Physiological Effects Of Nitric Oxide Research Articles

DNIC is a Structure Providing Specificity of Physiological Effects of NO.

Metabolism of nitric oxide (NO) donors: dinitrosyl iron complexes (DNIC), nitrosothiols (RSNO), and nitroprusside was studied on a chick embryo model. The obtained results give reason to assume that DNIC constituting the main pool of nitroso compounds in the vast majority of tissues are NO donors immediately interacting with the physiological target of NO, and other NO donors can perform this function after their transformation into DNIC. NO is released from DNIC not spontaneously, but under a joint influence of a factor destroying the complex and a target having chemical affinity for NO. A similar mechanism is apparently implicated in NO passage through the cell membrane.

New Approaches in Oncology for Repositioning Drugs: The Case of PDE5 Inhibitor Sildenafil.

The use of already-approved drugs to treat new or alternative diseases has proved to be beneficial in medicine, because it reduces both drug development costs and timelines. Most drugs can be used to treat different illnesses, due their mechanisms of action are not restricted to one molecular target, organ or illness. Diverging from its original intent offers an opportunity to repurpose previously approved drugs to treat other ailments. This is the case of sildenafil (Viagra), a phosphodiesterase-5 (PDE5) inhibitor, which was originally designed to treat systemic hypertension and angina but is currently commercialized as erectile dysfunction treatment. Sildenafil, tadalafil, and vardenafil are PDE5 inhibitors and potent vasodilators, that extend the physiological effects of nitric oxide and cyclic guanosine monophosphate (cGMP) signaling. Although most of the biological implications of these signaling regulations remain unknown, they offer a large therapeutic potential for several diseases. In addition, some PDE5 inhibitors’ molecular effects seem to play a key role in different illnesses such as kidney disease, diabetes mellitus, and cancer. In this review, we discuss the molecular effects of PDE5 inhibitors and their therapeutic repurposing in different types of cancer.

Nitric Oxide Overproduction by cue1 Mutants Differs on Developmental Stages and Growth Conditions.

The cue1 nitric oxide (NO) overproducer mutants are impaired in a plastid phosphoenolpyruvate/phosphate translocator, mainly expressed in Arabidopsis thaliana roots. cue1 mutants present an increased content of arginine, a precursor of NO in oxidative synthesis processes. However, the pathways of plant NO biosynthesis and signaling have not yet been fully characterized, and the role of CUE1 in these processes is not clear. Here, in an attempt to advance our knowledge regarding NO homeostasis, we performed a deep characterization of the NO production of four different cue1 alleles (cue1-1, cue1-5, cue1-6 and nox1) during seed germination, primary root elongation, and salt stress resistance. Furthermore, we analyzed the production of NO in different carbon sources to improve our understanding of the interplay between carbon metabolism and NO homeostasis. After in vivo NO imaging and spectrofluorometric quantification of the endogenous NO levels of cue1 mutants, we demonstrate that CUE1 does not directly contribute to the rapid NO synthesis during seed imbibition. Although cue1 mutants do not overproduce NO during germination and early plant development, they are able to accumulate NO after the seedling is completely established. Thus, CUE1 regulates NO homeostasis during post-germinative growth to modulate root development in response to carbon metabolism, as different sugars modify root elongation and meristem organization in cue1 mutants. Therefore, cue1 mutants are a useful tool to study the physiological effects of NO in post-germinative growth.

Nitric Oxide Balance in Health and Diseases: Implications for New Treatment Strategies

Nitric Oxide (NO) is an essential signaling molecule with diverse physiological functions in humans. The steady-state concentration and site of production of nitric oxide determine its effects in biological systems. The human cells are exposed to both beneficial and harmful effects of NO. These dual effects of NO could depend on its local concentration in the cells. Additionally, the rate of synthesis, translocation, direct interaction with other molecules, and signals contribute to the biochemical and physiological effects of NO. In this review, the biochemical and physiological role of NO, particularly in health and disease as touching on cell signaling, oxidative stress, immunity, as well as cardiovascular protection amongst others, is focused on. Therefore, this review objectively discusses the dual functionality of NO in living cells.

