1
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Baum O. Expression of neuronal NO synthase α- and β-isoforms in skeletal muscle of mice. Biochem J 2024; 481:601-613. [PMID: 38592741 DOI: 10.1042/bcj20230458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/27/2024] [Accepted: 04/09/2024] [Indexed: 04/10/2024]
Abstract
Knowledge of the primary structure of neuronal NO synthase (nNOS) in skeletal muscle is still conflicting and needs further clarification. To elucidate the expression patterns of nNOS isoforms at both mRNA and protein level, systematic reverse transcription (RT)-PCR and epitope mapping by qualitative immunoblot analysis on skeletal muscle of C57/BL6 mice were performed. The ability of the nNOS isoforms to form aggregates was characterized by native low-temperature polyacrylamide electrophoresis (LT-PAGE). The molecular analysis was focused on the rectus femoris (RF) muscle, a skeletal muscle with a nearly balanced ratio of nNOS α- and β-isoforms. RT-PCR amplificates from RF muscles showed exclusive exon-1d mRNA expression, either with or without exon-μ. Epitope mapping demonstrated the simultaneous expression of the nNOS splice variants α/μ, α/non-μ, β/μ and β/non-μ. Furthermore, immunoblotting suggests that the transition between nNOS α- and β-isoforms lies within exon-3. In LT-PAGE, three protein nNOS associated aggregates were detected in homogenates of RF muscle and tibialis anterior muscle: a 320 kDa band containing nNOS α-isoforms, while 250 and 300 kDa bands consist of nNOS β-isoforms that form homodimers or heterodimers with non-nNOS proteins.
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Affiliation(s)
- Oliver Baum
- Institute of Physiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
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2
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Baum O, Huber-Abel FAM, Flück M. nNOS Increases Fiber Type-Specific Angiogenesis in Skeletal Muscle of Mice in Response to Endurance Exercise. Int J Mol Sci 2023; 24:ijms24119341. [PMID: 37298293 DOI: 10.3390/ijms24119341] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
We studied the relationship between neuronal NO synthase (nNOS) expression and capillarity in the tibialis anterior (TA) muscle of mice subjected to treadmill training. The mRNA (+131%) and protein (+63%) levels of nNOS were higher (p ≤ 0.05) in the TA muscle of C57BL/6 mice undergoing treadmill training for 28 days than in those of littermates remaining sedentary, indicating an up-regulation of nNOS by endurance exercise. Both TA muscles of 16 C57BL/6 mice were subjected to gene electroporation with either the pIRES2-ZsGreen1 plasmid (control plasmid) or the pIRES2-ZsGreen1-nNOS gene-inserted plasmid (nNOS plasmid). Subsequently, one group of mice (n = 8) underwent treadmill training for seven days, while the second group of mice (n = 8) remained sedentary. At study end, 12-18% of TA muscle fibers expressed the fluorescent reporter gene ZsGreen1. Immunofluorescence for nNOS was 23% higher (p ≤ 0.05) in ZsGreen1-positive fibers than ZsGreen1-negative fibers from the nNOS-transfected TA muscle of mice subjected to treadmill training. Capillary contacts around myosin heavy-chain (MHC)-IIb immunoreactive fibers (14.2%; p ≤ 0.05) were only higher in ZsGreen1-positive fibers than ZsGreen1-negative fibers in the nNOS-plasmid-transfected TA muscles of trained mice. Our observations are in line with an angiogenic effect of quantitative increases in nNOS expression, specifically in type-IIb muscle fibers after treadmill training.
