced analytical performance in both phosphate-buffered saline and plasma (6–20× improvement in sensitivity depending on nitrosothiol type). Additionally, the ability to reduce sample volumes from milliliters to microliters provides increased clinical utility. To demonstrate its potential for biological analysis, this device was used to measure basal nitrosothiol levels from the vasculature of a healthy porcine model
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S-Nitrosothiol-modified nitric oxide-releasing chitosan oligosaccharides as antibacterial agents
Acta biomaterialia, 2014Co-Authors: Anand Shah, Rebecca A. Hunter, Robert J. Soto, Mark H. SchoenfischAbstract:Abstract S-Nitrosothiol-modified chitosan oligosaccharides were synthesized by reaction with 2-iminothiolane hydrochloride and 3-acetamido-4,4-dimethylthietan-2-one, followed by thiol nitrosation. The resulting nitric oxide (NO)-releasing chitosan oligosaccharides stored ∼0.3 μmol NO mg−1 chitosan. Both the chemical structure of the nitrosothiol (i.e. primary and tertiary) and the use of ascorbic acid as a trigger for NO donor decomposition were used to control the NO-release kinetics. With ascorbic acid, the S-nitrosothiol-modified chitosan oligosaccharides elicited a 4-log reduction in Pseudomonas aeruginosa viability. Confocal microscopy indicated that the primary S-nitrosothiol-modified chitosan oligosaccharides associated more with the bacteria relative to the tertiary S-nitrosothiol system. The primary S-nitrosothiol-modified chitosan oligosaccharides elicited minimal toxicity towards L929 mouse fibroblast cells at the concentration necessary for a 4-log reduction in bacterial viability, further demonstrating the potential of S-nitrosothiol-modified chitosan oligosaccharides as NO-release therapeutics.
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Stöber Synthesis of Nitric Oxide-Releasing S-Nitrosothiol-Modified Silica Particles.
Chemistry of materials : a publication of the American Chemical Society, 2011Co-Authors: Daniel A Riccio, Julia Nugent, Mark H. SchoenfischAbstract:We report the synthesis of S-nitrosothiol-modified silica particles capable of nitric oxide (NO) release. The thiol precursor modification to form S-nitrosothiol NO donors was introduced into the silica network via co-condensation of mercaptosilane and alkoxysilane precursors. Both the concentration of reactants (i.e., water, ammonia, and silane) and the silane feed rate into the reaction proved important in the yield of monodisperse, spherical particles with tunable diameters ranging from 241−718 nm. Subsequent nitrosation resulted in NO storage approaching ∼4.40 μmol NO mg−1, as determined by total NO release. Behaving similar to low molecular weight S-nitrosothiol NO donors, the NO release from the macromolecular silica vehicles was influenced by light, temperature, and metal ions.
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S-Nitrosothiol-Modified Dendrimers as Nitric Oxide Delivery Vehicles
Biomacromolecules, 2008Co-Authors: Nathan Stasko, Thomas H. Fischer, Mark H. SchoenfischAbstract:The synthesis and characterization of two generation-4 polyamidoamine (PAMAM) dendrimers with S-nitrosothiol exteriors are reported. The hyperbranched macromolecules were modified with either N-acetyl-d,l-penicillamine (NAP) or N-acetyl-l-cysteine (NACys) and analyzed via 1H and 13C NMR, UV absorption spectroscopy, MALDI-TOF mass spectrometry, and size exclusion chromatography. Treatment of the dendritic thiols with nitrite solutions yielded the corresponding S-nitrosothiol nitric oxide (NO) donors (G4-SNAP, G4-NACysNO). Chemiluminescent NO detection demonstrated that the dendrimers were capable of storing ∼2 µmol NO·mg−1 when exposed to triggers of S-nitrosothiol decomposition (e.g., light and copper). The kinetics of NO release were found to be highly dependent on the structure of the nitrosothiol (i.e., tertiary vs primary) and exhibited similar NO release characteristics to classical small molecule Nitrosothiols reported in the literature. As a demonstration of utility, the ability of G4-SNAP to inhib...
Jonathan S Stamler - One of the best experts on this subject based on the ideXlab platform.
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s nitrosothiol signaling regulates liver development and improves outcome following toxic liver injury
Cell Reports, 2014Co-Authors: Andrew G Cox, Jonathan S Stamler, Diane C Saunders, Peter B Kelsey, Allie A Conway, Yevgenia Tesmenitsky, Julio Flavio Meirelles Marchini, Kristin K Brown, Dorothy B Colagiovanni, Gary J RosenthalAbstract:Summary Toxic liver injury is a leading cause of liver failure and death because of the organ's inability to regenerate amidst massive cell death, and few therapeutic options exist. The mechanisms coordinating damage protection and repair are poorly understood. Here, we show that S-Nitrosothiols regulate liver growth during development and after injury in vivo; in zebrafish, nitric-oxide (NO) enhanced liver formation independently of cGMP-mediated vasoactive effects. After acetaminophen (APAP) exposure, inhibition of the enzymatic regulator S-nitrosoglutathione reductase (GSNOR) minimized toxic liver damage, increased cell proliferation, and improved survival through sustained activation of the cytoprotective Nrf2 pathway. Preclinical studies of APAP injury in GSNOR-deficient mice confirmed conservation of hepatoprotective properties of S-nitrosothiol signaling across vertebrates; a GSNOR-specific inhibitor improved liver histology and acted with the approved therapy N-acetylcysteine to expand the therapeutic time window and improve outcome. These studies demonstrate that GSNOR inhibitors will be beneficial therapeutic candidates for treating liver injury.
