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Theodorou AA, Chatzinikolaou PN, Margaritelis NV, Christodoulou F, Tsatalas T, Paschalis V. Short-Term L-Citrulline Supplementation Does Not Affect Inspiratory Muscle Oxygenation and Respiratory Performance in Older Adults. Nutrients 2023; 15:nu15081951. [PMID: 37111169 PMCID: PMC10145540 DOI: 10.3390/nu15081951] [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: 03/23/2023] [Revised: 04/06/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
In sports nutrition, nitric oxide (NO•) precursors such as L-citrulline are widely used to enhance NO• bioavailability, which is considered an ergogenic aid. Our study aimed to examine the effect of short-term L-citrulline supplementation on respiratory muscles' performance, fatigue, and oxygenation in older adults. Fourteen healthy older males took 6 g of L-citrulline or a placebo for seven days in a double-blind crossover design. Pulmonary function via spirometry (i.e., forced expired volume in 1 s (FEV1), forced vital capacity (FVC), and their ratio)), fractional exhaled nitric oxide (NO•), maximal inspiratory pressure (MIP), rate of perceived exertion, and sternocleidomastoid muscle oxygenation (i.e., oxyhemoglobin (Δ[O2Hb]) and de-oxyhemoglobin (Δ[HHb]), total hemoglobin concentration (Δ[tHb]), and tissue saturation index (TSI%)) were evaluated at baseline, after seven days of L-citrulline supplementation, and after incremental resistive breathing to task failure of the respiratory muscles. The exhaled NO• value was only significantly increased after the supplementation (26% p < 0.001) in the L-citrulline condition. Pulmonary function, MIP, rate of perceived exertion, and sternocleidomastoid muscle oxygenation were not affected by the L-citrulline supplementation. In the present study, although short-term L-citrulline supplementation increased exhaled NO•, no ergogenic aids were found on the examined parameters at rest and after resistive breathing to task failure in older adults.
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Affiliation(s)
- Anastasios A Theodorou
- Department of Life Sciences, School of Sciences, European University Cyprus, 1516 Nicosia, Cyprus
| | - Panagiotis N Chatzinikolaou
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, 61122 Thessaloniki, Greece
| | - Nikos V Margaritelis
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, 61122 Thessaloniki, Greece
| | - Filippos Christodoulou
- Department of Life Sciences, School of Sciences, European University Cyprus, 1516 Nicosia, Cyprus
| | - Themistoklis Tsatalas
- Department of Life Sciences, School of Sciences, European University Cyprus, 1516 Nicosia, Cyprus
- Department of Physical Education & Sport Science, University of Thessaly, 42100 Trikala, Greece
| | - Vassilis Paschalis
- School of Physical Education and Sport Science, National and Kapodistrian University of Athens, 17237 Athens, Greece
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2
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Supruniuk E, Górski J, Chabowski A. Endogenous and Exogenous Antioxidants in Skeletal Muscle Fatigue Development during Exercise. Antioxidants (Basel) 2023; 12:antiox12020501. [PMID: 36830059 PMCID: PMC9952836 DOI: 10.3390/antiox12020501] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/09/2023] [Accepted: 02/15/2023] [Indexed: 02/18/2023] Open
Abstract
Muscle fatigue is defined as a decrease in maximal force or power generated in response to contractile activity, and it is a risk factor for the development of musculoskeletal injuries. One of the many stressors imposed on skeletal muscle through exercise is the increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which intensifies as a function of exercise intensity and duration. Exposure to ROS/RNS can affect Na+/K+-ATPase activity, intramyofibrillar calcium turnover and sensitivity, and actin-myosin kinetics to reduce muscle force production. On the other hand, low ROS/RNS concentrations can likely upregulate an array of cellular adaptative responses related to mitochondrial biogenesis, glucose transport and muscle hypertrophy. Consequently, growing evidence suggests that exogenous antioxidant supplementation might hamper exercise-engendering upregulation in the signaling pathways of mitogen-activated protein kinases (MAPKs), peroxisome-proliferator activated co-activator 1α (PGC-1α), or mammalian target of rapamycin (mTOR). Ultimately, both high (exercise-induced) and low (antioxidant intervention) ROS concentrations can trigger beneficial responses as long as they do not override the threshold range for redox balance. The mechanisms underlying the two faces of ROS/RNS in exercise, as well as the role of antioxidants in muscle fatigue, are presented in detail in this review.
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Affiliation(s)
- Elżbieta Supruniuk
- Department of Physiology, Medical University of Białystok, 15-222 Białystok, Poland
- Correspondence: ; Tel.: +48-(85)-748-55-85
| | - Jan Górski
- Department of Medical Sciences, Academy of Applied Sciences, 18-400 Łomża, Poland
| | - Adrian Chabowski
- Department of Physiology, Medical University of Białystok, 15-222 Białystok, Poland
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3
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Margaritelis NV, Paschalis V, Theodorou AA, Kyparos A, Nikolaidis MG. Redox basis of exercise physiology. Redox Biol 2020; 35:101499. [PMID: 32192916 PMCID: PMC7284946 DOI: 10.1016/j.redox.2020.101499] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/20/2020] [Accepted: 03/05/2020] [Indexed: 12/15/2022] Open
Abstract
Redox reactions control fundamental processes of human biology. Therefore, it is safe to assume that the responses and adaptations to exercise are, at least in part, mediated by redox reactions. In this review, we are trying to show that redox reactions are the basis of exercise physiology by outlining the redox signaling pathways that regulate four characteristic acute exercise-induced responses (muscle contractile function, glucose uptake, blood flow and bioenergetics) and four chronic exercise-induced adaptations (mitochondrial biogenesis, muscle hypertrophy, angiogenesis and redox homeostasis). Based on our analysis, we argue that redox regulation should be acknowledged as central to exercise physiology.
