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Pouokam E. Effects of the gaseous signalling molecule nitroxyl (HNO) on myenteric neurons governing intestinal motility. J Basic Clin Physiol Pharmacol 2023; 34:683-687. [PMID: 36455291 DOI: 10.1515/jbcpp-2022-0233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/14/2022] [Indexed: 09/21/2023]
Abstract
OBJECTIVES The main function of myenteric neurons is the control of gut motility. As we recently showed that nitroxyl (HNO) induces intestinal smooth muscle relaxation, it was of interest to evaluate the effects of this signalling molecule on myenteric neurons in order to distinguish its properties in regard to myocytes. METHODS Myenteric neurons isolated from the ileum of 4-10 days old rats were used. HNO-induced changes in intracellular concentration of Ca2+ or membrane potential and ion currents were measured using the Ca2+-sensitive fluorescent dye fura-2 AM or by electrophysiological whole-cell recordings, respectively. Changes in intracellular thiol groups pool were evaluated using thiol tracker violet. Angeli's salt was used as HNO donor. RESULTS The HNO donor Angeli's salt induced a significant increase in the cytosolic Ca2+ concentration at the concentration 50 µM and a membrane hyperpolarization from a resting membrane potential of -56.1 ± 8.0 mV to -63.1 ± 8.7 mV (n=7). Although potassium channels primarily drive membrane potential changes in these cells, outwardly rectifying potassium currents were not significantly affected by 50 µM Angeli's salt. Fast inward sodium currents were slightly but not significantly reduced by HNO. In more sensitive cells, HNO tended to reduce the pool of thiol groups. CONCLUSIONS As in the case of smooth muscle cells, HNO causes hyperpolarization of myenteric neurons, an effect also associated with an increase in intracellular Ca2+ concentration. Pathways other than activation of potassium currents appear to drive the hyperpolarization evoked by HNO.
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Affiliation(s)
- Ervice Pouokam
- Department of Human medicine, MSB Medical School Berlin, Berlin, Germany
- Institute of Veterinary Physiology and Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
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2
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Hideko Tatakihara VL, Malvezi AD, Pereira RS, Lucchetti BFC, Dos Santos LF, Cecchini R, Yamauchi LM, Yamada-Ogatta SF, Miranda KM, Verri WA, Martins-Pinge MC, Pinge-Filho P. The Therapeutic Potential of Angeli's Salt in Mitigating Acute Trypanosoma cruzi Infection in Mice. Pathogens 2023; 12:1063. [PMID: 37624023 PMCID: PMC10458646 DOI: 10.3390/pathogens12081063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/14/2023] [Accepted: 08/17/2023] [Indexed: 08/26/2023] Open
Abstract
Chagas disease (CD), caused by Trypanosoma cruzi, is a neglected tropical disease prevalent in Latin America. Infected patients are treated to eliminate the parasite, reduce the cardiomyopathy risk, and interrupt the disease transmission cycle. The World Health Organization recognizes benznidazole (BZ) and nifurtimox as effective drugs for CD treatment. In the chronic phase, both drugs have low cure rates and serious side effects. T. cruzi infection causes intense tissue inflammation that controls parasite proliferation and CD evolution. Compounds that liberate nitric oxide (NO) (NO donors) have been used as anti-T. cruzi therapeutics. Currently, there is no evidence that nitroxyl (HNO) affects T. cruzi infection outcomes. This study investigated the effects of the HNO donor Angeli's salt (AS) on C57BL/6 mice infected with T. cruzi (Y strain, 5 × 103 trypomastigotes, intraperitoneally). AS reduced the number of parasites in the bloodstream and heart nests and increased the protective antioxidant capacity of erythrocytes in infected animals, reducing disease severity. Furthermore, in vitro experiments showed that AS treatment reduced parasite uptake and trypomastigote release by macrophages. Taken together, these findings from the murine model and in vitro testing suggest that AS could be a promising therapy for CD.
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Affiliation(s)
- Vera Lúcia Hideko Tatakihara
- Laboratório de Imunopatologia Experimental, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil (L.F.D.S.)
| | - Aparecida Donizette Malvezi
- Laboratório de Imunopatologia Experimental, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil (L.F.D.S.)
| | - Rito Santo Pereira
- Laboratório de Imunopatologia Experimental, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil (L.F.D.S.)
| | - Bruno Fernando Cruz Lucchetti
- Laboratório de Fisiologia e Fisiopatologia Cardiovascular, Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil
- Departamento de Fisioterapia, Centro Universitário do Vale do Araguaia, Barra do Garças 78603-209, Mato Grosso, Brazil
| | - Lucas Felipe Dos Santos
- Laboratório de Imunopatologia Experimental, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil (L.F.D.S.)
| | - Rubens Cecchini
- Laboratório de Fisiopatologia e Radicais Livres, Departamento de Imunologia, Parasitologia e Patologia Geral, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil
| | - Lucy Megumi Yamauchi
- Laboratório de Biologia Molecular de Microrganismos, Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil
| | - Sueli Fumie Yamada-Ogatta
- Laboratório de Biologia Molecular de Microrganismos, Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil
| | - Katrina M. Miranda
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Waldiceu A. Verri
- Laboratório de Pesquisa em Dor, Inflamação, Neuropatia e Câncer, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil
| | - Marli Cardoso Martins-Pinge
- Departamento de Fisioterapia, Centro Universitário do Vale do Araguaia, Barra do Garças 78603-209, Mato Grosso, Brazil
| | - Phileno Pinge-Filho
- Laboratório de Imunopatologia Experimental, Departamento de Imunologia, Parasitologia e Patologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina 86057-970, Paraná, Brazil (L.F.D.S.)
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Kamynina A, Guttzeit S, Eaton P, Cuello F. Nitroxyl Donor CXL-1020 Lowers Blood Pressure by Targeting C195 in Cyclic Guanosine-3',5'-Monophosphate-Dependent Protein Kinase I. Hypertension 2022; 79:946-956. [PMID: 35168371 DOI: 10.1161/hypertensionaha.122.18756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We previously demonstrated that nitroxyl causes vasodilation, at least in part, by inducing the formation of an intradisulfide bond between C117 and C195 in the high affinity cyclic guanosine monophosphate-binding site of PKGI (cyclic guanosine monophosphate-dependent protein kinase I). The aim of this study was to determine whether nitroxyl donors lower blood pressure via this novel PKGI activation mechanism in vivo. METHODS To determine this, a C195S PKGI knock-in mouse model was generated that ubiquitously and constitutively expresses a mutant kinase resistant to nitroxyl-induced intradisulfide activation. RESULTS Knock-in and wild-type littermates did not differ in appearance, body weight, in PKGI protein expression or blood gas content. Organ weight was similar between genotypes apart from the cecum that was significantly enlarged in knock-in animals. Mean arterial pressure and heart rate monitored in vivo over 24 hours by radio-telemetry revealed neither a significant difference between genotypes at baseline nor during angiotensin II-induced hypertension or sepsis. CXL-1020, a clinically relevant nitroxyl donor, did not lower blood pressure in normotensive animals. In contrast, administering CXL-1020 to hypertensive wild-type mice reduced their blood pressure by 10±4 mm Hg (P=0.0184), whereas the knock-in littermates were unaffected. CONCLUSIONS Oxidation of C195 in PKGI contributes to the antihypertensive effects observed in response to nitroxyl donors, emphasising the potential importance of nitroxyl donors in pathological scenarios when cyclic guanosine monophosphate levels are reduced and insufficient to activate PKGI.
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Affiliation(s)
- Alisa Kamynina
- William Harvey Research Institute, Queen Mary University of London, United Kingdom (A.K., S.G., P.E.)
| | - Sebastian Guttzeit
- William Harvey Research Institute, Queen Mary University of London, United Kingdom (A.K., S.G., P.E.)
| | - Philip Eaton
- William Harvey Research Institute, Queen Mary University of London, United Kingdom (A.K., S.G., P.E.)
| | - Friederike Cuello
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Germany (F.C.)
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Germany (F.C.)
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Velagic A, Li JC, Qin CX, Li M, Deo M, Marshall SA, Anderson D, Woodman OL, Horowitz JD, Kemp-Harper BK, Ritchie RH. Cardioprotective Actions of Nitroxyl Donor Angeli's Salt are Preserved in the Diabetic Heart and Vasculature in the Face of Nitric Oxide Resistance. Br J Pharmacol 2022; 179:4117-4135. [PMID: 35365882 PMCID: PMC9540873 DOI: 10.1111/bph.15849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 02/14/2022] [Accepted: 03/09/2022] [Indexed: 11/29/2022] Open
Abstract
Background and Purpose The risk of fatal cardiovascular events is increased in patients with type 2 diabetes mellitus (T2DM). A major contributor to poor prognosis is impaired nitric oxide (NO•) signalling at the level of tissue responsiveness, termed NO• resistance. This study aimed to determine if T2DM promotes NO• resistance in the heart and vasculature and whether tissue responsiveness to nitroxyl (HNO) is affected. Experimental Approach At 8 weeks of age, male Sprague–Dawley rats commenced a high‐fat diet. After 2 weeks, the rats received low‐dose streptozotocin (two intraperitoneal injections, 35 mg·kg−1, over two consecutive days) and continued on the same diet. Twelve weeks later, isolated hearts were Langendorff‐perfused to assess responses to the NO• donor diethylamine NONOate (DEA/NO) and the HNO donor Angeli's salt. Isolated mesenteric arteries were utilised to measure vascular responsiveness to the NO• donors sodium nitroprusside (SNP) and DEA/NO, and the HNO donor Angeli's salt. Key Results Inotropic, lusitropic and coronary vasodilator responses to DEA/NO were impaired in T2DM hearts, whereas responses to Angeli's salt were preserved or enhanced. Vasorelaxation to Angeli's salt was augmented in T2DM mesenteric arteries, which were hyporesponsive to the relaxant effects of SNP and DEA/NO. Conclusion and Implications This is the first evidence that inotropic and lusitropic responses are preserved, and NO• resistance in the coronary and mesenteric vasculature is circumvented, by the HNO donor Angeli's salt in T2DM. These findings highlight the cardiovascular therapeutic potential of HNO donors, especially in emergencies such as acute ischaemia or heart failure.
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Affiliation(s)
- Anida Velagic
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Jasmin Chendi Li
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Cheng Xue Qin
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Mandy Li
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Minh Deo
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Sarah A Marshall
- The Ritchie Centre, Department of Obstetrics and Gynaecology, School of Clinical Sciences, Monash University, VIC, Australia
| | - Dovile Anderson
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Owen L Woodman
- Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - John D Horowitz
- Basil Hetzel Institute, Queen Elizabeth Hospital, University of Adelaide, SA, Australia
| | - Barbara K Kemp-Harper
- Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Rebecca H Ritchie
- Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Biomedicine Discovery Institute, Department of Pharmacology, Monash University, Melbourne, VIC, Australia
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Kelly SS, Ni X, Yuen V, Radford MN, Xian M. C-Nitrosothioformamide: A Donor Template for Dual Release of HNO and H2S. Chembiochem 2022; 23:e202200101. [PMID: 35344248 DOI: 10.1002/cbic.202200101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 02/16/2022] [Revised: 03/25/2022] [Indexed: 11/09/2022]
Abstract
C-Nitrosothioformamide was demonstrated to be a donor template for dual release of HNO and COS triggered by a retro-Diels-Alder reaction. COS is an H2S precursor in the presence of carbonic anhydrase. This process produces HNO and H2S in a slow but steady manner. As such, the direct reaction between HNO and H2S under this situation appears to be minor. This may provide a useful tool to study the synergistic effects of HNO and H2S.
