1
|
Almquist NW, Wilhelmsen M, Ellefsen S, Sandbakk Ø, Rønnestad BR. Effects of Including Sprints in LIT Sessions during a 14-d Camp on Muscle Biology and Performance Measures in Elite Cyclists. Med Sci Sports Exerc 2021; 53:2333-2345. [PMID: 34081058 DOI: 10.1249/mss.0000000000002709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study investigated the effects of including sprints within low-intensity training (LIT) sessions during a 14-d training camp focusing on LIT, followed by 10-d recovery (Rec), on performance and performance-related measures in elite cyclists. METHODS During the camp, a sprint training group (SPR; n = 9) included 12 × 30-s maximal sprints during five LIT sessions, whereas a control group (CON; n = 9) performed distance-matched LIT only. Training load was equally increased in both groups by 48% ± 27% during the training camp and subsequently decreased by -56% ± 23% during the recovery period compared with habitual training. Performance tests were conducted before the training camp (Pre) and after Rec. Muscle biopsies, hematological measures, and stress/recovery questionnaires were collected Pre and after the camp (Post). RESULTS Thirty-second sprint (SPR vs CON: 4% ± 4%, P < 0.01) and 5-min mean power (SPR vs CON: 4% ± 8%, P = 0.04) changed differently between groups. In muscle, Na+-K+ β1 protein content changed differently between groups, decreasing in CON compared with SPR (-8% ± 14%, P = 0.04), whereas other proteins showed similar changes. SPR and CON displayed similar increases in red blood cell volume (SPR: 2.6% ± 4.7%, P = 0.07; CON: 3.9% ± 4.5%, P = 0.02) and V˙O2 at 4 mmol·L-1 [BLa-] (SPR: 2.5% ± 3.3%, P = 0.03; CON: 2.2% ± 3.0%, P = 0.04). No changes were seen for V˙O2max, Wmax, hematological measures, muscle enzyme activity, and stress/recovery measures. CONCLUSIONS Inclusion of 30-s sprints within LIT sessions during a high-volume training camp affected competition-relevant performance measures and Na+-K+ β1 protein content differently from LIT only, without affecting sport-specific stress/recovery or any other physiological measure in elite cyclists.
Collapse
Affiliation(s)
| | - Malene Wilhelmsen
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, NORWAY
| | - Stian Ellefsen
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, NORWAY
| | - Øyvind Sandbakk
- Centre for Elite Sports Research, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, NORWAY
| | - Bent R Rønnestad
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, NORWAY
| |
Collapse
|
2
|
Hosseinzadeh Z, Hauser S, Singh Y, Pelzl L, Schuster S, Sharma Y, Höflinger P, Zacharopoulou N, Stournaras C, Rathbun DL, Zrenner E, Schöls L, Lang F. Decreased Na +/K + ATPase Expression and Depolarized Cell Membrane in Neurons Differentiated from Chorea-Acanthocytosis Patients. Sci Rep 2020; 10:8391. [PMID: 32439941 PMCID: PMC7242441 DOI: 10.1038/s41598-020-64845-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 04/17/2020] [Indexed: 02/03/2023] Open
Abstract
Loss of function mutations of the chorein-encoding gene VPS13A lead to chorea-acanthocytosis (ChAc), a neurodegenerative disorder with accelerated suicidal neuronal cell death, which could be reversed by lithium. Chorein upregulates the serum and glucocorticoid inducible kinase SGK1. Targets of SGK1 include the Na+/K+-ATPase, a pump required for cell survival. To explore whether chorein-deficiency affects Na+/K+ pump capacity, cortical neurons were differentiated from iPSCs generated from fibroblasts of ChAc patients and healthy volunteers. Na+/K+ pump capacity was estimated from K+-induced whole cell outward current (pump capacity). As a result, the pump capacity was completely abolished in the presence of Na+/K+ pump-inhibitor ouabain (100 µM), was significantly smaller in ChAc neurons than in control neurons, and was significantly increased in ChAc neurons by lithium treatment (24 hours 2 mM). The effect of lithium was reversed by SGK1-inhibitor GSK650394 (24 h 10 µM). Transmembrane potential (Vm) was significantly less negative in ChAc neurons than in control neurons, and was significantly increased in ChAc neurons by lithium treatment (2 mM, 24 hours). The effect of lithium on Vm was virtually abrogated by ouabain. Na+/K+ α1-subunit transcript levels and protein abundance were significantly lower in ChAc neurons than in control neurons, an effect reversed by lithium treatment (2 mM, 24 hours). In conclusion, consequences of chorein deficiency in ChAc include impaired Na+/K+ pump capacity.