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Affiliation(s)
- N V Margaritelis
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece; Dialysis Unit, 424 General Military Hospital of Thessaloniki, Thessaloniki, Greece.
| | - V Paschalis
- School of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece
| | - A A Theodorou
- Department of Life Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
| | - A Kyparos
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - M G Nikolaidis
- Department of Physical Education and Sport Science at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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4
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Lamboley CR, Rouffet DM, Dutka TL, McKenna MJ, Lamb GD. Effects of high-intensity intermittent exercise on the contractile properties of human type I and type II skeletal muscle fibers. J Appl Physiol (1985) 2020; 128:1207-1216. [PMID: 32213115 DOI: 10.1152/japplphysiol.00014.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vitro studies have shown that alterations in redox state can cause a range of opposing effects on the properties of the contractile apparatus in skeletal muscle fibers. To test whether and how redox changes occurring in vivo affect the contractile properties, vastus lateralis muscle fibers from seven healthy young adults were examined at rest (PRE) and following (POST) high-intensity intermittent cycling exercise. Individual mechanically skinned muscle fibers were exposed to heavily buffered solutions at progressively higher free [Ca2+] to determine their force-Ca2+ relationship. Following acute exercise, Ca2+ sensitivity was significantly decreased in type I fibers (by 0.06 pCa unit) but not in type II fibers (0.01 pCa unit). Specific force decreased after the exercise in type II fibers (-18%) but was unchanged in type I fibers. Treatment with the reducing agent dithiothreitol (DTT) caused a small decrease in Ca2+-sensitivity in type II fibers at PRE (by ∼0.014 pCa units) and a significantly larger decrease at POST (∼0.035 pCa units), indicating that the exercise had increased S-glutathionylation of fast troponin I. DTT treatment also increased specific force (by ∼4%), but only at POST. In contrast, DTT treatment had no effect on either parameter in type I fibers at either PRE or POST. In type I fibers, the decreased Ca2+ sensitivity was not due to reversible oxidative changes and may have contributed to a decrease in power production during vigorous exercises. In type II fibers, exercise-induced redox changes help counter the decline in Ca2+-sensitivity while causing a small decline in maximum force.NEW & NOTEWORTHY This study identified important cellular changes occurring in human skeletal muscle fibers following high-intensity intermittent exercise: 1) a decrease in contractile apparatus Ca2+ sensitivity in type I but not type II fibers, 2) a decrease in specific force only in type II muscle fibers, and 3) a redox-dependent increase in Ca2+ sensitivity occurring only in type II fibers, which would help maintain muscle performance by countering the normal metabolite-induced decline in Ca2+ sensitivity.
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Affiliation(s)
- Cedric R Lamboley
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia.,School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - David M Rouffet
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia.,Department of Health and Sport Sciences, Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky
| | - Travis L Dutka
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - Graham D Lamb
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
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5
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Bailey SJ, Gandra PG, Jones AM, Hogan MC, Nogueira L. Incubation with sodium nitrite attenuates fatigue development in intact single mouse fibres at physiological P O 2 . J Physiol 2019; 597:5429-5443. [PMID: 31541562 DOI: 10.1113/jp278494] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/20/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Dietary nitrate supplementation increases plasma nitrite concentration, which provides an oxygen-independent source of nitric oxide and can delay skeletal muscle fatigue. Nitrate supplementation has been shown to increase myofibre calcium release and force production in mouse skeletal muscle during contractions at a supra-physiological oxygen tension, but it is unclear whether nitrite exposure can delay fatigue development and improve myofibre calcium handling at a near-physiological oxygen tension. Single mouse muscle fibres acutely treated with nitrite had a lower force and cytosolic calcium concentration during single non-fatiguing contractions at a near-physiological oxygen tension. Nitrite treatment delayed fatigue development during repeated fatiguing isometric contractions at near-physiological, but not at supra-physiological, oxygen tension in combination with better maintenance of myofilament calcium sensitivity and sarcoplasmic reticulum calcium pumping. These findings improve understanding of the mechanisms by which increased skeletal muscle nitrite exposure might be ergogenic and imply that this is related to improved calcium handling. ABSTRACT Dietary nitrate (NO3 - ) supplementation, which increases plasma nitrite (NO2 - ) concentration, has been reported to attenuate skeletal muscle fatigue development. Sarcoplasmic reticulum (SR) calcium (Ca2+ ) release is enhanced in isolated single skeletal muscle fibres following NO3 - supplementation or NO2 - incubation at a supra-physiological P O 2 but it is unclear whether NO2 - incubation can alter Ca2+ handling and fatigue development at a near-physiological P O 2 . We hypothesised that NO2 - treatment would improve Ca2+ handling and delay fatigue at a physiological P O 2 in intact single mouse skeletal muscle fibres. Each muscle fibre was perfused with Tyrode solution pre-equilibrated with either 20% ( P O 2 ∼150 Torr) or 2% O2 ( P O 2 = 15.6 Torr) in the absence and presence of 100 µM NaNO2 . At supra-physiological P O 2 (i.e. 20% O2 ), time to fatigue was lowered by 34% with NaNO2 (control: 257 ± 94 vs. NaNO2 : 159 ± 46 s, Cohen's d = 1.63, P < 0.05), but extended by 21% with NaNO2 at 2% O2 (control: 308 ± 217 vs. NaNO2 : 368 ± 242 s, d = 1.14, P < 0.01). During the fatiguing contraction protocol completed with NaNO2 at 2% O2 , peak cytosolic Ca2+ concentration ([Ca2+ ]c ) was not different (P > 0.05) but [Ca2+ ]c accumulation between contractions was lower, concomitant with a greater SR Ca2+ pumping rate (P < 0.05) compared to the control condition. These results demonstrate that increased exposure to NO2 - blunts fatigue development at near-physiological, but not at supra-physiological, P O 2 through enhancing SR Ca2+ pumping rate in single skeletal muscle fibres. These findings extend our understanding of the mechanisms by which increased NO2 - exposure can mitigate skeletal muscle fatigue development.