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Affiliation(s)
- Shane S Kelly
- Washington State University, Chemistry, UNITED STATES
| | - Xiang Ni
- Brown University, Chemistry, UNITED STATES
| | | | | | - Ming Xian
- Brown University, Department of Chemistry, 324 Brook Street, 02912, Providence, UNITED STATES
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6
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Stöckl SK, de Col R, Filipovic MR, Messlinger K. Nitroxyl Delivered by Angeli's Salt Causes Short-Lasting Activation Followed by Long-Lasting Deactivation of Meningeal Afferents in Models of Headache Generation. Int J Mol Sci 2022; 23:ijms23042330. [PMID: 35216445 PMCID: PMC8878050 DOI: 10.3390/ijms23042330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 11/16/2022] Open
Abstract
The role of TRPA1 receptor channels in meningeal nociception underlying the generation of headaches is still unclear. Activating as well as inhibitory effects of TRPA1 agonists have been reported in animal models of headache. The aim of the present study was to clarify the effect of the TRPA1 agonist nitroxyl (HNO) delivered by Angeli's salt in two rodent models of meningeal nociception. Single fibre recordings were performed using half-skull preparations of mice (C57BL/6) in vitro. Angeli's salt solution (AS, 300 µM) caused short-lasting vigorous increases in neuronal activity of primary meningeal afferents, followed by deactivation and desensitisation. These effects were similar in TRPA1 knockout and even more pronounced in TRPA1/TRPV1 double-knockout mice in comparison to wild-type mice. The activity of spinal trigeminal neurons with afferent input from the dura mater was recorded in vivo in anesthetised rats. AS (300 µM) or the TRPA1 agonist acrolein (100 and 300 µM) was applied to the exposed dura mater. AS caused no significant changes in spontaneous activity, while the mechanically evoked activity was reduced after acrolein application. These results do not confirm the assumption that activation of trigeminal TRPA1 receptor channels triggers the generation of headaches or contributes to its aggravation. Instead, there is evidence that TRPA1 activation may have an inhibitory function in the nociceptive trigeminal system.
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Affiliation(s)
- Stephanie K. Stöckl
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany; (S.K.S.); (R.d.C.)
| | - Roberto de Col
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany; (S.K.S.); (R.d.C.)
| | - Milos R. Filipovic
- Leibniz Institute for Analytical Sciences, ISAS e.V., 44227 Dortmund, Germany;
| | - Karl Messlinger
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany; (S.K.S.); (R.d.C.)
- Correspondence: ; Tel.: +49-160-5521215
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7
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Li JC, Velagic A, Qin CX, Li M, Leo CH, Kemp-Harper BK, Ritchie RH, Woodman OL. Diabetes Attenuates the Contribution of Endogenous Nitric Oxide but Not Nitroxyl to Endothelium Dependent Relaxation of Rat Carotid Arteries. Front Pharmacol 2021; 11:585740. [PMID: 33716721 PMCID: PMC7944142 DOI: 10.3389/fphar.2020.585740] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 12/16/2020] [Indexed: 12/27/2022] Open
Abstract
Endothelial dysfunction is a major risk factor for several of the vascular complications of diabetes, including ischemic stroke. Nitroxyl (HNO), the one electron reduced and protonated form of nitric oxide (NO•), is resistant to scavenging by superoxide, but the role of HNO in diabetes mellitus associated endothelial dysfunction in the carotid artery remains unknown. Aim: To assess how diabetes affects the role of endogenous NO• and HNO in endothelium-dependent relaxation in rat isolated carotid arteries. Methods: Male Sprague Dawley rats were fed a high-fat-diet (HFD) for 2 weeks prior to administration of low dose streptozotocin (STZ; 35 mg/kg i. p./day) for 2 days. The HFD was continued for a further 12 weeks. Sham rats were fed standard chow and administered with citrate vehicle. After 14 weeks total, rats were anesthetized and carotid arteries collected to assess responses to the endothelium-dependent vasodilator, acetylcholine (ACh) by myography. The combination of calcium-activated potassium channel blockers, TRAM-34 (1 μmol/L) and apamin (1 μmol/L) was used to assess the contribution of endothelium-dependent hyperpolarization to relaxation. The corresponding contribution of NOS-derived nitrogen oxide species to relaxation was assessed using the combination of the NO• synthase inhibitor, L-NAME (200 μmol/L) and the soluble guanylate cyclase inhibitor ODQ (10 μmol/L). Lastly, L-cysteine (3 mmol/L), a selective HNO scavenger, and hydroxocobalamin (HXC; 100 μmol/L), a NO• scavenger, were used to distinguish between NO• and HNO-mediated relaxation. Results: At study end, diabetic rats exhibited significantly retarded body weight gain and elevated blood glucose levels compared to sham rats. The sensitivity and the maximal relaxation response to ACh was significantly impaired in carotid arteries from diabetic rats, indicating endothelial dysfunction. The vasorelaxation evoked by ACh was abolished by L-NAME plus ODQ, but not affected by the apamin plus TRAM-34 combination, indicating that NOS-derived nitrogen oxide species are the predominant endothelium-derived vasodilators in sham and diabetic rat carotid arteries. The maximum relaxation to ACh was significantly decreased by L-cysteine in both sham and diabetic rats, whereas HXC attenuated ACh-induced relaxation only in sham rats, suggesting that diabetes impaired the contribution of NO•, whereas HNO-mediated vasorelaxation remained intact. Conclusion: Both NO• and HNO contribute to endothelium-dependent relaxation in carotid arteries. In diabetes, NO•-mediated relaxation is impaired, whereas HNO-mediated relaxation was preserved. The potential for preserved HNO activity under pathological conditions that are associated with oxidative stress indicates that HNO donors may represent a viable therapeutic approach to the treatment of vascular dysfunction.
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Affiliation(s)
- Jasmin Chendi Li
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
- Department of Pharmacology, University of Melbourne, Parkville, VIC, Australia
| | - Anida Velagic
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Cheng Xue Qin
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
- Department of Pharmacology, University of Melbourne, Parkville, VIC, Australia
| | - Mandy Li
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Department of Pharmacology, Cardiovascular Disease Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Chen Huei Leo
- Science, Maths and Technology Cluster, Singapore University of Technology & Design, Singapore, Singapore
| | - Barbara K. Kemp-Harper
- Department of Pharmacology, Cardiovascular Disease Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Rebecca H. Ritchie
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
- Department of Pharmacology, University of Melbourne, Parkville, VIC, Australia
- Department of Pharmacology, Cardiovascular Disease Program, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Owen L. Woodman
- Drug, Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Baker Heart & Diabetes Institute, Melbourne, VIC, Australia
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8
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Felker GM, McMurray JJV, Cleland JG, O'Connor CM, Teerlink JR, Voors AA, Belohlavek J, Böhm M, Borentain M, Bueno H, Cole RT, DeSouza MM, Ezekowitz JA, Filippatos G, Lang NN, Kessler PD, Martinez FA, Mebazaa A, Metra M, Mosterd A, Pang PS, Ponikowski P, Sato N, Seiffert D, Ye J. Effects of a Novel Nitroxyl Donor in Acute Heart Failure: The STAND-UP AHF Study. JACC Heart Fail 2020; 9:146-157. [PMID: 33248986 DOI: 10.1016/j.jchf.2020.10.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 10/04/2020] [Indexed: 01/24/2023]
Abstract
OBJECTIVES The primary objective was to identify well-tolerated doses of cimlanod in patients with acute heart failure (AHF). Secondary objectives were to identify signals of efficacy, including biomarkers, symptoms, and clinical events. BACKGROUND Nitroxyl (HNO) donors have vasodilator, inotropic and lusitropic effects. Bristol-Myers Squibb-986231 (cimlanod) is an HNO donor being developed for acute heart failure (AHF). METHODS This was a phase IIb, double-blind, randomized, placebo-controlled trial of 48-h treatment with cimlanod compared with placebo in patients with left ventricular ejection fraction ≤40% hospitalized for AHF. In part I, patients were randomized in a 1:1 ratio to escalating doses of cimlanod or matching placebo. In part II, patients were randomized in a 1:1:1 ratio to either of the 2 highest tolerated doses of cimlanod from part I or placebo. The primary endpoint was the rate of clinically relevant hypotension (systolic blood pressure <90 mm Hg or patients became symptomatic). RESULTS In part I (n = 100), clinically relevant hypotension was more common with cimlanod than placebo (20% vs. 8%; relative risk [RR]: 2.45; 95% confidence interval [CI]: 0.83 to 14.53). In part II (n = 222), the incidence of clinically relevant hypotension was 18% for placebo, 21% for cimlanod 6 μg/kg/min (RR: 1.15; 95% CI: 0.58 to 2.43), and 35% for cimlanod 12 μg/kg/min (RR: 1.9; 95% CI: 1.04 to 3.59). N-terminal pro-B-type natriuretic peptide and bilirubin decreased during infusion of cimlanod treatment compared with placebo, but these differences did not persist after treatment discontinuation. CONCLUSIONS Cimlanod at a dose of 6 μg/kg/min was reasonably well-tolerated compared with placebo. Cimlanod reduced markers of congestion, but this did not persist beyond the treatment period. (Evaluate the Safety and Efficacy of 48-Hour Infusions of HNO (Nitroxyl) Donor in Hospitalized Patients With Heart Failure [STANDUP AHF]; NCT03016325).
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Affiliation(s)
- G Michael Felker
- Duke University School of Medicine and the Duke Clinical Research Institute, Durham, North Carolina, USA.