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Affiliation(s)
- Oliver Baum
- Institute of Physiology, Charité-Universitätsmedizin, 10117 Berlin, Germany
| | | | - Martin Flück
- Heart Repair and Regeneration Laboratory, Department EMC, Faculty of Science and Medicine, University of Fribourg, 1700 Fribourg, Switzerland
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3
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Lee SH, Won GW, Choi SH, Kim MY, Oh CH, Park JT, Park JI. Antiaging effect of inotodiol on oxidative stress in human dermal fibroblasts. Biomed Pharmacother 2022; 153:113311. [PMID: 35759867 DOI: 10.1016/j.biopha.2022.113311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/06/2022] [Accepted: 06/15/2022] [Indexed: 11/24/2022] Open
Abstract
Oxidative damage is one of the major causes of human skin aging. Inotodiol is a lanostane triterpenoid that demonstrates antiviral, anticancer, and anti-inflammatory activities. Previous studies have reported that inotodiol also has antiallergic effects. However, whether inotodiol inhibits oxidative stress-induced human skin aging is not known. Stimulation of human dermal fibroblast cells with hydrogen peroxide is related to skin aging. Inotodiol inhibited the expression of mitogen-activated protein kinase (MAPK) and NADPH Oxidase 5 (NOX5). Moreover, inotodiol effectively decreased nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), as well as nitric oxide (NO), reactive oxygen species (ROS), cyclooxygenase-2 (COX-2), and cytokines such as IL-1β, IL-6, and TNF-α. Based on our results, inotodiol protects human dermal fibroblast by preventing MAPK-NOX5 and NF-κB activation and attenuates the expression of aging genes. Inotodiol may therefore be considered a potential candidate for developing natural antiaging products, because it protects the human skin from oxidative stress-induced skin aging by inhibiting the MAPK-NOX5 and NF-κB signaling pathways.
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Affiliation(s)
- Seung Hoon Lee
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea; Translational Immunology Institute, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Gun-Woo Won
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea; Brain Korea 21 FOUR Project for Medical Science, Chungnam National University, Daejeon, Republic of Korea
| | - Seung-Hyeon Choi
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea; Translational Immunology Institute, Chungnam National University College of Medicine, Daejeon, Republic of Korea
| | - Mi-Yoon Kim
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Cheong-Hae Oh
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Jong-Tae Park
- Department of Food Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea; CARBOEXPERT Inc., Daejeon 34134, Republic of Korea.
| | - Jong-Il Park
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea; Translational Immunology Institute, Chungnam National University College of Medicine, Daejeon, Republic of Korea; Brain Korea 21 FOUR Project for Medical Science, Chungnam National University, Daejeon, Republic of Korea.
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4
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Smith JR, Hirai DM, Copp SW, Ferguson SK, Holdsworth CT, Hageman KS, Poole DC, Musch TI. Exercise training decreases intercostal and transversus abdominis muscle blood flows in heart failure rats during submaximal exercise. Respir Physiol Neurobiol 2021; 292:103710. [PMID: 34091075 DOI: 10.1016/j.resp.2021.103710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/18/2021] [Accepted: 06/02/2021] [Indexed: 11/30/2022]
Abstract
Diaphragm muscle blood flow (BF) and vascular conductance (VC) are elevated with chronic heart failure (HF) during exercise. Exercise training (ExT) elicits beneficial respiratory muscle and pulmonary system adaptations in HF. We hypothesized that diaphragm BF and VC would be lower in HF rats following ExT than their sedentary counterparts (Sed). Respiratory muscle BFs and mean arterial pressure were measured via radiolabeled microspheres and carotid artery catheter, respectively, during submaximal treadmill exercise (20 m/min, 5 % grade). During exercise, no differences were present between HF + ExT and HF + Sed in diaphragm BFs (201 ± 36 vs. 227 ± 44 mL/min/100 g) or VCs (both, p > 0.05). HF + ExT compared to HF + Sed had lower intercostal BF (27 ± 3 vs. 41 ± 5 mL/min/100 g) and VC (0.21 ± 0.02 vs. 0.31 ± 0.04 mL/min/mmHg/100 g) during exercise (both, p < 0.05). Further, HF + ExT compared to HF + Sed had lower transversus abdominis BF (20 ± 1 vs. 35 ± 6 mL/min/100 g) and VC (0.14 ± 0.02 vs. 0.27 ± 0.05 mL/min/mmHg/100 g) during exercise (both, p < 0.05). These data suggest that exercise training lowers the intercostal and transversus abdominis BF responses in HF rats during submaximal treadmill exercise.
