1
|
Banerjee R, Kumar R. Gas regulation of complex II reversal via electron shunting to fumarate in the mammalian ETC. Trends Biochem Sci 2022. [PMID: 35397924 PMCID: PMC9288524 DOI: 10.1016/j.tibs.2022.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/22/2022] [Accepted: 03/14/2022] [Indexed: 12/24/2022]
Abstract
The electron transport chain (ETC) is a major currency converter that exchanges the chemical energy of fuel oxidation to proton motive force and, subsequently, ATP generation, using O2 as a terminal electron acceptor. Discussed herein, two new studies reveal that the mammalian ETC is forked. Hypoxia or H2S exposure promotes the use of fumarate as an alternate terminal electron acceptor. The fumarate/succinate and CoQH2/CoQ redox couples are nearly iso-potential, revealing that complex II is poised for facile reverse electron transfer, which is sensitive to CoQH2 and fumarate concentrations. The gas regulators, H2S and •NO, modulate O2 affinity and/or inhibit the electron transfer rate at complex IV. Their induction under hypoxia suggests a mechanism for how traffic at the ETC fork can be regulated.
Collapse
|
2
|
Ieda N, Hishikawa K, Eto K, Kitamura K, Kawaguchi M, Suzuki T, Fukuhara K, Miyata N, Furuta T, Nabekura J, Nakagawa H. A double bond-conjugated dimethylnitrobenzene-type photolabile nitric oxide donor with improved two-photon cross section. Bioorg Med Chem Lett 2015; 25:3172-5. [PMID: 26073004 DOI: 10.1016/j.bmcl.2015.05.095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 05/28/2015] [Accepted: 05/30/2015] [Indexed: 10/23/2022]
Abstract
Photocontrollable NO donors enable precise spatiotemporal release of NO under physiological conditions. We designed and synthesized a novel dimethylnitrobenzene-type NO donor, Flu-DNB-DB, which contains a carbon-carbon double bond in place of the amide bond of previously reported Flu-DNB. Flu-DNB-DB releases NO in response to one-photon activation in the blue wavelength region, and shows a greatly increased two-photon cross-section (δu) at 720 nm (Flu-DNB: 0.12 GM, Flu-DNB-DB: 0.98 GM). We show that Flu-DNB-DB enables precisely controlled intracellular release of NO in response to 950 nm pulse laser irradiation for as little as 1s. This near-infrared-light-controllable NO source should be a valuable tool for studies on the biological roles of NO.
Collapse
Affiliation(s)
- Naoya Ieda
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan
| | - Kazuhiro Hishikawa
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan
| | - Kei Eto
- National Institute of Physiological Sciences, 444-8585, Japan
| | - Kai Kitamura
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan
| | - Mitsuyasu Kawaguchi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan
| | - Takayoshi Suzuki
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 606-0823, Japan
| | | | - Naoki Miyata
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan
| | - Toshiaki Furuta
- Department of Biomolecular Science, Toho University, 274-8510, Japan
| | | | - Hidehiko Nakagawa
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 467-8603, Japan.
| |
Collapse
|
3
|
Sriram K, Salazar Vázquez BY, Tsai AG, Cabrales P, Intaglietta M, Tartakovsky DM. Autoregulation and mechanotransduction control the arteriolar response to small changes in hematocrit. Am J Physiol Heart Circ Physiol 2012; 303:H1096-106. [PMID: 22923620 DOI: 10.1152/ajpheart.00438.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Here, we present an analytic model of arteriolar mechanics that accounts for key autoregulation mechanisms, including the myogenic response and the vasodilatory effects of nitric oxide (NO) in the vasculature. It couples the fluid mechanics of blood flow in arterioles with solid mechanics of the vessel wall and includes the effects of wall shear stress- and stretch-induced endothelial NO production. The model can be used to describe the regulation of blood flow and NO transport under small changes in hematocrit and to analyze the regulatory response of arterioles to small changes in hematocrit. Our analysis revealed that the experimentally observed paradoxical increase in cardiac output with small increases in hematocrit results from the combination of increased NO production and the effects of a strong myogenic response modulated by elevated levels of WSS. Our findings support the hypothesis that vascular resistance varies inversely with blood viscosity for small changes in hematocrit in a healthy circulation that responds to shear stress stimuli. They also suggest beneficial effects independent of changes in O(2) carrying capacity associated with the postsurgical transfusion of one or two units of blood.
Collapse
Affiliation(s)
- Krishna Sriram
- Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093-0412, USA
| | | | | | | | | | | |
Collapse
|
4
|
Pereira ADC, Ford PC, da Silva RS, Bendhack LM. Ruthenium-nitrite complex as pro-drug releases NO in a tissue and enzyme-dependent way. Nitric Oxide 2011; 24:192-8. [DOI: 10.1016/j.niox.2011.03.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 02/21/2011] [Accepted: 03/01/2011] [Indexed: 11/28/2022]
|
5
|
da Silva FO, Gomes EC, Francisco TDS, Holanda AK, Diógenes IC, de Sousa EH, Lopes LG, Longhinotti E. NO donors cis-[Ru(bpy)2(L)NO]3+ and [Fe(CN)4(L)NO]− complexes immobilized on modified mesoporous silica spheres. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
6
|
Mikulski R, Tu C, Swenson ER, Silverman DN. Reactions of nitrite in erythrocyte suspensions measured by membrane inlet mass spectrometry. Free Radic Biol Med 2010; 48:325-31. [PMID: 19913092 PMCID: PMC2818671 DOI: 10.1016/j.freeradbiomed.2009.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 10/28/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022]
Abstract
The reactions of nitrite with deoxygenated human erythrocytes were examined using membrane inlet mass spectrometry to detect the accumulation of NO in an extracellular solution. In this method an inlet utilizing a silicon rubber membrane is submerged in cell suspensions and allows NO to pass from the extracellular solution into the mass spectrometer. This provides a direct, continuous, and quantitative determination of nitric oxide concentrations over long periods without the necessity of purging the suspension with inert gas. We have not observed accumulation of NO compared with controls on a physiologically relevant time scale and conclude that, within the limitations of the mass spectrometric method and our experimental conditions, erythrocytes do not generate a net efflux of NO after the addition of millimolar concentrations of nitrite. Moreover, there was no evidence at the mass spectrometer of the accumulation of a peak at mass 76 that would indicate N(2)O(3), an intermediate that decays into NO and NO(2). Inhibition of red cell membrane anion exchangers and aquaporins did not affect these processes.
