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Vigh-Larsen JF, Ørtenblad N, Nielsen J, Emil Andersen O, Overgaard K, Mohr M. The Role of Muscle Glycogen Content and Localization in High-Intensity Exercise Performance: A Placebo-Controlled Trial. Med Sci Sports Exerc 2022; 54:2073-2086. [PMID: 35868015 DOI: 10.1249/mss.0000000000003002] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We investigated the coupling between muscle glycogen content and localization and high-intensity exercise performance using a randomized, placebo-controlled, parallel-group design with emphasis on single-fiber subcellular glycogen concentrations and sarcoplasmic reticulum Ca 2+ kinetics. METHODS Eighteen well-trained participants performed high-intensity intermittent glycogen-depleting exercise, followed by randomization to a high- (CHO; ~1 g CHO·kg -1 ·h -1 ; n = 9) or low-carbohydrate placebo diet (PLA, <0.1 g CHO·kg -1 ·h -1 ; n = 9) for a 5-h recovery period. At baseline, after exercise, and after the carbohydrate manipulation assessments of repeated sprint ability (5 × 6-s maximal cycling sprints with 24 s of rest), neuromuscular function and ratings of perceived exertion during standardized high-intensity cycling (~90% Wmax ) were performed, while muscle and blood samples were collected. RESULTS The exercise and carbohydrate manipulations led to distinct muscle glycogen concentrations in CHO and PLA at the whole-muscle (291 ± 78 vs 175 ± 100 mmol·kg -1 dry weight (dw), P = 0.020) and subcellular level in each of three local regions ( P = 0.001-0.046). This was coupled with near-depleted glycogen concentrations in single fibers of both main fiber types in PLA, especially in the intramyofibrillar region (within the myofibrils). Furthermore, increased ratings of perceived exertion and impaired repeated sprint ability (~8% loss, P < 0.001) were present in PLA, with the latter correlating moderately to very strongly ( r = 0.47-0.71, P = 0.001-0.049) with whole-muscle glycogen and subcellular glycogen fractions. Finally, sarcoplasmic reticulum Ca 2+ uptake, but not release, was superior in CHO, whereas neuromuscular function, including prolonged low-frequency force depression, was unaffected by dietary manipulation. CONCLUSIONS Together, these results support an important role of muscle glycogen availability for high-intensity exercise performance, which may be mediated by reductions in single-fiber levels, particularly in distinct subcellular regions, despite only moderately lowered whole-muscle glycogen concentrations.
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Affiliation(s)
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK
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Aibara C, Okada N, Watanabe D, Shi J, Wada M. Effects of high-intensity interval exercise on muscle fatigue and SR function in rats: a comparison with moderate-intensity continuous exercise. J Appl Physiol (1985) 2020; 129:343-352. [DOI: 10.1152/japplphysiol.00223.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Over the past decade, high-intensity interval exercise (HIIE) training has received attention as a more efficient training to improve endurance capacity. It is unclear, however, whether the extent of acute exercise-related muscle fatigue differs between HIIE and moderate-intensity continuous exercise, traditional endurance training. Here we provide evidence that restoration of force production takes a longer time after HIIE, which is ascribable to long-lasting depressions in Ca2+ release of the sarcoplasmic reticulum.