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Affiliation(s)
- Joshua R Smith
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States.
| | - Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, United States
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - Scott K Ferguson
- Department of Kinesiology and Exercise Sciences, University of Hawaii, Hilo, HI, United States
| | - Clark T Holdsworth
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
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5
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Butenas ALE, Colburn TD, Baumfalk DR, Ade CJ, Hageman KS, Copp SW, Poole DC, Musch TI. Angiotensin converting enzyme inhibition improves cerebrovascular control during exercise in male rats with heart failure. Respir Physiol Neurobiol 2021; 286:103613. [PMID: 33421609 DOI: 10.1016/j.resp.2020.103613] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/21/2020] [Accepted: 12/27/2020] [Indexed: 01/08/2023]
Abstract
We investigated the effects of chronic (∼7 weeks) treatment with the angiotensin converting enzyme (ACE) inhibitor Captopril in rats with heart failure with reduced ejection fraction (HF-rEF) on brain blood flow (BF; radiolabeled microspheres) at rest and during submaximal exercise. We hypothesized that middle cerebral, posterior cerebral, and cerebellar BF during submaximal exercise (20 m/min, 5% incline) would be reduced in rats with HF-rEF (n = 10) compared to healthy (SHAM, n = 10) controls and HF-rEF rats chronically treated with Captopril (HF-rEF + Cap., n = 20). During submaximal exercise middle cerebral (HF-rEF + Cap.: 274 ± 12; HF-rEF: 234 ± 23; SHAM: 248 ± 24 ml/min/100 g) and cerebellar (HF-rEF + Cap.: 222 ± 14; HF-rEF: 243 ± 22; SHAM: 214 ± 23 ml/min/100 g) BF increased from rest in all groups with no difference among groups (P > 0.24). Posterior cerebral BF increased from rest in all groups but was lower than SHAM (394 ± 46 ml/min/100 g; P = 0.03) in HF-rEF (298 ± 19 ml/min/100 g) but not HF-rEF + Cap. (356 ± 18 ml/min/100 g; P = 0.14), supporting the concept that ACE inhibition in HF-rEF elevates brain BF increases, at least to the posterior cerebral region, during moderate intensity exercise/physical activity.
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Affiliation(s)
- Alec L E Butenas
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - Dryden R Baumfalk
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - K Sue Hageman
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, KS, United States; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, United States.
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6
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Kithas AC, Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Hydren JR, Nelson AD, Jessop JE, Bledsoe AD, Morgan DE, Richardson RS. Nitric oxide synthase inhibition with N(G)-monomethyl-l-arginine: Determining the window of effect in the human vasculature. Nitric Oxide 2020; 104-105:51-60. [PMID: 32979497 DOI: 10.1016/j.niox.2020.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/07/2020] [Accepted: 09/21/2020] [Indexed: 11/17/2022]
Abstract
Nitric oxide synthase (NOS) inhibition with N(G)-monomethyl-l-arginine (L-NMMA) is often used to assess the role of NO in human cardiovascular function. However, the window of effect for L-NMMA on human vascular function is unknown, which is critical for designing and interpreting human-based studies. This study utilized the passive leg movement (PLM) assessment of vascular function, which is predominantly NO-mediated, in 7 young male subjects under control conditions, immediately following intra-arterial L-NMMA infusion (0.24 mg⋅dl-1⋅min-1), and at 45-60 and 90-105 min post L-NMMA infusion. The leg blood flow (LBF) and leg vascular conductance (LVC) responses to PLM, measured with Doppler ultrasound and expressed as the change from baseline to peak (ΔLBFpeak and ΔLVCpeak) and area under the curve (LBFAUC and LVCACU), were assessed. PLM-induced robust control ΔLBFpeak (1135 ± 324 ml⋅min-1) and ΔLVCpeak (10.7 ± 3.6 ml⋅min-1⋅mmHg-1) responses that were significantly attenuated (704 ± 196 ml⋅min-1 and 6.7 ± 2 ml⋅min-1⋅mmHg-1) immediately following L-NMMA infusion. Likewise, control condition PLM ΔLBFAUC (455 ± 202 ml) and ΔLVCAUC (4.0 ± 1.4 ml⋅mmHg-1) were significantly attenuated (141 ± 130 ml and 1.3 ± 1.2 ml⋅mmHg-1) immediately following L-NMMA infusion. However, by 45-60 min post L-NMMA infusion all PLM variables were not significantly different from control, and this was still the case at 90-105 min post L-NMMA infusion. These findings reveal that the potent reduction in NO bioavailability afforded by NOS inhibition with L-NMMA has a window of effect of less than 45-60 min in the human vasculature. These data are particularly important for the commonly employed approach of pharmacologically inhibiting NOS with L-NMMA in the human vasculature.