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Affiliation(s)
- Stephen J Bailey
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.,School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Paulo G Gandra
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA.,Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (Unicamp), Campinas, Brazil
| | - Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Michael C Hogan
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA
| | - Leonardo Nogueira
- Section of Physiology; Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, University of California, San Diego, CA, USA.,Instituto de Bioquímica Médica Leopoldo de Meis (Medical Biochemistry Institute Leopoldo de Meis), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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6
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Bagni MA, Colombini B, Nocella M, Pregno C, S Cornachione A, Rassier DE. The effects of fatigue and oxidation on contractile function of intact muscle fibers and myofibrils isolated from the mouse diaphragm. Sci Rep 2019; 9:4422. [PMID: 30872655 PMCID: PMC6418105 DOI: 10.1038/s41598-019-39353-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 01/18/2019] [Indexed: 11/09/2022] Open
Abstract
The goal of this study was to investigate the effects of repetitive stimulation and the oxidant H2O2 on fatigue of diaphragm intact fibers and in myofibrils measured with different Ca2+ concentrations. Intact fibers were isolated from mice diaphragm, and twitch and tetanic contractions (500 ms duration) were performed at different frequencies of stimulation ranging from 15 Hz to 150 Hz to establish a force-frequency relation before and after a fatigue and recovery protocol, without or after a treatment with H2O2. Fatigue was induced with isometric contractions (500 ms, 40 Hz) evoked every 0.8 seconds, with a total of 625 tetani. After the fatigue, the force recovery was followed by invoking tetanic contractions (500 ms, 40 Hz) every 1 min, with a total duration of 30 min. Individual myofibrils were also isolated from the mouse diaphragm and were tested for isometric contractions before and after treatment with H2O2 and NAC. In a second series of experiments, myofibrils were activated at different pCa (pCa = -log10 [Ca2+]), before and after H2O2 treatment. After 15 minutes of H2O2 treatment, the myofibrillar force was decreased to 54 ± 12% of its control, maximal value, and a result that was reversed by NAC treatment. The force was also decreased after myofibrils were treated with H2O2 and activated in pCa ranging between 4.5 and 5.7. These results suggest that fatigue in diaphragm intact fibers and at the myofibrils level is caused partially by oxidation of the contractile proteins that may be responsible for changing the force in various levels of Ca2+ activation.
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Affiliation(s)
- M Angela Bagni
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Barbara Colombini
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Marta Nocella
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Claudio Pregno
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Anabelle S Cornachione
- Dept Kinesiology and Physical Education, Faculty of Education, McGill University, Montreal, Canada
| | - Dilson E Rassier
- Dept Kinesiology and Physical Education, Faculty of Education, McGill University, Montreal, Canada.
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7
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Kanzaki K, Watanabe D, Aibara C, Kawakami Y, Yamada T, Takahashi Y, Wada M. l-arginine ingestion inhibits eccentric contraction-induced proteolysis and force deficit via S-nitrosylation of calpain. Physiol Rep 2019; 6. [PMID: 29368397 PMCID: PMC5789731 DOI: 10.14814/phy2.13582] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/14/2017] [Accepted: 12/20/2017] [Indexed: 11/24/2022] Open
Abstract
It has been shown that calpains are involved in the proteolysis of muscle proteins that occurs with eccentric contraction (ECC) and that exogenously applied nitric oxide decreases the calpain‐mediated proteolysis. The aim of this study was to examine the effects of ingestion of l‐arginine (ARG), a nitric oxide precursor, on ECC‐related calpain activation. In the first and second experiments, male Wistar rats were given ARG in water for 7 days starting from 3 days before the ECC protocol (average ingestion, ~600 mg kg‐body wt−1 day−1). Tibialis anterior muscles underwent 200 repeated ECCs and, subsequently, were excised 3 days later. Whole muscle analyses (the first experiment) revealed that ARG attenuated ECC‐induced force deficit and autolysis of calpain‐1, and increased the amounts of S‐nitrosylated calpain‐1. Regarding ryanodine receptor (RyR) and dihydropyridine receptor (DHPR), ECC‐induced proteolysis was completely inhibited by ARG, whereas the inhibition was partial for junctophilin‐1 (JP1). Skinned fiber analyses (the second experiment) showed that ARG also inhibited ECC‐elicited reductions in the ratio of depolarization‐induced to maximum Ca2+‐activated force. In the third experiment, homogenates of rested muscles were treated with S‐nitrosylating agent, S‐nitrosoglutathione (GSNO), and/or high Ca2+ concentration ([Ca2+]). Treatment with high [Ca2+] and without GSNO produced proteolysis of RyR, DHPR, and JP1. On the other hand, treatment with high [Ca2+] and GSNO caused complete inhibition of RyR and DHPR proteolysis and partial inhibition of JP1 proteolysis. These results indicate that ARG ingestion can attenuate ECC‐induced proteolysis of Ca2+ regulatory proteins and force deficit by decreasing calpain activation via S‐nitrosylation.
