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Debold EP, Westerblad H. New insights into the cellular and molecular mechanisms of skeletal muscle fatigue: the Marion J. Siegman Award Lectureships. Am J Physiol Cell Physiol 2024; 327:C946-C958. [PMID: 39069825 DOI: 10.1152/ajpcell.00213.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/30/2024]
Abstract
Skeletal muscle fibers need to have mechanisms to decrease energy consumption during intense physical exercise to avoid devastatingly low ATP levels, with the formation of rigor cross bridges and defective ion pumping. These protective mechanisms inevitably lead to declining contractile function in response to intense exercise, characterizing fatigue. Through our work, we have gained insights into cellular and molecular mechanisms underlying the decline in contractile function during acute fatigue. Key mechanistic insights have been gained from studies performed on intact and skinned single muscle fibers and more recently from studies performed and single myosin molecules. Studies on intact single fibers revealed several mechanisms of impaired sarcoplasmic reticulum Ca2+ release and experiments on single myosin molecules provide direct evidence of how putative agents of fatigue impact myosin's ability to generate force and motion. We conclude that changes in metabolites due to an increased dependency on anaerobic metabolism (e.g., accumulation of inorganic phosphate ions and H+) act to directly and indirectly (via decreased Ca2+ activation) inhibit myosin's force and motion-generating capacity. These insights into the acute mechanisms of fatigue may help improve endurance training strategies and reveal potential targets for therapies to attenuate fatigue in chronic diseases.
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Affiliation(s)
- Edward P Debold
- Muscle Biophysics Lab, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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2
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Housley SN, Gardolinski EA, Nardelli P, Reed J, Rich MM, Cope TC. Mechanosensory encoding in ex vivo muscle-nerve preparations. Exp Physiol 2024; 109:35-44. [PMID: 37119460 PMCID: PMC10613129 DOI: 10.1113/ep090763] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/12/2023] [Indexed: 05/01/2023]
Abstract
Our objective was to evaluate an ex vivo muscle-nerve preparation used to study mechanosensory signalling by low threshold mechanosensory receptors (LTMRs). Specifically, we aimed to assess how well the ex vivo preparation represents in vivo firing behaviours of the three major LTMR subtypes of muscle primary sensory afferents, namely type Ia and II muscle spindle (MS) afferents and type Ib tendon organ afferents. Using published procedures for ex vivo study of LTMRs in mouse hindlimb muscles, we replicated earlier reports on afferent firing in response to conventional stretch paradigms applied to non-contracting, that is passive, muscle. Relative to in vivo studies, stretch-evoked firing for confirmed MS afferents in the ex vivo preparation was markedly reduced in firing rate and deficient in encoding dynamic features of muscle stretch. These deficiencies precluded conventional means of discriminating type Ia and II afferents. Muscle afferents, including confirmed Ib afferents were often indistinguishable based on their similar firing responses to the same physiologically relevant stretch paradigms. These observations raise uncertainty about conclusions drawn from earlier ex vivo studies that either attribute findings to specific afferent types or suggest an absence of treatment effects on dynamic firing. However, we found that replacing the recording solution with bicarbonate buffer resulted in afferent firing rates and profiles more like those seen in vivo. Improving representation of the distinctive sensory encoding properties in ex vivo muscle-nerve preparations will promote accuracy in assigning molecular markers and mechanisms to heterogeneous types of muscle mechanosensory neurons.
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Affiliation(s)
- Stephen N. Housley
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | | | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - J'Ana Reed
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - Mark M. Rich
- Department of Neuroscience, Cell Biology and PhysiologyWright State UniversityDaytonOHUSA
| | - Timothy C. Cope
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
- W.H. Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of Technology, Georgia Institute of TechnologyAtlantaGAUSA
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3
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Hoshino D, Wada R, Mori Y, Takeda R, Nonaka Y, Kano R, Takagi R, Kano Y. Cooling of male rat skeletal muscle during endurance-like contraction attenuates contraction-induced PGC-1α mRNA expression. Physiol Rep 2023; 11:e15867. [PMID: 37962014 PMCID: PMC10644292 DOI: 10.14814/phy2.15867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/02/2023] [Accepted: 11/02/2023] [Indexed: 11/15/2023] Open
Abstract
This study aimed to determine effects of cooling on contraction-induced peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and vascular endothelial growth factor (VEGF) gene expression, phosphorylations of its related protein kinases, and metabolic responses. Male rats were separated into two groups; room temperature (RT) or ice-treated (COLD) on the right tibialis anterior (TA). The TA was contracted isometrically using nerve electrical stimulation (1-s stimulation × 30 contractions, with 1-s intervals, for 10 sets with 1-min intervals). The TA was treated before the contraction and during 1-min intervals with an ice pack for the COLD group and a water pack at RT for the RT group. The muscle temperature of the COLD group decreased to 19.42 ± 0.44°C (p < 0.0001, -36.4%) compared with the RT group after the experimental protocol. An increase in mRNA expression level of PGC-1α, not VEGF, after muscle contractions was significantly lower in the COLD group than in the RT group (p < 0.0001, -63.0%). An increase in phosphorylated AMP-activated kinase (AMPK) (p = 0.0037, -28.8%) and a decrease in glycogen concentration (p = 0.0231, +106.3%) after muscle contraction were also significantly inhibited by cooling. Collectively, muscle cooling attenuated the post-contraction increases in PGC-1α mRNA expression coinciding with decreases in AMPK phosphorylation and glycogen degradation.
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Affiliation(s)
- Daisuke Hoshino
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
| | - Ryota Wada
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
| | - Yutaro Mori
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
| | - Reo Takeda
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
| | - Yudai Nonaka
- Institute of Liberal Arts and Science, Kanazawa UniversityKanazawaJapan
| | - Ryotaro Kano
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
| | - Ryo Takagi
- Ritsumeikan Global Innovation Research OrganizationRitsumeikan UniversityKusatsu, ShigaJapan
| | - Yutaka Kano
- Bioscience and Technology Program, Department of Engineering ScienceThe University of Electro‐CommunicationsChofu, TokyoJapan
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4
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Jalali F, Nazari MA, Bahrami A, Perrier P, Payan Y. FIM: A fatigued-injured muscle model based on the sliding filament theory. Comput Biol Med 2023; 164:107367. [PMID: 37595519 DOI: 10.1016/j.compbiomed.2023.107367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/24/2023] [Accepted: 08/12/2023] [Indexed: 08/20/2023]
Abstract
Skeletal muscle modeling has a vital role in movement studies and the development of therapeutic approaches. In the current study, a Huxley-based model for skeletal muscle is proposed, which demonstrates the impact of impairments in muscle characteristics. This model focuses on three identified ions: H+, inorganic phosphate Pi, and Ca2+. Modifications are made to actin-myosin attachment and detachment rates to study the effects of H+ and Pi. Additionally, an activation coefficient is included to represent the role of calcium ions interacting with troponin, highlighting the importance of Ca2+. It is found that maximum isometric muscle force decreases by 9.5% due to a reduction in pH from 7.4 to 6.5 and by 47.5% in case of the combination of a reduction in pH and an increase of Pi concentration up to 30 mM, respectively. Then the force decline caused by a fall in the active calcium ions is studied. When only 15% of the total calcium in the myofibrillar space is able to interact with troponin, up to 80% force drop is anticipated by the model. The proposed fatigued-injured muscle model is useful to study the effect of various shortening velocities and initial muscle-tendon lengths on muscle force; in addition, the benefits of the model go beyond predicting the force in different conditions as it can also predict muscle stiffness and power. The power and stiffness decrease by 40% and 6.5%, respectively, due to the pH reduction, and the simultaneous accumulation of H+ and Pi leads to a 50% and 18% drop in power and stiffness.