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Affiliation(s)
- Andrew C Kithas
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Joel D Trinity
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Jayson R Gifford
- Department of Exercise Sciences, Brigham Young University, Provo, UT, USA
| | - Oh Sung Kwon
- Department of Kinesiology, University of Connecticut, Storrs, CT, USA
| | - Jay R Hydren
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - David E Morgan
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City, VAMC, UT, USA.
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7
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Pelegrino MT, Paganotti A, Seabra AB, Weller RB. Photochemistry of nitric oxide and S-nitrosothiols in human skin. Histochem Cell Biol 2020; 153:431-441. [PMID: 32162135 PMCID: PMC7300104 DOI: 10.1007/s00418-020-01858-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2020] [Indexed: 12/11/2022]
Abstract
Nitric oxide (NO) is related to a wide range of physiological processes such as vasodilation, macrophages cytotoxicity and wound healing. The human skin contains NO precursors (NOx). Those are mainly composed of nitrite (NO2-), nitrate (NO3-), and S-nitrosothiols (RSNOs) which forms a large NO store. These NOx stores in human skin can mobilize NO to blood stream upon ultraviolet (UV) light exposure. The main purpose of this study was to evaluate the most effective UV light wavelength to generate NO and compare it to each NO precursor in aqueous solution. In addition, the UV light might change the RSNO content on human skin. First, we irradiated pure aqueous solutions of NO2- and NO3- and mixtures of NO2- and glutathione and NO3- and S-nitrosoglutathione (GSNO) to identify the NO release profile from those species alone. In sequence, we evaluated the NO generation profile on human skin slices. Human skin was acquired from redundant plastic surgical samples and the NO and RSNO measurements were performed using a selective NO electrochemical sensor. The data showed that UV light could trigger the NO generation in skin with a peak at 280-285 nm (UVB range). We also observed a significant RSNO formation in irradiated human skin, with a peak at 320 nm (UV region) and at 700 nm (visible region). Pre-treatment of the human skin slice using NO2- and thiol (RSHs) scavengers confirmed the important role of these molecules in RSNO formation. These findings have important implications for clinical trials with potential for new therapies.
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Affiliation(s)
- Milena T Pelegrino
- Center for Natural and Human Sciences, Universidade Federal Do ABC, Av. dos Estados 5001, Santo André, SP, CEP 09210-580, Brazil
| | - André Paganotti
- Laboratory of Materials and Mechanical Manufacture, Universidade Federal de São Paulo, Diadema, SP, Brazil
| | - Amedea B Seabra
- Center for Natural and Human Sciences, Universidade Federal Do ABC, Av. dos Estados 5001, Santo André, SP, CEP 09210-580, Brazil
| | - Richard B Weller
- Centre for Inflammation Research, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.