Collapse
Affiliation(s)
- Rose Mikulski
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Chingkuang Tu
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Erik R. Swenson
- Departments of Medicine and Physiology, Pulmonary Section, University of Washington, Seattle, WA 98108
| | - David N. Silverman
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL 32610, USA
- Corresponding author: D. N. Silverman, Box 100267 Health Center, University of Florida, Gainesville, FL 32610-0267, USA. Fax: 352 392-9696.
| |
Collapse
|
7
|
|
8
|
Abstract
Clarity about the nitric oxide (NO) concentrations existing physiologically is essential for developing a quantitative understanding of NO signalling, for performing experiments with NO that emulate reality, and for knowing whether or not NO concentrations become abnormal in disease states. A decade ago, a value of about 1 μM seemed reasonable based on early electrode measurements and a provisional estimate of the potency of NO for its guanylyl cyclase-coupled receptors, which mediate physiological NO signal transduction. Since then, numerous efforts to measure NO concentrations directly using electrodes in cells and tissues have yielded an irreconcilably large spread of values. In compensation, data from several alternative approaches have now converged to provide a more coherent picture. These approaches include the quantitative analysis of NO-activated guanylyl cyclase, computer modelling based on the type, activity and amount of NO synthase enzyme contained in cells, the use of novel biosensors to monitor NO release from single endothelial cells and neurones, and the use of guanylyl cyclase as an endogenous NO biosensor in tissue subjected to a variety of challenges. All these independent lines of evidence suggest the physiological NO concentration range to be 100 pM (or below) up to ∼5 nM, orders of magnitude lower than was once thought.
Collapse
Affiliation(s)
- Catherine N Hall
- Department of Neuroscience, Physiology and Pharmacology, University College London, UK
| | | |
Collapse
|
9
|
|
10
|
Holanda AK, da Silva FO, Sousa JR, Diógenes IC, Carvalho IM, Moreira ÍS, Clarke MJ, Lopes LG. Photochemical NO release from nitrosyl RuII complexes with C-bound imidazoles. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.02.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
11
|
Zanichelli PG, Estrela HFG, Spadari-Bratfisch RC, Grassi-Kassisse DM, Franco DW. The effects of ruthenium tetraammine compounds on vascular smooth muscle. Nitric Oxide 2007; 16:189-96. [PMID: 17123848 DOI: 10.1016/j.niox.2006.10.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 09/13/2006] [Accepted: 10/03/2006] [Indexed: 11/17/2022]
Abstract
The time course of the relaxation effect induced by a single dose (3 x 10(-6) mol/L) of trans-[Ru(NH3)4L(NO)]3+ (L=nic, 4-pic, py, imN, P(OEt)3, SO(3)(2-), NH3, and pz) species and sodium nitroprusside (4 x 10(-9) mol/L) was studied in aortic rings without endothelium and pre-contracted with noradrenaline (1 x 10(-6) mol/L). All the compounds induced a relaxing effect in the aortic rings, but the intensity and time of relaxation were different. Only the species where L=py, 4-pic, and P(OEt)3 were able to induce 100% (99-100%) of the relaxing effect during the assay. trans-[Ru(NH3)4(L)(NO)]3+ (L=SO(3)(2-) and NH3) showed the lowest relaxing effect (36 and 37%, respectively) when compared with the other compounds. Relationship was observed between the time corresponding to half of the maximum relaxation intensity observed and, respectively, k-NO, E0'[Ru(NO)]3+/[Ru(NO)]2+ in trans-[Ru(NH3)4(L)(NO)]3+ species and E0'Ru(III)/Ru(II) in trans-[Ru(NH3)4(L)(H2O)]3+ ions. These relationships strongly suggested that the NO liberation from the reduced nitrosyl complexes was responsible for the observed relaxation.
Collapse
Affiliation(s)
- P G Zanichelli
- Departamento de Química Inorgânica, Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
| | | | | | | | | |
Collapse
|
12
|
Madhani M, Patra AK, Miller TW, Eroy-Reveles AA, Hobbs AJ, Fukuto JM, Mascharak PK. Biological activity of designed photolabile metal nitrosyls: light-dependent activation of soluble guanylate cyclase and vasorelaxant properties in rat aorta. J Med Chem 2007; 49:7325-30. [PMID: 17149862 DOI: 10.1021/jm0604629] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biological and pharmacological utility of nitric oxide (NO) has led to the development of many classes of NO-donor compounds as both research tools and therapeutic agents. Many donors currently in use rely on thermal decomposition or bioactivation for the release of NO. We have developed several photolabile metal-nitrosyl donors that release NO when exposed to either visible or UV light. Herein, we show that these donors are capable of activating the primary "NO receptor", soluble guanylate cyclase (sGC), in a light-dependent fashion leading to increases in cGMP. Moreover, we demonstrate that these donors are capable of eliciting light-dependent increases of cGMP in smooth muscle cells and vasorelaxation of rat aortic smooth muscle tissue, all effects that are attributed to activation of sGC. The potential utility of these compounds as drugs and/or research tools is discussed.
Collapse
MESH Headings
- Animals
- Aorta/drug effects
- Aorta/physiology
- Cells, Cultured
- Cyclic GMP/biosynthesis
- Enzyme Activation
- Guanylate Cyclase/chemistry
- Guanylate Cyclase/isolation & purification
- In Vitro Techniques
- Iron
- Light
- Manganese
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide Donors/chemical synthesis
- Nitric Oxide Donors/pharmacology
- Nitric Oxide Donors/radiation effects
- Organometallic Compounds/chemical synthesis
- Organometallic Compounds/pharmacology
- Organometallic Compounds/radiation effects
- Rats
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/isolation & purification
- Ruthenium
- Soluble Guanylyl Cyclase
- Structure-Activity Relationship
- Vasodilation/drug effects
- Vasodilator Agents/chemical synthesis
- Vasodilator Agents/pharmacology
- Vasodilator Agents/radiation effects
Collapse
Affiliation(s)
- Melanie Madhani
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6AE, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
The reported EC(50) of vasorelaxation for authentic nitric oxide (NO) is from the nM to muM range. The cause of this large difference is undetermined. In this study, NO electrodes were used to monitor the actual NO concentration in the organ chamber during the recording of the relaxation of rat aortic rings. It was demonstrated that both the O(2) concentration in the solution and the rate of stirring the solution markedly affected the actual NO concentration, while the vasorelaxation response to NO was also changed with the composition of the buffer solution. It was observed that the apparent EC(50) of aortic relaxation for authentic NO is 340+/-40nM and 81+/-4nM in the conventional organ chamber containing Krebs-Ringer buffer bubbled with a high content (95% O(2)+5% CO(2)) and a low content (20% O(2)+5% CO(2)+75% N(2)) of O(2) gas mixture, respectively. The apparent EC(50) was further reduced to 45+/-2nM after the Krebs-Ringer buffer, a bicarbonate buffer, was replaced by a phosphate buffer solution bubbled with a low content of O(2) gas mixture (20% O(2)+80% N(2)) or with air. By using an organ chamber, which makes low concentrations of NO more stable in the solution, it was determined that the apparent EC(50) was 9.7+/-0.4nM and the threshold of NO concentration in dilating the aortas was approximately 0.3nM. This modified organ chamber will be useful for quantitatively measuring EC(50) of vasorelaxation for authentic NO under physiological and pathological conditions.