Collapse
Affiliation(s)
- Zohreh Hosseinzadeh
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.,Department of Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Stefan Hauser
- German Center for Neurodegenerative Diseases, Tübingen, Germany.,Department of Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Yogesh Singh
- Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Lisann Pelzl
- Transfusion Medicine, Medical Faculty, Eberhard Karl University, Tübingen, Germany
| | - Stefanie Schuster
- German Center for Neurodegenerative Diseases, Tübingen, Germany.,Department of Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Yamini Sharma
- Department of Internal Medicine III, University of Tübingen, Tübingen, Germany
| | - Philip Höflinger
- German Center for Neurodegenerative Diseases, Tübingen, Germany.,Department of Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Nefeli Zacharopoulou
- Department of Biochemistry, University of Crete Medical School, Heraklion, Greece.,Department of Vegetative and Clinical Physiology, University of Tübingen, Tübingen, Germany
| | - Christos Stournaras
- Department of Biochemistry, University of Crete Medical School, Heraklion, Greece
| | - Daniel L Rathbun
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany.,Department Ophthalmology, Bionics and Vision, Henry Ford Hospital, Henry Ford, United States
| | - Eberhart Zrenner
- Department of Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Ludger Schöls
- German Center for Neurodegenerative Diseases, Tübingen, Germany.,Department of Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Florian Lang
- Department of Vegetative and Clinical Physiology, University of Tübingen, Tübingen, Germany.
| |
Collapse
|
3
|
Almquist NW, Nygaard H, Vegge G, Hammarström D, Ellefsen S, Rønnestad BR. Systemic and muscular responses to effort-matched short intervals and long intervals in elite cyclists. Scand J Med Sci Sports 2020; 30:1140-1150. [PMID: 32267032 DOI: 10.1111/sms.13672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/25/2020] [Accepted: 03/25/2020] [Indexed: 01/01/2023]
Abstract
The purpose of this study was to compare the acute effects of time- and effort-matched high-intensity intervals on physiological, endocrine, and skeletal muscle molecular variables in elite cyclists. Eight elite cyclists performed short intervals (SI: 30-seconds) and long intervals (LI: 5-minutes) with work:recovery ratio 2:1, using a randomized crossover design. SI was associated with 14% ± 3% higher mean power output (SI; 421 ± 27 vs LI; 371 ± 22 W), and longer working time above 90% of maximal oxygen uptake (VO2max , 54% ± 76%) and 90% peak heart rate (HRpeak , 153% ± 148%) than LI (all P < .05), despite similar degrees of perceived exertion, blood lactate levels and muscle activation measured using EMG root mean square (EMG rms). In blood, SI was associated with more pronounced increases in testosterone and testosterone-to-sex hormone-binding globulin (SHBG) ratios, as well as prolonged cortisol responses (P < .05). In skeletal muscle (m. Vastus lateralis), SI and LI led to similar changes in mRNA abundance for a range of transcripts, with the exception of NHE1 mRNA, which decreased after SI (P < .05). Overall, SI was associated with more pronounced physiological and endocrine responses than LI in elite cyclists, suggesting that such training might lead to superior adaptations in elite cyclists.