Allosteric activation of the nitric oxide receptor soluble guanylate cyclase mapped by cryo-electron microscopy.

Soluble guanylate cyclase (sGC) is the primary receptor for nitric oxide (NO) in mammalian nitric oxide signaling. We determined structures of full-length Manduca sexta sGC in both inactive and active states using cryo-electron microscopy. NO and the sGC-specific stimulator YC-1 induce a 71° rotation of the heme-binding β H-NOX and PAS domains. Repositioning of the β H-NOX domain leads to a straightening of the coiled-coil domains, which, in turn, use the motion to move the catalytic domains into an active conformation. YC-1 binds directly between the β H-NOX domain and the two CC domains. The structural elongation of the particle observed in cryo-EM was corroborated in solution using small angle X-ray scattering (SAXS). These structures delineate the endpoints of the allosteric transition responsible for the major cyclic GMP-dependent physiological effects of NO.

The evolution of nitric oxide signalling diverges between animal and green lineages.

Nitric oxide (NO) is a ubiquitous signalling molecule with widespread distribution in prokaryotes and eukaryotes where it is involved in countless physiological processes. While the mechanisms governing nitric oxide (NO) synthesis and signalling are well established in animals, the situation is less clear in the green lineage. Recent investigations have shown that NO synthase, the major enzymatic source for NO in animals, is absent in land plants but present in a limited number of algae. The first detailed analysis highlighted that these new NO synthases are functional but display specific structural features and probably original catalytic activities. Completing this picture, analyses were undertaken in order to investigate whether major components of the prototypic NO/cyclic GMP signalling cascades mediating many physiological effects of NO in animals were also present in plants. Only a few homologues of soluble guanylate cyclases, cGMP-dependent protein kinases, cyclic nucleotide-gated channels, and cGMP-regulated phosphodiesterases were identified in some algal species and their presence did not correlate with that of NO synthases. In contrast, S-nitrosoglutathione reductase, a critical regulator of S-nitrosothiols, was recurrently found. Overall, these findings highlight that plants do not mediate NO signalling through the classical NO/cGMP signalling module and support the concept that S-nitrosation is a ubiquitous NO-dependent signalling mechanism.

Nitric Oxide-cGMP Signaling Stimulates Erythropoiesis through Multiple Lineage-Specific Transcription Factors: Clinical Implications and a Novel Target for Erythropoiesis

Much attention has been directed to the physiological effects of nitric oxide (NO)-cGMP signaling, but virtually nothing is known about its hematologic effects. We reported for the first time that cGMP signaling induces human γ-globin gene expression. Aiming at developing novel therapeutics for anemia, we examined here the hematologic effects of NO-cGMP signaling in vivo and in vitro. We treated wild-type mice with NO to activate soluble guanylate cyclase (sGC), a key enzyme of cGMP signaling. Compared to untreated mice, NO-treated mice had higher red blood cell counts and total hemoglobin but reduced leukocyte counts, demonstrating that when activated, NO-cGMP signaling exerts hematopoietic effects on multiple types of blood cells in vivo. We next generated mice which overexpressed rat sGC in erythroid and myeloid cells. The forced expression of sGCs activated cGMP signaling in both lineage cells. Compared with non-transgenic littermates, sGC mice exhibited hematologic changes similar to those of NO-treated mice. Consistently, a membrane-permeable cGMP enhanced the differentiation of hematopoietic progenitors toward erythroid-lineage cells but inhibited them toward myeloid-lineage cells by controlling multiple lineage-specific transcription factors. Human γ-globin gene expression was induced at low but appreciable levels in sGC mice carrying the human β-globin locus. Together, these results demonstrate that NO-cGMP signaling is capable of stimulating erythropoiesis in both in vitro and vivo settings by controlling the expression of multiple lineage-specific transcription factors, suggesting that cGMP signaling upregulates erythropoiesis at the level of gene transcription. The NO-cGMP signaling axis may constitute a novel target to stimulate erythropoiesis in vivo.