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Affiliation(s)
- Chihiro Aibara
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Naoki Okada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Daiki Watanabe
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
| | - Jiayu Shi
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Masanobu Wada
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
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Jannas-Vela S, Brownell S, Petrick HL, Heigenhauser GJF, Spriet LL, Holloway GP. Assessment of Na+/K+ ATPase Activity in Small Rodent and Human Skeletal Muscle Samples. Med Sci Sports Exerc 2020; 51:2403-2409. [PMID: 31634296 DOI: 10.1249/mss.0000000000002063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION In skeletal muscle, the Na/K ATPase (NKA) plays essential roles in processes linked to muscle contraction, fatigue, and energy metabolism; however, very little information exists regarding the regulation of NKA activity. The scarcity of information regarding NKA function in skeletal muscle likely stems from methodological constraints, as NKA contributes minimally to total cellular ATP utilization, and therefore contamination from other ATPases prevents the assessment of NKA activity in muscle homogenates. Here we introduce a method that improves accuracy and feasibility for the determination of NKA activity in small rodent muscle samples (5-10 mg) and in human skeletal muscle. METHODS Skeletal muscle homogenates from mice (n = 6) and humans (n = 3) were used to measure NKA and sarcoplasmic reticulum Ca ATPase (SERCA) activities with the addition of specific ATPase inhibitors to minimize "background noise." RESULTS We observed that myosin ATPase activity was the major interfering factor for estimation of NKA activity in skeletal muscle homogenates, as the addition of 25 μM of blebbistatin, a specific myosin ATPase inhibitor, considerably minimized "background noise" (threefold) and enabled the determination of NKA maximal activity with values three times higher than previously reported. The specificity of the assay was demonstrated after the addition of 2 mM ouabain, which completely inhibited NKA. On the other hand, the addition of blebbistatin did not affect the ability to measure SERCA function. The coefficient of variation for NKA and SERCA assays were 6.2% and 4.4%, respectively. CONCLUSION The present study has improved the methodology to determine NKA activity. We further show the feasibility of measuring NKA and SERCA activities from a common muscle homogenate. This methodology is expected to aid in our long-term understanding of how NKA affects skeletal muscle metabolic homeostasis and contractile function in diverse situations.
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Affiliation(s)
- Sebastian Jannas-Vela
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA.,Exercise Science Laboratory, Faculty of Medicine, School of Kinesiology, Universidad Finis Terrae, Santiago, CHILE
| | - Stuart Brownell
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | - Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | | | - Lawrence L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
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Kissane RWP, Egginton S, Askew GN. Regional variation in the mechanical properties and fibre-type composition of the rat extensor digitorum longus muscle. Exp Physiol 2017; 103:111-124. [DOI: 10.1113/ep086483] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 10/23/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Roger W. P. Kissane
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Stuart Egginton
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
| | - Graham N. Askew
- School of Biomedical Sciences; Faculty of Biological Sciences, University of Leeds; Leeds UK
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Sarcoplasmic Reticulum Phospholipid Fatty Acid Composition and Sarcolipin Content in Rat Skeletal Muscle. J Membr Biol 2015; 248:1089-96. [PMID: 26193810 DOI: 10.1007/s00232-015-9822-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 07/14/2015] [Indexed: 10/23/2022]
Abstract
In a previous study, we reported lower sarcoplasmic reticulum (SR) Ca(2+) pump ionophore ratios in rat soleus compared to red and white gastrocnemius (RG, WG) muscles which may be indicative of greater SR Ca(2+) permeability in soleus. Here we assessed the lipid composition of the SR membranes obtained from these muscles to determine if SR docosahexaenoic acid (DHA) content and fatty acid unsaturation could help to explain the previously observed differences in SR Ca(2+) permeability. Since we have shown previously that sarcolipin may also influence SR Ca(2+) permeability, we also examined the levels of sarcolipin in rat muscle. We found that SR membrane DHA content was significantly higher in soleus (5.3 ± 0.2 %) compared to RG (4.2 ± 0.2 %) and WG (3.3 ± 0.2 %). Likewise, total SR membrane unsaturation and unsaturation index (UI) were significantly higher in soleus (% unsaturation: 59.1 ± 2.4; UI: 362.9 ± 0.8) compared to RG (% unsaturation: 55.3 ± 1.0; UI: 320.9 ± 2.5) and WG (% unsaturation: 52.6 ± 1.1; UI: 310. ± 2.2). Sarcolipin protein was 17-fold more abundant in rat soleus compared to RG and was not detected in WG; however, comparisons between soleus, RG, and WG in sarcolipin-null mice revealed that, in the absence of sarcolipin, ionophore ratios are still lowest in soleus and highest in WG. Overall, our results suggest that SR membrane DHA content and unsaturation, and, in part, sarcolipin expression may contribute to SR Ca(2+) permeability and, in turn, may have implications in muscle-based metabolism and diet-induced obesity.