Collapse
Affiliation(s)
- Nicki W Almquist
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Håvard Nygaard
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Geir Vegge
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Daniel Hammarström
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Stian Ellefsen
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - Bent R Rønnestad
- Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway
| |
Collapse
|
4
|
Christiansen D. Molecular stressors underlying exercise training-induced improvements in K + regulation during exercise and Na + ,K + -ATPase adaptation in human skeletal muscle. Acta Physiol (Oxf) 2019; 225:e13196. [PMID: 30288889 DOI: 10.1111/apha.13196] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/12/2018] [Accepted: 09/28/2018] [Indexed: 12/28/2022]
Abstract
Despite substantial progress made towards a better understanding of the importance of skeletal muscle K+ regulation for human physical function and its association with several disease states (eg type-II diabetes and hypertension), the molecular basis underpinning adaptations in K+ regulation to various stimuli, including exercise training, remains inadequately explored in humans. In this review, the molecular mechanisms essential for enhancing skeletal muscle K+ regulation and its key determinants, including Na+ ,K+ -ATPase function and expression, by exercise training are examined. Special attention is paid to the following molecular stressors and signaling proteins: oxygenation, redox balance, hypoxia, reactive oxygen species, antioxidant function, Na+ ,K+ , and Ca2+ concentrations, anaerobic ATP turnover, AMPK, lactate, and mRNA expression. On this basis, an update on the effects of different types of exercise training on K+ regulation in humans is provided, focusing on recent discoveries about the muscle fibre-type-dependent regulation of Na+ ,K+ -ATPase-isoform expression. Furthermore, with special emphasis on blood-flow-restricted exercise as an exemplary model to modulate the key molecular mechanisms identified, it is discussed how training interventions may be designed to maximize improvements in K+ regulation in humans. The novel insights gained from this review may help us to better understand how exercise training and other strategies, such as pharmacological interventions, may be best designed to enhance K+ regulation and thus the physical function in humans.
Collapse
Affiliation(s)
- Danny Christiansen
- Department of Nutrition, Exercise and Sports (NEXS) University of Copenhagen Copenhagen Denmark
- Institute for Health and Sport (IHES) Victoria University Melbourne Victoria Australia
| |
Collapse
|
5
|
Christiansen D, Murphy RM, Bangsbo J, Stathis CG, Bishop DJ. Increased FXYD1 and PGC-1α mRNA after blood flow-restricted running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle. Acta Physiol (Oxf) 2018; 223:e13045. [PMID: 29383885 PMCID: PMC5969286 DOI: 10.1111/apha.13045] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/01/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022]
Abstract
Aim This study explored the effects of blood flow restriction (BFR) on mRNA responses of PGC‐1α (total, 1α1, and 1α4) and Na+,K+‐ATPase isoforms (NKA; α1‐3, β1‐3, and FXYD1) to an interval running session and determined whether these effects were related to increased oxidative stress, hypoxia, and fibre type‐specific AMPK and CaMKII signalling, in human skeletal muscle. Methods In a randomized, crossover fashion, 8 healthy men (26 ± 5 year and 57.4 ± 6.3 mL kg−1 min−1) completed 3 exercise sessions: without (CON) or with blood flow restriction (BFR), or in systemic hypoxia (HYP, ~3250 m). A muscle sample was collected before (Pre) and after exercise (+0 hour, +3 hours) to quantify mRNA, indicators of oxidative stress (HSP27 protein in type I and II fibres, and catalase and HSP70 mRNA), metabolites, and α‐AMPK Thr172/α‐AMPK, ACC Ser221/ACC, CaMKII Thr287/CaMKII, and PLBSer16/PLB ratios in type I and II fibres. Results Muscle hypoxia (assessed by near‐infrared spectroscopy) was matched between BFR and HYP, which was higher than CON (~90% vs ~70%; P < .05). The mRNA levels of FXYD1 and PGC‐1α isoforms (1α1 and 1α4) increased in BFR only (P < .05) and were associated with increases in indicators of oxidative stress and type I fibre ACC Ser221/ACC ratio, but dissociated from muscle hypoxia, lactate, and CaMKII signalling. Conclusion Blood flow restriction augmented exercise‐induced increases in muscle FXYD1 and PGC‐1α mRNA in men. This effect was related to increased oxidative stress and fibre type‐dependent AMPK signalling, but unrelated to the severity of muscle hypoxia, lactate accumulation, and modulation of fibre type‐specific CaMKII signalling.
