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Janaszak-Jasiecka A, Siekierzycka A, Płoska A, Dobrucki IT, Kalinowski L. Endothelial Dysfunction Driven by Hypoxia-The Influence of Oxygen Deficiency on NO Bioavailability. Biomolecules 2021; 11:biom11070982. [PMID: 34356605 PMCID: PMC8301841 DOI: 10.3390/biom11070982] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/25/2021] [Accepted: 07/02/2021] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death worldwide. The initial stage of CVDs is characterized by endothelial dysfunction, defined as the limited bioavailability of nitric oxide (NO). Thus, any factors that interfere with the synthesis or metabolism of NO in endothelial cells are involved in CVD pathogenesis. It is well established that hypoxia is both the triggering factor as well as the accompanying factor in cardiovascular disease, and diminished tissue oxygen levels have been reported to influence endothelial NO bioavailability. In endothelial cells, NO is produced by endothelial nitric oxide synthase (eNOS) from L-Arg, with tetrahydrobiopterin (BH4) as an essential cofactor. Here, we discuss the mechanisms by which hypoxia affects NO bioavailability, including regulation of eNOS expression and activity. What is particularly important is the fact that hypoxia contributes to the depletion of cofactor BH4 and deficiency of substrate L-Arg, and thus elicits eNOS uncoupling-a state in which the enzyme produces superoxide instead of NO. eNOS uncoupling and the resulting oxidative stress is the major driver of endothelial dysfunction and atherogenesis. Moreover, hypoxia induces impairment in mitochondrial respiration and endothelial cell activation; thus, oxidative stress and inflammation, along with the hypoxic response, contribute to the development of endothelial dysfunction.
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Affiliation(s)
- Anna Janaszak-Jasiecka
- Department of Medical Laboratory Diagnostics—Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, 80-211 Gdansk, Poland; (A.J.-J.); (A.S.); (A.P.)
- Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.pl), 80-211 Gdansk, Poland
| | - Anna Siekierzycka
- Department of Medical Laboratory Diagnostics—Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, 80-211 Gdansk, Poland; (A.J.-J.); (A.S.); (A.P.)
- Laboratory of Trace Elements Neurobiology, Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Poland
| | - Agata Płoska
- Department of Medical Laboratory Diagnostics—Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, 80-211 Gdansk, Poland; (A.J.-J.); (A.S.); (A.P.)
- Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.pl), 80-211 Gdansk, Poland
| | - Iwona T. Dobrucki
- University of Illinois at Urbana-Champaign Beckman Institute for Advanced Science and Technology, 405 N Mathews Ave, MC-251, Urbana, IL 61801, USA;
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Leszek Kalinowski
- Department of Medical Laboratory Diagnostics—Fahrenheit Biobank BBMRI.pl, Medical University of Gdansk, 80-211 Gdansk, Poland; (A.J.-J.); (A.S.); (A.P.)
- Biobanking and Biomolecular Resources Research Infrastructure Poland (BBMRI.pl), 80-211 Gdansk, Poland
- BioTechMed Centre, Department of Mechanics of Materials and Structures, Gdansk University of Technology, 80-233 Gdansk, Poland
- Correspondence:
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Cumpstey AF, Hennis PJ, Gilbert-Kawai ET, Fernandez BO, Poudevigne M, Cobb A, Meale P, Mitchell K, Moyses H, Pöhnl H, Mythen MG, Grocott MPW, Feelisch M, Martin DS. Effects of dietary nitrate on respiratory physiology at high altitude - Results from the Xtreme Alps study. Nitric Oxide 2017; 71:57-68. [PMID: 29042272 PMCID: PMC5687938 DOI: 10.1016/j.niox.2017.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/10/2017] [Accepted: 10/13/2017] [Indexed: 11/30/2022]
Abstract