Collapse
Affiliation(s)
- Qingtao Yan
- Davis Heart and Lung Research Institute, The Division of Cardiovascular Medicine, Department of Internal Medicine, and Biomedical Engineering Department, The Ohio State University, 473 W. 12th Avenue, Columbus, OH 43210, United States
| | | | | | | |
Collapse
|
14
|
Abstract
Nitric oxide (NO) elicits physiological effects in cells largely by activating guanylyl cyclase (GC)-coupled receptors, leading to cGMP accumulation. Like other receptor-coupled effector mechanisms, NO stimulation of GC activity was previously considered to be a graded, concentration-dependent response, with deactivation following swiftly once the agonist disappeared. Recently, a new and unconventional mechanism has been proposed from experiments on purified protein [Cary, S. P. L., Winger, J. A. & Marletta, M. A. (2005) Proc. Natl. Acad. Sci. USA 102, 13064-13069]. It was concluded that GC in vivo will display a dual regulation by NO: a long-lasting tonic activity (10-20% of maximum) due to persistent occupation by NO of the heme binding site and phasic activity due to engagement of another unidentified, lower affinity site. The hypothesis was first tested by monitoring GC activity in rat platelets maintained in vitro and exposed to calibrated NO transients. The kinetics was as expected for a single binding site for NO (EC(50) = 10 nM), with activation and deactivation of enzyme activity conforming to the predictions of a simple receptor model. No tonic GC activity attributable to long-term NO binding was detected after exposure to the full range of active NO concentrations (peaking at 2-500 nM). Comparable results were obtained by using neural cells isolated from the cerebellum. After exposure to high NO concentrations, persistent GC activity could be recorded, but this activity was caused artifactually by secondary NO sources being formed in the medium. The new scheme for regulation of GC activity by NO is of doubtful relevance to cells.
Collapse
Affiliation(s)
- Brijesh Roy
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
15
|
Sarkar S, Sarkar B, Chanda N, Kar S, Mobin SM, Fiedler J, Kaim W, Lahiri GK. Complex series [Ru(tpy)(dpk)(X)]n+ (tpy = 2,2':6',2''-terpyridine; dpk = 2,2'-dipyridyl ketone; X = Cl-, CH3CN, NO2(-), NO+, NO*, NO-): substitution and electron transfer, structure, and spectroscopy. Inorg Chem 2006; 44:6092-9. [PMID: 16097830 DOI: 10.1021/ic050533e] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The complex framework [Ru(tpy)(dpk)]2+ has been used to study the generation and reactivity of the nitrosyl complex [Ru(tpy)(dpk)(NO)]3+ ([4]3+). Stepwise conversion of the chloro complex [Ru(tpy)(dpk)(Cl)]+ ([1]+) via [Ru(tpy)(dpk)(CH3CN)]2+ ([2]2+) and the nitro compound [Ru(tpy)(dpk)(NO2)]+ ([3]+) yielded [4]3+; all four complexes were structurally characterized as perchlorates. Electrochemical oxidation and reduction was investigated as a function of the monodentate ligand as was the IR and UV-vis spectroscopic response (absorption/emission). The kinetics of the conversion [4]3+/[3]+ in aqueous environment were also studied. Two-step reduction of [4]3+ was monitored via EPR, UV-vis, and IR (nu(NO), nu(CO)) spectroelectrochemistry to confirm the {RuNO}7 configuration of [4]2+ and to exhibit a relatively intense band at 505 nm for [4]+, attributed to a ligand-to-ligand transition originating from bound NO-.
Collapse
Affiliation(s)
- Sounak Sarkar
- Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Sauaia MG, de Lima RG, Tedesco AC, da Silva RS. Nitric Oxide Production by Visible Light Irradiation of Aqueous Solution of Nitrosyl Ruthenium Complexes. Inorg Chem 2005; 44:9946-51. [PMID: 16363866 DOI: 10.1021/ic051346j] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](PF(6))(5) (L is NH(3), py, or 4-acpy) was prepared with good yields in a straightforward way by mixing an equimolar ratio of cis-[Ru(NO(2))(bpy)(2)(NO)](PF(6))(2), sodium azide (NaN(3)), and trans-[RuL(NH(3))(4)(pz)] (PF(6))(2) in acetone. These binuclear compounds display nu(NO) at ca. 1945 cm(-)(1), indicating that the nitrosyl group exhibits a sufficiently high degree of nitrosonium ion (NO(+)). The electronic spectrum of the [Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](5+) complex in aqueous solution displays the bands in the ultraviolet and visible regions typical of intraligand and metal-to-ligand charge transfers, respectively. Cyclic voltammograms of the binuclear complexes in acetonitrile give evidence of three one-electron redox processes consisting of one oxidation due to the Ru(2+/3+) redox couple and two reductions concerning the nitrosyl ligand. Flash photolysis of the [Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](5+) complex is capable of releasing nitric oxide (NO) upon irradiation at 355 and 532 nm. NO production was detected and quantified by an amperometric technique with a selective electrode (NOmeter). The irradiation at 532 nm leads to NO release as a consequence of a photoinduced electron transfer. All species exhibit similar photochemical behavior, a feature that makes their study extremely important for their future application in the upgrade of photodynamic therapy in living organisms.