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Affiliation(s)
- Fatemeh Jalali
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Mohammad Ali Nazari
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran; Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, 38000, Grenoble, France.
| | - Arash Bahrami
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Pascal Perrier
- Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, 38000, Grenoble, France
| | - Yohan Payan
- Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, 38000, Grenoble, France
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5
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Michel CP, Bendahan D, Giannesini B, Vilmen C, Le Fur Y, Messonnier LA. Effects of hydroxyurea on skeletal muscle energetics and force production in a sickle cell disease murine model. J Appl Physiol (1985) 2023; 134:415-425. [PMID: 36603048 DOI: 10.1152/japplphysiol.00333.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hydroxyurea (HU) is commonly used as a treatment for patients with sickle cell disease (SCD) to enhance fetal hemoglobin production. This increased production is expected to reduce anemia (which depresses oxygen transport) and abnormal Hb content alleviating clinical symptoms such as vaso-occlusive crisis and acute chest syndrome. The effects of HU on skeletal muscle bioenergetics in vivo are still unknown. Due to the beneficial effects of HU upon oxygen delivery, improved skeletal muscle energetics and function in response to a HU treatment have been hypothesized. Muscle energetics and function were analyzed during a standardized rest-exercise-recovery protocol, using 31P-magnetic resonance spectroscopy in Townes SCD mice. Measurements were performed in three groups of mice: one group of 2-mo-old mice (SCD2m, n = 8), another one of 4-mo-old mice (SCD4m, n = 8), and a last group of 4-mo-old mice that have been treated from 2 mo of age with HU at 50 mg/kg/day (SCD4m-HU, n = 8). As compared with SCD2m mice, SCD4m mice were heavier and displayed a lower acidosis. As lower specific forces were developed by SCD4m compared with SCD2m, greater force-normalized phosphocreatine consumption and oxidative and nonoxidative costs of contraction were also reported. HU-treated mice (SCD4m-HU) displayed a significantly higher specific force production as compared with untreated mice (SCD4m), whereas muscle energetics was unchanged. Overall, our results support a beneficial effect of HU on muscle function.NEW & NOTEWORTHY Our results highlighted that force production decreases between 2 and 4 mo of age in SCD mice thereby indicating a decrease of muscle function during this period. Of interest, HU treatment seemed to blunt the observed age effect given that SCD4m-HU mice displayed a higher specific force production as compared with SCD4m mice. In that respect, HU treatment would help to maintain a higher capacity of force production during aging in SCD.
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Affiliation(s)
| | - David Bendahan
- CNRS, CRMBM, Aix-Marseille Université, Marseille, France
| | | | | | - Yann Le Fur
- CNRS, CRMBM, Aix-Marseille Université, Marseille, France
| | - Laurent A Messonnier
- Laboratoire Interuniversitaire de Biologie de la Motricité EA7424, Université Savoie Mont Blanc, Chambéry, France
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6
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Månsson A, Rassier DE. Insights into Muscle Contraction Derived from the Effects of Small-Molecular Actomyosin-Modulating Compounds. Int J Mol Sci 2022; 23:ijms232012084. [PMID: 36292937 PMCID: PMC9603234 DOI: 10.3390/ijms232012084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 09/25/2022] [Accepted: 10/03/2022] [Indexed: 01/10/2023] Open
Abstract
Bottom-up mechanokinetic models predict ensemble function of actin and myosin based on parameter values derived from studies using isolated proteins. To be generally useful, e.g., to analyze disease effects, such models must also be able to predict ensemble function when actomyosin interaction kinetics are modified differently from normal. Here, we test this capability for a model recently shown to predict several physiological phenomena along with the effects of the small molecular compound blebbistatin. We demonstrate that this model also qualitatively predicts effects of other well-characterized drugs as well as varied concentrations of MgATP. However, the effects of one compound, amrinone, are not well accounted for quantitatively. We therefore systematically varied key model parameters to address this issue, leading to the increased amplitude of the second sub-stroke of the power stroke from 1 nm to 2.2 nm, an unchanged first sub-stroke (5.3−5.5 nm), and an effective cross-bridge attachment rate that more than doubled. In addition to better accounting for the effects of amrinone, the modified model also accounts well for normal physiological ensemble function. Moreover, a Monte Carlo simulation-based version of the model was used to evaluate force−velocity data from small myosin ensembles. We discuss our findings in relation to key aspects of actin−myosin operation mechanisms causing a non-hyperbolic shape of the force−velocity relationship at high loads. We also discuss remaining limitations of the model, including uncertainty of whether the cross-bridge elasticity is linear or not, the capability to account for contractile properties of very small actomyosin ensembles (<20 myosin heads), and the mechanism for requirements of a higher cross-bridge attachment rate during shortening compared to during isometric contraction.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82 Kalmar, Sweden
- Correspondence: ; Tel.: +46-708-866243
| | - Dilson E. Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada
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Biochemical and tensometric analysis of C(60) fullerenes protective effect on the development of skeletal muscle fatigue. UKRAINIAN BIOCHEMICAL JOURNAL 2021. [DOI: 10.15407/ubj93.04.093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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8
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Gordon RJ, Tyler CJ, Castelli F, Diss CE, Tillin NA. Progressive hyperthermia elicits distinct responses in maximum and rapid torque production. J Sci Med Sport 2021; 24:811-817. [DOI: 10.1016/j.jsams.2021.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/18/2021] [Accepted: 03/09/2021] [Indexed: 11/30/2022]
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9
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Maximal muscular power: lessons from sprint cycling. SPORTS MEDICINE-OPEN 2021; 7:48. [PMID: 34268627 PMCID: PMC8282832 DOI: 10.1186/s40798-021-00341-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/29/2021] [Indexed: 02/07/2023]
Abstract
Maximal muscular power production is of fundamental importance to human functional capacity and feats of performance. Here, we present a synthesis of literature pertaining to physiological systems that limit maximal muscular power during cyclic actions characteristic of locomotor behaviours, and how they adapt to training. Maximal, cyclic muscular power is known to be the main determinant of sprint cycling performance, and therefore we present this synthesis in the context of sprint cycling. Cyclical power is interactively constrained by force-velocity properties (i.e. maximum force and maximum shortening velocity), activation-relaxation kinetics and muscle coordination across the continuum of cycle frequencies, with the relative influence of each factor being frequency dependent. Muscle cross-sectional area and fibre composition appear to be the most prominent properties influencing maximal muscular power and the power-frequency relationship. Due to the role of muscle fibre composition in determining maximum shortening velocity and activation-relaxation kinetics, it remains unclear how improvable these properties are with training. Increases in maximal muscular power may therefore arise primarily from improvements in maximum force production and neuromuscular coordination via appropriate training. Because maximal efforts may need to be sustained for ~15-60 s within sprint cycling competition, the ability to attenuate fatigue-related power loss is also critical to performance. Within this context, the fatigued state is characterised by impairments in force-velocity properties and activation-relaxation kinetics. A suppression and leftward shift of the power-frequency relationship is subsequently observed. It is not clear if rates of power loss can be improved with training, even in the presence adaptations associated with fatigue-resistance. Increasing maximum power may be most efficacious for improving sustained power during brief maximal efforts, although the inclusion of sprint interval training likely remains beneficial. Therefore, evidence from sprint cycling indicates that brief maximal muscular power production under cyclical conditions can be readily improved via appropriate training, with direct implications for sprint cycling as well as other athletic and health-related pursuits.