Inhaled Nitric Oxide Augments Left Ventricular Assist Device Capacity by Ameliorating Secondary Right Ventricular Failure.

Clinical right ventricular (RV) impairment can occur with left ventricular assist device (LVAD) use, thereby compromising the therapeutic effectiveness. The underlying mechanism of this RV failure may be related to induced abnormalities of septal wall motion, RV distension and ischemia, decreased LV filling, and aberrations of LVAD flow. Inhaled nitric oxide (NO), a potent pulmonary vasodilator, may reduce RV afterload, and thereby increase LV filling, LVAD flow, and cardiac output (CO). To investigate the mechanisms associated with LVAD-induced RV dysfunction and its treatment, we created a swine model of hypoxia-induced pulmonary hypertension and acute LVAD-induced RV failure and assessed the physiological effects of NO. Increased LVAD speed resulted in linear increases in LVAD flow until pulse pressure narrowed. Higher speeds induced flow instability, LV collapse, a precipitous fall of both LVAD flow and CO. Nitric oxide (20 ppm) treatment significantly increased the maximal achievable LVAD speed, LVAD flow, CO, and LV diameter. Nitric oxide resulted in decreased pulmonary vascular resistance and RV distension, increased RV ejection, promoted LV filling and improved LVAD performance. Inhaled NO may thus have broad utility for the management of biventricular disease managed by LVAD implantation through the effects of NO on LV and RV wall dynamics.

Photomanipulation of vasodilation with a blue-light-controllable nitric oxide releaser.

Spatiotemporally controllable nitric oxide (NO)-releasers allow us to analyze the physiological effects of NO, a gaseous mediator that modulates many biological signaling networks, and are also candidate chemotherapeutic agents. We designed and synthesized a blue-light-controllable NO releaser, named NOBL-1, which bears an N-nitrosoaminophenol moiety for NO release tethered to a BODIPY dye moiety for harvesting blue light. Photoinduced electron transfer from N-nitrosoaniline to the antenna moiety upon irradiation with relatively noncytotoxic blue light (470-500 nm) should result in NO release with formation of a stable quinone moiety. NO release from NOBL-1 was confirmed by ESR spin trapping and fluorescence detection. Spatially controlled NO release in cells was observed with DAR-4M AM, a fluorogenic NO probe. We also demonstrated temporally controlled vasodilation of rat aorta ex vivo by blue-light-induced NO release from NOBL-1. This compound should be useful for precise examination of the functions of NO with excellent spatiotemporal control.

Nitric oxide (NO) in bird embryogenesis: physiological role and ability of practical use

Nitric oxide (NO) is generated in human and animal tissues from L-arginine. Its known effects include mediation of the parasympathetic nervous system (effects of acetylcholine), smooth muscle tonus, apoptosis, and tissue differentiation. The physiological effects of NO attract significant theoretical and practical interest in medicine and agriculture due to its possible regulation of physiological functions.It is known that embryo development involves intensive NO production, but the exact role of NO in embryogenesis is not clear. Elucidation of the features of NO metabolism in the embryo and their correlation with its development is necessary for the clarification of this role. The avian embryo is a convenient object for such research, because of its relatively large size and its development outside the dam, which allows control of all stages of the development.This article reviews the scientific information on the physiological effects of NO, current hypotheses about their mechanism, and, finally, some perspectives of practical application in poultry breeding. It also reviews of the basic results of our own research that is conducted according to the program of RAAS. It has been observed that NO metabolites contents in embryo amnion and allantois of both egg laying and meat poultry breeds are very different. The value of the difference is more than one order of magnitude, which is seen in more than 30 lines and crosses of hen, quail, turkey and ostrich. It is possible that elucidation of the mechanism of action will allow active regulation of embryo development, as well as the potential for using the indices of NO metabolites content in selection work.