| | - John J V McMurray
- British Heart Foundation Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - John G Cleland
- Robertson Centre for Biostatistics, Institute of Health and Wellbeing, University of Glasgow, Glasgow Royal Infirmary, Glasgow, United Kingdom and National Heart & Lung Institute Imperial College, London, United Kingdom
| | | | - John R Teerlink
- Section of Cardiology, San Francisco Veterans Affairs Medical Center and School of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Adriaan A Voors
- University of Groningen, Department of Cardiology, University Medical Center Groningen, Groningen, the Netherlands
| | - Jan Belohlavek
- 2nd Department of Internal Medicine, Cardiovascular Medicine, General University Hospital, Charles University in Prague, Czech Republic
| | - Michael Böhm
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Saarland University, Homburg/Saar, Germany
| | | | - Hector Bueno
- Cardiology Department, Hospital Universitario 12 de Octubre and Instituto de Investigación Sanitaria Hospital 12 de Octubre, Madrid, Spain
| | - Robert T Cole
- Inova Heart and Vascular Institute, Falls Church, Virginia, USA
| | | | - Justin A Ezekowitz
- Canadian VIGOUR Centre at the University of Alberta, Edmonton, Alberta, Canada
| | - Gerasimos Filippatos
- National and Kapodisrian University of Athens, School of Medicine, Athens, Greece
| | - Ninian N Lang
- British Heart Foundation Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Alex Mebazaa
- Department of Anaesthesiology and Critical Care Medicine, Saint Louis Lariboisière University Hospitals, Assistance Publique - Hôpitaux de Paris, Université de Paris, Inserm 942-MASCOT, FHU PROMICE, Paris, France
| | - Marco Metra
- Institute of Cardiology, ASST Spedali Civili di Brescia and Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, Brescia, Italy
| | - Arend Mosterd
- Department of Cardiology, Meander Medical Center, Amersfoort, the Netherlands and Dutch Network for Cardiovascular Research, Utrecht, the Netherlands
| | - Peter S Pang
- Indiana University School of Medicine, Indianapolis, Indiana, USA
| | | | - Naoki Sato
- Cardiology and Intensive Care Unit, Nippon Medical School, Musashi-Kosugi Hospital, Kawasaki, Japan
| | | | - June Ye
- Bristol-Myers-Squibb, Princeton, New Jersey, USA
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9
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Diering S, Stathopoulou K, Goetz M, Rathjens L, Harder S, Piasecki A, Raabe J, Schulz S, Brandt M, Pflaumenbaum J, Fuchs U, Donzelli S, Sadayappan S, Nikolaev VO, Flenner F, Ehler E, Cuello F. Receptor-independent modulation of cAMP-dependent protein kinase and protein phosphatase signaling in cardiac myocytes by oxidizing agents. J Biol Chem 2020; 295:15342-15365. [PMID: 32868295 PMCID: PMC7650233 DOI: 10.1074/jbc.ra120.014467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 08/28/2020] [Indexed: 02/04/2023] Open
Abstract
The contraction and relaxation of the heart is controlled by stimulation of the β1-adrenoreceptor (AR) signaling cascade, which leads to activation of cAMP-dependent protein kinase (PKA) and subsequent cardiac protein phosphorylation. Phosphorylation is counteracted by the main cardiac protein phosphatases, PP2A and PP1. Both kinase and phosphatases are sensitive to intramolecular disulfide formation in their catalytic subunits that inhibits their activity. Additionally, intermolecular disulfide formation between PKA type I regulatory subunits (PKA-RI) has been described to enhance PKA's affinity for protein kinase A anchoring proteins, which alters its subcellular distribution. Nitroxyl donors have been shown to affect contractility and relaxation, but the mechanistic basis for this effect is unclear. The present study investigates the impact of several nitroxyl donors and the thiol-oxidizing agent diamide on cardiac myocyte protein phosphorylation and oxidation. Although all tested compounds equally induced intermolecular disulfide formation in PKA-RI, only 1-nitrosocyclohexalycetate (NCA) and diamide induced reproducible protein phosphorylation. Phosphorylation occurred independently of β1-AR activation, but was abolished after pharmacological PKA inhibition and thus potentially attributable to increased PKA activity. NCA treatment of cardiac myocytes induced translocation of PKA and phosphatases to the myofilament compartment as shown by fractionation, immunofluorescence, and proximity ligation assays. Assessment of kinase and phosphatase activity within the myofilament fraction of cardiac myocytes after exposure to NCA revealed activation of PKA and inhibition of phosphatase activity thus explaining the increase in phosphorylation. The data suggest that the NCA-mediated effect on cardiac myocyte protein phosphorylation orchestrates alterations in the kinase/phosphatase balance.
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Affiliation(s)
- Simon Diering
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Konstantina Stathopoulou
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mara Goetz
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Laura Rathjens
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sönke Harder
- Institut für Klinische Chemie und Laboratoriumsmedizin, Massenspektrometrische Proteomanalytik, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Angelika Piasecki
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Janice Raabe
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Steven Schulz
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mona Brandt
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Julia Pflaumenbaum
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ulrike Fuchs
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sonia Donzelli
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sakthivel Sadayappan
- University of Cincinnati Heart, Lung and Vascular Institute, Cardiovascular Center, Cincinnati, Ohio USA
| | - Viacheslav O Nikolaev
- DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Institute of Experimental Cardiovascular Research, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Frederik Flenner
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics (School of Basic and Medical Biosciences) and School of Cardiovascular Medicine and Sciences, British Heart Foundation Research Excellence Center, King's College London, London, United Kingdom
| | - Friederike Cuello
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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10
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Ju Y, Wang A, Li X, Xu X, Lu J. A caged 2-hydroxyethyl luciferin for bioluminescence imaging of nitroxyl in living cells. LUMINESCENCE 2020; 35:1384-1390. [PMID: 32542844 DOI: 10.1002/bio.3902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 05/07/2020] [Revised: 06/05/2020] [Accepted: 06/11/2020] [Indexed: 11/07/2022]
Abstract
Nitroxyl (HNO), a one-electron reduction product of nitric oxide, demonstrates distinct biological and pharmacological activities. Here we designed a bioluminescent turn-on probe, HNO-8, that could be used to visualize HNO without the need for excitation light. HNO-8 was prepared by caging 2-hydroxyethyl luciferin with a triphenylphosphine unit, in which 2-hydroxyethyl luciferin as a novel substrate of firefly luciferase was characterized by stronger and more sustained bioluminescent signals than the most popular substrates of d-luciferin and 6'-aminoluciferin. In vitro experiments showed that HNO-8 could selectively respond to HNO generated from Angeli's salt(AS) in the range 1-50 μM, with a limit of detection of 0.196 μM. The probe was successfully applied for visualizing HNO in luciferase-transfected Huh7 cancer cells. We envision that HNO-8 could be used as a powerful bioluminescent sensor for researching HNO biological roles.
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Affiliation(s)
- Yong Ju
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
| | - Anni Wang
- School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai, China
| | - Xuewei Li
- School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai, China
| | - Xu Xu
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China
| | - Jianzhong Lu
- School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai, China
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11
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Velagic A, Qin C, Woodman OL, Horowitz JD, Ritchie RH, Kemp-Harper BK. Nitroxyl: A Novel Strategy to Circumvent Diabetes Associated Impairments in Nitric Oxide Signaling. Front Pharmacol 2020; 11:727. [PMID: 32508651 PMCID: PMC7248192 DOI: 10.3389/fphar.2020.00727] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 05/01/2020] [Indexed: 12/19/2022] Open
Abstract
Diabetes is associated with an increased mortality risk due to cardiovascular complications. Hyperglycemia-induced oxidative stress underlies these complications, leading to an impairment in endogenous nitric oxide (NO•) generation, together with reductions in NO• bioavailability and NO• responsiveness in the vasculature, platelets and myocardium. The latter impairment of responsiveness to NO•, termed NO• resistance, compromises the ability of traditional NO•-based therapeutics to improve hemodynamic status during diabetes-associated cardiovascular emergencies, such as acute myocardial infarction. Whilst a number of agents can ameliorate (e.g. angiotensin converting enzyme [ACE] inhibitors, perhexiline, statins and insulin) or circumvent (e.g. nitrite and sGC activators) NO• resistance, nitroxyl (HNO) donors offer a novel opportunity to circumvent NO• resistance in diabetes. With a suite of vasoprotective properties and an ability to enhance cardiac inotropic and lusitropic responses, coupled with preserved efficacy in the setting of oxidative stress, HNO donors have intact therapeutic potential in the face of diminished NO• signaling. This review explores the major mechanisms by which hyperglycemia-induced oxidative stress drives NO• resistance, and the therapeutic potential of HNO donors to circumvent this to treat cardiovascular complications in type 2 diabetes mellitus.
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Affiliation(s)
- Anida Velagic
- Heart Failure Pharmacology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Chengxue Qin
- Heart Failure Pharmacology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Owen L Woodman
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - John D Horowitz
- Basil Hetzel Institute, Queen Elizabeth Hospital, University of Adelaide, Adelaide, SA, Australia
| | - Rebecca H Ritchie
- Heart Failure Pharmacology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia.,Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Barbara K Kemp-Harper
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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12
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Abstract
Significance: As one-electron reduced molecule of nitric oxide (NO), nitroxyl (HNO) has gained enormous attention because of its novel physiological or pharmacological properties, ranging from cardiovascular protective actions to antitumoricidal effects. Recent Advances: HNO is emerging as a new entity with therapeutic advantages over its redox sibling, NO. The interests in the chemical, pharmacological, and biological characteristics of HNO have broadened our current understanding of its role in physiology and pathophysiology. Critical Issues: In particular, the experimental evidence suggests the therapeutic potential of HNO in tumor pharmacology, such as neuroblastoma, gastrointestinal tumor, ovarian, lung, and breast cancers. Indeed, HNO donors have been demonstrated to attenuate tumor proliferation and angiogenesis. Future Directions: In this review, the generation and detection of HNO are outlined, and the roles of HNO in cancer progression are further discussed. We anticipate that the completion of this review might give novel insights into the roles of HNO in cancer pharmacology and open up a novel field of cancer therapy based on HNO.
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Affiliation(s)
- Hai-Jian Sun
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Wei-Thye Lee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Bin Leng
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Zhi-Yuan Wu
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Yong Yang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing, China
| | - Jin-Song Bian
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,National University of Singapore (Suzhou) Research Institute, Suzhou, China
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13
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Qin CX, Anthonisz J, Leo CH, Kahlberg N, Velagic A, Li M, Jap E, Woodman OL, Parry LJ, Horowitz JD, Kemp-Harper BK, Ritchie RH. Nitric Oxide Resistance, Induced in the Myocardium by Diabetes, Is Circumvented by the Nitric Oxide Redox Sibling, Nitroxyl. Antioxid Redox Signal 2020; 32:60-77. [PMID: 31680536 DOI: 10.1089/ars.2018.7706] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Aim: Impairment of tissue responsiveness to exogenous and endogenous nitric oxide (NO•), known as NO• resistance, occurs in many cardiovascular disease states, prominently in diabetes and especially in the presence of marked hyperglycemia. In this study, we sought to determine in moderate and severe diabetes (i) whether NO• resistance also occurs in the myocardium, and (ii) whether the NO• redox sibling nitroxyl (HNO) circumvents this. Results: The spectrum of acute NO• effects (induced by diethylamine-NONOate), including vasodilation, and enhanced myocardial contraction and relaxation were impaired by moderately diabetic rats ([blood glucose] ∼20 mM). In contrast, acute HNO effects (induced by isopropylamine-NONOate) were preserved even in more severe diabetes ([blood glucose] >28 mM). Intriguingly, the positive inotropic effects of HNO were significantly enhanced in diabetic rat hearts. Further, progressive attenuation of soluble guanylyl cyclase (sGC) contribution to myocardial NO• responses occurred with increasing severity of diabetes. Nevertheless, activation of sGC by HNO remained intact in the myocardium. Innovation: Diabetes is associated with marked attenuation of vascular and myocardial effects of NO and NO donors, and this NO• resistance is circumvented by HNO, suggesting potential therapeutic utility for HNO donors in cardiovascular emergencies in diabetics. Conclusion: These results provide the first evidence that NO• resistance occurs in diabetic hearts, and that HNO largely circumvents this problem. Further, the positive inotropic and lusitropic effects of HNO are enhanced in a severely diabetic myocardium, a finding that warrants further mechanistic interrogation. The results support a potential role for therapeutic HNO administration in acute treatment of ischemia and/or heart failure in diabetics.