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10
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Martin-Rincon M, Gelabert-Rebato M, Perez-Valera M, Galvan-Alvarez V, Morales-Alamo D, Dorado C, Boushel R, Hallen J, Calbet JAL. Functional reserve and sex differences during exercise to exhaustion revealed by post-exercise ischaemia and repeated supramaximal exercise. J Physiol 2021; 599:3853-3878. [PMID: 34159610 DOI: 10.1113/jp281293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 06/17/2021] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Females have lower fatigability than males during single limb isometric and dynamic contractions, but whether sex-differences exist during high-intensity whole-body exercise remains unknown. This study shows that males and females respond similarly to repeated supramaximal whole-body exercise, and that at task failure a large functional reserve remains in both sexes. Using post-exercise ischaemia with repeated exercise, we have shown that this functional reserve depends on the glycolytic component of substrate-level phosphorylation and is almost identical in both sexes. Metaboreflex activation during post-exercise ischaemia and the O2 debt per kg of active lean mass are also similar in males and females after supramaximal exercise. Females have a greater capacity to extract oxygen during repeated supramaximal exercise and reach lower P ETC O 2 , experiencing a larger drop in brain oxygenation than males, without apparent negative repercussion on performance. Females had no faster recovery of performance after accounting for sex differences in lean mass. ABSTRACT The purpose of this study was to ascertain what mechanisms explain sex differences at task failure and to determine whether males and females have a functional reserve at exhaustion. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation were determined in 18 males and 18 females (21-36 years old) in two sessions consisting of three bouts of constant-power exercise at 120% of V ̇ O 2 max until exhaustion interspaced by 20 s recovery periods. In one of the two sessions, the circulation of both legs was occluded instantaneously (300 mmHg) during the recovery periods. Females had a higher muscle O2 extraction during fatiguing supramaximal exercise than males. Metaboreflex activation, and lean mass-adjusted O2 deficit and debt were similar in males and females. Compared to males, females reached lower P ETC O 2 and brain oxygenation during supramaximal exercise, without apparent negative consequences on performance. After the occlusions, males and females were able to restart exercising at 120% of V ̇ O 2 max , revealing a similar functional reserve, which depends on glycolytic component of substrate-level phosphorylation and its rate of utilization. After ischaemia, muscle O2 extraction was increased, and muscle V ̇ O 2 was similarly reduced in males and females. The physiological response to repeated supramaximal exercise to exhaustion is remarkably similar in males and females when differences in lean mass are considered. Both sexes fatigue with a large functional reserve, which depends on the glycolytic energy supply, yet females have higher oxygen extraction capacity, but reduced P ETC O 2 and brain oxygenation.
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Affiliation(s)
- Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Miriam Gelabert-Rebato
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Mario Perez-Valera
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Victor Galvan-Alvarez
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Robert Boushel
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jostein Hallen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Jose A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
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11
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Rockenfeller R, Günther M, Stutzig N, Haeufle DFB, Siebert T, Schmitt S, Leichsenring K, Böl M, Götz T. Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model. Front Physiol 2020; 11:306. [PMID: 32431619 PMCID: PMC7214688 DOI: 10.3389/fphys.2020.00306] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/19/2020] [Indexed: 12/01/2022] Open
Abstract
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Affiliation(s)
| | - Michael Günther
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
- Friedrich-Schiller-University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel F. B. Haeufle
- Hertie-Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls-University, Tübingen, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Syn Schmitt
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
| | - Kay Leichsenring
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Thomas Götz
- Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany
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12
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Olsson K, Cheng AJ, Al‐Ameri M, Wyckelsma VL, Rullman E, Westerblad H, Lanner JT, Gustafsson T, Bruton JD. Impaired sarcoplasmic reticulum Ca2+release is the major cause of fatigue‐induced force loss in intact single fibres from human intercostal muscle. J Physiol 2019; 598:773-787. [DOI: 10.1113/jp279090] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 11/22/2019] [Indexed: 12/15/2022] Open
Affiliation(s)
- Karl Olsson
- Department of Laboratory MedicineSection of Clinical PhysiologyKarolinska Institutet Alfred Nobels Allé 8 141 52 Huddinge Sweden
| | - Arthur J. Cheng
- Department of Physiology and PharmacologyBiomedicum C5Karolinska Institutet Tomtebodavägen 16 Solna 171 65 Sweden
- School of Kinesiology and Health ScienceFaculty of HealthYork University 4700 Keele Street Toronto Canada M3J 1P3
| | - Mamdoh Al‐Ameri
- Department of Molecular Medicine and SurgeryKarolinska InstitutetKarolinska University Hospital Solna 171 76 Stockholm Sweden
| | - Victoria L. Wyckelsma
- Department of Physiology and PharmacologyBiomedicum C5Karolinska Institutet Tomtebodavägen 16 Solna 171 65 Sweden
| | - Eric Rullman
- Department of Laboratory MedicineSection of Clinical PhysiologyKarolinska Institutet Alfred Nobels Allé 8 141 52 Huddinge Sweden
| | - Håkan Westerblad
- Department of Physiology and PharmacologyBiomedicum C5Karolinska Institutet Tomtebodavägen 16 Solna 171 65 Sweden
| | - Johanna T. Lanner
- Department of Physiology and PharmacologyBiomedicum C5Karolinska Institutet Tomtebodavägen 16 Solna 171 65 Sweden
| | - Thomas Gustafsson
- Department of Laboratory MedicineSection of Clinical PhysiologyKarolinska Institutet Alfred Nobels Allé 8 141 52 Huddinge Sweden
| | - Joseph D. Bruton
- Department of Physiology and PharmacologyBiomedicum C5Karolinska Institutet Tomtebodavägen 16 Solna 171 65 Sweden
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13