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Poole DC, Copp SW, Colburn TD, Craig JC, Allen DL, Sturek M, O'Leary DS, Zucker IH, Musch TI. Guidelines for animal exercise and training protocols for cardiovascular studies. Am J Physiol Heart Circ Physiol 2020; 318:H1100-H1138. [PMID: 32196357 DOI: 10.1152/ajpheart.00697.2019] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Whole body exercise tolerance is the consummate example of integrative physiological function among the metabolic, neuromuscular, cardiovascular, and respiratory systems. Depending on the animal selected, the energetic demands and flux through the oxygen transport system can increase two orders of magnitude from rest to maximal exercise. Thus, animal models in health and disease present the scientist with flexible, powerful, and, in some instances, purpose-built tools to explore the mechanistic bases for physiological function and help unveil the causes for pathological or age-related exercise intolerance. Elegant experimental designs and analyses of kinetic parameters and steady-state responses permit acute and chronic exercise paradigms to identify therapeutic targets for drug development in disease and also present the opportunity to test the efficacy of pharmacological and behavioral countermeasures during aging, for example. However, for this promise to be fully realized, the correct or optimal animal model must be selected in conjunction with reproducible tests of physiological function (e.g., exercise capacity and maximal oxygen uptake) that can be compared equitably across laboratories, clinics, and other proving grounds. Rigorously controlled animal exercise and training studies constitute the foundation of translational research. This review presents the most commonly selected animal models with guidelines for their use and obtaining reproducible results and, crucially, translates state-of-the-art techniques and procedures developed on humans to those animal models.
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Affiliation(s)
- David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - David L Allen
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - Michael Sturek
- Department of Anatomy, Cell Biology and Physiology, Indiana University, Indianapolis, Indiana
| | - Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Irving H Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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9
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Williams IM, McClatchey PM, Bracy DP, Valenzuela FA, Wasserman DH. Acute Nitric Oxide Synthase Inhibition Accelerates Transendothelial Insulin Efflux In Vivo. Diabetes 2018; 67:1962-1975. [PMID: 30002132 PMCID: PMC6152344 DOI: 10.2337/db18-0288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/03/2018] [Indexed: 12/22/2022]
Abstract
Before insulin can stimulate glucose uptake in muscle, it must be delivered to skeletal muscle (SkM) through the microvasculature. Insulin delivery is determined by SkM perfusion and the rate of movement of insulin across the capillary endothelium. The endothelium therefore plays a central role in regulating insulin access to SkM. Nitric oxide (NO) is a key regulator of endothelial function and stimulates arterial vasodilation, which increases SkM perfusion and the capillary surface area available for insulin exchange. The effects of NO on transendothelial insulin efflux (TIE), however, are unknown. We hypothesized that acute reduction of endothelial NO would reduce TIE. However, intravital imaging of TIE in mice revealed that reduction of NO by l-NG-nitro-l-arginine methyl ester (l-NAME) enhanced the rate of TIE by ∼30% and increased total extravascular insulin delivery. This accelerated TIE was associated with more rapid insulin-stimulated glucose lowering. Sodium nitroprusside, an NO donor, had no effect on TIE in mice. The effects of l-NAME on TIE were not due to changes in blood pressure alone, as a direct-acting vasoconstrictor (phenylephrine) did not affect TIE. These results demonstrate that acute NO synthase inhibition increases the permeability of capillaries to insulin, leading to an increase in delivery of insulin to SkM.