Nitric oxide (NO) production plays a central role in conferring tolerance to hypoxia. Tibetan highlanders, successful high-altitude dwellers for millennia, have higher circulating nitrate and exhaled NO (ENO) levels than native lowlanders. Since nitrate itself can reduce the oxygen cost of exercise in normoxia it may confer additional benefits at high altitude. Xtreme Alps was a double-blinded randomised placebo-controlled trial to investigate how dietary nitrate supplementation affects physiological responses to hypoxia in 28 healthy adult volunteers resident at 4559 m for 1 week; 14 receiving a beetroot-based high-nitrate supplement and 14 receiving a low-nitrate 'placebo' of matching appearance/taste. ENO, vital signs and acute mountain sickness (AMS) severity were recorded at sea level (SL) and daily at altitude. Moreover, standard spirometric values were recorded, and saliva and exhaled breath condensate (EBC) collected. There was no significant difference in resting cardiorespiratory variables, peripheral oxygen saturation or AMS score with nitrate supplementation at SL or altitude. Median ENO levels increased from 1.5/3.0 mPa at SL, to 3.5/7.4 mPa after 5 days at altitude (D5) in the low and high-nitrate groups, respectively (p = 0.02). EBC nitrite also rose significantly with dietary nitrate (p = 0.004), 1.7-5.1 μM at SL and 1.6-6.3 μM at D5, and this rise appeared to be associated with increased levels of ENO. However, no significant changes occurred to levels of EBC nitrate or nitrosation products (RXNO). Median salivary nitrite/nitrate concentrations increased from 56.5/786 μM to 333/5,194 μM with nitrate supplementation at SL, and changed to 85.6/641 μM and 341/4,553 μM on D5. Salivary RXNO rose markedly with treatment at SL from 0.55 μM to 5.70 μM. At D5 placebo salivary RXNO had increased to 1.90 μM whilst treatment RXNO decreased to 3.26 μM. There was no association with changes in any observation variables or AMS score. In conclusion, dietary nitrate supplementation is well tolerated at altitude and significantly increases pulmonary NO availability and both salivary and EBC NO metabolite concentrations. Surprisingly, this is not associated with changes in hemodynamics, oxygen saturation or AMS development.
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Affiliation(s)
- Andrew F Cumpstey
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Tremona Road, Southampton, SO16 6YD UK; Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK; Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, University of Southampton, Tremona Road, Southampton, SO16 6YD UK
| | - Philip J Hennis
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK
| | - Edward T Gilbert-Kawai
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK
| | - Bernadette O Fernandez
- Clinical & Experimental Sciences, Faculty of Medicine, NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK; Warwick Medical School, Division of Metabolic and Vascular Health, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Matthieu Poudevigne
- Clinical & Experimental Sciences, Faculty of Medicine, NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK
| | - Alexandra Cobb
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK
| | - Paula Meale
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK
| | - Kay Mitchell
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Tremona Road, Southampton, SO16 6YD UK; Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK; Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, University of Southampton, Tremona Road, Southampton, SO16 6YD UK
| | - Helen Moyses
- Clinical & Experimental Sciences, Faculty of Medicine, NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK
| | - Helmut Pöhnl
- AURAPA, Paul-Heidelbauer-Straße 26, 74321 Bietigheim-Bissingen, Germany
| | - Monty G Mythen
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK
| | - Michael P W Grocott
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Tremona Road, Southampton, SO16 6YD UK; Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK; Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, University of Southampton, Tremona Road, Southampton, SO16 6YD UK
| | - Martin Feelisch
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Tremona Road, Southampton, SO16 6YD UK; Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, University of Southampton, Tremona Road, Southampton, SO16 6YD UK; Clinical & Experimental Sciences, Faculty of Medicine, NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton, SO16 6YD UK; Warwick Medical School, Division of Metabolic and Vascular Health, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
| | - Daniel S Martin
- UCL Centre for Altitude, Space and Extreme Environment (CASE) Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport Exercise & Health, 170 Tottenham Court Road, London, W1T 7HA, UK.