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Cooney AL, Thornell IM, Singh BK, Shah VS, Stoltz DA, McCray PB, Zabner J, Sinn PL. A Novel AAV-mediated Gene Delivery System Corrects CFTR Function in Pigs. Am J Respir Cell Mol Biol 2019; 61:747-754. [PMID: 31184507 PMCID: PMC6890402 DOI: 10.1165/rcmb.2019-0006oc] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 06/05/2019] [Indexed: 11/24/2022] Open
Abstract
Cystic fibrosis is an autosomal-recessive disease that is caused by a mutant CFTR (cystic fibrosis transmembrane conductance regulator) gene and is characterized by chronic bacterial lung infections and inflammation. Complementation with functional CFTR normalizes anion transport across the airway surface. Adeno-associated virus (AAV) is a useful vector for gene therapy because of its low immunogenicity and ability to persist for months to years. However, because its episomal expression may decrease after cell division, readministration of the AAV vector may be required. To overcome this, we designed an integrating AAV-based CFTR-expressing vector, termed piggyBac (PB)/AAV, carrying CFTR flanked by the terminal repeats of the piggyBac transposon. With codelivery of the piggyBac transposase, PB/AAV can integrate into the host genome. Because of the packaging constraints of AAV, careful consideration was required to ensure that the vector would package and express its CFTR cDNA cargo. In this short-term study, PB/AAV-CFTR was aerosolized to the airways of CF pigs in the absence of the transposase. Two weeks later, transepithelial Cl- current was restored in freshly excised tracheal and bronchial tissue. Additionally, we observed an increase in tracheal airway surface liquid pH and bacterial killing in comparison with untreated CF pigs. Airway surface liquid from primary airway cells cultured from treated CF pigs exhibited increased pH correlating with decreased viscosity. Together, these results show that complementing CFTR in CF pigs with PB/AAV rescues the anion transport defect in a large-animal CF model. Delivery of this integrating viral vector system to airway progenitor cells could lead to persistent, life-long expression in vivo.
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Affiliation(s)
- Ashley L. Cooney
- Stead Family Department of Pediatrics
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
| | - Ian M. Thornell
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Brajesh K. Singh
- Stead Family Department of Pediatrics
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
| | - Viral S. Shah
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - David A. Stoltz
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Paul B. McCray
- Stead Family Department of Pediatrics
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
| | - Joseph Zabner
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Patrick L. Sinn
- Stead Family Department of Pediatrics
- Pappajohn Biomedical Institute
- Center for Gene Therapy, and
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14
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Månsson A. The effects of inorganic phosphate on muscle force development and energetics: challenges in modelling related to experimental uncertainties. J Muscle Res Cell Motil 2019; 42:33-46. [PMID: 31620962 PMCID: PMC7932973 DOI: 10.1007/s10974-019-09558-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 10/09/2019] [Indexed: 02/03/2023]
Abstract
Muscle force and power are developed by myosin cross-bridges, which cyclically attach to actin, undergo a force-generating transition and detach under turnover of ATP. The force-generating transition is intimately associated with release of inorganic phosphate (Pi) but the exact sequence of events in relation to the actual Pi release step is controversial. Details of this process are reflected in the relationships between [Pi] and the developed force and shortening velocity. In order to account for these relationships, models have proposed branched kinetic pathways or loose coupling between biochemical and force-generating transitions. A key hypothesis underlying the present study is that such complexities are not required to explain changes in the force–velocity relationship and ATP turnover rate with altered [Pi]. We therefore set out to test if models without branched kinetic paths and Pi-release occurring before the main force-generating transition can account for effects of varied [Pi] (0.1–25 mM). The models tested, one assuming either linear or non-linear cross-bridge elasticity, account well for critical aspects of muscle contraction at 0.5 mM Pi but their capacity to account for the maximum power output vary. We find that the models, within experimental uncertainties, account for the relationship between [Pi] and isometric force as well as between [Pi] and the velocity of shortening at low loads. However, in apparent contradiction with available experimental findings, the tested models produce an anomalous force–velocity relationship at elevated [Pi] and high loads with more than one possible velocity for a given load. Nevertheless, considering experimental uncertainties and effects of sarcomere non-uniformities, these discrepancies are insufficient to refute the tested models in favour of more complex alternatives.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Universitetskajen, 391 82, Kalmar, Sweden.
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15
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Physiological Significance of the Force-Velocity Relation in Skeletal Muscle and Muscle Fibers. Int J Mol Sci 2019; 20:ijms20123075. [PMID: 31238505 PMCID: PMC6627110 DOI: 10.3390/ijms20123075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/09/2019] [Accepted: 06/14/2019] [Indexed: 11/16/2022] Open
Abstract
The relation between the force (load) and the velocity of shortening (V) in contracting skeletal muscle is part of a rectangular hyperbola: (P + a) V = b(Po − P); where Po is the maximum isometric force and a and b are constants. The force–velocity (P–V) relation suggests that muscle can regulate its energy output depending on the load imposed on it (Hill, 1938). After the establishment of the sliding filament mechanism (H.E. Huxley and Hanson, 1954), the P–V relation has been regarded to reflect the cyclic interaction between myosin heads in myosin filaments and the corresponding myosin-binding sites in actin filaments, coupled with ATP hydrolysis (A.F. Huxley, 1957). In single skeletal muscle fibers, however, the P–V relation deviates from the hyperbola at the high force region, indicating complicated characteristics of the cyclic actin–myosin interaction. To correlate the P–V relation with kinetics of actin–myosin interaction, skinned muscle fibers have been developed, in which the surface membrane is removed to control chemical and ionic conditions around the 3D lattice of actin and myosin filaments. This article also deals with experimental methods with which the structural instability of skinned fibers can be overcome by applying parabolic decreases in fiber length.