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Affiliation(s)
- Cheng Xue Qin
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia.,Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Australia.,Department of Medicine (Central Clinical School), Monash University, Melbourne, Australia
| | - Jarryd Anthonisz
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia.,Department of Medicine (Central Clinical School), Monash University, Melbourne, Australia
| | - Chen Huei Leo
- School of Biosciences, University of Melbourne, Parkville, Australia.,Science and Maths Cluster, Singapore University of Technology & Design, Singapore Singapore
| | - Nicola Kahlberg
- School of Biosciences, University of Melbourne, Parkville, Australia
| | - Anida Velagic
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia.,Department of Medicine (Central Clinical School), Monash University, Melbourne, Australia
| | - Mandy Li
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia
| | - Edwina Jap
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia
| | - Owen L Woodman
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia
| | - Laura J Parry
- School of Biosciences, University of Melbourne, Parkville, Australia
| | - John D Horowitz
- Cardiology Unit, The Queen Elizabeth Hospital, Basil Hetzel Institute, The University of Adelaide, Woodville SA, Australia
| | - Barbara K Kemp-Harper
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Rebecca H Ritchie
- Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, Australia.,Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Australia.,Department of Medicine (Central Clinical School), Monash University, Melbourne, Australia
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14
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Cowart D, Venuti RP, Lynch K, Guptill JT, Noveck RJ, Foo SY. A Phase 1 Randomized Study of Single Intravenous Infusions of the Novel Nitroxyl Donor BMS-986231 in Healthy Volunteers. J Clin Pharmacol 2019; 59:717-730. [PMID: 30703258 PMCID: PMC6519195 DOI: 10.1002/jcph.1364] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 11/21/2018] [Indexed: 12/25/2022]
Abstract
Nitroxyl (HNO) is a reactive nitrogen molecule that has potential therapeutic benefits for patients with acute heart failure. The results of the first‐in‐human study for BMS‐986231, a novel HNO donor, are reported. The aim of this sequential cohort study was to evaluate the safety, tolerability, and pharmacokinetic profile of BMS‐986231 after 24‐ and 48‐hour intravenous infusions in healthy volunteers. Eighty subjects were randomized and dosed. Seven cohorts (stratum A) received BMS‐986231 0.1, 0.33, 1, 3, 5, 10, and 15 μg/kg/min or placebo, infused over 24 hours. An additional cohort (stratum B) received 10 μg/kg/min or placebo, infused over 48 hours. Adverse events (AEs) were reported for 30 days after completion of infusion. Blood/urine samples were collected at regular intervals; other parameters (blood pressure, heart rate/rhythm, cardiac index) were also assessed. Headaches were the most commonly reported drug‐related AE (48%) in those who received BMS‐986231, although their severity was reduced by hydration. No other significant drug‐related AEs were noted. BMS‐986231 was associated with dose‐dependent and well‐tolerated reductions in systolic and diastolic blood pressure versus baseline; cardiac index, as measured noninvasively, was increased. BMS‐986231 had no clinically significant effect on heart rate/rhythm or laboratory parameters. Its mean elimination half‐life was 0.7‐2.5 hours. BMS‐986231 was safe and well‐tolerated for up to 24 hours (15 μg/kg/min) or 48 hours (10 μg/kg/min), with a favorable hemodynamic profile observed. Ongoing studies continue to evaluate the potential benefit of BMS‐986231 in patients with acute heart failure.
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Affiliation(s)
| | | | - Kim Lynch
- Duke Early Phase Clinical Research Unit, Durham, NC, USA
| | | | | | - Shi Yin Foo
- Cardioxyl Pharmaceuticals, Inc., Chapel Hill, NC, USA
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15
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An W, Ryan LS, Reeves AG, Bruemmer KJ, Mouhaffel L, Gerberich JL, Winters A, Mason RP, Lippert AR. A Chemiluminescent Probe for HNO Quantification and Real-Time Monitoring in Living Cells. Angew Chem Int Ed Engl 2018; 58:1361-1365. [PMID: 30476360 DOI: 10.1002/anie.201811257] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [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: 09/30/2018] [Revised: 11/07/2018] [Indexed: 01/28/2023]
Abstract
Azanone (HNO) is a reactive nitrogen species with pronounced biological activity and high therapeutic potential for cardiovascular dysfunction. A critical barrier to understanding the biology of HNO and furthering clinical development is the quantification and real-time monitoring of its delivery in living systems. Herein, we describe the design and synthesis of the first chemiluminescent probe for HNO, HNOCL-1, which can detect HNO generated from concentrations of Angeli's salt as low as 138 nm with high selectivity based on the reaction with a phosphine group to form a self-cleavable azaylide intermediate. We have capitalized on this high sensitivity to develop a generalizable kinetics-based approach, which provides real-time quantitative measurements of HNO concentration at the picomolar level. HNOCL-1 can monitor dynamics of HNO delivery in living cells and tissues, demonstrating the versatility of this method for tracking HNO in living systems.
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Affiliation(s)
- Weiwei An
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
| | - Lucas S Ryan
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
| | - Audrey G Reeves
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
| | - Kevin J Bruemmer
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
| | - Lyn Mouhaffel
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
| | - Jeni L Gerberich
- Prognostic Imaging Research Laboratory (PIRL), Pre-clinical Imaging Section, Department of Radiology, UT Southwestern Medical Center, Dallas, TX, 75390-9058, USA
| | - Alexander Winters
- Prognostic Imaging Research Laboratory (PIRL), Pre-clinical Imaging Section, Department of Radiology, UT Southwestern Medical Center, Dallas, TX, 75390-9058, USA
| | - Ralph P Mason
- Prognostic Imaging Research Laboratory (PIRL), Pre-clinical Imaging Section, Department of Radiology, UT Southwestern Medical Center, Dallas, TX, 75390-9058, USA
| | - Alexander R Lippert
- Department of Chemistry, Center for Drug Discovery, Design, and Delivery (CD4), and, Center for Global Health Impact (CGHI), Southern Methodist University, Dallas, TX, 75205-0314, USA
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16
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Palanisamy S, Wang YL, Chen YJ, Chen CY, Tsai FT, Liaw WF, Wang YM. In Vitro and in Vivo Imaging of Nitroxyl with Copper Fluorescent Probe in Living Cells and Zebrafish. Molecules 2018; 23:molecules23102551. [PMID: 30301224 PMCID: PMC6222915 DOI: 10.3390/molecules23102551] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/03/2018] [Accepted: 10/03/2018] [Indexed: 01/16/2023] Open
Abstract
Nitroxyl (HNO) plays a critical role in many physiological processes which includes vasorelaxation in heart failure, neuroregulation, and myocardial contractility. Powerful imaging tools are required to obtain information for understanding the mechanisms involved in these in vivo processes. In order to develop a rapid and high sensitive probe for HNO detection in living cells and the zebrafish model organism, 2-((2-(benzothiazole-2yl)benzylidene) amino)benzoic acid (AbTCA) as a ligand, and its corresponding copper(II) complex Cu(II)-AbTCA were synthesized. The reaction results of Cu(II)-AbTCA with Angeli's salt showed that Cu(II)-AbTCA could detect HNO quantitatively in a range of 40⁻360 µM with a detection limit of 9.05 µM. Furthermore, Cu(II)-AbTCA is more selective towards HNO over other biological species including thiols, reactive nitrogen, and reactive oxygen species. Importantly, Cu(II)-AbTCA was successfully applied to detect HNO in living cells and zebrafish. The collective data reveals that Cu(II)-AbTCA could be used as a potential probe for HNO detection in living systems.
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Affiliation(s)
- Sathyadevi Palanisamy
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, Center For Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, 75 Bo-Ai Street, Hsinchu 300, Taiwan.
| | - Yu-Liang Wang
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, Center For Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, 75 Bo-Ai Street, Hsinchu 300, Taiwan.
| | - Yu-Jen Chen
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, Center For Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, 75 Bo-Ai Street, Hsinchu 300, Taiwan.
| | - Chiao-Yun Chen
- Department of Radiology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Medical Imaging, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
| | - Fu-Te Tsai
- Department of Chemistry, National Tsing Hua University, Hsinchu 30043, Taiwan.
| | - Wen-Feng Liaw
- Department of Chemistry, National Tsing Hua University, Hsinchu 30043, Taiwan.
| | - Yun-Ming Wang
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, Center For Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, 75 Bo-Ai Street, Hsinchu 300, Taiwan.
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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17
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Hartman JC, del Rio CL, Reardon JE, Zhang K, Sabbah HN. Intravenous Infusion of the Novel HNO Donor BMS-986231 Is Associated With Beneficial Inotropic, Lusitropic, and Vasodilatory Properties in 2 Canine Models of Heart Failure. JACC Basic Transl Sci 2018; 3:625-638. [PMID: 30456334 PMCID: PMC6234500 DOI: 10.1016/j.jacbts.2018.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/22/2018] [Accepted: 07/05/2018] [Indexed: 12/16/2022]
Abstract
The effects of the nitroxyl donor BMS-986231 on hemodynamics, left ventricular (LV) function, and pro-arrhythmic potential were assessed using canine heart failure models. BMS-986231 significantly (p < 0.05) increased LV end-systolic elastance, pre-load-recruitable stroke work, ejection fraction, stroke volume, cardiac output, ratio of early-to-late filling time integrals, and early mitral valve inflow velocity deceleration time. BMS-986231 significantly decreased LV filling pressures, end-diastolic stiffness, the time-constant of relaxation, end-diastolic wall stress, systemic vascular resistance, and myocardial oxygen consumption. BMS-986231 had little effect on heart rate and did not induce de novo arrhythmias. Thus, BMS-986231 has beneficial inotropic, lusitropic, and vasodilatory effects.
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Key Words
- DT, deceleration time of early mitral inflow velocity
- EDPVR, end-diastolic pressure–volume relationship
- ESPVR, end-systolic pressure–volume relationship
- Ei/Ai, the ratio of early-to-late filling time integrals
- HEX, Hextend (plasma volume-expanding solution)
- LVEDWS, left ventricular end-diastolic circumferential wall stress
- LVEF, left ventricular ejection fraction
- LVFAS, left ventricular fractional area shortening
- MHC, myosin heavy chain
- MLC1, myosin light chain 1
- PRSW, pre-load-recruitable stroke work
- RyR2, ryanodine receptor 2
- SH, thiol group
- SV, stroke volume
- SVR, systemic vascular resistance
- Tau, left ventricular relaxation time-constant
- canine
- cardiomyopathies
- heart failure
- hemodynamics
- nitroxyl
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Affiliation(s)
| | | | | | - Kefei Zhang
- Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Hospital, Detroit, Michigan
| | - Hani N. Sabbah
- Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Hospital, Detroit, Michigan
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18
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Heurich T, Qu ZW, Kunzmann R, Schnakenburg G, Engeser M, Nožinović S, Streubel R. Styrene Polymerization under Ambient Conditions by using a Transient 1,3,2-Diazaphospholane-2-oxyl Complex. Chemistry 2018; 24:6473-6478. [PMID: 29470864 DOI: 10.1002/chem.201800413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 01/26/2018] [Indexed: 12/12/2022]
Abstract
A combined theoretical and experimental study on the formation and reactivity of a P-OTEMP (P-bound TEMPO (TEMPO=2,2,6,6-tetramethyl-piperidin-1-oxyl)) substituted 1,3,2-diazaphospholane W(CO)5 complex is presented, including DFT-based mechanistic details. The complex possesses a thermally labile O-N bond that cleaves homolytically yielding the transient 1,3,2-diazaphospholane-2-oxyl complex [(CO)5 W(R2 PO. )], which acts as a radical initiator for styrene polymerization under ambient conditions.