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Affiliation(s)
- Keita Kanzaki
- Department of Clinical Nutrition, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Okayama, Japan
| | - Daiki Watanabe
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Chihiro Aibara
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Yuki Kawakami
- Department of Nutritional Science, Faculty of Health and Welfare Science, Okayama Prefectural University, Okayama, Japan
| | - Takashi Yamada
- Graduate School of Health Sciences, Sapporo Medical University, Hokkaido, Japan
| | - Yoshitaka Takahashi
- Department of Nutritional Science, Faculty of Health and Welfare Science, Okayama Prefectural University, Okayama, Japan
| | - Masanobu Wada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
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8
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Dutka TL, Mollica JP, Lamboley CR, Weerakkody VC, Greening DW, Posterino GS, Murphy RM, Lamb GD. S-nitrosylation and S-glutathionylation of Cys134 on troponin I have opposing competitive actions on Ca2+ sensitivity in rat fast-twitch muscle fibers. Am J Physiol Cell Physiol 2017; 312:C316-C327. [DOI: 10.1152/ajpcell.00334.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 11/22/2022]
Abstract
Nitric oxide is generated in skeletal muscle with activity and decreases Ca2+ sensitivity of the contractile apparatus, putatively by S-nitrosylation of an unidentified protein. We investigated the mechanistic basis of this effect and its relationship to the oxidation-induced increase in Ca2+ sensitivity in mammalian fast-twitch (FT) fibers mediated by S-glutathionylation of Cys134 on fast troponin I (TnIf). Force-[Ca2+] characteristics of the contractile apparatus in mechanically skinned fibers were assessed by direct activation with heavily Ca2+-buffered solutions. Treatment with S-nitrosylating agents, S-nitrosoglutathione (GSNO) or S-nitroso- N-acetyl-penicillamine (SNAP), decreased pCa50 ( = −log10 [Ca2+] at half-maximal activation) by ~−0.07 pCa units in rat and human FT fibers without affecting maximum force, but had no effect on rat and human slow-twitch fibers or toad or chicken FT fibers, which all lack Cys134. The Ca2+ sensitivity decrease was 1) fully reversed with dithiothreitol or reduced glutathione, 2) at least partially reversed with ascorbate, indicative of involvement of S-nitrosylation, and 3) irreversibly blocked by low concentration of the alkylating agent, N-ethylmaleimide (NEM). The biotin-switch assay showed that both GSNO and SNAP treatments caused S-nitrosylation of TnIf. S-glutathionylation pretreatment blocked the effects of S-nitrosylation on Ca2+ sensitivity, and vice-versa. S-nitrosylation pretreatment prevented NEM from irreversibly blocking S-glutathionylation of TnIf and its effects on Ca2+ sensitivity, and likewise S-glutathionylation pretreatment prevented NEM block of S-nitrosylation. Following substitution of TnIf into rat slow-twitch fibers, S-nitrosylation treatment caused decreased Ca2+ sensitivity. These findings demonstrate that S-nitrosylation and S-glutathionylation exert opposing effects on Ca2+ sensitivity in mammalian FT muscle fibers, mediated by competitive actions on Cys134 of TnIf.
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Affiliation(s)
- T. L. Dutka
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - J. P. Mollica
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - C. R. Lamboley
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - V. C. Weerakkody
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - D. W. Greening
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - G. S. Posterino
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - R. M. Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - G. D. Lamb
- School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
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9
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Kaltsatou A, Sakkas GK, Poulianiti KP, Koutedakis Y, Tepetes K, Christodoulidis G, Stefanidis I, Karatzaferi C. Uremic myopathy: is oxidative stress implicated in muscle dysfunction in uremia? Front Physiol 2015; 6:102. [PMID: 25870564 PMCID: PMC4378187 DOI: 10.3389/fphys.2015.00102] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/13/2015] [Indexed: 12/14/2022] Open
Abstract
Renal failure is accompanied by progressive muscle weakness and premature fatigue, in part linked to hypokinesis and in part to uremic toxicity. These changes are associated with various detrimental biochemical and morphological alterations. All of these pathological parameters are collectively termed uremic myopathy. Various interventions while helpful can't fully remedy the pathological phenotype. Complex mechanisms that stimulate muscle dysfunction in uremia have been proposed, and oxidative stress could be implicated. Skeletal muscles continuously produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) at rest and more so during contraction. The aim of this mini review is to provide an update on recent advances in our understanding of how ROS and RNS generation might contribute to muscle dysfunction in uremia. Thus, a systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. While few studies met our criteria their findings are discussed making reference to other available literature data. Oxidative stress can direct muscle cells into a catabolic state and chronic exposure to it leads to wasting. Moreover, redox disturbances can significantly affect force production per se. We conclude that oxidative stress can be in part responsible for some aspects of uremic myopathy. Further research is needed to discern clear mechanisms and to help efforts to counteract muscle weakness and exercise intolerance in uremic patients.