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16
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Sundberg CW, Fitts RH. Bioenergetic basis of skeletal muscle fatigue. CURRENT OPINION IN PHYSIOLOGY 2019; 10:118-127. [PMID: 31342000 DOI: 10.1016/j.cophys.2019.05.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Energetic demand from high-intensity exercise can easily exceed ATP synthesis rates of mitochondria leading to a reliance on anaerobic metabolism. The reliance on anaerobic metabolism results in the accumulation of intracellular metabolites, namely inorganic phosphate (Pi) and hydrogen (H+), that are closely associated with exercise-induced reductions in power. Cellular and molecular studies have revealed several steps where these metabolites impair contractile function demonstrating a causal role in fatigue. Elevated Pi or H+ directly inhibits force and power of the cross-bridge and decreases myofibrillar Ca2+ sensitivity, whereas Pi also inhibits Ca2+ release from the sarcoplasmic reticulum (SR). When both metabolites are elevated, they act synergistically to cause marked reductions in power, indicating that fatigue during high-intensity exercise has a bioenergetic basis.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI.,Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI
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17
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Mami S, Khaje G, Shahriari A, Gooraninejad S. Evaluation of Biological Indicators of Fatigue and Muscle Damage in Arabian Horses After Race. J Equine Vet Sci 2019; 78:74-78. [PMID: 31203988 DOI: 10.1016/j.jevs.2019.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/20/2019] [Accepted: 04/18/2019] [Indexed: 11/18/2022]
Abstract
The aim of this study was to assay changes in blood biochemical parameters that resulted from exercise-induced muscle fatigue in horses participating in the two races (1,250 and 1,400 meters). Six male Arabian horses (3 to 6 years old) were used in this study. Blood samples were collected at time intervals including 1 hour before the race, immediately after the race, 1 and 24 hours after the end of race. Catalase (CAT), superoxide dismutase, glutathione peroxidase (GPX) activities, the blood level of malondialdehyde, protein carbonyl, and total antioxidant capacity (TAC) were measured, as well as muscle damage biomarkers including aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) activities, and myoglobin were measured. The results showed that CAT activity and plasma TAC in the horse increased immediately after the race and then gradually decreased. The highest GPX activity in red blood cells was recorded 1 hour before the start of the race. Superoxide dismutase showed an incremental pattern after the race. Immediately after the race, there was a significant increase in the plasma levels of AST, which continued until 1 hour after the race. The activity of LDH and CK reached its highest value 1 hour after the race. According to our findings, it can be concluded that the horses were tired and antioxidant enzymes altered under fatigue conditions. Muscle damage biomarkers have increased, but these increases were in their natural ranges and did not indicate muscle damage in horses.
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Affiliation(s)
- Sajad Mami
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Gholamhossein Khaje
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Ali Shahriari
- Department of Basic Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
| | - Saad Gooraninejad
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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18
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Månsson A. Comparing models with one versus multiple myosin-binding sites per actin target zone: The power of simplicity. J Gen Physiol 2019; 151:578-592. [PMID: 30872560 PMCID: PMC6445577 DOI: 10.1085/jgp.201812301] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 02/16/2019] [Indexed: 01/21/2023] Open
Abstract
Mechanokinetic statistical models describe the mechanisms of muscle contraction on the basis of the average behavior of a large ensemble of actin-myosin motors. Such models often assume that myosin II motor domains bind to regularly spaced, discrete target zones along the actin-based thin filaments and develop force in a series of strain-dependent transitions under the turnover of ATP. The simplest models assume that there is just one myosin-binding site per target zone and a uniform spatial distribution of the myosin motor domains in relation to each site. However, most of the recently developed models assume three myosin-binding sites per target zone, and some models include a spatially explicit 3-D treatment of the myofilament lattice and thereby of the geometry of the actin-myosin contact points. Here, I show that the predictions for steady-state contractile behavior of muscle are very similar whether one or three myosin-binding sites per target zone is assumed, provided that the model responses are appropriately scaled to the number of sites. Comparison of the model predictions for isometrically contracting mammalian muscle cells suggests that each target zone contains three or more myosin-binding sites. Finally, I discuss the strengths and weaknesses of one-site spatially inexplicit models in relation to three-site models, including those that take into account the detailed 3-D geometry of the myofilament lattice. The results of this study suggest that single-site models, with reduced computational cost compared with multisite models, are useful for several purposes, e.g., facilitated molecular mechanistic insights.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
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19
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Thornell IM, Li X, Tang XX, Brommel CM, Karp PH, Welsh MJ, Zabner J. Nominal carbonic anhydrase activity minimizes airway-surface liquid pH changes during breathing. Physiol Rep 2019; 6. [PMID: 29380953 PMCID: PMC5789725 DOI: 10.14814/phy2.13569] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/29/2017] [Accepted: 12/04/2017] [Indexed: 12/26/2022] Open
Abstract
The airway-surface liquid pH (pHASL ) is slightly acidic relative to the plasma and becomes more acidic in airway diseases, leading to impaired host defense. CO2 in the large airways decreases during inspiration (0.04% CO2 ) and increases during expiration (5% CO2 ). Thus, we hypothesized that pHASL would fluctuate during the respiratory cycle. We measured pHASL on cultures of airway epithelia while changing apical CO2 concentrations. Changing apical CO2 produced only very slow pHASL changes, occurring in minutes, inconsistent with respiratory phases that occur in a few seconds. We hypothesized that pH changes were slow because airway-surface liquid has little carbonic anhydrase activity. To test this hypothesis, we applied the carbonic anhydrase inhibitor acetazolamide and found minimal effects on CO2 -induced pHASL changes. In contrast, adding carbonic anhydrase significantly increased the rate of change in pHASL . Using pH-dependent rates obtained from these experiments, we modeled the pHASL during respiration to further understand how pH changes with physiologic and pathophysiologic respiratory cycles. Modeled pHASL oscillations were small and affected by the respiration rate, but not the inspiratory:expiratory ratio. Modeled equilibrium pHASL was affected by the inspiratory:expiratory ratio, but not the respiration rate. The airway epithelium is the only tissue that is exposed to large and rapid CO2 fluctuations. We speculate that the airways may have evolved minimal carbonic anhydrase activity to mitigate large changes in the pHASL during breathing that could potentially affect pH-sensitive components of ASL.