Collapse
Affiliation(s)
- D. Christiansen
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - R. M. Murphy
- Department of Biochemistry and Genetics; La Trobe Institute for Molecular Science; La Trobe University; Melbourne Vic. Australia
| | - J. Bangsbo
- Department of Nutrition, Exercise and Sports (NEXS); University of Copenhagen; Copenhagen N Denmark
| | - C. G. Stathis
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - D. J. Bishop
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
- School of Medical and Health Sciences; Edith Cowan University; Perth WA Australia
| |
Collapse
|
6
|
Christiansen D, Bishop DJ, Broatch JR, Bangsbo J, McKenna MJ, Murphy RM. Cold-water immersion after training sessions: effects on fiber type-specific adaptations in muscle K + transport proteins to sprint-interval training in men. J Appl Physiol (1985) 2018; 125:429-444. [PMID: 29745801 DOI: 10.1152/japplphysiol.00259.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Effects of regular use of cold-water immersion (CWI) on fiber type-specific adaptations in muscle K+ transport proteins to intense training, along with their relationship to changes in mRNA levels after the first training session, were investigated in humans. Nineteen recreationally active men (24 ± 6 yr, 79.5 ± 10.8 kg, 44.6 ± 5.8 ml·kg-1·min-1) completed six weeks of sprint-interval cycling, either without (passive rest; CON) or with training sessions followed by CWI (15 min at 10°C; COLD). Muscle biopsies were obtained before and after training to determine abundance of Na+, K+-ATPase isoforms (α1-3, β1-3) and phospholemman (FXYD1) and after recovery treatments (+0 h and +3 h) on the first day of training to measure mRNA content. Training increased ( P < 0.05) the abundance of α1 and β3 in both fiber types and β1 in type-II fibers and decreased FXYD1 in type-I fibers, whereas α2 and α3 abundance was not altered by training ( P > 0.05). CWI after each session did not influence responses to training ( P > 0.05). However, α2 mRNA increased after the first session in COLD (+0 h, P < 0.05) but not in CON ( P > 0.05). In both conditions, α1 and β3 mRNA increased (+3 h; P < 0.05) and β2 mRNA decreased (+3 h; P < 0.05), whereas α3, β1, and FXYD1 mRNA remained unchanged ( P > 0.05) after the first session. In summary, Na+,K+-ATPase isoforms are differently regulated in type I and II muscle fibers by sprint-interval training in humans, which, for most isoforms, do not associate with changes in mRNA levels after the first training session. CWI neither impairs nor improves protein adaptations to intense training of importance for muscle K+ regulation. NEW & NOTEWORTHY Although cold-water immersion (CWI) after training and competition has become a routine for many athletes, limited published evidence exists regarding its impact on training adaptation. Here, we show that CWI can be performed regularly without impairing training-induced adaptations at the fiber-type level important for muscle K+ handling. Furthermore, sprint-interval training invoked fiber type-specific adaptations in K+ transport proteins, which may explain the dissociated responses of whole-muscle protein levels and K+ transport function to training previously reported.