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Affiliation(s)
- Antonia Kaltsatou
- Department of Physical Education and Sport Sciences (DPESS), School of Physical Education (PE), University of Thessaly Trikala, Greece
| | - Giorgos K Sakkas
- Department of Physical Education and Sport Sciences (DPESS), School of Physical Education (PE), University of Thessaly Trikala, Greece ; Institute for Research and Technology-Centre for Research and Technology Hellas Trikala, Greece
| | - Konstantina P Poulianiti
- Department of Physical Education and Sport Sciences (DPESS), School of Physical Education (PE), University of Thessaly Trikala, Greece
| | - Yiannis Koutedakis
- Department of Physical Education and Sport Sciences (DPESS), School of Physical Education (PE), University of Thessaly Trikala, Greece
| | - Konstantinos Tepetes
- Department of Surgery, Faculty of Medicine, University of Thessaly Larissa, Greece
| | | | - Ioannis Stefanidis
- Department of Nephrology, Faculty of Medicine, University of Thessaly Larissa, Greece
| | - Christina Karatzaferi
- Department of Physical Education and Sport Sciences (DPESS), School of Physical Education (PE), University of Thessaly Trikala, Greece
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10
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Gross SM, Lehman SL. Accessibility of myofilament cysteines and effects on ATPase depend on the activation state during exposure to oxidants. PLoS One 2013; 8:e69110. [PMID: 23894416 PMCID: PMC3716824 DOI: 10.1371/journal.pone.0069110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 06/05/2013] [Indexed: 11/28/2022] Open
Abstract
Signaling by reactive oxygen species has emerged as a major physiological process. Due to its high metabolic rate, striated muscle is especially subject to oxidative stress, and there are multiple examples in cardiac and skeletal muscle where oxidative stress modulates contractile function. Here we assessed the potential of cysteine oxidation as a mechanism for modulating contractile function in skeletal and cardiac muscle. Analyzing the cysteine content of the myofilament proteins in striated muscle, we found that cysteine residues are relatively rare, but are very similar between different muscle types and different vertebrate species. To refine this list of cysteines to those that may modulate function, we estimated the accessibility of oxidants to cysteine residues using protein crystal structures, and then sharpened these estimates using fluorescent labeling of cysteines in cardiac and skeletal myofibrils. We demonstrate that cysteine accessibility to oxidants and ATPase rates depend on the contractile state in which preparations are exposed. Oxidant exposure of skeletal and cardiac myofibrils in relaxing solution exposes myosin cysteines not accessible in rigor solution, and these modifications correspond to a decrease in maximum ATPase. Oxidant exposure under rigor conditions produces modifications that increase basal ATPase and calcium sensitivity in ventricular myofibrils, but these effects were muted in fast twitch muscle. These experiments reveal how structural and sequence variations can lead to divergent effects from oxidants in different muscle types.
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Affiliation(s)
- Sean M. Gross
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
| | - Steven L. Lehman
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
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11
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Radak Z, Zhao Z, Koltai E, Ohno H, Atalay M. Oxygen consumption and usage during physical exercise: the balance between oxidative stress and ROS-dependent adaptive signaling. Antioxid Redox Signal 2013; 18:1208-46. [PMID: 22978553 PMCID: PMC3579386 DOI: 10.1089/ars.2011.4498] [Citation(s) in RCA: 395] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein-protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling.
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Affiliation(s)
- Zsolt Radak
- Faculty of Physical Education and Sport Science, Institute of Sport Science, Semmelweis University, Budapest, Hungary.
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Palmer LA, May WJ, deRonde K, Brown-Steinke K, Bates JN, Gaston B, Lewis SJ. Ventilatory responses during and following exposure to a hypoxic challenge in conscious mice deficient or null in S-nitrosoglutathione reductase. Respir Physiol Neurobiol 2012. [PMID: 23183419 DOI: 10.1016/j.resp.2012.11.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Exposure to a hypoxic challenge increases ventilation in wild-type (WT) mice that diminish during the challenge (roll-off) whereas return to room air causes an increase in ventilation (short-term facilitation, STF). Since plasma and tissue levels of ventilatory excitant S-nitrosothiols such as S-nitrosoglutathione (GSNO) increase during hypoxia, this study examined whether (1) the initial increase in ventilation is due to generation of GSNO, (2) roll-off is due to increased activity of the GSNO degrading enzyme, GSNO reductase (GSNOR), and (3) STF is limited by GSNOR activity. Initial ventilatory responses to hypoxic challenge (10% O(2), 90% N(2)) were similar in WT, GSNO+/- and GSNO-/- mice. These responses diminished markedly during hypoxic challenge in WT mice whereas there was minimal roll-off in GSNOR+/- and GSNOR-/- mice. Finally, STF was greater in GSNOR+/- and GSNOR-/- mice than in WT mice (especially females). This study suggests that GSNOR degradation of GSNO is a vital step in the expression of ventilatory roll-off and that GSNOR suppresses STF.