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Affiliation(s)
- Ian M Williams
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - P Mason McClatchey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Deanna P Bracy
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
| | | | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
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10
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Dombernowsky NW, Ölmestig JNE, Witting N, Kruuse C. Role of neuronal nitric oxide synthase (nNOS) in Duchenne and Becker muscular dystrophies - Still a possible treatment modality? Neuromuscul Disord 2018; 28:914-926. [PMID: 30352768 DOI: 10.1016/j.nmd.2018.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/07/2018] [Accepted: 09/05/2018] [Indexed: 02/08/2023]
Abstract
Neuronal nitric oxide synthase (nNOS) is involved in nitric oxide (NO) production and suggested to play a crucial role in blood flow regulation of skeletal muscle. During activation of the muscle, NO helps attenuate the sympathetic vasoconstriction to accommodate increased metabolic demands, a phenomenon known as functional sympatholysis. In inherited myopathies such as the dystrophinopathies Duchenne and Becker muscle dystrophies (DMD and BMD), nNOS is lost from the sarcolemma. The loss of nNOS may cause functional ischemia contributing to skeletal and cardiac muscle cell injury. Effects of NO is augmented by inhibiting degradation of the second messenger cyclic guanosine monophosphate (cGMP) using sildenafil and tadalafil, both of which inhibit the enzyme phosphodiesterase 5 (PDE5). In animal models of DMD, PDE5-inhibitors prevent functional ischemia, reduce post-exercise skeletal muscle pathology and fatigue, show amelioration of cardiac muscle cell damage and increase cardiac performance. However, effect on clinical outcomes in DMD and BMD patients have been disappointing with minor effects on upper limb performance and none on ambulation. This review aims to summarize the current knowledge of nNOS function related to functional sympatholysis in skeletal muscle and studies on PDE5-inhibitor treatment in nNOS-deficient animal models and patients.
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Affiliation(s)
- Nanna W Dombernowsky
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Joakim N E Ölmestig
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark
| | - Nanna Witting
- Department of Neurology, Rigshospitalet Glostrup, University of Copenhagen, Denmark
| | - Christina Kruuse
- Department of Neurology, Neurovascular Research Unit, Herlev Gentofte Hospital, University of Copenhagen, Denmark; PDE Research Group, Lundbeck Foundation Center for Neurovascular Research (LUCENS), Denmark.
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11
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Relation of nNOS isoforms to mitochondrial density and PGC-1alpha expression in striated muscles of mice. Nitric Oxide 2018; 77:35-43. [PMID: 29678764 DOI: 10.1016/j.niox.2018.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 04/10/2018] [Accepted: 04/16/2018] [Indexed: 01/16/2023]
Abstract
The expression of neuronal NO synthase (nNOS) alpha- and beta-isoforms in skeletal muscle is well documented but only little information is available about their regulation/functions. Using different mouse models, we now assessed whether the expression of nNOS-isoforms in muscle fibers is related to mitochondria content/activity and regulated by peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha). Catalytic histochemistry revealed highest nNOS-concentrations to be present in type-2 oxidative muscle fibers. Differences in mitochondrial density between nNOS-KO-mice and WT-littermates established by morphometry after transmission electron microscopy were significant in the oxidative portion of the tibialis anterior muscle (TA) but not in rectus femoris muscle (RF) indicating an nNOS-dependent mitochondrial pool in TA. Quantitative immunoblotting displayed the nNOS alpha-isoform to preponderate in those striated muscles of C57BL/6-mice that comprise of many type-2 oxidative fibers, e.g. TA, while roughly even levels of the two nNOS-isoforms were expressed in those muscles that mainly consist of type-2 glycolytic fibers, e.g. RF. Differences in citrate synthase-activity in muscle homogenates between nNOS-KO-mice and WT-littermates were positively related to nNOS alpha-isoform levels. In transgenic-mice over-expressing muscular PGC-1alpha compared to WT-littermates, immunoblotting revealed a significant shift in nNOS-expression in favor of the alpha-isoform in six out of eight striated muscles (exceptions: soleus muscle and tongue) without consistent relationship to changes in the expression of mitochondrial markers. In summary, our study demonstrated the nNOS alpha-isoform expression to be related to mitochondrial content/activity and to be up-regulated by up-stream PGC-1alpha in striated muscles, particularly in those enriched with type-2 oxidative fibers implying a functional convergence of the two signaling systems in these fibers.
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