Collapse
Affiliation(s)
- Danny Christiansen
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.,Department of Nutrition, Exercise, and Sports, University of Copenhagen , Copenhagen , Denmark
| | - David J Bishop
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.,School of Medical and Health Sciences, Edith Cowan University , Perth, Western Australia , Australia
| | - James R Broatch
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Jens Bangsbo
- Department of Nutrition, Exercise, and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Robyn M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University , Melbourne, Victoria , Australia
| |
Collapse
|
7
|
Lewis P, O'Halloran KD. Diaphragm Muscle Adaptation to Sustained Hypoxia: Lessons from Animal Models with Relevance to High Altitude and Chronic Respiratory Diseases. Front Physiol 2016; 7:623. [PMID: 28018247 PMCID: PMC5149537 DOI: 10.3389/fphys.2016.00623] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/28/2016] [Indexed: 12/13/2022] Open
Abstract
The diaphragm is the primary inspiratory pump muscle of breathing. Notwithstanding its critical role in pulmonary ventilation, the diaphragm like other striated muscles is malleable in response to physiological and pathophysiological stressors, with potential implications for the maintenance of respiratory homeostasis. This review considers hypoxic adaptation of the diaphragm muscle, with a focus on functional, structural, and metabolic remodeling relevant to conditions such as high altitude and chronic respiratory disease. On the basis of emerging data in animal models, we posit that hypoxia is a significant driver of respiratory muscle plasticity, with evidence suggestive of both compensatory and deleterious adaptations in conditions of sustained exposure to low oxygen. Cellular strategies driving diaphragm remodeling during exposure to sustained hypoxia appear to confer hypoxic tolerance at the expense of peak force-generating capacity, a key functional parameter that correlates with patient morbidity and mortality. Changes include, but are not limited to: redox-dependent activation of hypoxia-inducible factor (HIF) and MAP kinases; time-dependent carbonylation of key metabolic and functional proteins; decreased mitochondrial respiration; activation of atrophic signaling and increased proteolysis; and altered functional performance. Diaphragm muscle weakness may be a signature effect of sustained hypoxic exposure. We discuss the putative role of reactive oxygen species as mediators of both advantageous and disadvantageous adaptations of diaphragm muscle to sustained hypoxia, and the role of antioxidants in mitigating adverse effects of chronic hypoxic stress on respiratory muscle function.
Collapse
Affiliation(s)
- Philip Lewis
- Department of Physiology, School of Medicine, University College CorkCork, Ireland; Environmental Medicine and Preventative Research, Institute and Policlinic for Occupational Medicine, University of CologneCologne, Germany
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, University College Cork Cork, Ireland
| |
Collapse
|
8
|
|
9
|
Matchkov VV, Krivoi II. Specialized Functional Diversity and Interactions of the Na,K-ATPase. Front Physiol 2016; 7:179. [PMID: 27252653 PMCID: PMC4879863 DOI: 10.3389/fphys.2016.00179] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/04/2016] [Indexed: 12/22/2022] Open
Abstract
Na,K-ATPase is a protein ubiquitously expressed in the plasma membrane of all animal cells and vitally essential for their functions. A specialized functional diversity of the Na,K-ATPase isozymes is provided by molecular heterogeneity, distinct subcellular localizations, and functional interactions with molecular environment. Studies over the last decades clearly demonstrated complex and isoform-specific reciprocal functional interactions between the Na,K-ATPase and neighboring proteins and lipids. These interactions are enabled by a spatially restricted ion homeostasis, direct protein-protein/lipid interactions, and protein kinase signaling pathways. In addition to its "classical" function in ion translocation, the Na,K-ATPase is now considered as one of the most important signaling molecules in neuronal, epithelial, skeletal, cardiac and vascular tissues. Accordingly, the Na,K-ATPase forms specialized sub-cellular multimolecular microdomains which act as receptors to circulating endogenous cardiotonic steroids (CTS) triggering a number of signaling pathways. Changes in these endogenous cardiotonic steroid levels and initiated signaling responses have significant adaptive values for tissues and whole organisms under numerous physiological and pathophysiological conditions. This review discusses recent progress in the studies of functional interactions between the Na,K-ATPase and molecular microenvironment, the Na,K-ATPase-dependent signaling pathways and their significance for diversity of cell function.