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S-nitrosylation in health and disease
Trends in Molecular Medicine, 2003Co-Authors: Matthew W. Foster, Timothy J Mcmahon, Jonathan S StamlerAbstract:S-nitrosylation is a ubiquitous redox-related modification of cysteine thiol by nitric oxide (NO), which transduces NO bioactivity. Accumulating evidence suggests that the products of S-nitrosylation, S-Nitrosothiols (SNOs), play key roles in human health and disease. In this review, we focus on the reaction mechanisms underlying the biological responses mediated by SNOs. We emphasize reactions that can be identified with complex (patho)physiological responses, and that best rationalize the observed increase or decrease in specific classes of SNOs across a spectrum of disease states. Thus, changes in the levels of various SNOs depend on specific defects in both enzymatic and non-enzymatic mechanisms of nitrosothiol formation, processing and degradation. An understanding of these mechanisms is crucial for the development of an integrated model of NO biology, and for effective treatment of diseases associated with dysregulation of NO homeostasis.
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bronchodilator s nitrosothiol deficiency in asthmatic respiratory failure
The Lancet, 1998Co-Authors: Benjamin Gaston, Stephen Sears, Jon Woods, Michael Ponaman, Timothy J Mcmahon, John Hunt, Jonathan S StamlerAbstract:Summary Background Nitric oxide (NO) gas concentrations are high in the expired air of individuals with asthma, but not consistently so in the expired air of people with pneumonia. S-Nitrosothiols are naturally occurring bronchodilators, the concentrations of which are raised in the airways of patients with pneumonia. Airway S-Nitrosothiols have not been studied in asthma. Methods Tracheal S-nitrosothiol concentrations from eight asthmatic children in respiratory failure were compared with those of 21 children undergoing elective surgery. Results Mean S-nitrosothiol concentrations in asthmatic children were lower than in normal children (65 [SD 45] nmol/L vs 502 [SD 429] nmol/L) and did not vary with inspired oxygen concentration or airway thiol concentration. Interpretation Severe asthma is associated with low concentrations of airway S-Nitrosothiols. This is the first reported deficiency of an endogenous bronchodilator in the human asthmatic airway lining fluid. We suggest that S-nitrosothiol metabolism may be a target for the development of new asthma therapies.
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no no and no donation by s Nitrosothiols implications for regulation of physiological functions by s nitrosylation and acceleration of disulfide formation
Archives of Biochemistry and Biophysics, 1995Co-Authors: Derrick R Arnelle, Jonathan S StamlerAbstract:The biological effects of S-Nitrosothiols have been attributed to homolytic cleavage of the S-N bond with release of nitric oxide (NO.). Rates of NO. release from several S-Nitrosothiols were determined by monitoring the oxidation of oxymyoglobin to metmyoglobin at pH 7.4; half-lives for oxymyoglobin oxidation ranged from seconds to hours. Transnitrosation reactions between S-Nitrosothiols and thiol-containing amino acids, peptides, and proteins, which indicate the ability of Nitrosothiols to act as nitrosyl (NO+) donors, occurred more rapidly than spontaneous NO. release. Decomposition of S-nitrosodithiols were examined as models for the reaction of nitrogen oxides with vicinal thiols on proteins. Rapid disulfide formation was accompanied by formation of hydroxylamine and nitrous oxide, indicative of nitroxyl (NO−) release. Taken together, these model studies demonstrate the ability of S-Nitrosothiols to act as NO+, NO., and NO− donors under physiological conditions, Transnitrosation and acceleration of disulfide formation suggest mechanisms of regulation of protein function through the intermediacy of Nitrosothiols, and support the notion that biological activities of S-Nitrosothiols may be associated with heterolytic as well as homolytic mechanisms of decomposition.
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inhibition of sphincter of oddi function by the nitric oxide carrier s nitroso n acetylcysteine in rabbits and humans
Journal of Clinical Investigation, 1994Co-Authors: A Slivka, Joseph Loscalzo, Ram Chuttani, David L Carrlocke, Lester Kobzik, David S Bredt, Jonathan S StamlerAbstract:Nitric oxide (NO) is an inhibitor of gastrointestinal smooth muscle. Model systems of the gut predict the NO will complex with biological thiol (SH) groups, yielding S-Nitrosothiols (RS-NO), which may limit the propensity to form mutagenic nitrosamines. The inhibitory effects of NO and its biologically relevant adducts on sphincter of Oddi (SO) motility have been inferred from animal studies; however, their importance in regulating human SO is not known. The objectives of this study were to (a) provide histologic confirmation of nitric oxide synthase (NOS) in human SO; (b) characterize the pharmacology of S-nitroso-N-acetylcysteine (SNAC), an exemplary S-nitrosothiol, on SO motility in a rabbit model; and (c) study the effects of topical SNAC on SO motility in humans. Immunocytochemical and histochemical identification of NOS was performed in human SO. The pharmacologic response of SNAC was defined in isolated rabbit SO using a standard bioassay. Topical SNAC was then applied to the duodenal papilla in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) and biliary manometry. NOS was localized to nerve fibers and bundles of the SO in rabbits and humans. SNAC inhibited spontaneous motility (frequency and amplitude) as well as acetylcholine-induced elevations in SO basal pressure in the rabbit model. In patients undergoing ERCP and biliary manometry, topical SNAC inhibited SO contraction freqency, basal pressure, and duodenal motility. NOS is localized to neural elements in human SO, implicating a role for NO in regulating SO function. Supporting this concept, SNAC is an inhibitor of SO and duodenal motility when applied topically to humans during ERCP. Our data suggest a novel clinical approach using local NO donors to control gastrointestinal motility and regulate sphincteric function.