Collapse
Affiliation(s)
- Marília Gama Sauaia
- Departamento de Química da Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. dos Bandeirantes 3900, 14040-901, Ribeirão Preto, São Paulo, Brazil
| | | | | | | |
Collapse
|
17
|
Kwak YL, Jones KA, Warner DO, Perkins WJ. NO responsiveness in pulmonary artery and airway smooth muscle: the role of cGMP regulation. Am J Physiol Lung Cell Mol Physiol 2005; 290:L200-8. [PMID: 16113048 DOI: 10.1152/ajplung.00186.2005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to assess intrinsic smooth muscle mechanisms contributing to greater nitric oxide (NO) responsiveness in pulmonary vascular vs. airway smooth muscle. Canine pulmonary artery smooth muscle (PASM) and tracheal smooth muscle (TSM) strips were used to perform concentration response studies to an NO donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO). PASM exhibited a greater NO responsiveness whether PASM and TSM were contracted with receptor agonists, phenylephrine and acetylcholine, respectively, or with KCl. The >10-fold difference in NO sensitivity in PASM was observed with both submaximal and maximal contractions. This difference in NO responsiveness was not due to differences in endothelial or epithelial barriers, since these were removed, nor was it due to the presence of cGMP-independent NO-mediated relaxation in either tissue. At equal concentrations of NO, the intracellular cGMP concentration ([cGMP]i) was also greater in PASM than in TSM. Phosphodiesterase (PDE) inhibition using isobutylmethylxanthine indicated that the greater [cGMP]i in PASM was not due to greater PDE activity in TSM. Expression of soluble guanylate cyclase (sGC) subunit mRNA (2 +/- 0.2 and 1.3 +/- 0.2 attomol/microg total RNA, respectively) and protein (47.4 +/- 2 and 27.8 +/- 3.9 ng/mg soluble homogenate protein, respectively) was greater in PASM than in TSM. sGCalpha1 and sGCbeta1 mRNA expression was equal in PASM but was significantly different in TSM, suggesting independent regulation of their expression. An intrinsic smooth muscle mechanism accounting for greater NO responsiveness in PASM vs. TSM is greater sGC activity.
Collapse
MESH Headings
- Animals
- Cyclic GMP/metabolism
- Dogs
- Dose-Response Relationship, Drug
- Female
- Guanylate Cyclase
- Humans
- In Vitro Techniques
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Male
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide/pharmacology
- Nitric Oxide Donors/administration & dosage
- Nitric Oxide Donors/pharmacology
- Phosphoric Diester Hydrolases/metabolism
- Pulmonary Artery/drug effects
- Pulmonary Artery/metabolism
- RNA, Messenger/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Soluble Guanylyl Cyclase
- Trachea/drug effects
- Trachea/metabolism
- Triazenes/administration & dosage
- Triazenes/pharmacology
- Vasoconstriction/drug effects
Collapse
Affiliation(s)
- Young L Kwak
- Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
| | | | | | | |
Collapse
|
18
|
Jeffers A, Xu X, Huang KT, Cho M, Hogg N, Patel RP, Kim-Shapiro DB. Hemoglobin mediated nitrite activation of soluble guanylyl cyclase. Comp Biochem Physiol A Mol Integr Physiol 2005; 142:130-5. [PMID: 15936233 DOI: 10.1016/j.cbpb.2005.04.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 04/06/2005] [Accepted: 04/07/2005] [Indexed: 11/22/2022]
Abstract
Nitrite has long been known to be vasoactive when present at large concentrations but it was thought to be inactive under physiological conditions. Surprisingly, we have recently shown that supraphysiological and near physiological concentrations of nitrite cause vasodilation in the human circulation. These effects appeared to result from reduction of nitrite by deoxygenated hemoglobin. Thus, nitrite was proposed to play a role in hypoxic vasodilation. We now discuss these results in the context of nitrite reacting with hemoglobin and effecting vasodilation and present new data modeling the nitric oxide (NO) export from the red blood cell and measurements of soluble guanylate cyclase (sGC) activation. We conclude that NO generated within the interior of the red blood cell is not likely to be effectively exported directly as nitric oxide. Thus, an intermediate species must be formed by the nitrite/deoxyhemoglobin reaction that escapes the red cell and effects vasodilation.
Collapse
Affiliation(s)
- Anne Jeffers
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27109-7507 USA
| | | | | | | | | | | | | |
Collapse
|
19
|
Toma HE, Alexiou AD, Formiga ALB, Nakamura M, Dovidauskas S, Eberlin MN, Tomazela DM. A nitric oxide releaser based on the μ-oxo-hexaacetate-bis(4-methylpyridine)triruthenium nitrosyl complex. Inorganica Chim Acta 2005. [DOI: 10.1016/j.ica.2004.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
20
|
Karidi K, Garoufis A, Tsipis A, Hadjiliadis N, den Dulk H, Reedijk J. Synthesis, characterization, in vitro antitumor activity, DNA-binding properties and electronic structure (DFT) of the new complex cis-(Cl,Cl)[RuIICl2(NO+)(terpy)]Cl. Dalton Trans 2005:1176-87. [PMID: 15782252 DOI: 10.1039/b418838a] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complex cis-(Cl,Cl)-[RuCl2(terpy)(NO)]Cl (1) has been synthesized by the reaction of [RuCl3(H2O)2(NO)] with terpyridine (terpy) and characterized by various spectroscopic, analytical techniques and using electronic structure calculation (DFT) methods. The cytotoxic activity and the DNA-binding properties of have also been studied using biochemical techniques. The results establish unequivocally that corresponds to a so-called [RuNO]6 species, which readily releases the nitrosyl ligand upon irradiation with a mercury lamp in acetonitrile solution. DFT calculations provided a satisfactory description of structural, bonding, electronic and related properties of the new compound and throw light on the mechanism of the photo-induced NO release. Screening on A2780 (human ovarian carcinoma) cell lines showed significant cytotoxicity with an IC50 value of 0.49 microM. 31P and 23Na NMR spectroscopy along with electrophoretic mobility studies illustrated that complex primarily binds by coordination to DNA without any pi-interaction between the planar terpy ligand and the DNA bases, while weak electrostatic interactions could not be excluded. Studies on the inhibition of the restriction enzymes DraI and SmaI revealed that prefers the guanine and cytosine bases of DNA.