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Affiliation(s)
- Lisa A Palmer
- Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Turki A, Hayot M, Carnac G, Pillard F, Passerieux E, Bommart S, Raynaud de Mauverger E, Hugon G, Pincemail J, Pietri S, Lambert K, Belayew A, Vassetzky Y, Juntas Morales R, Mercier J, Laoudj-Chenivesse D. Functional muscle impairment in facioscapulohumeral muscular dystrophy is correlated with oxidative stress and mitochondrial dysfunction. Free Radic Biol Med 2012; 53:1068-79. [PMID: 22796148 DOI: 10.1016/j.freeradbiomed.2012.06.041] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 06/05/2012] [Accepted: 06/28/2012] [Indexed: 11/25/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD), the most frequent muscular dystrophy, is an autosomal dominant disease. In most individuals with FSHD, symptoms are restricted to muscles of the face, arms, legs, and trunk. FSHD is genetically linked to contractions of the D4Z4 repeat array causing activation of several genes. One of these maps in the repeat itself and expresses the DUX4 (the double homeobox 4) transcription factor causing a gene deregulation cascade. In addition, analyses of the RNA or protein expression profiles in muscle have indicated deregulations in the oxidative stress response. Since oxidative stress affects peripheral muscle function, we investigated mitochondrial function and oxidative stress in skeletal muscle biopsies and blood samples from patients with FSHD and age-matched healthy controls, and evaluated their association with physical performances. We show that specifically, oxidative stress (lipid peroxidation and protein carbonylation), oxidative damage (lipofuscin accumulation), and antioxidant enzymes (catalase, copper-zinc-dependent superoxide dismutase, and glutathione reductase) were higher in FSHD than in control muscles. FSHD muscles also presented abnormal mitochondrial function (decreased cytochrome c oxidase activity and reduced ATP synthesis). In addition, the ratio between reduced (GSH) and oxidized glutathione (GSSG) was strongly decreased in all FSHD blood samples as a consequence of GSSG accumulation. Patients with FSHD also had reduced systemic antioxidative response molecules, such as low levels of zinc (a SOD cofactor), selenium (a GPx cofactor involved in the elimination of lipid peroxides), and vitamin C. Half of them had a low ratio of gamma/alpha tocopherol and higher ferritin concentrations. Both systemic oxidative stress and mitochondrial dysfunction were correlated with functional muscle impairment. Mitochondrial ATP production was significantly correlated with both quadriceps endurance (T(LimQ)) and maximal voluntary contraction (MVC(Q)) values (rho=0.79, P=0.003; rho=0.62, P=0.05, respectively). The plasma concentration of oxidized glutathione was negatively correlated with the T(LimQ), MVC(Q) values, and the 2-min walk distance (MWT) values (rho=-0.60, P=0.03; rho=-0.56, P=0.04; rho=-0.93, P<0.0001, respectively). Our data characterized oxidative stress in patients with FSHD and demonstrated a correlation with their peripheral skeletal muscle dysfunction. They suggest that antioxidants that might modulate or delay oxidative insult may be useful in maintaining FSHD muscle functions.
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Affiliation(s)
- Ahmed Turki
- Université Montpellier 1 et Université Montpellier 2, INSERM, U1046, Montpellier, F-34000, France
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Dutka TL, Verburg E, Larkins N, Hortemo KH, Lunde PK, Sejersted OM, Lamb GD. ROS-mediated decline in maximum Ca2+-activated force in rat skeletal muscle fibers following in vitro and in vivo stimulation. PLoS One 2012; 7:e35226. [PMID: 22629297 PMCID: PMC3358267 DOI: 10.1371/journal.pone.0035226] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/13/2012] [Indexed: 11/22/2022] Open
Abstract
We hypothesised that normal skeletal muscle stimulated intensely either in vitro or in situ would exhibit reactive oxygen species (ROS)-mediated contractile apparatus changes common to many pathophysiological conditions. Isolated soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat were bubbled with 95% O2 and stimulated in vitro at 31°C to give isometric tetani (50 Hz for 0.5 s every 2 s) until maximum force declined to ≤30%. Skinned superficial slow-twitch fibers from the SOL muscles displayed a large reduction (∼41%) in maximum Ca2+-activated specific force (Fmax), with Ca2+-sensitivity unchanged. Fibers from EDL muscles were less affected. The decrease in Fmax in SOL fibers was evidently due to oxidation effects on cysteine residues because it was reversed if the reducing agent DTT was applied prior to activating the fiber. The GSH∶GSSG ratio was ∼3-fold lower in the cytoplasm of superficial fibers from stimulated muscle compared to control, confirming increased oxidant levels. The presence of Tempol and L-NAME during in vitro stimulation prevented reduction in Fmax. Skinned fibers from SOL muscles stimulated in vivo at 37°C with intact blood supply also displayed reduction in Fmax, though to a much smaller extent (∼12%). Thus, fibers from muscles stimulated even with putatively adequate O2 supply display a reversible oxidation-induced decrease in Fmax without change in Ca2+-sensitivity, consistent with action of peroxynitrite (or possibly superoxide) on cysteine residues of the contractile apparatus. Significantly, the changes closely resemble the contractile deficits observed in a range of pathophysiological conditions. These findings highlight how readily muscle experiences ROS-related deficits, and also point to potential difficulties when defining muscle performance and fatigue.