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Affiliation(s)
- Ian M Thornell
- Department of Internal Medicine, University of Iowa, Iowa City, IA.,Howard Hughes Medical Institute, University of Iowa, Iowa City, IA
| | - Xiaopeng Li
- Department of Internal Medicine, University of Iowa, Iowa City, IA
| | - Xiao Xiao Tang
- Department of Internal Medicine, University of Iowa, Iowa City, IA.,Howard Hughes Medical Institute, University of Iowa, Iowa City, IA
| | | | - Philip H Karp
- Department of Internal Medicine, University of Iowa, Iowa City, IA.,Howard Hughes Medical Institute, University of Iowa, Iowa City, IA
| | - Michael J Welsh
- Department of Internal Medicine, University of Iowa, Iowa City, IA.,Howard Hughes Medical Institute, University of Iowa, Iowa City, IA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Joseph Zabner
- Department of Internal Medicine, University of Iowa, Iowa City, IA
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20
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Alghaith JM, Balanos GM, Eves FF, White MJ. Sensitivity of the human ventilatory response to muscle metaboreflex activation during concurrent mild hypercapnia. Exp Physiol 2018; 104:359-367. [PMID: 30588681 DOI: 10.1113/ep087224] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/14/2018] [Indexed: 01/08/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the relationship between the level of systemic hypercapnia and the magnitude of the additional hyperpnoea produced in response to a standardized level of muscle metaboreflex activation? What is the main finding and its importance? When a standardized activation of the muscle metaboreflex was combined with exposure to increasing levels of hypercapnia, the hyperpnoea this caused increased linearly. The concept of a synergistic interaction between the muscle metaboreflex and the central chemoreflex in humans is supported by this finding. ABSTRACT Ventilation increases during muscle metaboreflex activation when postexercise circulatory occlusion (PECO) traps metabolites in resting human muscle, but only in conditions of concurrent systemic hypercapnia. We hypothesize that a linear relationship exists between the level of hypercapnia and the magnitude of the additional hyperpnoea produced in response to a standardized level of muscle metaboreflex activation. Fifteen male subjects performed four trials, in which the end-tidal partial pressure of carbon dioxide ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:mrow> <mml:mrow><mml:mi>ET</mml:mi> <mml:mo>,</mml:mo> <mml:mi>C</mml:mi></mml:mrow> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> ) was elevated by 1, 3, 7 or 10 mmHg above resting values using a dynamic end-tidal forcing system. In each trial, subjects were seated in an isometric dynamometer designed to measure ankle plantar flexor force. Rest for 2 min in room air was followed by 15 min of exposure to one of the four levels of hypercapnia, at which 5 min further rest was followed by 2 min of sustained isometric calf muscle contraction at 50% of predetermined maximal voluntary strength. Immediately before cessation of exercise, a cuff around the upper leg was inflated to a suprasystolic pressure to cause PECO for 3 min, before its deflation and a further 5 min of rest, concluding exposure to hypercapnia. The PECO consistently elevated mean arterial blood pressure by ∼10 mmHg in all trials, indicating similar levels of metaboreflex activation. Increased ventilation during PECO was related to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:mrow> <mml:mrow><mml:mi>ET</mml:mi> <mml:mo>,</mml:mo> <mml:mi>C</mml:mi></mml:mrow> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> as described by the following linear regression equation: Change in minute ventilation (l min-1 ) = 0.85 × <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:mrow> <mml:mrow><mml:mi>ET</mml:mi> <mml:mo>,</mml:mo> <mml:mi>C</mml:mi></mml:mrow> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> (mmHg) + 0.80 (l min-1 ). This finding supports our hypothesis and furthers the idea of a synergistic interaction between muscle metaboreflex activation and central chemoreflex stimulation.
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Affiliation(s)
- Jassim M Alghaith
- School of Sport, Exercise and Rehabilitation Sciences , University of Birmingham, Birmingham, UK
| | - George M Balanos
- School of Sport, Exercise and Rehabilitation Sciences , University of Birmingham, Birmingham, UK
| | - Francis F Eves
- School of Sport, Exercise and Rehabilitation Sciences , University of Birmingham, Birmingham, UK
| | - Michael J White
- School of Sport, Exercise and Rehabilitation Sciences , University of Birmingham, Birmingham, UK
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21
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Mitrou GI, Sakkas GK, Poulianiti KP, Karioti A, Tepetes K, Christodoulidis G, Giakas G, Stefanidis I, Geeves MA, Koutedakis Y, Karatzaferi C. Evidence of functional deficits at the single muscle fiber level in experimentally-induced renal insufficiency. J Biomech 2018; 82:259-265. [PMID: 30447801 DOI: 10.1016/j.jbiomech.2018.10.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 10/27/2018] [Accepted: 10/30/2018] [Indexed: 11/27/2022]
Abstract
Chronic kidney disease patients present with metabolic and functional muscle abnormalities, called uremic myopathy, whose mechanisms have not yet been fully elucidated. We investigated whether chronic renal insufficiency (CRI) affects skeletal muscle contractile properties at the cellular level. CRI was induced surgically in New Zealand rabbits (UREM), with sham-operation for controls (CON), and samples were collected at 3 months post-surgery, following euthanasia. All protocols had University Ethics approval following national and European guidelines. Sample treatments and evaluations were blinded. Maximal isometric force was assessed in 382 permeabilized psoas fibers (CON, n = 142, UREM, n = 240) initially at pH7, 10 °C ('standard' conditions), in subsets of fibers in acidic conditions (pH6.2, 10 °C) but also at near physiological temperature (pH7, 30 °C and pH6.2, 30 °C). CRI resulted in significant smaller average cross sectional areas (CSAs) by ∼11% for UREM muscle fibers (vs CON, P < 0.01). At standard conditions, UREM fibers produced lower absolute and specific forces (i.e. normalized force per fiber CSA) (vs CON, P < 0.01); force increased in 30 °C for both groups (P < 0.01), but the disparity between UREM and CON remained significant. Acidosis significantly reduced force (vs pH7, 10 °C P < 0.01), similarly in both groups (in UREM by -48% and in CON by -43%, P > 0.05). For the first time, we give evidence that CRI can induce significant impairments in single psoas muscle fibers force generation, only partly explained by fiber atrophy, thus affecting muscle mechanics at the cellular level.
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Affiliation(s)
- Georgia I Mitrou
- Muscle Physiology & Mechanics Group, CREHP, DPESS, University of Thessaly, Trikala, Greece; Faculty of Sport and Health Sciences, University of St Mark and St John (Marjon), Plymouth, United Kingdom
| | - Giorgos K Sakkas
- Muscle Physiology & Mechanics Group, CREHP, DPESS, University of Thessaly, Trikala, Greece; Institute for Research and Technology Thessaly-CERTH, Trikala, Greece; Faculty of Sport and Health Sciences, University of St Mark and St John (Marjon), Plymouth, United Kingdom
| | | | - Aggeliki Karioti
- Muscle Physiology & Mechanics Group, CREHP, DPESS, University of Thessaly, Trikala, Greece
| | - Konstantinos Tepetes
- Department of Surgery, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | | | - Giannis Giakas
- Institute for Research and Technology Thessaly-CERTH, Trikala, Greece; Human Performance Group, CREHP, DPESS, University of Thessaly, Trikala, Greece
| | - Ioannis Stefanidis
- Department of Nephrology, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | | | - Yiannis Koutedakis
- Human Performance Group, CREHP, DPESS, University of Thessaly, Trikala, Greece; Institute for Research and Technology Thessaly-CERTH, Trikala, Greece; School of Sport, Performing Arts and Leisure, Wolverhampton University, United Kingdom
| | - Christina Karatzaferi
- Muscle Physiology & Mechanics Group, CREHP, DPESS, University of Thessaly, Trikala, Greece; Institute for Research and Technology Thessaly-CERTH, Trikala, Greece; Faculty of Sport and Health Sciences, University of St Mark and St John (Marjon), Plymouth, United Kingdom.