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Smith IC, Bombardier E, Vigna C, Tupling AR. ATP consumption by sarcoplasmic reticulum Ca²⁺ pumps accounts for 40-50% of resting metabolic rate in mouse fast and slow twitch skeletal muscle. PLoS One 2013; 8:e68924. [PMID: 23840903 PMCID: PMC3698183 DOI: 10.1371/journal.pone.0068924] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/03/2013] [Indexed: 11/18/2022] Open
Abstract
The main purpose of this study was to directly quantify the relative contribution of Ca2+ cycling to resting metabolic rate in mouse fast (extensor digitorum longus, EDL) and slow (soleus) twitch skeletal muscle. Resting oxygen consumption of isolated muscles (VO2, µL/g wet weight/s) measured polarographically at 30°C was ~20% higher (P<0.05) in soleus (0.326 ± 0.022) than in EDL (0.261 ± 0.020). In order to quantify the specific contribution of Ca2+ cycling to resting metabolic rate, the concentration of MgCl2 in the bath was increased to 10 mM to block Ca2+ release through the ryanodine receptor, thus eliminating a major source of Ca2+ leak from the sarcoplasmic reticulum (SR), and thereby indirectly inhibiting the activity of the sarco(endo) plasmic reticulum Ca2+-ATPases (SERCAs). The relative (%) reduction in muscle VO2 in response to 10 mM MgCl2 was similar between soleus (48.0±3.7) and EDL (42.4±3.2). Using a different approach, we attempted to directly inhibit SERCA ATPase activity in stretched EDL and soleus muscles (1.42x optimum length) using the specific SERCA inhibitor cyclopiazonic acid (CPA, up to 160 µM), but were unsuccessful in removing the energetic cost of Ca2+ cycling in resting isolated muscles. The results of the MgCl2 experiments indicate that ATP consumption by SERCAs is responsible for 40–50% of resting metabolic rate in both mouse fast- and slow-twitch muscles at 30°C, or 12–15% of whole body resting VO2. Thus, SERCA pumps in skeletal muscle could represent an important control point for energy balance regulation and a potential target for metabolic alterations to oppose obesity.
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Affiliation(s)
- Ian Curtis Smith
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Eric Bombardier
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Chris Vigna
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - A. Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
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Norris SM, Bombardier E, Smith IC, Vigna C, Tupling AR. ATP consumption by sarcoplasmic reticulum Ca2+ pumps accounts for 50% of resting metabolic rate in mouse fast and slow twitch skeletal muscle. Am J Physiol Cell Physiol 2009; 298:C521-9. [PMID: 20018953 DOI: 10.1152/ajpcell.00479.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we aimed to directly quantify the relative contribution of Ca(2+) cycling to resting metabolic rate in mouse fast-twitch (extensor digitorum longus, EDL) and slow-twitch (soleus) skeletal muscle. Resting oxygen consumption of isolated muscles (Vo(2), microl.g wet wt(-1).s(-1)) measured polarographically at 30 degrees C was approximately 25% higher in soleus (0.61 +/- .03) than in EDL (0.46 +/- .03). To quantify the specific contribution of Ca(2+) cycling to resting metabolic rate, cyclopiazonic acid (CPA), a highly specific inhibitor of sarco(endo)plasmic reticulum Ca(2+) ATPases (SERCAs), was added to the bath at different concentrations (1, 5, 10, and 15 microM). There was a concentration-dependent effect of CPA on Vo(2), with increasing CPA concentrations up to 10 microM resulting in progressively greater reductions in muscle Vo(2). There were no differences between 10 and 15 microM CPA, indicating that 10 microM CPA induces maximal inhibition of SERCAs in isolated muscle preparations. Relative reduction in muscle Vo(2) in response to CPA was nearly identical in EDL (1 microM, 10.6 +/- 3.0%; 5 microM, 33.2 +/- 3.4%; 10 microM, 49.2 +/- 2.9%; 15 microM, 50.9 +/- 2.1%) and soleus (1 microM, 11.2 +/- 1.5%; 5 microM, 37.7 +/- 2.4%; 10 microM, 50.0 +/- 1.3%; 15 microM, 49.9 +/- 1.6%). The results indicate that ATP consumption by SERCAs is responsible for approximately 50% of resting metabolic rate in both mouse fast- and slow-twitch muscles at 30 degrees C. Thus SERCA pumps in skeletal muscle could represent an important control point for energy balance regulation and a potential target for metabolic alterations to oppose obesity.