Collapse
Affiliation(s)
- Konstantina Karidi
- Laboratory of Inorganic and General Chemistry, Department of Chemistry, University of Ioannina, Greece
| | | | | | | | | | | |
Collapse
|
21
|
Abstract
The detailed molecular mechanism for the reversible inhibition of mitochondrial respiration by NO has puzzled investigators: The rate constants for the binding of NO and O2 to the reduced binuclear center CuB/a3 of cytochrome oxidase (COX) are similar, and NO is able to dissociate slowly from this center whereas O2 is kinetically trapped, which altogether seems to favor the complex of COX with O2 over the complex of COX with NO. Paradoxically, the inhibition of COX by NO is observed at high ratios of O2 to NO (in the 40-500 range) and is very fast (seconds or faster). In this work, we used simple mathematical models to investigate this paradox and other important biological questions concerning the inhibition of COX by NO. The results showed that all known features of the inhibition of COX by NO can be accounted for by a direct competition between NO and O2 for the reduced binuclear center CuB/a3 of COX. Besides conciliating apparently contradictory data, this work provided an explanation for the so-called excess capacity of COX by showing that the COX activity found in tissues actually is optimized to avoid an excessive inhibition of mitochondrial respiration by NO, allowing a moderate, but not excessive, overlap between the roles of NO in COX inhibition and in cellular signaling. In pathological situations such as COX-deficiency diseases and chronic inflammation, an excessive inhibition of the mitochondrial respiration is predicted.
Collapse
Affiliation(s)
- Fernando Antunes
- Grupo de Bioquímica dos Oxidantes e Antioxidantes, Centro de Química e Bioquímica, da Faculdade de Ciências da Universidade de Lisboa, P-1749-016 Lisbon, Portugal.
| | | | | |
Collapse
|
22
|
Czap A, Heinemann FW, van Eldik R. Influence of Terpyridine as π-Acceptor Ligand on the Kinetics and Mechanism of the Reaction of NO with Ruthenium(III) Complexes. Inorg Chem 2004; 43:7832-43. [PMID: 15554649 DOI: 10.1021/ic0350685] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics of the unusually fast reaction of cis- and trans-[Ru(terpy)(NH3)2Cl]2+ (with respect to NH3; terpy=2,2':6',2"-terpyridine) with NO was studied in acidic aqueous solution. The multistep reaction pathway observed for both isomers includes a rapid and reversible formation of an intermediate Ru(III)-NO complex in the first reaction step, for which the rate and activation parameters are in good agreement with an associative substitution behavior of the Ru(III) center (cis isomer, k1=618 +/- 2 M(-1) s(-1), DeltaH(++) = 38 +/- 3 kJ mol(-1), DeltaS(++) = -63 +/- 8 J K(-1) mol(-1), DeltaV(++) = -17.5 +/- 0.8 cm3 mol(-1); k -1 = 0.097 +/- 0.001 s(-1), DeltaH(++) = 27 +/- 8 kJ mol(-1), DeltaS(++) = -173 +/- 28 J K(-1) mol(-1), DeltaV(++) = -17.6 +/- 0.5 cm3 mol(-1); trans isomer, k1 = 1637 +/- 11 M(-1) s(-1), DeltaH(++) = 34 +/- 3 kJ mol(-1), DeltaS(++) = -69 +/-11 J K(-1) mol(-1), DeltaV(++) = -20 +/- 2 cm3 mol(-1); k(-1)=0.47 +/- 0.08 s(-1), DeltaH(++)=39 +/- 5 kJ mol(-1), DeltaS(++) = -121 +/-18 J K(-1) mol(-1), DeltaV(++) = -18.5 +/- 0.4 cm3 mol(-1) at 25 degrees C). The subsequent electron transfer step to form Ru(II)-NO+ occurs spontaneously for the trans isomer, followed by a slow nitrosyl to nitrite conversion, whereas for the cis isomer the reduction of the Ru(III) center is induced by the coordination of an additional NO molecule (cis isomer, k2=51.3 +/- 0.3 M(-1) s(-1), DeltaH(++) = 46 +/- 2 kJ mol(-1), DeltaS(++) = -69 +/- 5 J K(-1) mol(-1), DeltaV(++) = -22.6 +/- 0.2 cm3 mol(-1) at 45 degrees C). The final reaction step involves a slow aquation process for both isomers, which is interpreted in terms of a dissociative substitution mechanism (cis isomer, DeltaV(++) = +23.5 +/- 1.2 cm3 mol(-1); trans isomer, DeltaV(++) = +20.9 +/- 0.4 cm3 mol(-1) at 55 degrees C) that produces two different reaction products, viz. [Ru(terpy)(NH3)(H2O)NO]3+ (product of the cis isomer) and trans-[Ru(terpy)(NH3)2(H2O)]2+. The pi-acceptor properties of the tridentate N-donor chelate (terpy) predominantly control the overall reaction pattern.
Collapse
Affiliation(s)
- Almut Czap
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstr. 1, 91058 Erlangen, Germany
| | | | | |
Collapse
|
23
|
Carlos RM, Ferro AA, Silva HA, Gomes MG, Borges SS, Ford PC, Tfouni E, Franco DW. Photochemical reactions of trans-[Ru(NH3)4L(NO)]3+ complexes. Inorganica Chim Acta 2004; 357:1381-8. [DOI: 10.1016/j.ica.2003.11.023] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
24
|
Bonaventura D, de S Oliveira F, Togniolo V, Tedesco AC, da Silva RS, Bendhack LM. A macrocyclic nitrosyl ruthenium complex is a NO donor that induces rat aorta relaxation. Nitric Oxide 2004; 10:83-91. [PMID: 15135361 DOI: 10.1016/j.niox.2004.03.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 03/17/2004] [Indexed: 11/20/2022]
Abstract
The vasorelaxation induced by a nitrosyl macrocyclic ruthenium complex, proposed as a new nitric oxide (NO) carrier, was studied in rat isolated aorta. The compound trans-[RuCl([15]aneN4)NO]2+ was characterized by elemental analysis, UV-visible spectrum, and infrared spectrum. Based on the electrochemical process, the reduction of the compound was followed by NO release, which was also observed using norepinephrine as a reducing agent and NO released was analyzed by a sensor. Vasorelaxation induced by this NO donor was studied and compared to those obtained with sodium nitroprusside (SNP). The relaxation induced by the compound was concentration-dependent in denuded rat aortas and occurred only in pre-contracted arteries with norepinephrine. The macrocyclic compound induced relaxation with a similar efficacy as SNP, although the potency of SNP was slightly greater. The time to reach maximum relaxation (595 s) was longer than that of SNP (195 s). Relaxation was completely abolished by oxyhemoglobin, a known NO scavenger.