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22
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Jarvis K, Woodward M, Debold EP, Walcott S. Acidosis affects muscle contraction by slowing the rates myosin attaches to and detaches from actin. J Muscle Res Cell Motil 2018; 39:135-147. [PMID: 30382520 DOI: 10.1007/s10974-018-9499-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/19/2018] [Indexed: 11/24/2022]
Abstract
The loss of muscle force and power during fatigue from intense contractile activity is associated with, and likely caused by, elevated levels of phosphate ([Formula: see text]) and hydrogen ions (decreased pH). To understand how these deficits in muscle performance occur at the molecular level, we used direct measurements of mini-ensembles of myosin generating force in the laser trap assay at pH 7.4 and 6.5. The data are consistent with a mechanochemical model in which a decrease in pH reduces myosin's detachment from actin (by slowing ADP release), increases non-productive myosin binding (by detached myosin rebinding without a powerstroke), and reduces myosin's attachment to actin (by slowing the weak-to-strong binding transition). Additional support of this mechanism is found by incorporating it into a branched pathway model for the effects of [Formula: see text] on myosin's interaction with actin. Including pH-dependence in one additional parameter (acceleration of [Formula: see text]-induced detachment), the model reproduces experimental measurements at high and low pH, and variable [Formula: see text], from the single molecule to large ensemble levels. Furthermore, when scaled up, the model predicts force-velocity relationships that are consistent with muscle fiber measurements. The model suggests that reducing pH has two opposing effects, a decrease in attachment favoring a decrease in muscle force and a decrease in detachment favoring an increase in muscle force. Depending on experimental details, the addition of [Formula: see text] can strengthen one or the other effect, resulting in either synergistic or antagonistic effects. This detailed molecular description suggests a molecular basis for contractile failure during muscle fatigue.
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Affiliation(s)
- Katelyn Jarvis
- Department of Mathematics, University of California, Davis, Davis, CA, 95616, USA
| | - Mike Woodward
- Department of Kinesiology, University of Massachusetts, Amherst, Amherst, MA, 01003, USA
| | - Edward P Debold
- Department of Kinesiology, University of Massachusetts, Amherst, Amherst, MA, 01003, USA
| | - Sam Walcott
- Department of Mathematics, University of California, Davis, Davis, CA, 95616, USA.
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23
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Glass LD, Cheng AJ, MacIntosh BR. Role of Ca 2+ in changing active force during intermittent submaximal stimulation in intact, single mouse muscle fibers. Pflugers Arch 2018; 470:1243-1254. [PMID: 29671103 PMCID: PMC6060763 DOI: 10.1007/s00424-018-2143-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 12/27/2022]
Abstract
Fatigue of single mouse fibers during repeated high-frequency stimulation results initially from decreased Ca2+ sensitivity while free myoplasmic calcium concentration ([Ca2+]m) increases, followed by decreasing [Ca2+]m. Recovery of active force with low-frequency stimulation is slow and persistent fatigue results from low [Ca2+]m. However, the consequences of intermittent submaximal contractions are not known. The aim of the present study was to investigate the changes in [Ca2+]m and active force during intermittent submaximal contractions and subsequent recovery. Single fibers of mouse flexor digitorum brevis muscles at 32 °C were stimulated with 40 or 50 Hz, for 350 ms every 2 s for 2 min and then every 1 s until < 40% of initial force. Values obtained during the intermittent stimulation were compared with a control force-[Ca2+]m relationship. A "P"-shaped pattern in the force-[Ca2+]m relationship was observed during intermittent stimulation. Early in the intermittent stimulation, [Ca2+]m increased while active force decreased. Subsequent force potentiation was accompanied by increased Ca2+ sensitivity. Later, as active force declined, [Ca2+]m decreased significantly (p < 0.001). This was followed, in the final phase, by a significant decrease in Ca2+ sensitivity determined by [Ca2+]m at half-maximal force (Ca50) (p = 0.001). Low-frequency fatigue persisted during recovery while Ca50 was not significantly different from prefatigue (p > 0.5). In conclusion, the main mechanism of fatigue is due to decreases in both [Ca2+]m and Ca2+ sensitivity following the initial force potentiation. The intermittent submaximal contractions resulted in persistent low-frequency fatigue seen during recovery, which was explained by depressed [Ca2+]m with no change in Ca2+ sensitivity.
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Affiliation(s)
- Lisa D. Glass
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta T2N 1N4 Canada
| | - Arthur J. Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Brian R. MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta T2N 1N4 Canada
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Woodward M, Debold EP. Acidosis and Phosphate Directly Reduce Myosin's Force-Generating Capacity Through Distinct Molecular Mechanisms. Front Physiol 2018; 9:862. [PMID: 30042692 PMCID: PMC6048269 DOI: 10.3389/fphys.2018.00862] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 06/18/2018] [Indexed: 12/04/2022] Open
Abstract
Elevated levels of the metabolic by-products, including acidosis (i.e., high [H+]) and phosphate (Pi) are putative agents of muscle fatigue; however, the mechanism through which they affect myosin’s function remain unclear. To elucidate these mechanisms, we directly examined the effect of acidosis (pH 6.5 vs. 7.4), alone and in combination with elevated levels of Pi on the force-generating capacity of a mini-ensemble of myosin using a laser trap assay. Acidosis decreased myosin’s average force-generating capacity by 20% (p < 0.05). The reduction was due to both a decrease in the force generated during each actomyosin interaction, as well as an increase in the number of binding events generating negative forces. Adding Pi to the acidic condition resulted in a quantitatively similar decrease in force but was solely due to an elimination of all high force-generating events (>2 pN), resulting from an acceleration of the myosin’s rate of detachment from actin. Acidosis and Pi also had distinct effects on myosin’s steady state ATPase rate with acidosis slowing it by ∼90% (p > 0.05), while the addition of Pi under acidic conditions caused a significant recovery in the ATPase rate. These data suggest that these two fatigue agents have distinct effects on myosin’s cross-bridge cycle that may underlie the synergistic effect that they have muscle force. Thus these data provide novel molecular insight into the mechanisms underlying the depressive effects of Pi and H+ on muscle contraction during fatigue.