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Affiliation(s)
- Tobias Heurich
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Zheng-Wang Qu
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstraße 4, 53115, Bonn, Germany
| | - Robert Kunzmann
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Gregor Schnakenburg
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Marianne Engeser
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Senada Nožinović
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Rainer Streubel
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
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Roof SR, Ueyama Y, Mazhari R, Hamlin RL, Hartman JC, Ziolo MT, Reardon JE, Del Rio CL. CXL-1020, a Novel Nitroxyl (HNO) Prodrug, Is More Effective than Milrinone in Models of Diastolic Dysfunction-A Cardiovascular Therapeutic: An Efficacy and Safety Study in the Rat. Front Physiol 2017; 8:894. [PMID: 29209225 PMCID: PMC5701606 DOI: 10.3389/fphys.2017.00894] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/24/2017] [Indexed: 01/08/2023] Open
Abstract
The nitroxyl (HNO) prodrug, CXL-1020, induces vasorelaxation and improves cardiac function in canine models and patients with systolic heart failure (HF). HNO's unique mechanism of action may be applicable to a broader subset of cardiac patients. This study investigated the load-independent safety and efficacy of CXL-1020 in two rodent (rat) models of diastolic heart failure and explored potential drug interactions with common HF background therapies. In vivo left-ventricular hemodynamics/pressure-volume relationships assessed before/during a 30 min IV infusion of CXL-1020 demonstrated acute load-independent positive inotropic, lusitropic, and vasodilatory effects in normal rats. In rats with only diastolic dysfunction due to bilateral renal wrapping (RW) or pronounced diastolic and mild systolic dysfunction due to 4 weeks of chronic isoproterenol exposure (ISO), CXL-1020 attenuated the elevated LV filling pressures, improved the end diastolic pressure volume relationship, and accelerated relaxation. CXL-1020 facilitated Ca2+ re-uptake and enhanced myocyte relaxation in isolated cardiomyocytes from ISO rats. Compared to milrinone, CXL-1020 more effectively improved Ca2+ reuptake in ISO rats without concomitant chronotropy, and did not enhance Ca2+ entry via L-type Ca2+ channels nor increase myocardial arrhythmias/ectopic activity. Acute-therapy with CXL-1020 improved ventricular relaxation and Ca2+ cycling, in the setting of chronic induced diastolic dysfunction. CXL-1020's lusitropic effects were greater than those seen with the cAMP-dependent agent milrinone, and unlike milrinone it did not produce chronotropy or increased ectopy. HNO is a promising new potential therapy for both systolic and diastolic heart failure.
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Affiliation(s)
| | | | - Reza Mazhari
- Cardioxyl Pharmaceuticals, Chapel Hill, NC, United States
| | | | | | - Mark T Ziolo
- Ohio State University Columbus, Columbus, OH, United States
| | - John E Reardon
- Cardioxyl Pharmaceuticals, Chapel Hill, NC, United States
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Teicher C, De Col R, Messlinger K. Hydrogen Sulfide Mediating both Excitatory and Inhibitory Effects in a Rat Model of Meningeal Nociception and Headache Generation. Front Neurol 2017; 8:336. [PMID: 28769868 PMCID: PMC5509793 DOI: 10.3389/fneur.2017.00336] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 06/27/2017] [Indexed: 01/18/2023] Open
Abstract
Background/purpose Hydrogen sulfide (H2S) is a neuromodulator acting through nitroxyl (HNO) when it reacts with nitric oxide (NO). HNO activates transient receptor potential channels of the ankyrin type 1 (TRPA1) causing release of calcitonin gene-related peptide from primary afferents. Activation of meningeal nociceptors projecting to the human spinal trigeminal nucleus (STN) may lead to headaches. In a rat model of meningeal nociception, the activity of spinal trigeminal neurons was used as read-out for the interaction between H2S and NO. Methods In anesthetized rats extracellular recordings from single neurons in the STN were made. Sodium sulfide (Na2S) producing H2S in the tissue and the NO donor diethylamine-NONOate (DEA-NONOate) were infused intravenously. H2S was also locally applied onto the exposed cranial dura mater or the medulla. Endogenous production of H2S was inhibited by oxamic acid, and NO production was inhibited by nitro-l-arginine methyl ester hydrochloride (l-NAME) to manipulate endogenous HNO formation. Key results Systemic administration of Na2S was followed either by increased ongoing activity (in 73%) or decreased activity (in 27% of units). Topical application of Na2S onto the cranial dura mater caused a short-lasting activation followed by a long-lasting decrease in activity in the majority of units (70%). Systemic administration of DEA-NONOate increased neuronal activity, subsequent infusion of Na2S added to this effect, whereas DEA-NONOate did not augment the activity after Na2S. The stimulating effect of DEA-NONOate was inhibited by oxamic acid in 75% of units, and l-NAME following Na2S administration returned the activity to baseline. Conclusion Individual spinal trigeminal neurons may be activated or (less frequently) inhibited by the TRPA1 agonist HNO, presumably formed by H2S and NO in the STN, whereby endogenous H2S production seems to be rate-limiting. Activation of meningeal afferents by HNO may induce decreased spinal trigeminal activity, consistent with the elevation of the electrical threshold caused by TRPA1 activation in afferent fibers. Thus, the effects of H2S–NO–TRPA1 signaling depend on the site of action and the type of central neurons. The role of H2S–NO–TRPA1 in headache generation seems to be ambiguous.
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Affiliation(s)
- Christiane Teicher
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Roberto De Col
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Karl Messlinger
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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21
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Peng H, Shen J, Edmonds KA, Luebke JL, Hickey AK, Palmer LD, Chang FJ, Bruce KA, Kehl-Fie TE, Skaar EP, Giedroc DP. Sulfide Homeostasis and Nitroxyl Intersect via Formation of Reactive Sulfur Species in Staphylococcus aureus. mSphere 2017; 2:e00082-17. [PMID: 28656172 DOI: 10.1128/mSphere.00082-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 06/02/2017] [Indexed: 12/30/2022] Open
Abstract
Hydrogen sulfide (H2S) is a toxic molecule and a recently described gasotransmitter in vertebrates whose function in bacteria is not well understood. In this work, we describe the transcriptomic response of the major human pathogen Staphylococcus aureus to quantified changes in levels of cellular organic reactive sulfur species, which are effector molecules involved in H2S signaling. We show that nitroxyl (HNO), a recently described signaling intermediate proposed to originate from the interplay of H2S and nitric oxide, also induces changes in cellular sulfur speciation and transition metal homeostasis, thus linking sulfide homeostasis to an adaptive response to antimicrobial reactive nitrogen species. Staphylococcus aureus is a commensal human pathogen and a major cause of nosocomial infections. As gaseous signaling molecules, endogenous hydrogen sulfide (H2S) and nitric oxide (NO·) protect S. aureus from antibiotic stress synergistically, which we propose involves the intermediacy of nitroxyl (HNO). Here, we examine the effect of exogenous sulfide and HNO on the transcriptome and the formation of low-molecular-weight (LMW) thiol persulfides of bacillithiol, cysteine, and coenzyme A as representative of reactive sulfur species (RSS) in wild-type and ΔcstR strains of S. aureus. CstR is a per- and polysulfide sensor that controls the expression of a sulfide oxidation and detoxification system. As anticipated, exogenous sulfide induces the cst operon but also indirectly represses much of the CymR regulon which controls cysteine metabolism. A zinc limitation response is also observed, linking sulfide homeostasis to zinc bioavailability. Cellular RSS levels impact the expression of a number of virulence factors, including the exotoxins, particularly apparent in the ΔcstR strain. HNO, like sulfide, induces the cst operon as well as other genes regulated by exogenous sulfide, a finding that is traced to a direct reaction of CstR with HNO and to an endogenous perturbation in cellular RSS, possibly originating from disassembly of Fe-S clusters. More broadly, HNO induces a transcriptomic response to Fe overload, Cu toxicity, and reactive oxygen species and reactive nitrogen species and shares similarity with the sigB regulon. This work reveals an H2S/NO· interplay in S. aureus that impacts transition metal homeostasis and virulence gene expression. IMPORTANCE Hydrogen sulfide (H2S) is a toxic molecule and a recently described gasotransmitter in vertebrates whose function in bacteria is not well understood. In this work, we describe the transcriptomic response of the major human pathogen Staphylococcus aureus to quantified changes in levels of cellular organic reactive sulfur species, which are effector molecules involved in H2S signaling. We show that nitroxyl (HNO), a recently described signaling intermediate proposed to originate from the interplay of H2S and nitric oxide, also induces changes in cellular sulfur speciation and transition metal homeostasis, thus linking sulfide homeostasis to an adaptive response to antimicrobial reactive nitrogen species.
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22
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Heurich T, Qu ZW, Nožinović S, Schnakenburg G, Matsuoka H, Grimme S, Schiemann O, Streubel R. Synthesis and Rearrangement of P- Nitroxyl-Substituted P(III) and P(V) Phosphanes: A Combined Experimental and Theoretical Case Study. Chemistry 2016; 22:10102-10. [PMID: 27283725 DOI: 10.1002/chem.201504900] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [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: 12/04/2015] [Indexed: 11/08/2022]
Abstract
Low-temperature generation of P-nitroxyl phosphane 2 (Ph2 POTEMP), which was obtained by the reaction of Ph2 PH (1) with two equivalents of TEMPO, is presented. Upon warming, phosphane 2 decomposed to give P-nitroxyl phosphane P-oxide 3 (Ph2 P(O)OTEMP) as one of the final products. This facile synthetic protocol also enabled access to P-sulfide and P-borane derivatives 7 and 13, respectively, by using Ph2 P(S)H (6) or Ph2 P(BH3 )H (11) and TEMPO. Phosphane sulfide 7 revealed a rearrangement to phosphane oxide 8 (Ph2 P(O)STEMP) in CDCl3 at ambient temperature, whereas in THF, thermal decomposition of sulfide 7 yielded salt 10 ([TEMP-H2 ][Ph2 P(S)O]). As well as EPR and detailed NMR kinetic studies, indepth theoretical studies provided an insight into the reaction pathways and spin-density distributions of the reactive intermediates.
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Affiliation(s)
- Tobias Heurich
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Zheng-Wang Qu
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Senada Nožinović
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Gregor Schnakenburg
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Hideto Matsuoka
- Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstr. 12, 53115, Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstr. 4, 53115, Bonn, Germany.
| | - Olav Schiemann
- Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstr. 12, 53115, Bonn, Germany.
| | - Rainer Streubel
- Institut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.
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23
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Abstract
Phosphine-based detection strategies for both nitroxyl (HNO) and S-nitrosothiols (RSNO) were investigated and compared. Phosphorus NMR studies show that azaylides derived from HNO or organic RSNO efficiently participate in subsequent reductive ligation required for fluorescence generation in properly substituted substrates. S-Azaylides derived from biological RSNO containing free amine and carboxylic acid groups primarily yield phosphine oxides suggesting these groups facilitate nonligation pathways such as hydrolysis. The fluorescence response of a phosphine-based fluorophore toward the same RSNO confirms these differences and indicates that these probes selectively react with HNO. Flow cytometry experiments in HeLa cells reinforce the reactivity difference and offer a potential fast screening approach for endogenous HNO sources.