Collapse
Affiliation(s)
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University St. Petersburg, Russia
| |
Collapse
|
10
|
Kravtsova VV, Petrov AM, Matchkov VV, Bouzinova EV, Vasiliev AN, Benziane B, Zefirov AL, Chibalin AV, Heiny JA, Krivoi II. Distinct α2 Na,K-ATPase membrane pools are differently involved in early skeletal muscle remodeling during disuse. ACTA ACUST UNITED AC 2016; 147:175-88. [PMID: 26755774 PMCID: PMC4727944 DOI: 10.1085/jgp.201511494] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/22/2015] [Indexed: 11/29/2022]
Abstract
Location, location, location. The Na-K pump of skeletal muscle is regulated differently at neuromuscular junctions. The Na,K-ATPase is essential for the contractile function of skeletal muscle, which expresses the α1 and α2 subunit isoforms of Na,K-ATPase. The α2 isozyme is predominant in adult skeletal muscles and makes a greater contribution in working compared with noncontracting muscles. Hindlimb suspension (HS) is a widely used model of muscle disuse that leads to progressive atrophy of postural skeletal muscles. This study examines the consequences of acute (6–12 h) HS on the functioning of the Na,K-ATPase α1 and α2 isozymes in rat soleus (disused) and diaphragm (contracting) muscles. Acute disuse dynamically and isoform-specifically regulates the electrogenic activity, protein, and mRNA content of Na,K-ATPase α2 isozyme in rat soleus muscle. Earlier disuse-induced remodeling events also include phospholemman phosphorylation as well as its increased abundance and association with α2 Na,K-ATPase. The loss of α2 Na,K-ATPase activity results in reduced electrogenic pump transport and depolarized resting membrane potential. The decreased α2 Na,K-ATPase activity is caused by a decrease in enzyme activity rather than by altered protein and mRNA content, localization in the sarcolemma, or functional interaction with the nicotinic acetylcholine receptors. The loss of extrajunctional α2 Na,K-ATPase activity depends strongly on muscle use, and even the increased protein and mRNA content as well as enhanced α2 Na,K-ATPase abundance at this membrane region after 12 h of HS cannot counteract this sustained inhibition. In contrast, additional factors may regulate the subset of junctional α2 Na,K-ATPase pool that is able to recover during HS. Notably, acute, low-intensity muscle workload restores functioning of both α2 Na,K-ATPase pools. These results demonstrate that the α2 Na,K-ATPase in rat skeletal muscle is dynamically and acutely regulated by muscle use and provide the first evidence that the junctional and extrajunctional pools of the α2 Na,K-ATPase are regulated differently.
Collapse
Affiliation(s)
- Violetta V Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | | | - Elena V Bouzinova
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8240 Risskov, Denmark
| | - Alexander N Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Boubacar Benziane
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Andrey L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Alexander V Chibalin
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| |
Collapse
|
11
|
Isoform-specific Na,K-ATPase alterations precede disuse-induced atrophy of rat soleus muscle. BIOMED RESEARCH INTERNATIONAL 2015; 2015:720172. [PMID: 25654120 PMCID: PMC4309216 DOI: 10.1155/2015/720172] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/18/2014] [Indexed: 11/17/2022]
Abstract
This study examines the isoform-specific effects of short-term hindlimb suspension (HS) on the Na,K-ATPase in rat soleus muscle. Rats were exposed to 24–72 h of HS and we analyzed the consequences on soleus muscle mass and contractile parameters; excitability and the resting membrane potential (RMP) of muscle fibers; the electrogenic activity, protein, and mRNA content of the α1 and α2 Na,K-ATPase; the functional activity and plasma membrane localization of the α2 Na,K-ATPase. Our results indicate that 24–72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. The α2 mRNA and protein content increased after 24 h of HS and returned to initial levels at 72 h; however, even the increased content was not able to restore α2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization of α2 Na,K-ATPase. The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required for α2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.
Collapse
|
12
|
Döker S, Hazar M, Uslu M, Okan İ, Kafkas E, Boşgelmez İİ. Influence of training frequency on serum concentrations of some essential trace elements and electrolytes in male swimmers. Biol Trace Elem Res 2014; 158:15-21. [PMID: 24531911 DOI: 10.1007/s12011-014-9912-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 02/03/2014] [Indexed: 11/25/2022]
Abstract
Elemental fluctuations during physical performances have been a point of interest. This study was designed to investigate the effect of swimming frequency on serum concentrations of some trace elements (chromium, iron, copper, zinc, selenium) and electrolytes (sodium, magnesium, potassium, calcium). Three groups of different-level male swimmers were included in the study, as elite swimmers (n = 14), amateur swimmers (n = 11), and sedentary individuals (n = 10). Elite and amateur swimmer groups followed a 3-week training program. At the end of the period, all volunteers were subjected to a controlled swimming test, and blood samples were collected at the beginning of (pre-test), immediately after (post-test), and 1 h after this activity. Element concentrations were determined by inductively coupled plasma mass spectrometry using a dilute and shoot procedure. Apart from the swimming test applied, pre-test calcium and potassium levels were higher in elite swimmers compared to amateurs and controls. The difference in pre-test levels of these elements can be associated with adaptive mechanisms emerged by the frequent training. Regarding the test applied, changes in magnesium, calcium, copper, zinc, and selenium levels exhibited a common pattern in all study groups, with higher post-test serum concentrations. Another point of note was a drop of copper, zinc, and selenium levels at 1 h after the test in elite swimmers. The decrease in serum zinc was also observed in the other groups. Results highlight the value of regular control of elemental status to provide insight into transient effects and deficiencies.