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Duhamel TA, Green HJ, Stewart RD, Foley KP, Smith IC, Ouyang J. Muscle metabolic, SR Ca2+-cycling responses to prolonged cycling, with and without glucose supplementation. J Appl Physiol (1985) 2007; 103:1986-98. [DOI: 10.1152/japplphysiol.01440.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study investigated the effects of prolonged exercise, with and without glucose supplementation, on metabolism and sarcoplasmic reticulum (SR) Ca2+-handling properties in working vastus lateralis muscle. Fifteen untrained volunteers [peak O2consumption (V̇o2peak) = 3.45 ± 0.17 l/min; mean ± SE] cycled at ∼60% V̇o2peakon two occasions, during which they were provided with either an artificially sweetened placebo beverage (NG) or a 6% glucose (G) beverage (∼1.00 g carbohydrate/kg body mass). Beverage supplementation started at 30 min of exercise and continued every 15 min thereafter. SR Ca2+handling, metabolic, and substrate responses were assessed in tissue extracted from the vastus lateralis at rest, after 30 min and 90 min of exercise, and at fatigue in both conditions. Plasma glucose during G was 15–23% higher ( P < 0.05) than those observed during NG following 60 min of exercise until fatigue. Cycle time to fatigue was increased ( P < 0.05) by ∼19% during G (137 ± 7 min) compared with NG (115 ± 6 min). Prolonged exercise reduced ( P < 0.05) maximal Ca2+-ATPase activity (−18.4%), SR Ca2+uptake (−27%), and both Phase 1 (−22.2%) and Phase 2 (−34.2%) Ca2+-release rates during NG. The exercise-induced reductions in SR Ca2+-cycling properties were not altered during G. The metabolic responses to exercise were all unaltered by glucose supplementation, since no differences in respiratory exchange ratios, carbohydrate and lipid oxidation rates, and muscle metabolite and glycogen contents were observed between NG and G. These results indicate that the maintenance of blood glucose homeostasis by glucose supplementation is without effect in modifying the muscle metabolic, endogenous glycogen, or SR Ca2+-handling responses.
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Tupling AR, Vigna C, Ford RJ, Tsuchiya SC, Graham DA, Denniss SG, Rush JWE. Effects of buthionine sulfoximine treatment on diaphragm contractility and SR Ca2+ pump function in rats. J Appl Physiol (1985) 2007; 103:1921-8. [PMID: 17717121 DOI: 10.1152/japplphysiol.00529.2007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to examine the effects of glutathione (GSH) depletion and cellular oxidation on rat diaphragm contractility and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) function in vitro under basal conditions and following fatiguing stimulation. Buthionine sulfoximine (BSO) treatment (n = 10) for 10 days (20 mM in drinking water) reduced (P < 0.05) diaphragm GSH content (nmol/mg protein) and the ratio of GSH to glutathione disulfide (GSH/GSSG) by 91% and 71%, respectively, compared with controls (CTL) (n = 10). Western blotting showed that Hsp70 expression in diaphragm was not increased (P > 0.05) with BSO treatment. As hypothesized, basal peak twitch force (g/mm(2)) was increased (P < 0.05), and fatigability in response to repetitive stimulation (350-ms trains at 100 Hz once every 1 s for 5 min) was also increased (P < 0.05) in BSO compared with CTL. Both Ca(2+) uptake and maximal SERCA activity (mumol.g protein(-1).min(-1)) measured in diaphragm homogenates that were prepared at rest were increased (P < 0.05) with BSO treatment, an effect that could be partly explained by a twofold increase (P < 0.05) in SERCA2a expression with BSO. In response to the 5-min stimulation protocol, both Ca(2+) uptake and maximal SERCA activity were increased (P < 0.05) in CTL but not (P > 0.05) in BSO diaphragm. We conclude that 1) cellular redox state is more optimal for contractile function and fatigability is increased in rat diaphragm following BSO treatment, 2) SERCA2a expression is modulated by redox signaling, and 3) regulation of SERCA function in working diaphragm is altered following BSO treatment.
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Affiliation(s)
- A R Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
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