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Affiliation(s)
- Zhengrui Miao
- Department of Chemistry Wake Forest University Winston-Salem NC 27109 USA
| | - S Bruce King
- Department of Chemistry Wake Forest University Winston-Salem NC 27109 USA
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Tseng YT, Chen CH, Lin JY, Li BH, Lu YH, Lin CH, Chen HT, Weng TC, Sokaras D, Chen HY, Soo YL, Lu TT. To Transfer or Not to Transfer? Development of a Dinitrosyl Iron Complex as a Nitroxyl Donor for the Nitroxylation of an Fe(III) -Porphyrin Center. Chemistry 2015; 21:17570-3. [PMID: 26437878 DOI: 10.1002/chem.201503176] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [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: 08/11/2015] [Indexed: 12/16/2022]
Abstract
A positive myocardial inotropic effect achieved using HNO/NO(-) , compared with NO⋅, triggered attempts to explore novel nitroxyl donors for use in clinical applications in vascular and myocardial pharmacology. To develop M-NO complexes for nitroxyl chemistry and biology, modulation of direct nitroxyl-transfer reactivity of dinitrosyl iron complexes (DNICs) is investigated in this study using a Fe(III) -porphyrin complex and proteins as a specific probe. Stable dinuclear {Fe(NO)2 }(9) DNIC [Fe(μ-(Me) Pyr)(NO)2 ]2 was discovered as a potent nitroxyl donor for nitroxylation of Fe(III) -heme centers through an associative mechanism. Beyond the efficient nitroxyl transfer, transformation of DNICs into a chemical biology probe for nitroxyl and for pharmaceutical applications demands further efforts using in vitro/in vivo studies.
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Affiliation(s)
- Yu-Ting Tseng
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Chien-Hong Chen
- School of Medical Applied Chemistry, Chung Shan Medical University, No. 110, Section 1, Jianguo North Rd. Taichung, 40201 (Taiwan)
| | - Jing-Yu Lin
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Bing-Han Li
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Yu-Huan Lu
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Chia-Her Lin
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Hsin-Tsung Chen
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan)
| | - Tsu-Chien Weng
- SLAC National Accelerator Laboratory 2575 Sand Hill Rd. Menlo Park, CA 94025 (USA)
| | - Dimosthenes Sokaras
- SLAC National Accelerator Laboratory 2575 Sand Hill Rd. Menlo Park, CA 94025 (USA)
| | - Huang-Yeh Chen
- National Synchrotron Radiation Research Center No. 101, Xin'an Rd., Hsinchu, 30076 (Taiwan)
| | - Yun-Liang Soo
- National Synchrotron Radiation Research Center No. 101, Xin'an Rd., Hsinchu, 30076 (Taiwan).,Department of Physics, National Tsing Hua University No. 101, Section 2, Guangfu Rd., Hsinchu, 30013 (Taiwan)
| | - Tsai-Te Lu
- Department of Chemistry, Chung Yuan Christian University No. 200, Chung Pei Rd. Taoyuan, 32023 (Taiwan).
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25
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Cortese-Krott MM, Kuhnle GG, Dyson A, Fernandez BO, Grman M, DuMond JF, Barrow MP, McLeod G, Nakagawa H, Ondrias K, Nagy P, King SB, Saavedra JE, Keefer LK, Singer M, Kelm M, Butler AR, Feelisch M. Key bioactive reaction products of the NO/H2S interaction are S/N-hybrid species, polysulfides, and nitroxyl. Proc Natl Acad Sci U S A 2015; 112:E4651-60. [PMID: 26224837 DOI: 10.1073/pnas.1509277112] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Experimental evidence suggests that nitric oxide (NO) and hydrogen sulfide (H2S) signaling pathways are intimately intertwined, with mutual attenuation or potentiation of biological responses in the cardiovascular system and elsewhere. The chemical basis of this interaction is elusive. Moreover, polysulfides recently emerged as potential mediators of H2S/sulfide signaling, but their biosynthesis and relationship to NO remain enigmatic. We sought to characterize the nature, chemical biology, and bioactivity of key reaction products formed in the NO/sulfide system. At physiological pH, we find that NO and sulfide form a network of cascading chemical reactions that generate radical intermediates as well as anionic and uncharged solutes, with accumulation of three major products: nitrosopersulfide (SSNO(-)), polysulfides, and dinitrososulfite [N-nitrosohydroxylamine-N-sulfonate (SULFI/NO)], each with a distinct chemical biology and in vitro and in vivo bioactivity. SSNO(-) is resistant to thiols and cyanolysis, efficiently donates both sulfane sulfur and NO, and potently lowers blood pressure. Polysulfides are both intermediates and products of SSNO(-) synthesis/decomposition, and they also decrease blood pressure and enhance arterial compliance. SULFI/NO is a weak combined NO/nitroxyl donor that releases mainly N2O on decomposition; although it affects blood pressure only mildly, it markedly increases cardiac contractility, and formation of its precursor sulfite likely contributes to NO scavenging. Our results unveil an unexpectedly rich network of coupled chemical reactions between NO and H2S/sulfide, suggesting that the bioactivity of either transmitter is governed by concomitant formation of polysulfides and anionic S/N-hybrid species. This conceptual framework would seem to offer ample opportunities for the modulation of fundamental biological processes governed by redox switching and sulfur trafficking.
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Miao Z, Reisz JA, Mitroka SM, Pan J, Xian M, King SB. A selective phosphine-based fluorescent probe for nitroxyl in living cells. Bioorg Med Chem Lett 2015; 25:16-9. [PMID: 25465170 PMCID: PMC4355083 DOI: 10.1016/j.bmcl.2014.11.041] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 11/11/2014] [Accepted: 11/13/2014] [Indexed: 12/31/2022]
Abstract
A novel fluorescein-based fluorescent probe for nitroxyl (HNO) based on the reductive Staudinger ligation of HNO with an aromatic phosphine was prepared. This probe reacts with HNO derived from Angeli's salt and 4-bromo Piloty's acid under physiological conditions without interference by other biological redox species. Confocal microscopy demonstrates this probe detects HNO by fluorescence in HeLa cells and mass spectrometric analysis of cell lysates confirms this probe detects HNO following the proposed mechanism.
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Affiliation(s)
- Zhengrui Miao
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Julie A. Reisz
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Susan M. Mitroka
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Jia Pan
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Ming Xian
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - S. Bruce King
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
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27
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Chin KY, Qin C, Cao N, Kemp-Harper BK, Woodman OL, Ritchie RH. The concomitant coronary vasodilator and positive inotropic actions of the nitroxyl donor Angeli's salt in the intact rat heart: contribution of soluble guanylyl cyclase-dependent and -independent mechanisms. Br J Pharmacol 2014; 171:1722-34. [PMID: 24372173 DOI: 10.1111/bph.12568] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [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: 12/17/2012] [Revised: 12/11/2013] [Accepted: 12/20/2013] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE The NO redox sibling nitroxyl (HNO) elicits soluble guanylyl cyclase (sGC)-dependent vasodilatation. HNO has high reactivity with thiols, which is attributed with HNO-enhanced left ventricular (LV) function. Here, we tested the hypothesis that the concomitant vasodilatation and inotropic actions induced by a HNO donor, Angeli's salt (sodium trioxodinitrate), were sGC-dependent and sGC-independent respectively. EXPERIMENTAL APPROACH Haemodynamic responses to Angeli's salt (10 pmol-10 μmol), alone and in the presence of scavengers of HNO (L-cysteine, 4 mM) or of NO [hydroxocobalamin (HXC), 100 μM] or a selective inhibitor of sGC [1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10 μM], a CGRP receptor antagonist (CGRP8-37 , 0.1 μM) or a blocker of voltage-dependent potassium channels [4-aminopyridine (4-AP), 1 mM] were determined in isolated hearts from male rats. KEY RESULTS Angeli's salt elicited concomitant, dose-dependent increases in coronary flow and LV systolic and diastolic function. Both L-cysteine and ODQ shifted (but did not abolish) the dose-response curve of each of these effects to the right, implying contributions from HNO and sGC in both the vasodilator and inotropic actions. In contrast, neither HXC, CGRP8-37 nor 4-AP affected these actions. CONCLUSIONS AND IMPLICATIONS Both vasodilator and inotropic actions of the HNO donor Angeli's salt were mediated in part by sGC-dependent mechanisms, representing the first evidence that sGC contributes to the inotropic and lusitropic action of HNO in the intact heart. Thus, HNO acutely enhances LV contraction and relaxation, while concomitantly unloading the heart, potentially beneficial actions in failing hearts.
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Affiliation(s)
- Kai Yee Chin
- Heart Failure Pharmacology, Baker IDI Heart & Diabetes Institute, Melbourne, Vic., Australia; School of Medical Sciences, RMIT University, Bundoora, Vic., Australia
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Prozument K, Suleimanov YV, Buesser B, Oldham JM, Green WH, Suits AG, Field RW. A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling. J Phys Chem Lett 2014; 5:3641-3648. [PMID: 26278732 DOI: 10.1021/jz501758p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.
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Affiliation(s)
| | | | - Beat Buesser
- §IBM Research, Smarter Cities Technology Centre, Dublin 15, Ireland
| | - James M Oldham
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | | | - Arthur G Suits
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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29
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Holland RJ, Paulisch R, Cao Z, Keefer LK, Saavedra JE, Donzelli S. Enzymatic generation of the NO/HNO-releasing IPA/NO anion at controlled rates in physiological media using β-galactosidase. Nitric Oxide 2013; 35:131-6. [PMID: 24126017 DOI: 10.1016/j.niox.2013.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 09/19/2013] [Accepted: 10/04/2013] [Indexed: 11/21/2022]
Abstract
We introduce a strategy for generating mixtures of nitric oxide (NO) and nitroxyl (HNO) at tunable rates in physiological media. The approach involves converting a spontaneously HNO/NO-generating ion to a caged (prodrug) form that is essentially stable in neutral media, but that can be activated for HNO/NO release by adding an enzyme capable of efficiently opening the cage to regenerate the ion. By judiciously choosing the enzyme, substrate, and reaction conditions, unwanted scavenging of the HNO and NO by the protein can be minimised and the catalytic efficiency of the enzyme can be maintained. We illustrate this approach with a proof-of-concept study wherein the prodrug is Gal-IPA/NO, a diazeniumdiolate of structure iPrHN-N(O)NOR, with R=β-d-galactosyl. Escherichia coli-derived β-d-galactosidase at concentrations of 1.9-15nM hydrolysed 56μM substrate with half-lives of 140-19min, respectively, producing the IPA/NO anion (iPrHN-N(O)NO(-), half-life ∼3min), which in turn spontaneously hydrolysed to mixtures of HNO with NO. Using saturating substrate concentrations furnished IPA/NO generation rates that were directly proportional to enzyme concentration. Consistent with these data, the enzyme/substrate combination applied to ventricular myocytes isolated from wild-type mouse hearts resulted not only in a significant positive inotropic effect, but also rescued the cells from the negative inotropy, hypercontractions, and occasional cell death seen with the enzyme alone. This mechanism represents an alternate approach for achieving controlled fluxes of NO/HNO to investigate their biological actions.