Collapse
Affiliation(s)
- Serhat Döker
- Faculty of Science, Department of Chemistry, Çankırı Karatekin University, 18100, Çankırı, Turkey,
| | | | | | | | | | | |
Collapse
|
13
|
Persson AB, Persson PB. Cycling in physiology. Acta Physiol (Oxf) 2012; 206:1-3. [PMID: 22863297 DOI: 10.1111/j.1748-1716.2012.02446.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
14
|
|
15
|
Affiliation(s)
- J Henriksson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
| |
Collapse
|
16
|
Green HJ, Duhamel TA, Smith IC, Rich SM, Thomas MM, Ouyang J, Yau JE. Muscle fatigue and excitation-contraction coupling responses following a session of prolonged cycling. Acta Physiol (Oxf) 2011; 203:441-55. [PMID: 21707930 DOI: 10.1111/j.1748-1716.2011.02335.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM The mechanisms underlying the fatigue that occurs in human muscle following sustained activity are thought to reside in one or more of the excitation-contraction coupling (E-C coupling) processes. This study investigated the association between the changes in select E-C coupling properties and the impairment in force generation that occurs with prolonged cycling. METHODS Ten volunteers with a peak aerobic power (VO(2peak)) of 2.95 ± 0.27 L min(-1) (mean ± SE), exercised for 2 h at 62 ± 1.3%. Quadriceps function was assessed and tissue properties (vastus lateralis) were measured prior to (E1-pre) and following (E1-post) exercise and on three consecutive days of recovery (R1, R2 and R3). RESULTS While exercise failed to depress the maximal activity (V(max) ) of the Na(+) ,K(+) -ATPase (P = 0.10), reductions (P < 0.05) were found at E1-post in V(max) of sarcoplasmic reticulum Ca(2+) -ATPase (-22%), Ca(2+) -uptake (-26%) and phase 1(-33%) and 2 (-38%) Ca(2+) -release. Both V(max) and Ca(2+) -release (phase 2) recovered by R1, whereas Ca(2+) -uptake and Ca(2+) -release (phase 1) remained depressed (P < 0.05) at R1 and at R1 and R2 and possibly R3 (P < 0.06) respectively. Compared with E1-pre, fatigue was observed (P < 0.05) at 10 Hz electrical stimulation at E1-post (-56%), which persisted throughout recovery. The exercise increased (P < 0.05) overall content of the Na(+), K(+)-ATPase (R1, R2 and R3) and the isoforms β2 (R1, R2 and R3) and β3 (R3), but not β1 or the α-isoforms (α1, α2 and α3). CONCLUSION These results suggest a possible direct role for Ca(2+)-release in fatigue and demonstrate a single exercise session can induce overlapping perturbations and adaptations (particularly to the Na(+), K(+)-ATPase).
Collapse
Affiliation(s)
- H J Green
- Department of Kinesiology, University of Waterloo, ON, Canada.