Characterization of Iron Dinitrosyl Species Formed in the Reaction of Nitric Oxide with a Biological Rieske Center

Reactions of nitric oxide with cysteine-ligated iron-sulfur cluster proteins typically result in disassembly of the iron-sulfur core and formation of dinitrosyl iron complexes (DNICs). Here we report the first evidence that DNICs also form in the reaction of NO with Rieske-type [2Fe-2S] clusters. Upon treatment of a Rieske protein, component C of toluene/o-xylene monooxygenase from Pseudomonas sp. OX1, with an excess of NO(g) or NO-generators S-nitroso-N-acetyl-D,L-pencillamine and diethylamine NONOate, the absorbance bands of the [2Fe-2S] cluster are extinguished and replaced by a new feature that slowly grows in at 367 nm. Analysis of the reaction products by electron paramagnetic resonance, Mössbauer, and nuclear resonance vibrational spectroscopy reveals that the primary product of the reaction is a thiolate-bridged diiron tetranitrosyl species, [Fe(2)(μ-SCys)(2)(NO)(4)], having a Roussin's red ester (RRE) formula, and that mononuclear DNICs account for only a minor fraction of nitrosylated iron. Reduction of this RRE reaction product with sodium dithionite produces the one-electron-reduced RRE, having absorptions at 640 and 960 nm. These results demonstrate that NO reacts readily with a Rieske center in a protein and suggest that dinuclear RRE species, not mononuclear DNICs, may be the primary iron dinitrosyl species responsible for the pathological and physiological effects of nitric oxide in such systems in biology.

ROLE OF NITRIC OXIDE IN EXHALED AIR IN BRONCHIALASTHMA

In this review the main physiological effects of nitric oxide in the human body have been considered, as well as its pathophysiologic role in bronchial asthma. Methods for determination of nitric oxide in exhaled air have been described. The importance of determining the level of nitric oxide in patients with bronchial asthma has been analyzed.

Mechanisms of Interaction of Nitric Oxide (NO) and its Metabolites with Enzymes Responsible for the Physiological Effects of NO

It is known that nitric oxide (NO) realizes its basic physiological effects by affecting activity of specific enzymes, such as guanylate cyclase and caspase. Since NO itself in physiological conditions is a short-lived substance, it is considered that it acts by means of some metabolites such as nitrosothiols and some nitro-compounds, which may serve as NO - donors. These NO metabolites are relatively stable substances and their concentrations in biological tissues are also relatively stable. But in this case it is unclear how their physiological effects are controlled. Could they, for example, respond to the certain factors, be accumulated in the right place at the right time or just dissociate releasing NO? In scientific literature these questions remain unanswered. In this review we present the result of our analysis of the available scientific data from the different researchers on the interaction of some NO-donors with guanylate cyclase, caspase and catalase. We propose that NO-like effects of these NOdonors are not the result of only their simple dissociation with releasing of NO. Mostly it is a complex process that starts with initial transformation of these substances into nitrosyl-iron complexes. NO-group of this complex becomes available for the interaction as nitrosation agent only at the moment of destabilization of the complex, which can be initiated by variation of iron associated ligands included in the complex. The ligand content in the medium can be changed depending on physiological conditions. Keywords: Nitric oxide, nitroso- and nitro, –, compounds, guanylate cyclase, caspase, catalase

10.1007/s11828-008-1002-3

The paper reviews the molecular mechanism underlying the physiological effects of nitric oxide (NO), the role of the signalling system: NO-soluble guanylate cyclase-cyclic 3',5'-guanosine monophosphate (cGMP) in the realization of NO action. The data concerning the basic chemical characteristics of guanylate cyclase, such as the subunits structure, isoforms, modem concepts of the catalytic and regulatory centers of the enzyme are presented. The role of guanylate cyclase heme and the enzyme itself in the realization of physiological effects of NO is demonstrated. The data concerning a new NO-independent, allosteric activator of soluble guanylate cyclase, YC-1 (benzyl indasol derivative) synergistically increased the NO-dependent activation of soluble guanylate cyclase are presented. The data on guanylate cyclase sites responsible for binding of the enzyme with YC-1 and possible molecular mechanism underlying the synergistic increase of NO-dependent activation of soluble guanylate cyclase by YC-1 are presented. New compounds of endogenous nature capable to potentiate and synergistically increase the activation of guanylate cyclase by NO-donors have been revealed and investigated. The important physiological, pharmacotherapeutical and pathophysiological significance of this new fact is discussed.