Collapse
Affiliation(s)
- Daniella Bonaventura
- Laboratório de Farmacologia, Depto. de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP Av. do Café s/no, 14040-903 Ribeirão Preto, SP, Brazil
| | | | | | | | | | | |
Collapse
|
25
|
Sauaia MG, de Souza Oliveira F, Tedesco AC, Santana da Silva R. Control of NO release by light irradiation from nitrosyl–ruthenium complexes containing polypyridyl ligands. Inorganica Chim Acta 2003. [DOI: 10.1016/s0020-1693(03)00271-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
26
|
Chen Y, Shepherd RE. Different isomers of [RuII(NO+)(hedta)(H2O)] prepared from Ru(NO)Cl3 via chelation by hedta3− than by NO2− addition to [Ru(H2O)(hedta)]−. Inorganica Chim Acta 2003; 343:281-7. [DOI: 10.1016/s0020-1693(02)01199-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
27
|
Ward MS, Lin F, Shepherd RE. Coordination of {RuII(NO+)}3+ and {RuII(H2O)}2+ to bleomycin: most favored [RuII(L)(BLM-A2)] structure according to 1H NMR and molecular mechanics methods. Inorganica Chim Acta 2003; 343:231-43. [DOI: 10.1016/s0020-1693(02)01174-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
28
|
Abstract
The effect of the basal cerebral blood flow (CBF) on both the magnitude and dynamics of the functional hemodynamic response in humans has not been fully investigated. Thus, the hemodynamic response to visual stimulation was measured using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in human subjects in a 7-T magnetic field under different basal conditions: hypocapnia, normocapnia, and hypercapnia. Hypercapnia was induced by inhalation of a 5% carbon dioxide gas mixture and hypocapnia was produced by hyperventilation. As the fMRI baseline signal increased linearly with expired CO2 from hypocapnic to hypercapnic levels, the magnitude of the BOLD response to visual stimulation decreased linearly. Measures of the dynamics of the visually evoked BOLD response (onset time, full-width-at-half-maximum, and time-to-peak) increased linearly with the basal fMRI signal and the end-tidal CO2 level. The basal CBF level, modulated by the arterial partial pressure of CO2, significantly affects both the magnitude and dynamics of the BOLD response induced by neural activity. These results suggest that caution should be exercised when comparing stimulus-induced fMRI responses under different physiologic or pharmacologic states.
Collapse
Affiliation(s)
- Eric R Cohen
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis 55455, USA
| | | | | |
Collapse
|
29
|
Works CF, Jocher CJ, Bart GD, Bu X, Ford PC. Photochemical nitric oxide precursors: synthesis, photochemistry, and ligand substitution kinetics of ruthenium salen nitrosyl and ruthenium salophen nitrosyl complexes. Inorg Chem 2002; 41:3728-39. [PMID: 12099878 DOI: 10.1021/ic020248k] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Described are syntheses, characterizations, and photochemical reactions of the nitrosyl complexes Ru(salen)(ONO)(NO) (I, salen = N,N'-ethylenebis(salicylideneiminato) dianion), Ru(salen)(Cl)(NO) (II), Ru((t)Bu(4)salen)(Cl)(NO) (III,(t)Bu(4)salen = N,N'-ethylenebis(3,5-di-tert-butylsalicylideneiminato) dianion), Ru((t)Bu(4)salen)(ONO)(NO) (IV), Ru((t)Bu(2)salophen)(Cl)(NO) (V, (t)Bu(2)salophen = N,N'-1,2-phenylenediaminebis(3-tert-butylsalicylideneiminato) dianion), and Ru((t)Bu(4)salophen)(Cl)(NO) (VI, (t)Bu(4)salophen = N,N'-1,2-phenylenebis(3,5-di-tert-butylsalicylideneiminato) dianion). Upon photolysis, these Ru(L)(X)(NO) compounds undergo NO dissociation to give the ruthenium(III) solvento products Ru(L)(X)(Sol). Quantum yields for 365 nm irradiation in acetonitrile solution fall in a fairly narrow range (0.055-0.13) but decreased at longer lambda(irr). The quantum yield (lambda(irr) = 365 nm) for NO release from the water soluble complex [Ru(salen)(H(2)O)(NO)]Cl (VII) was 0.005 in water. Kinetics of thermal back-reactions to re-form the nitrosyl complexes demonstrated strong solvent dependence with second-order rate constants k(NO) varying from 5 x 10(-4) M(-1) s(-1) for the re-formation of II in acetonitrile to 5 x 10(8) M(-1) s(-1) for re-formation of III in cyclohexane. Pressure and temperature effects on the back-reaction rates were also examined. These results are relevant to possible applications of photochemistry for nitric oxide delivery to biological targets, to the mechanisms by which NO reacts with metal centers to form metal-nitrosyl bonds, and to the role of photochemistry in activating similar compounds as catalysts for several organic transformations. Also described are the X-ray crystal structures of I and V.
Collapse
Affiliation(s)
- Carmen F Works
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | | | | | | | | |
Collapse
|
30
|
Affiliation(s)
- Peng George Wang
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
| | | | | | | | | | | | | |
Collapse
|
31
|
Affiliation(s)
- Trevor W Hayton
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | | | | |
Collapse
|
32
|
Buerk DG. Can we model nitric oxide biotransport? A survey of mathematical models for a simple diatomic molecule with surprisingly complex biological activities. Annu Rev Biomed Eng 2002; 3:109-43. [PMID: 11447059 DOI: 10.1146/annurev.bioeng.3.1.109] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nitric oxide (NO) is a remarkable free radical gas whose presence in biological systems and whose astonishing breadth of physiological and pathophysiological activities have only recently been recognized. Mathematical models for NO biotransport, just beginning to emerge in the literature, are examined in this review. Some puzzling and paradoxical properties of NO may be understood by modeling proposed mechanisms with known parameters. For example, it is not obvious how NO can survive strong scavenging by hemoglobin and still be a potent vasodilator. Recent models do not completely explain how tissue NO can reach effective levels in the vascular wall, and they point toward mechanisms that need further investigation. Models help to make sense of extremely low partial pressures of NO exhaled from the lung and may provide diagnostic information. The role of NO as a gaseous neurotransmitter is also being understood through modeling. Studies on the effects of NO on O2 transport and metabolism, also reviewed, suggest that previous mathematical models of transport of O2 to tissue need to be revised, taking the biological activity of NO into account.