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Chalupsky K, Kračun D, Kanchev I, Bertram K, Görlach A. Folic Acid Promotes Recycling of Tetrahydrobiopterin and Protects Against Hypoxia-Induced Pulmonary Hypertension by Recoupling Endothelial Nitric Oxide Synthase. Antioxid Redox Signal 2015; 23:1076-91. [PMID: 26414244 PMCID: PMC4657514 DOI: 10.1089/ars.2015.6329] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 09/21/2015] [Accepted: 09/21/2015] [Indexed: 01/29/2023]
Abstract
AIMS Nitric oxide (NO) derived from endothelial NO synthase (eNOS) has been implicated in the adaptive response to hypoxia. An imbalance between 5,6,7,8-tetrahydrobiopterin (BH4) and 7,8-dihydrobiopterin (BH2) can result in eNOS uncoupling and the generation of superoxide instead of NO. Dihydrofolate reductase (DHFR) can recycle BH2 to BH4, leading to eNOS recoupling. However, the role of DHFR and eNOS recoupling in the response to hypoxia is not well understood. We hypothesized that increasing the capacity to recycle BH4 from BH2 would improve NO bioavailability as well as pulmonary vascular remodeling (PVR) and right ventricular hypertrophy (RVH) as indicators of pulmonary hypertension (PH) under hypoxic conditions. RESULTS In human pulmonary artery endothelial cells and murine pulmonary arteries exposed to hypoxia, eNOS was uncoupled as indicated by reduced superoxide production in the presence of the nitric oxide synthase inhibitor, L-(G)-nitro-L-arginine methyl ester (L-NAME). Concomitantly, NO levels, BH4 availability, and expression of DHFR were diminished under hypoxia. Application of folic acid (FA) restored DHFR levels, NO bioavailability, and BH4 levels under hypoxia. Importantly, FA prevented the development of hypoxia-induced PVR, right ventricular pressure increase, and RVH. INNOVATION FA-induced upregulation of DHFR recouples eNOS under hypoxia by improving BH4 recycling, thus preventing hypoxia-induced PH. CONCLUSION FA might serve as a novel therapeutic option combating PH.
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Affiliation(s)
- Karel Chalupsky
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Damir Kračun
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Ivan Kanchev
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Katharina Bertram
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
| | - Agnes Görlach
- Experimental and Molecular Pediatric Cardiology, German Heart Center Munich at the Technical University Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich, Germany
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Strobl M, Schreiber C, Panzenböck A, Winter MP, Bergmeister H, Jakowitsch J, Mascherbauer J, Lang IM, Wexberg P, Bonderman D. Exhaled nitric oxide measurement to monitor pulmonary hypertension in a pneumonectomy-monocrotaline rat model. Am J Physiol Lung Cell Mol Physiol 2013; 305:L485-90. [PMID: 23893296 PMCID: PMC3798763 DOI: 10.1152/ajplung.00087.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 07/21/2013] [Indexed: 11/22/2022] Open
Abstract
The use of fractional exhaled nitric oxide (FeNO) has been suggested as a quantitative marker for pulmonary arterial hypertension (PAH) in humans. To further characterize FeNO in PAH we investigated this marker in a rodent model. Since there is no standardized technique for FeNO measurement in animals, we intended to reduce measuring errors and confounders of an existing published method by mathematical modification and tested its applicability in an NO-regulating therapy concept of PAH. Thirty-three male Sprague-Dawley rats underwent unilateral pneumonectomy and monocrotaline (MCT) injection and were observed for 49 days. A telemetric catheter was introduced into the left pulmonary artery to continuously record mean pulmonary arterial pressure (mPAP), and FeNO was assessed. After 35 days, animals were randomized to receive either oral l-arginine (300 mg/kg) in combination with tetrahydrobiopterin (20 mg/kg) therapy (n = 12) or vehicle (n = 11) daily over a period of 14 days. mPAP at baseline was 17.19 ± 9.62 mmHg, which increased to 53.1 ± 10.63 mmHg 28 days after monocrotaline exposure (P < 0.001). Using the modified technique, we found an inverse correlation between exhaled NO and pulmonary pressures before (r = -0.366, P = 0.043) and after MCT (r = -0.363, P = 0.038) as well as after therapy administration (r = -0.657, P = 0.02). Our modified technique proved robust in a rodent model, since valid and reproducible data were gained and showed an inverse correlation between exhaled NO and mPAP, whereas the existing method did not.
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Affiliation(s)
- Magdalena Strobl
- 2 med. Dept., Rudolfstiftung, Juchgasse 25, A-1030 Vienna, Austria.
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