Synthesis and characterization of carnitine nitro-derivatives

Nitric oxide (NO) acts as an autacoid molecule that diffuses from its endothelial production site to the neighboring muscular cells. NO-donors are often used to mimic the physiological effects of NO in biological systems. Organic nitrates are commonly used as NO-donors; the most popular, glycerol trinitrate (GTN), has been used in therapy for more than a century. Carnitine nitrates have been synthesized using an endogenous non-toxic molecule: ( l)-carnitine. The biotransformation of carnitine nitro-derivatives in biological fluids (saliva and blood plasma) and in red blood cells (RBC) has been monitored by an electrochemical assay and the interaction of carnitine nitrates with the plasma membrane carnitine transporter has been investigated. Differences in the way carnitine nitro-derivatives are metabolized in biological fluids and cells and transported by OCTN2 transporter are modulated by the chemical structures and by the length of the acyl template which carries the nitro-group.

Inhibition of Endogenous Nitric Oxide Synthase Augments Contractile Response to Adenylyl Cyclase Stimulation Without Altering Mechanical Efficiency in Patients With Idiopathic Dilated Cardiomyopathy

Increased nitric oxide (NO) in the failing heart attenuates the myocardial contractile response to beta-adrenergic receptor stimulation. However, the physiological effects of NO on the beta-adrenergic post-receptor signaling system are unknown. The objective of the present study was to examine the effects of cardiac NO synthase (NOS) inhibition on left ventricular (LV) hemodynamics and mechanoenergetics in response to adenylyl cyclase stimulation in human heart failure. The study group comprised 13 patients with heart failure because of idiopathic cardiomyopathy (IDC). Emax was examined as an index of LV contractility, LV external work (EW), pressure-volume area (PVA), myocardial oxygen consumption (MVO2), and mechanical efficiency (EW/MVO2) with the use of conductance and coronary sinus thermodilution catheters before and during colforsin daropate infusion, and during concurrent infusion of colforsin daropate with the NOS inhibitor, NG-monomethyl-L-arginine (L-NMMA; 200 micromol). Colforsin daropate increased Emax by 53% and EW by 18%, and reduced PVA by 14%, without altering MVO2 or mechanical efficiency. The combination of colforsin daropate with L-NMMA further increased Emax by 26% and reduced PVA by 9%, without altering MVO2 or mechanical efficiency. These findings suggest endogenous NO may modulate beta-adrenergic post-receptor pathways and preserve myocardial efficiency in patients with IDC.

Autowave mode of the functioning of the nitric oxide + free iron + thiols system as a basis for control of the biological action of nitric oxide and its endogenous compounds

The NO + Fe2+ + thiols system in an aqueous solution has been found earlier to exhibit temporal oscillatory changes in the concentration of paramagnetic dinitrosyl iron complexes with thiol-containing ligands and S-nitrosothiols, as well as in the concentration of free iron (not included in the complexes). It is proposed that autowaves can appear in this system characterized by periodic changes in the concentrations of its components in time and space. Such changes may form a basis for the control of the physiological effects of nitric oxide, dinitrosyl iron complexes, and S-nitrosothiols as agents affecting various cellular and tissue targets.

Spatiotemporal analysis of NO production upon NMDA and tetanic stimulation of the hippocampus