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Affiliation(s)
- Travis L Dutka
- Department of Zoology, La Trobe University, Melbourne, Australia.
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Abstract
Reactive oxygen and nitrogen species (ROS/RNS) are involved in numerous aspects of cellular signaling. Classically ROS/RNS have been associated with cellular dysfunction and disease, but it is now clear that they are also of integral importance under normal conditions. In this review, we discuss ROS/RNS effects in skeletal muscle, with special focus on changes in contractile function. The review deals with the tentative roles of ROS/RNS for acute changes that can occur during strenuous exercise resulting in muscle fatigue, for the recovery from fatigue, and for the effects of training/overtraining. We also discuss two groups of inherited diseases; muscle dystrophies, where recent data suggest that ROS/RNS may be of unexpectedly large importance, and mitochondrial myopathies, where the role of ROS seems more limited than originally thought.
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Affiliation(s)
- Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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Hirai DM, Copp SW, Schwagerl PJ, Musch TI, Poole DC. Acute effects of hydrogen peroxide on skeletal muscle microvascular oxygenation from rest to contractions. J Appl Physiol (1985) 2011; 110:1290-8. [PMID: 21372096 DOI: 10.1152/japplphysiol.01489.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Reactive oxygen species, such as hydrogen peroxide (H(2)O(2)), exert a critical regulatory role on skeletal muscle function. Whether acute increases in H(2)O(2) modulate muscle microvascular O(2) delivery-utilization (Qo(2)/Vo(2)) matching [i.e., microvascular partial pressure of O(2) (Pmv(O(2)))] at rest and following the onset of contractions is unknown. The hypothesis was tested that H(2)O(2) treatment (exogenous H(2)O(2)) would enhance Pmv(O(2)) and slow Pmv(O(2)) kinetics during contractions compared with control. Anesthetized, healthy young Sprague-Dawley rats had their spinotrapezius muscles either exposed for measurement of blood flow (and therefore QO(2)), VO(2), and Pmv(O(2)), or exteriorized for measurement of force production. Electrically stimulated twitch contractions (1 Hz, ~7 V, 2-ms pulse duration, 3 min) were evoked following acute superfusion with Krebs-Henseleit (control) and H(2)O(2) (100 μM). Relative to control, H(2)O(2) treatment elicited disproportionate increases in QO(2) and VO(2) that elevated Pmv(O(2)) at rest and throughout contractions and slowed overall Pmv(O(2)) kinetics (i.e., ~85% slower mean response time; P < 0.05). Accordingly, H(2)O(2) resulted in ~33% greater overall Pmv(O(2)), as assessed by the area under the Pmv(O(2)) curve (P < 0.05). Muscle force production was not altered with H(2)O(2) treatment (P > 0.05), evidencing reduced economy during contractions (~40% decrease in the force/VO(2) relationship; P < 0.05). These findings indicate that, although increasing the driving force for blood-myocyte O(2) flux (i.e., Pmv(O(2))), transient elevations in H(2)O(2) impair skeletal muscle function (i.e., reduced economy during contractions), which mechanistically may underlie, in part, the reduced exercise tolerance in conditions associated with oxidative stress.
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Affiliation(s)
- Daniel M Hirai
- Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506-5802, USA
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Dutka TL, Mollica JP, Posterino GS, Lamb GD. Modulation of contractile apparatus Ca2+ sensitivity and disruption of excitation-contraction coupling by S-nitrosoglutathione in rat muscle fibres. J Physiol 2010; 589:2181-96. [PMID: 21115647 DOI: 10.1113/jphysiol.2010.200451] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
S-Nitrosoglutathione (GSNO) is generated in muscle and may S-glutathionylate and/or S-nitrosylate various proteins involved in excitation–contraction (EC) coupling, such as Na+-K+-ATPases, voltage-sensors (VSs) and Ca2+ release channels (ryanodine receptors,RyRs), possibly changing their properties. Using mechanically skinned fibres from rat extensor digitorum longus muscle, we sought to identify which EC coupling processes are most susceptible to GSNO-modulated changes and whether these changes could be important in muscle function and fatigue. For comparison, we examined the effect of other oxidation, nitrosylation, or glutathionylation treatments (S-nitroso-N-acetyl-penicillamine (SNAP), hydrogen peroxide,2,2-dithiodipyridine and reduced glutathione) on twitch and tetanic force, action potential (AP) repriming, sarcoplasmic reticulum (SR) Ca2+ loading and leakage, and contractile apparatus properties. None of the treatments detectably altered AP repriming, indicating that t-system excitability was relatively insensitive to such oxidative modification. Importantly, the overall effect on twitch and tetanic force of a given treatment was determined primarily by its action on Ca2+ sensitivity of the contractile apparatus. For example, S-nitrosylation with the NO• donor,SNAP, caused matching decreases in the contractile Ca2+ sensitivity and twitch response, and GSNO applied ∼10 min after preparation had very similar effects. The only exception was when GSNO was applied immediately after preparation, which resulted in irreversible decreases in twitch and tetanic responses even though it concomitantly increased Ca2+ sensitivity by∼0.1 pCaunits, the latter evidently due to S-glutathionylation of the contractile apparatus. This decrease in AP-mediated force responses was due to impaired VS–RyR coupling and was accompanied by increased Ca2+ leakage through RyRs. Such oxidation-related impairment of coupling could be responsible for prolonged low frequency fatigue in certain circumstances.