Collapse
Affiliation(s)
- D G Buerk
- Departments of Physiology, Bioengineering, and Institute for Environmental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6085, USA.
| |
Collapse
|
33
|
Bellamy TC, Garthwaite J. The receptor-like properties of nitric oxide-activated soluble guanylyl cyclase in intact cells. Mol Cell Biochem 2002; 230:165-76. [PMID: 11952092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Soluble guanylyl cyclase (sGC) is the main receptor for nitric oxide (NO), and so mediates a wide range of effects (e.g. vasodilatation, platelet disaggregation and neural signalling) through the accumulation of cGMP and the engagement of various downstream targets, such as protein kinases and ion channels. Until recently, our understanding of sGC functioning has been derived exclusively from studies of the enzyme in tissue homogenates or in its purified form. Here, NO binds to the haem prosthetic group of sGC, triggering a conformational change and a large increase in catalytic activity. The potency (EC50) of NO appears to be about 100-200 nM. The rate of activation of sGC by NO is rapid (milliseconds) and, in the presence of excess substrate, cGMP is formed at a constant rate; on removal of NO, sGC deactivates slowly (seconds-minutes). Recent investigation of the way that sGC behaves in its natural environment, within cells, has revealed several key differences. For example, the enzyme exhibits a rapidly desensitizing profile of activity; the potency of NO is 45 nM for the minimally-desensitized enzyme but becomes higher with time, deactivation of sGC on removal of NO is 25-fold faster than the fastest estimate for purified sGC. Overall, within cells, sGC behaves in a way that is analogous to the way that classical neurotransmitter receptors operate. The properties of cellular sGC have important implications for the understanding of NO-cGMP signalling. For example, the dynamics of the enzyme means that fluctuations in the rate of NO formation, even on subsecond time scale, will result in closely synchronized sGC activity in neighbouring cells; desensitization of sGC provides an economical way of generating a cellular cGMP signal and, in concert with phosphodiesterases, provides the basis for cGMP signal diversity, allowing different targets (outputs) to be selected from a common input (NO). Thus, despite exhibiting only limited molecular heterogeneity, cellular sGC functions in a way that introduces speed, complexity, and versatility into NO-cGMP signalling pathways.
Collapse
Affiliation(s)
- Tomas C Bellamy
- Wolfson Institute for Biomedical Research, University College London, UK.
| | | |
Collapse
|
34
|
Abstract
1. The functioning of nitric oxide (NO) as a biological messenger necessitates that there be an inactivation mechanism. Cell suspensions from a rat brain region rich in the NO signalling pathway (cerebellum) were used to investigate the existence of such a mechanism and to determine its properties. 2. The cells consumed NO in a manner that could not be explained by reaction with O(2), superoxide ions or contaminating red blood cells. Functionally, the mechanism was able to convert constant rates of NO formation into low steady-state NO concentrations. For example, with NO produced at 90 nM min(-1), the cells (20 x 10(6) ml(-1)) held NO at 20 nM. Various other cell types behaved similarly. 3. The influence of NO inactivation on the ability of NO to access its receptor, soluble guanylyl cyclase, was explored by measuring cGMP accumulation in response to the clamped NO concentrations. The extrapolated steady-state EC(50) for NO was 2 nM, a concentration readily achieved by low NO release rates, despite inactivation. 4. When confronted by higher NO release rates for several minutes, the clamping mechanism failed, resulting in a progressive rise in NO concentration. While the clamp was maintained, cellular respiration was unaffected but, as it failed, respiration became inhibited by NO. The IC(50) was measured to be 120 nM (at 100-140 microM O(2)). 5. It is concluded that cerebellar (and other) cells possess a powerful NO inactivation mechanism that, extrapolated to the whole tissue, would impose on NO a half-life of around 100 ms. This and other properties of the device appear ideal for shaping low-level NO signals for activating its receptor, soluble guanylyl cyclase, whilst avoiding adverse effects on mitochondrial function. The exhaustibility of the mechanism provides a scenario for NO to become toxic.
Collapse
Affiliation(s)
- C Griffiths
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | | |
Collapse
|
35
|
Slocik JM, Somayajula KV, Shepherd RE. Electrospray mass spectrometry of trans-[Ru(NO)Cl(dpaH)2]2+ (dpaH=2,2′-dipyridylamine) and ‘caged NO’, [RuCl3(NO)(H2O)2]: loss of HCl and NO from positive ions versus NO and Cl from negative ions. Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00487-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
36
|
Slocik JM, Ward MS, Shepherd RE. Synthesis and characterization of meso-[Ru(NO)Cl(dioxocyclam)] and the 1H NMR comparison with [MII(dioxocyclam)] complexes (MII=NiII and PdII) (dioxocyclam=1,4,8,11-tetraazacyclotetradecane-5,7-dione). Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00427-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
37
|
Abstract
S-Nitrosohemoglobin (SNO-Hb) is a vasodilator whose activity is allosterically modulated by oxygen ("thermodyamic linkage"). Blood vessel contractions are favored in the oxygenated structure, and vasorelaxant activity is "linked" to deoxygenation, as illustrated herein. We further show that transnitrosation reactions between SNO-Hb and ambient thiols transduce the NO-related bioactivity, whereas NO itself is inactive. One remaining problem is that the amounts of SNO-Hb present in vivo are so large as to be incompatible with life were all the S-nitrosothiols transformed into bioactive equivalents during each arterial-venous cycle. Experiments were therefore undertaken to address how SNO-Hb conserves its NO-related activity. Our studies show that 1) increased O(2) affinity of SNO-Hb (which otherwise retains allosteric responsivity) restricts the hypoxia-induced allosteric transition that exchanges NO groups with ambient thiols for vasorelaxation; 2) some NO groups released from Cys(beta93) upon transition to T structure are autocaptured by the hemes, even in the presence of glutathione; and 3) an O(2)-dependent equilibrium between SNO-Hb and iron nitrosylhemoglobin acts to conserve NO. Thus, by sequestering a significant fraction of NO liberated upon transition to T structure, Hb can conserve NO groups that would otherwise be released in an untimely or deleterious manner.