Nitric oxide (NO) is a gaseous neuromessenger. Although increasing evidence reveals significant physiological effects of NO in the hippocampal synaptic plasticity, the spatial distribution of NO production has remained largely uncharacterized due to the poor development of techniques for real-time NO imaging. In this work, using a NO-reactive fluorescent dye, diaminorhodamine-4M (DAR-4M), time-dependent heterogeneous NO production is demonstrated in hippocampal slices upon N-methyl-D-aspartate (NMDA) stimulation or tetanic stimulation. NMDA-induced DAR fluorescence increase in the CA1 was found to be twice that in the CA3 and the dentate gyrus (DG). Intracellular Ca(2+) concentration was also investigated. NMDA induced similar Ca(2+) responses both in the CA1 and DG, which were approx. 13% greater than that in the CA3. Subsequently, spatial distribution of NO production in the CA1 upon a tetanic stimulation of Schaffer collateral was investigated, because there are contradictory reports on the effect of NO on long-term potentiation (LTP), and that NO is known to exert various physiological effects depending on its concentration. In the stratum radiatum (sr), DAR fluorescence increase upon tetanus was largest at the vicinity of a stimulating electrode and decreased as a function of increasing distance from the stimulating electrode, suggesting the possibility that the effect of NO in LTP is dependent on the distance between stimulating and recording electrodes. The tetanus-induced Ca(2+) response observed in the sr showed the same but weak distant dependence from the stimulating electrode. Taken together, the observed heterogeneity in the distribution of NO production is suggestive of region-specific effects of NO in the hippocampus.

Soluble guanylate cyclase is allosterically inhibited by direct interaction with 2-substituted adenine nucleotides.

Nitric oxide (NO), the principal endogenous ligand for soluble guanylate cyclase (sGC), stimulates that enzyme and accumulation of intracellular cGMP, which mediates many of the (patho) physiological effects of NO. Previous studies demonstrated that 2-substituted adenine nucleotides, including 2-methylthioATP (2MeSATP) and 2-chloroATP (2ClATP), allosterically inhibit guanylate cyclase C, the membrane-bound receptor for the Escherichia coli heat-stable enterotoxin in the intestine. The present study examined the effects of 2-substituted adenine nucleotides on crude and purified sGC. 2-Substituted nucleotides inhibited basal and NO-activated crude and purified sGC, when Mg2+ served as the substrate cation cofactor. Similarly, 2-substituted adenine nucleotides inhibited those enzymes when Mn2+, which activates sGC in a ligand-independent fashion, served as the substrate cation cofactor. Inhibition of sGC by 2-substituted nucleotides was associated with a decrease in Vmax, consistent with a noncompetitive mechanism. In contrast to guanylate cyclase C, 2-substituted nucleotides inhibited sGC by a guanine nucleotide-independent mechanism. These studies demonstrate that 2-substituted adenine nucleotides allosterically inhibit basal and ligand-stimulated sGC. They support the suggestion that allosteric inhibition by adenine nucleotides is a general characteristic of the family of guanylate cyclases. This allosteric inhibition is mediated by direct interaction of adenine nucleotides with sGC, likely at the catalytic domain in a region outside the substrate-binding site.

Anesthetic-like Interactions of Nitric Oxide with Albumin and Hemeproteins: A MECHANISM FOR CONTROL OF PROTEIN FUNCTION

Noncovalent bonding interactions of nitric oxide (NO) with human serum albumin (HSA), human hemoglobin A, bovine myoglobin, and bovine cytochrome c oxidase (CcO) have been explored. The anesthetic nitrous oxide (NNO) occupies multiple sites within each protein, but does not bind to heme iron. Infrared (IR) spectra of NNO molecules sequestered within albumin, with NO present, support the binding of NO and NNO to the same sites with comparable affinities. Perturbations of IR spectra of the Cys(34) thiol of HSA indicate NO, NNO, halothane, and chloroform can induce similar changes in protein structure. Experiments evaluating the relative affinities of binding of NO and carbon monoxide (CO) to iron(II) sites of the hemeproteins led to evidence of NO binding to noniron, nonsulfur sites as well. With HbA, IR spectra of cysteine thiols and/or the iron(II) N-O stretching region denote changes in protein structure due to NO, NNO, or CO occupying noniron sites with an order of decreasing affinities of NO > NNO > CO. Loss of NO from some, not all, noniron sites in hemeproteins is very slow (t(1/2) approximately hours). These findings provide examples in which NO and anesthetics alter the structure and properties of protein similarly, and support the hypothesis that some physiological effects of NO (and possibly CO) result from anesthetic-like noncovalent bonding to sites within protein or other tissue components. Such bonding may be involved in mechanisms for control of oxygen transport, mitochondrial respiration, and activation of soluble guanylate cyclase by NO.