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Sabbah HN, Tocchetti CG, Wang M, Daya S, Gupta RC, Tunin RS, Mazhari R, Takimoto E, Paolocci N, Cowart D, Colucci WS, Kass DA. Nitroxyl (HNO): A novel approach for the acute treatment of heart failure. Circ Heart Fail 2013; 6:1250-8. [PMID: 24107588 DOI: 10.1161/circheartfailure.113.000632] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND The nitroxyl (HNO) donor, Angeli's salt, exerts positive inotropic, lusitropic, and vasodilator effects in vivo that are cAMP independent. Its clinical usefulness is limited by chemical instability and cogeneration of nitrite which itself has vascular effects. Here, we report on effects of a novel, stable, pure HNO donor (CXL-1020) in isolated myoctyes and intact hearts in experimental models and in patients with heart failure (HF). METHODS AND RESULTS CXL-1020 converts solely to HNO and inactive CXL-1051 with a t1/2 of 2 minutes. In adult mouse ventricular myocytes, it dose dependently increased sarcomere shortening by 75% to 210% (50-500 μmol/L), with a ≈30% rise in the peak Ca(2+) transient only at higher doses. Neither inhibition of protein kinase A nor soluble guanylate cyclase altered this contractile response. Unlike isoproterenol, CXL-1020 was equally effective in myocytes from normal or failing hearts. In anesthetized dogs with coronary microembolization-induced HF, CXL-1020 reduced left ventricular end-diastolic pressure and myocardial oxygen consumption while increasing ejection fraction from 27% to 40% and maximal ventricular power index by 42% (both P<0.05). In conscious dogs with tachypacing-induced HF, CXL-1020 increased contractility assessed by end-systolic elastance and provided venoarterial dilation. Heart rate was minimally altered. In patients with systolic HF, CXL-1020 reduced both left and right heart filling pressures and systemic vascular resistance, while increasing cardiac and stroke volume index. Heart rate was unchanged, and arterial pressure declined modestly. CONCLUSIONS These data show the functional efficacy of a novel pure HNO donor to enhance myocardial function and present first-in-man evidence for its potential usefulness in HF. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01096043, NCT01092325.
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Affiliation(s)
- Hani N Sabbah
- Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Hospital, Detroit, MI
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31
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Johnson GM, Chozinski TJ, Salmon DJ, Moghaddam AD, Chen HC, Miranda KM. Quantitative detection of nitroxyl upon trapping with glutathione and labeling with a specific fluorogenic reagent. Free Radic Biol Med 2013; 63:476-84. [PMID: 23685286 DOI: 10.1016/j.freeradbiomed.2013.05.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 05/08/2013] [Indexed: 11/25/2022]
Abstract
Donors of nitroxyl (HNO) have shown promise for treatment of stroke, heart failure, alcoholism and cancer. However, comparing the pharmacological capacities of various donors is difficult without first quantifying the amount of HNO released from each donor. Detection and quantitation of HNO has been complicated by the rapid self-consumption of HNO through irreversible dimerization, poor selectivity of trapping agents against other nitrogen oxides, and/or low sensitivity towards HNO. Here, an assay is described for the trapping of HNO by glutathione (GSH) followed by labeling of GSH with the fluorogenic agent, naphthalene-2,3-dicarboxaldehyde (NDA), and subsequent quantitation by fluorescence difference. The newly developed assay was used to validate the pH-dependence of HNO release from isopropylamine NONOate (IPA/NO), which is a dual donor of HNO and NO at physiological pH. Furthermore, varied assay conditions were utilized to suggest the ratios of the products of the reaction of GSH with HNO. At intracellular concentrations of GSH, the disulfide (GSSG) was the major product, but significant concentrations of glutathione sulfinamide (GS(O)NH₂) were also detected. This suggests that GS(O)NH₂, which is a selective biomarker of HNO, may be produced in concentrations that are amenable to in vivo analysis.
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Affiliation(s)
- Gail M Johnson
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
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32
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Dautov RF, Ngo DTM, Licari G, Liu S, Sverdlov AL, Ritchie RH, Kemp-Harper BK, Horowitz JD, Chirkov YY. The nitric oxide redox sibling nitroxyl partially circumvents impairment of platelet nitric oxide responsiveness. Nitric Oxide 2013; 35:72-8. [PMID: 24012721 DOI: 10.1016/j.niox.2013.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 08/21/2013] [Accepted: 08/28/2013] [Indexed: 01/17/2023]
Abstract
Impaired platelet responsiveness to nitric oxide (NO resistance) is a common characteristic of many cardiovascular disease states and represents an independent risk factor for cardiac events and mortality. NO resistance reflects both scavenging of NO by superoxide (O2(-)), and impairment of the NO receptor, soluble guanylate cyclase (sGC). There is thus an urgent need for circumvention of NO resistance in order to improve clinical outcomes. Nitroxyl (HNO), like NO, produces vasodilator and anti-aggregatory effects, largely via sGC activation, but is not inactivated by O2(-). We tested the hypothesis that HNO circumvents NO resistance in human platelets. In 57 subjects with or without ischemic heart disease, platelet responses to the HNO donor isopropylamine NONOate (IPA/NO) and the NO donor sodium nitroprusside (SNP) were compared. While SNP (10μM) induced 29±3% (p<0.001) inhibition of platelet aggregation, IPA/NO (10μM) caused 75±4% inhibition (p<0.001). In NO-resistant subjects (n=28), the IPA/NO:SNP response ratio was markedly increased (p<0.01), consistent with partial circumvention of NO resistance. Similarly, cGMP accumulation in platelets was greater (p<0.001) with IPA/NO than with SNP stimulation. The NO scavenger carboxy-PTIO (CPTIO, 200μM) inhibited SNP and IPA/NO responses by 92±7% and 17±4% respectively (p<0.001 for differential inhibition), suggesting that effects of IPA/NO are only partially NO-mediated. ODQ (10μM) inhibited IPA/NO responses by 36±8% (p<0.001), consistent with a contribution of sGC/haem to IPA/NO inhibition of aggregation. There was no significant relationship between whole blood ROS content and IPA/NO responses. Thus the HNO donor IPA/NO substantially circumvents platelet NO resistance while acting, at least partially, as a haem-mediated sGC activator.
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Affiliation(s)
- R F Dautov
- Cardiology Unit, Basil Hetzel Institute, The Queen Elizabeth Hospital, University of Adelaide, Woodville, Australia.
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33
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Campos JC, Gomes KMS, Ferreira JCB. Impact of exercise training on redox signaling in cardiovascular diseases. Food Chem Toxicol 2013; 62:107-19. [PMID: 23978413 DOI: 10.1016/j.fct.2013.08.035] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/05/2013] [Accepted: 08/18/2013] [Indexed: 02/07/2023]
Abstract
Reactive oxygen and nitrogen species regulate a wide array of signaling pathways that governs cardiovascular physiology. However, oxidant stress resulting from disrupted redox signaling has an adverse impact on the pathogenesis and progression of cardiovascular diseases. In this review, we address how redox signaling and oxidant stress affect the pathophysiology of cardiovascular diseases such as ischemia-reperfusion injury, hypertension and heart failure. We also summarize the benefits of exercise training in tackling the hyperactivation of cellular oxidases and mitochondrial dysfunction seen in cardiovascular diseases.
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Affiliation(s)
- Juliane C Campos
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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34
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Abstract
An efficient catalytic method has been developed for aerobic oxidation of primary amines to the corresponding nitriles. The reactions proceed at room temperature and employ a catalyst consisting of (4,4'- t Bu2bpy)CuI/ABNO (ABNO = 9-azabicyclo[3.3.1]nonan-3-one N-oxyl). The reactions exhibit excellent functional group compatibility and substrate scope, and are effective with benzylic, allylic and aliphatic amines. Preliminary mechanistic studies suggest that aerobic oxidation of the Cu catalyst is the turnover-limiting step of the reaction.
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Affiliation(s)
- Jinho Kim
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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35
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Irvine JC, Cao N, Gossain S, Alexander AE, Love JE, Qin C, Horowitz JD, Kemp-Harper BK, Ritchie RH. HNO/cGMP-dependent antihypertrophic actions of isopropylamine-NONOate in neonatal rat cardiomyocytes: potential therapeutic advantages of HNO over NO. Am J Physiol Heart Circ Physiol 2013; 305:H365-77. [PMID: 23729209 DOI: 10.1152/ajpheart.00495.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitroxyl (HNO) is a redox congener of NO. We now directly compare the antihypertrophic efficacy of HNO and NO donors in neonatal rat cardiomyocytes and compare their contributing mechanisms of actions in this setting. Isopropylamine-NONOate (IPA-NO) elicited concentration-dependent inhibition of endothelin-1 (ET1)-induced increases in cardiomyocyte size, with similar suppression of hypertrophic genes. Antihypertrophic IPA-NO actions were significantly attenuated by l-cysteine (HNO scavenger), Rp-8-pCTP-cGMPS (cGMP-dependent protein kinase inhibitor), and 1-H-(1,2,4)-oxodiazolo-quinxaline-1-one [ODQ; to target soluble guanylyl cyclase (sGC)] but were unaffected by carboxy-PTIO (NO scavenger) or CGRP8-37 (calcitonin gene-related peptide antagonist). Furthermore, IPA-NO significantly increased cardiomyocyte cGMP 3.5-fold (an l-cysteine-sensitive effect) and stimulated sGC activity threefold, without detectable NO release. IPA-NO also suppressed ET1-induced cardiomyocyte superoxide generation. The pure NO donor diethylamine-NONOate (DEA-NO) reproduced these IPA-NO actions but was sensitive to carboxy-PTIO rather than l-cysteine. Although IPA-NO stimulation of purified sGC was preserved under pyrogallol oxidant stress (in direct contrast to DEA-NO), cardiomyocyte sGC activity after either donor was attenuated by this stress. Excitingly IPA-NO also exhibited acute antihypertrophic actions in response to pressure overload in the intact heart. Together these data strongly suggest that IPA-NO protection against cardiomyocyte hypertrophy is independent of both NO and CGRP but rather utilizes novel HNO activation of cGMP signaling. Thus HNO acutely limits hypertrophy independently of NO, even under conditions of elevated superoxide. Development of longer-acting HNO donors may thus represent an attractive new strategy for the treatment of cardiac hypertrophy, as stand-alone and/or add-on therapy to standard care.
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Affiliation(s)
- Jennifer C Irvine
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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36
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Landino LM, Hagedorn TD, Kim SB, Hogan KM. Inhibition of tubulin polymerization by hypochlorous acid and chloramines. Free Radic Biol Med 2011; 50:1000-8. [PMID: 21256958 PMCID: PMC3051002 DOI: 10.1016/j.freeradbiomed.2011.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [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: 12/10/2010] [Revised: 01/11/2011] [Accepted: 01/13/2011] [Indexed: 02/05/2023]
Abstract
Protein thiol oxidation and modification by nitric oxide and glutathione are emerging as common mechanisms to regulate protein function and to modify protein structure. Also, thiol oxidation is a probable outcome of cellular oxidative stress and is linked to degenerative disease progression. We assessed the effect of the oxidants hypochlorous acid and chloramines on the cytoskeletal protein tubulin. Total cysteine oxidation by the oxidants was monitored by labeling tubulin with the thiol-selective reagent 5-iodoacetamidofluorescein; by reaction with Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid); and by detecting interchain tubulin disulfides by Western blot under nonreducing conditions. Whereas HOCl induced both cysteine and methionine oxidation of tubulin, chloramines were predominantly cysteine oxidants. Cysteine oxidation of tubulin, rather than methionine oxidation, was associated with loss of microtubule polymerization activity, and treatment of oxidized tubulin with disulfide reducing agents restored a considerable portion of the polymerization activity that was lost after oxidation. By comparing the reactivity of hypochlorous acid and chloramines with the previously characterized oxidants, peroxynitrite and the nitroxyl donor Angeli's salt, we have identified tubulin thiol oxidation, not methionine oxidation or tyrosine nitration, as a common outcome responsible for decreased polymerization activity.