| | | | | | | | | | | | | |
Collapse
|
17
|
Rasmussen MK, Juel C, Nordsborg NB. Exercise-induced regulation of muscular Na+-K+ pump, FXYD1, and NHE1 mRNA and protein expression: importance of training status, intensity, and muscle type. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1209-20. [PMID: 21325644 DOI: 10.1152/ajpregu.00635.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is investigated if exercise-induced mRNA changes cause similar protein expression changes of Na(+)-K(+) pump isoforms (α(1), α(2), β(1), β(2)), FXYD1, and Na(+)/K(+) exchanger (NHE1) in rat skeletal muscle. Expression was evaluated (n = 8 per group) in soleus and extensor digutorum longus after 1 day, 3 days, and 3 wk (5 sessions/wk) of either sprint (4 × 3-min sprint + 1-min rest) or endurance (20 min) running. Two hours after exercise on day 1, no change in protein expression was apparent in either training group or muscle, whereas sprint exercise increased the mRNA of soleus α(2) (4.9 ± 0.8-fold; P < 0.05), β(2) (13.2 ± 4.4-fold; P < 0.001), and NHE1 (12.0 ± 3.1-fold; P < 0.01). Two hours after sprint exercise, protein expression normalized to control samples was higher on day 3 than day 1 for soleus α(1) (41 ± 18% increase vs. 15 ± 8% reduction; P < 0.05), α(2) (64 ± 35% increase vs. 37 ± 12% reduction; P < 0.05), β(1) (17 ± 21% increase vs. 14 ± 29% reduction; P < 0.05), and FXYD1 (35 ± 16% increase vs. 13 ± 10% reduction; P < 0.05). In contrast, on day 3, soleus α(1) (0.1 ± 0.1-fold; P < 0.001), α(2) (0.2 ± 0.1-fold; P < 0.001), β(1) (0.4 ± 0.1-fold; P < 0.05), and β(2)-mRNA (2.9 ± 1.7-fold; P < 0.001) expression was lower than after exercise on day 1. After 3 wk of training, no change in protein expression relative to control existed. In conclusion, increased expression of Na(+)-K(+) pump subunits, FXYD1 and NHE1 after 3 days exercise training does not appear to be an effect of increased constitutive mRNA levels. Importantly, sprint exercise can reduce mRNA expression concomitant with increased protein expression.
Collapse
Affiliation(s)
- Martin Krøyer Rasmussen
- Dept. of Exercise and Sport Sciences, University of Copenhagen, Universitetsparken 13, Copenhagen, Denmark
| | | | | |
Collapse
|
18
|
González-Haro C, Soria M, López-Colón JL, Llorente MT, Escanero JF. Plasma trace elements levels are not altered by submaximal exercise intensities in well-trained endurance euhydrated athletes. J Trace Elem Med Biol 2011; 25 Suppl 1:S54-8. [PMID: 21146385 DOI: 10.1016/j.jtemb.2010.10.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
Abstract
The purpose of this study was to assess the effect of relative exercise intensity on various plasma trace elements in euhydrated endurance athletes. Twenty-seven well-trained endurance athletes performed a cycloergometer test: after a warm-up of 10 min at 2.0 W kg⁻¹, workload increased by 0.5 W kg⁻¹ every 10 min until exhaustion. Oxygen uptake, blood lactate concentration ([La⁻](b)), and plasma ions (Zn, Se, Mn and Co) were measured at rest, at the end of each stage, and 3, 5 and 7 min post-exercise. Urine specific gravity (U(SG)) was measured before and after the test, and subjects drank water ad libitum. Fat oxidation (FAT(OXR)), carbohydrate oxidation (CHO(OXR)), energy expenditure from fat (EE(FAT)), from carbohydrates (EE(CHO)) and total EE (EE(T)) were estimated using stoichiometric equations. A repeated measure (ANOVA) was used to compare plasma ion levels at each exercise intensity level. The significance level was set at P<0.05. No significant differences were found in U(SG) between, before, and after the test (1.014±0.004 vs. 1.014±0.004 g cm⁻³) or in any plasma ion level as a function of intensity. There were weak significant correlations of Zn (r=0.332, P<0.001) and Se (r=0.242, P<0.01) with [La⁻](b), but no relationships were established between [La⁻](b), VO₂, FAT(OXR), CHO(OXR), EE(FAT), EE(CHO), or EE(T) and plasma ion levels. Acute exercise at different submaximal intensities in euhydrated well-trained endurance athletes does not provoke a change in plasma trace element levels, suggesting that plasma volume plays an important role in the homeostasis of these elements during exercise.
Collapse
Affiliation(s)
- Carlos González-Haro
- Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, Spain.
| | | | | | | | | |
Collapse
|