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Affiliation(s)
- T L Dutka
- Department of Zoology, La Trobe University, Melbourne, Victoria, 3086, Australia.
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Lamb GD, Westerblad H. Acute effects of reactive oxygen and nitrogen species on the contractile function of skeletal muscle. J Physiol 2010; 589:2119-27. [PMID: 21041533 DOI: 10.1113/jphysiol.2010.199059] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Reactive oxygen and nitrogen species (ROS/RNS) are important for skeletal muscle function under both physiological and pathological conditions. ROS/RNS induce long-term and acute effects and the latter are the focus of the present review. Upon repeated muscle activation both oxygen and nitrogen free radicals likely increase and acutely affect contractile function. Although fluorescent indicators often detect only modest increases in ROS during repeated activation, there are numerous studies showing that manipulations of ROS can affect muscle fatigue development and recovery. Exposure of intact muscle fibres to the oxidant hydrogen peroxide (H(2)O(2)) affects mainly the myofibrillar function, where an initial increase in Ca(2+) sensitivity is followed by a decrease. Experiments on skinned fibres show that these effects can be attributed to H(2)O(2) interacting with glutathione and myoglobin, respectively. The primary RNS, nitric oxide (NO()), may also acutely affect myofibrillar function and decrease the Ca(2+) sensitivity. H(2)O(2) can oxidize the sarcoplasmic reticulum Ca(2+) release channels. This oxidation has a large stimulatory effect on Ca(2+)-induced Ca(2+) release of isolated channels, whereas it has little or no effect on the physiological, action potential-induced Ca(2+) release in skinned and intact muscle fibres. Thus, acute effects of ROS/RNS on muscle function are likely to be mediated by changes in myofibrillar Ca(2+) sensitivity, which can contribute to the development of muscle fatigue or alternatively help counter it.
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Affiliation(s)
- Graham D Lamb
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
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Abstract
Nitric oxide (NO*) is synthesized in skeletal muscle and its production increases during contractile activity. Although myosin is the most abundant protein in muscle, it is not known whether myosin is a target of NO* or NO* derivatives. In the present study, we have shown that exercise increases protein S-nitrosylation in muscle, and, among contractile proteins, myosin is the principal target of exogenous SNOs (S-nitrosothiols) in both skinned skeletal muscle fibres and differentiated myotubes. The reaction of isolated myosin with S-nitrosoglutathione results in S-nitrosylation at multiple cysteine thiols and produces two populations of protein-bound SNOs with different stabilities. The less-stable population inhibits the physiological ATPase activity, without affecting the affinity of myosin for actin. However, myosin is neither inhibited nor S-nitrosylated by the NO* donor diethylamine NONOate, indicating a requirement for transnitrosylation between low-mass SNO and myosin cysteine thiols rather than a direct reaction of myosin with NO* or its auto-oxidation products. Interestingly, alkylation of the most reactive thiols of myosin by N-ethylmaleimide does not inhibit formation of a stable population of protein-SNOs, suggesting that these sites are located in less accessible regions of the protein than those that affect activity. The present study reveals a new link between exercise and S-nitrosylation of skeletal muscle contractile proteins that may be important under (patho)physiological conditions.
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EMD 57033 partially reverses ventilator-induced diaphragm muscle fibre calcium desensitisation. Pflugers Arch 2009; 459:475-83. [PMID: 19798510 DOI: 10.1007/s00424-009-0744-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 09/21/2009] [Accepted: 09/23/2009] [Indexed: 10/20/2022]
Abstract
In critically ill patients, ventilator-induced diaphragm muscle fibre dysfunction (VIDD) contributes to weaning problems, increasing hospitalisation time and related costs. VIDD pathophysiology remains partially unknown, especially the characterisation of the contractile dysfunction. In the present study, it was hypothesised that Ca(2+) activation is affected during VIDD. Ca(2+) sensitivity of contraction was therefore evaluated at the single skinned diaphragm muscle fibre level in piglets randomised into sham operation or 5-day mechanical ventilation. Ca(2+) sensitivities of force and stiffness in fibres were significantly impaired in all mechanically ventilated piglets compared with sham-operated controls, suggesting a less efficient Ca(2+) activation of cells, i.e. a lower relative number of strongly attached cross-bridges for each sub-maximal concentration of Ca(2+). In an attempt to test whether this negative effect of VIDD is reversible, single muscle fibres were exposed to the EMD 57033 Ca(2+) sensitiser. EMD 57033 (30 microM) improved the Ca(2+) sensitivity of force and stiffness in fibres from animals that were mechanically ventilated for 5 days as well as in sham-operated piglets. Thus, EMD 57033 partly restored the Ca(2+) activation of cells, reducing VIDD. This finding offers a strong basis for evaluating the effect of Ca(2+) sensitisers on diaphragm function in vivo.
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