Collapse
Affiliation(s)
- T J McMahon
- Howard Hughes Medical Institute, Department of Medicine, and the Nicholas School for the Environment, Duke University Medical Center, Durham, North Carolina 27710, USA
| | | | | | | | | |
Collapse
|
38
|
Bellamy TC, Wood J, Goodwin DA, Garthwaite J. Rapid desensitization of the nitric oxide receptor, soluble guanylyl cyclase, underlies diversity of cellular cGMP responses. Proc Natl Acad Sci U S A 2000; 97:2928-33. [PMID: 10717006 PMCID: PMC16032 DOI: 10.1073/pnas.97.6.2928] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A major receptor for nitric oxide (NO) is the cGMP-synthesizing enzyme, soluble guanylyl cyclase (sGC), but it is not known how this enzyme behaves in cells. In cerebellar cells, NO (from diethylamine NONOate) increased astrocytic cGMP with a potency (EC(50) </= 20 nM) higher than that reported for purified sGC. Deactivation of NO-stimulated sGC activity, studied by trapping free NO with hemoglobin, took place within seconds (or less) rather than the minute time scale reported for the purified enzyme. Measurement of the rates of accumulation and degradation of cGMP were used to follow the activity of sGC over time. The peak activity, occurring within seconds of adding NO, was swiftly followed by desensitization to a steady-state level 8-fold lower. The same desensitizing profile was observed when the net sGC activity was increased or decreased or when cGMP breakdown was inhibited. Recovery from desensitization was relatively slow (half-time = 1.5 min). When the cells were lysed, sGC desensitization was lost. Analysis of the transient cGMP response to NO in human platelets showed that sGC underwent a similar desensitization. The results indicate that, in its natural environment, sGC behaves much more like a neurotransmitter receptor than had been expected from previous enzymological studies, and that hitherto unknown sGC regulatory factors exist. Rapid sGC desensitization, in concert with variations in the rate of cGMP breakdown, provides a fundamental mechanism for shaping cellular cGMP responses and is likely to be important in decoding NO signals under physiological and pathophysiological conditions.
Collapse
Affiliation(s)
- T C Bellamy
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | | | | | | |
Collapse
|
39
|
Seifriz I, Konzen M, Paula MM, Gonçalves NS, Spoganickz B, Creczynski-Pasa TB, Bonetti VR, Beirith A, Calixto JB, Franco CV. Synthesis, potentiometric titration, electrochemical investigation and biological properties of trans-[RuCl2(dinic)4] (dinic = 3,5-pyridinecarboxylic acid). J Inorg Biochem 1999; 76:153-63. [PMID: 10605834 DOI: 10.1016/s0162-0134(99)00111-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This work discusses both the synthesis of trans-[RuCl2(dinic)4], dinic = 3,5-pyridinecarboxylic acid, and its main characteristics including potentiometric titration, spectroscopic and electrochemical properties, and some biological properties. The complex was synthesized using ruthenium blue solution as the precursor in a synthetic route. The complex was characterized using electronic spectroscopy, vibrational FT-IR spectroscopy, and Raman spectroscopy, as well as 1H and 13C NMR. The results indicated that the complex exhibits a trans-geometry. Cyclic voltammetry carried out in water:acetone 1:1 solution revealed a quasi-reversible process centered on the Ru(II) atom, as well as a dependence of the redox potential, E1/2, on pH. An analysis of the electronic spectra revealed that the MLCT (metal ligand charge transfer) band underwent a hypsochromic shift as the pH increased. Spectroelectrochemical analysis indicated that the visible region band progressively faded out upon oxidation. The equilibrium constants for the eight protons of the complex were determined by potentiometric titration. The complex neither inhibits the activity of nitrogen monoxide synthase nor acts as a scavenger for nitrogen monoxide. Nevertheless, the complex shows antinociceptive properties and acts as a scavenger for hydroxyl radicals.
Collapse
Affiliation(s)
- I Seifriz
- Departamentos de Química, Universidade Federal de Santa Catarina UFSC, Florianópolis, Brazil
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Simonsen U, Wadsworth RM, Buus NH, Mulvany MJ. In vitro simultaneous measurements of relaxation and nitric oxide concentration in rat superior mesenteric artery. J Physiol 1999; 516 ( Pt 1):271-82. [PMID: 10066940 PMCID: PMC2269215 DOI: 10.1111/j.1469-7793.1999.271aa.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
1. The relationship between nitric oxide (NO) concentration measured with an NO-specific microelectrode and endothelium-dependent relaxation was investigated in isolated rat superior mesenteric artery contracted with 1 microM noradrenaline. 2. Acetylcholine (10 microM) induced endothelium-dependent simultaneous increases in luminal NO concentration of 21 +/- 6 nM, and relaxations with pD2 values and maximum of 6.95 +/- 0.32 and 97.5 +/- 0.7 % (n = 7), respectively. An inhibitor of NO synthase, N G-nitro-L-arginine (L-NOARG, 100 microM) inhibited the relaxations and increases in NO concentration induced by acetylcholine. 3. Oxyhaemoglobin (10 microM) reversed the relaxations and increases in NO concentrations induced by acetylcholine, S-nitroso-N-acetylpenicillamine (SNAP) and S-morpholino-sydnonimine (SIN-1), but not the relaxations induced with forskolin. Oxyhaemoglobin also decreased the NO concentration below baseline level. 4. In the presence of L-NOARG (100 microM), a small relaxation to acetylcholine (10 microM) of noradrenaline-contracted segments was still seen; oxyhaemogobin inhibited this relaxation and decreased the NO concentration by 14 +/- 4 nM (n = 4). 5. The NO concentration-relaxation relationship for acetylcholine resembled that for SNAP and SIN-1 more than for authentic NO. Thus while 7-17 nM NO induced half-maximal relaxations in response to SNAP or SIN-1, 378 +/- 129 nM NO (n = 4) was needed for half-maximal relaxation to authentic NO. 6. The present study provides direct evidence that the relaxation of the rat superior mesenteric artery with the endothelium-dependent vasodilator acetylcholine is correlated to the endogeneous release of NO. The study also suggests that NO mediates the L-NOARG-resistant relaxations in this artery, and that there is a basal NO release.
Collapse
MESH Headings
- Acetylcholine/pharmacology
- Animals
- Endothelium, Vascular/enzymology
- Endothelium, Vascular/physiology
- Enzyme Inhibitors/pharmacology
- In Vitro Techniques
- Male
- Mesenteric Artery, Superior/chemistry
- Mesenteric Artery, Superior/metabolism
- Mesenteric Artery, Superior/physiology
- Microelectrodes
- Molsidomine/analogs & derivatives
- Molsidomine/pharmacology
- Muscle Relaxation/physiology
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide/analysis
- Nitric Oxide/metabolism
- Nitric Oxide Donors/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase Type III
- Nitroarginine/pharmacology
- Oxyhemoglobins/pharmacology
- Penicillamine/analogs & derivatives
- Penicillamine/pharmacology
- Rats
- Rats, Wistar
- S-Nitroso-N-Acetylpenicillamine
Collapse
Affiliation(s)
- U Simonsen
- Department of Pharmacology, University of Aarhus, 8000 Aarhus C, Denmark.
| | | | | | | |
Collapse
|