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Affiliation(s)
- Lisa M Landino
- Department of Chemistry, The College of William and Mary, Williamsburg, VA 23187–8795, USA.
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37
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Jackson MI, Han TH, Serbulea L, Dutton A, Ford E, Miranda KM, Houk K, Wink DA, Fukuto JM. Kinetic feasibility of nitroxyl reduction by physiological reductants and biological implications. Free Radic Biol Med 2009; 47:1130-9. [PMID: 19577638 PMCID: PMC7370859 DOI: 10.1016/j.freeradbiomed.2009.06.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [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: 05/14/2009] [Revised: 06/17/2009] [Accepted: 06/26/2009] [Indexed: 10/20/2022]
Abstract
Nitroxyl (HNO), the one-electron reduced and protonated congener of nitric oxide (NO), is a chemically unique species with potentially important biological activity. Although HNO-based pharmaceuticals are currently being considered for the treatment of chronic heart failure or stroke/transplant-derived ischemia, the chemical events leading to therapeutic responses are not established. The interaction of HNO with oxidants results in the well-documented conversion to NO, but HNO is expected to be readily reduced as well. Recent thermodynamic calculations predict that reduction of HNO is biologically accessible. Herein, kinetic analysis suggests that the reactions of HNO with several mechanistically distinct reductants are also biologically feasible. Product analysis verified that the reductants had in fact been oxidized and that in several instances HNO had been converted to hydroxylamine. Moreover, a theoretical analysis suggests that in the reaction of HNO with thiol reductants, the pathway producing sulfinamide is significantly more favorable than that leading to disulfide. Additionally, simultaneous production of HNO and NO yielded a biphasic oxidative capacity.
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Affiliation(s)
- Matthew I. Jackson
- Interdepartmental Program in Molecular Toxicology, School of Public Health, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Tae H. Han
- Department of Chemical Engineering, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Laura Serbulea
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Andrew Dutton
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Eleonora Ford
- Department of Molecular and Medical Pharmacology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | | | - K.N. Houk
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - David A. Wink
- Radiation Biology Branch, National Cancer Institute, Bethesda, MD 20892, USA
| | - Jon M. Fukuto
- Department of Chemistry, Sonoma State University, Rohnert Park, CA 94928, USA
- Corresponding author. Fax: +1 707 664 3378. (J.M. Fukuto)
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38
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Donzelli S, Espey MG, Flores-Santana W, Switzer CH, Yeh GC, Huang J, Stuehr DJ, King SB, Miranda KM, Wink DA. Generation of nitroxyl by heme protein-mediated peroxidation of hydroxylamine but not N-hydroxy-L-arginine. Free Radic Biol Med 2008; 45:578-84. [PMID: 18503778 PMCID: PMC2562766 DOI: 10.1016/j.freeradbiomed.2008.04.036] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [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: 11/21/2007] [Revised: 04/04/2008] [Accepted: 04/21/2008] [Indexed: 11/29/2022]
Abstract
The chemical reactivity, toxicology, and pharmacological responses to nitroxyl (HNO) are often distinctly different from those of nitric oxide (NO). The discovery that HNO donors may have pharmacological utility for treatment of cardiovascular disorders such as heart failure and ischemia reperfusion has led to increased speculation of potential endogenous pathways for HNO biosynthesis. Here, the ability of heme proteins to utilize H2O2 to oxidize hydroxylamine (NH2OH) or N-hydroxy-L-arginine (NOHA) to HNO was examined. Formation of HNO was evaluated with a recently developed selective assay in which the reaction products in the presence of reduced glutathione (GSH) were quantified by HPLC. Release of HNO from the heme pocket was indicated by formation of sulfinamide (GS(O)NH2), while the yields of nitrite and nitrate signified the degree of intramolecular recombination of HNO with the heme. Formation of GS(O)NH2 was observed upon oxidation of NH2OH, whereas NOHA, the primary intermediate in oxidation of L-arginine by NO synthase, was apparently resistant to oxidation by the heme proteins utilized. In the presence of NH2OH, the highest yields of GS(O)NH2 were observed with proteins in which the heme was coordinated to a histidine (horseradish peroxidase, lactoperoxidase, myeloperoxidase, myoglobin, and hemoglobin) in contrast to a tyrosine (catalase) or cysteine (cytochrome P450). That peroxidation of NH2OH by horseradish peroxidase produced free HNO, which was able to affect intracellular targets, was verified by conversion of 4,5-diaminofluorescein to the corresponding fluorophore within intact cells.
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Affiliation(s)
- Sonia Donzelli
- Tumor Biology Section, Radiation Biology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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39
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He X, Azarov I, Jeffers A, Presley T, Richardson J, King SB, Gladwin MT, Kim-Shapiro DB. The potential of Angeli's salt to decrease nitric oxide scavenging by plasma hemoglobin. Free Radic Biol Med 2008; 44:1420-32. [PMID: 18243145 PMCID: PMC2376831 DOI: 10.1016/j.freeradbiomed.2007.12.038] [Citation(s) in RCA: 13] [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: 08/15/2007] [Revised: 12/21/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
Release of hemoglobin from the erythrocyte during intravascular hemolysis contributes to the pathology of a variety of diseased states. This effect is partially due to the enhanced ability of cell-free plasma hemoglobin, which is primarily found in the ferrous, oxygenated state, to scavenge nitric oxide. Oxidation of the cell-free hemoglobin to methemoglobin, which does not effectively scavenge nitric oxide, using inhaled nitric oxide has been shown to be effective in limiting pulmonary and systemic vasoconstriction. However, the ferric heme species may be reduced back to ferrous hemoglobin in plasma and has the potential to drive injurious redox chemistry. We propose that compounds that selectively convert cell-free hemoglobin to ferric, and ideally iron-nitrosylated heme species that do not actively scavenge nitric oxide, would effectively treat intravascular hemolysis. We show here that nitroxyl generated by Angeli's salt (sodium alpha-oxyhyponitrite, Na2N2O3) preferentially reacts with cell-free hemoglobin compared to that encapsulated in the red blood cell under physiologically relevant conditions. Nitroxyl oxidizes oxygenated ferrous hemoglobin to methemoglobin and can convert the methemoglobin to a more stable, less toxic species, iron-nitrosyl hemoglobin. These results support the notion that Angeli's salt or a similar compound could be used to effectively treat conditions associated with intravascular hemolysis.
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Affiliation(s)
- Xiaojun He
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - Ivan Azarov
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - Anne Jeffers
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - Tennille Presley
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - Jodi Richardson
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - S. Bruce King
- Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109
| | - Mark T. Gladwin
- Vascular Medicine Branch, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892
- Critical Care Medicine Department, Clinical Center; NIH, Bethesda, MD 20892
| | - Daniel B. Kim-Shapiro
- Vascular Medicine Branch, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892
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Kots AY, Grafov MA, Khropov YV, Betin VL, Belushkina NN, Busygina OG, Yazykova MY, Ovchinnikov IV, Kulikov AS, Makhova NN, Medvedeva NA, Bulargina TV, Severina IS. Vasorelaxant and antiplatelet activity of 4,7-dimethyl-1,2, 5-oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide: role of soluble guanylate cyclase, nitric oxide and thiols. Br J Pharmacol 2000; 129:1163-77. [PMID: 10725265 PMCID: PMC1571938 DOI: 10.1038/sj.bjp.0703156] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
1. Certain heterocyclic N-oxides are vasodilators and inhibitors of platelet aggregation. The pharmacological activity of the furoxan derivative condensed with pyridazine di-N-oxide 4,7-dimethyl-1,2, 5-oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide (FPTO) and the corresponding furazan (FPDO) was studied. 2. FPTO reacted with thiols generating nitrite (NO), S-nitrosoglutathione and hydroxylamine (nitroxyl) and converted oxyHb to metHb. FPDO did not generate detectable amounts of NO-like species but reacted with thiols and oxyHb. 3. FPTO and FPDO haem-dependently stimulated the activity of soluble guanylate cyclase (sGC) and this stimulation was inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and by 0.1 mM dithiothreitol. 4. FPTO relaxed noradrenaline-precontracted aortic rings and its concentration-response curve was biphasic (pIC(50)=9. 03+/-0.13 and 5.85+/-0.06). FPDO was significantly less potent vasodilator (pIC(50)=5.19+/-0.14). The vasorelaxant activity of FPTO and FPDO was inhibited by ODQ. oxyHb significantly inhibited only FPTO-dependent relaxation. 5. FPTO and FPDO were equipotent inhibitors of ADP-induced platelet aggregation (IC(50)=0.63+/-0.15 and 0.49+/-0. 05 microM, respectively). The antiplatelet activity of FPTO (but not FPDO) was partially suppressed by oxyHb. The antiaggregatory effects of FPTO and FPDO were only partially blocked by sGC inhibitors. 6. FPTO and FPDO (10 - 20 microM) significantly increased cyclic GMP levels in aortic rings and platelets and this increase was blocked by ODQ. 7. Thus, FPTO can generate NO and, like FPDO, reacts with thiols and haem. The vasorelaxant activity of FPTO and FPDO is sGC-dependent and a predominant role is played by NO at FPTO concentrations below 1 microM. On the contrary, inhibition of platelet aggregation is only partially related to sGC activation.
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Affiliation(s)
- A Y Kots
- Laboratory of Enzyme Chemistry, School of Biology, Lomonosov Moscow State University, Moscow, 119899, Russia.
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Abstract
The nitric-oxide synthase (NOS; EC 1.14.13.39) reaction is formulated as a partially tetrahydrobiopterin (H4Bip)-dependent 5-electron oxidation of a terminal guanidino nitrogen of L-arginine (Arg) associated with stoichiometric consumption of dioxygen (O2) and 1.5 mol of NADPH to form L-citrulline (Cit) and nitric oxide (.NO). Analysis of NOS activity has relied largely on indirect methods such as quantification of nitrite/nitrate or the coproduct Cit; we therefore sought to directly quantify .NO formation from purified NOS. However, by two independent methods, NOS did not yield detectable .NO unless superoxide dismutase (SOD; EC 1.15.1.1) was present. In the presence of H4Bip, internal .NO standards were only partially recovered and the dismutation of superoxide (O2-.), which otherwise scavenges. .NO to yield ONOO-, was a plausible mechanism of action of SOD. Under these conditions, a reaction between NADPH and ONOO- resulted in considerable overestimation of enzymatic NADPH consumption. SOD lowered the NADPH:Cit stoichiometry to 0.8-1.1, suggesting either that additional reducing equivalents besides NADPH are required to explain Arg oxidation to .NO or that .NO was not primarily formed. The latter was supported by an additional set of experiments in the absence of H4Bip. Here, recovery of internal .NO standards was unaffected. Thus, a second activity of SOD, the conversion of nitroxyl (NO-) to .NO, was a more likely mechanism of action of SOD. Detection of NOS-derived nitrous oxide (N2O) and hydroxylamine (NH2OH), which cannot arise from .NO decomposition, was consistent with formation of an .NO precursor molecule such as NO-. When, in the presence of SOD, glutathione was added, S-nitrosoglutathione was detected. Our results indicate that .NO is not the primary reaction product of NOS-catalyzed Arg turnover and an alternative reaction mechanism and stoichiometry have to be taken into account.
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Affiliation(s)
- H H Schmidt
- Clinical Biochemistry and Pathobiochemistry, Julius-Maximilians-Universität, Würzburg, Germany.
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