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Affiliation(s)
- Mike Woodward
- Muscle Biophysics Lab, Department of Kinesiology, University of Massachusetts, Amherst, MA, United States
| | - Edward P Debold
- Muscle Biophysics Lab, Department of Kinesiology, University of Massachusetts, Amherst, MA, United States
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25
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Westerblad H. Acidosis Is Not a Significant Cause of Skeletal Muscle Fatigue. Med Sci Sports Exerc 2018; 48:2339-2342. [PMID: 27755383 DOI: 10.1249/mss.0000000000001044] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Affiliation(s)
- Robert H Fitts
- Department of Biological Sciences Marquette University Milwaukee, WI
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27
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Cheng AJ, Place N, Westerblad H. Molecular Basis for Exercise-Induced Fatigue: The Importance of Strictly Controlled Cellular Ca 2+ Handling. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029710. [PMID: 28432118 DOI: 10.1101/cshperspect.a029710] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The contractile function of skeletal muscle declines during intense or prolonged physical exercise, that is, fatigue develops. Skeletal muscle fibers fatigue acutely during highly intense exercise when they have to rely on anaerobic metabolism. Early stages of fatigue involve impaired myofibrillar function, whereas decreased Ca2+ release from the sarcoplasmic reticulum (SR) becomes more important in later stages. SR Ca2+ release can also become reduced with more prolonged, lower intensity exercise, and it is then related to glycogen depletion. Increased reactive oxygen/nitrogen species can cause long-lasting impairments in SR Ca2+ release resulting in a prolonged force depression after exercise. In this article, we discuss molecular and cellular mechanisms of the above fatigue-induced changes, with special focus on multiple mechanisms to decrease SR Ca2+ release to avoid energy depletion and preserve muscle fiber integrity. We also discuss fatigue-related effects of exercise-induced Ca2+ fluxes over the sarcolemma and between the cytoplasm and mitochondria.
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Affiliation(s)
- Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Nicolas Place
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
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Nozdrenko DM, Zavodovskyi DO, Matvienko TY, Zay SY, Bogutska KI, Prylutskyy YI, Ritter U, Scharff P. C 60 Fullerene as Promising Therapeutic Agent for the Prevention and Correction of Skeletal Muscle Functioning at Ischemic Injury. NANOSCALE RESEARCH LETTERS 2017; 12:115. [PMID: 28228000 PMCID: PMC5309190 DOI: 10.1186/s11671-017-1876-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 01/27/2017] [Indexed: 06/06/2023]
Abstract
The therapeutic effect of pristine C60 fullerene aqueous colloid solution (C60FAS) on the functioning of the rat soleus muscle at ischemic injury depending on the time of the general pathogenesis of muscular system and method of administration C60FAS in vivo was investigated. It was found that intravenous administration of C60FAS is the optimal for correction of speed macroparameters of contraction for ischemic muscle damage. At the same time, intramuscular administration of C60FAS shows pronounced protective effect in movements associated with the generation of maximum force responses or prolonged contractions, which increase the muscle fatigue level. Analysis of content concentration of creatine phosphokinase and lactate dehydrogenase enzymes in the blood of experimental animals indicates directly that C60FAS may be a promising therapeutic agent for the prevention and correction of ischemic-damaged skeletal muscle function.
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Affiliation(s)
- D. M. Nozdrenko
- ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., Kyiv, 01601 Ukraine
| | - D. O. Zavodovskyi
- ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., Kyiv, 01601 Ukraine
| | - T. Yu. Matvienko
- ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., Kyiv, 01601 Ukraine
| | - S. Yu. Zay
- Lesya Ukrainka Eastern European National University, 13 Volya Av., 43025 Lutsk, Ukraine
| | - K. I. Bogutska
- ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., Kyiv, 01601 Ukraine
| | - Yu. I. Prylutskyy
- ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., Kyiv, 01601 Ukraine
| | - U. Ritter
- Institute of Chemistry and Biotechnology, Technical University of Ilmenau, 25 Weimarer St., 98693 Ilmenau, Germany
| | - P. Scharff
- Institute of Chemistry and Biotechnology, Technical University of Ilmenau, 25 Weimarer St., 98693 Ilmenau, Germany
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Karatzaferi C, Adamek N, Geeves MA. Modulators of actin-myosin dissociation: basis for muscle type functional differences during fatigue. Am J Physiol Cell Physiol 2017; 313:C644-C654. [PMID: 28931538 PMCID: PMC5814585 DOI: 10.1152/ajpcell.00023.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The muscle types present with variable fatigue tolerance, in part due to the myosin isoform expressed. However, the critical steps that define “fatigability” in vivo of fast vs. slow myosin isoforms, at the molecular level, are not yet fully understood. We examined the modulation of the ATP-induced myosin subfragment 1 (S1) dissociation from pyrene-actin by inorganic phosphate (Pi), pH, and temperature using a specially modified stopped-flow system that allowed fast kinetics measurements at physiological temperature. We contrasted the properties of rabbit psoas (fast) and bovine masseter (slow) myosins (obtained from samples collected from New Zealand rabbits and from a licensed abattoir, respectively, according to institutional and national ethics permits). To identify ATP cycling biochemical intermediates, we assessed ATP binding to a preequilibrated mixture of actomyosin and variable [ADP], pH (pH 7 vs. pH 6.2), and Pi (zero, 15, or 30 added mM Pi) in a range of temperatures (5 to 45°C). Temperature and pH variations had little, if any, effect on the ADP dissociation constant (KADP) for fast S1, but for slow S1, KADP was weakened with increasing temperature or low pH. In the absence of ADP, the dissociation constant for phosphate (KPi) was weakened with increasing temperature for fast S1. In the presence of ADP, myosin type differences were revealed at the apparent phosphate affinity, depending on pH and temperature. Overall, the newly revealed kinetic differences between myosin types could help explain the in vivo observed muscle type functional differences at rest and during fatigue.
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Affiliation(s)
- Christina Karatzaferi
- Muscle Physiology and Mechanics Group, DPESS, University of Thessaly, Trikala, Greece.,Experimental Myology and Integrative Physiology Cluster, FSHS, University of St Mark and St John , Plymouth , United Kingdom
| | - Nancy Adamek
- School of Biosciences, University of Kent, Kent, United Kingdom
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Mechanical isolation, and measurement of force and myoplasmic free [Ca 2+] in fully intact single skeletal muscle fibers. Nat Protoc 2017; 12:1763-1776. [PMID: 28771237 DOI: 10.1038/nprot.2017.056] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mechanical dissection of single intact mammalian skeletal muscle fibers permits real-time measurement of intracellular properties and contractile function of living fibers. A major advantage of mechanical over enzymatic fiber dissociation is that single fibers can be isolated with their tendons remaining attached, which allows contractile forces (in the normal expected range of 300-450 kN/m2) to be measured during electrical stimulation. Furthermore, the sarcolemma of single fibers remains fully intact after mechanical dissection, and hence the living fibers can be studied with intact intracellular milieu and normal function and metabolic properties, as well as ionic control. Given that Ca2+ is the principal regulator of the contractile force, measurements of myoplasmic free [Ca2+] ([Ca2+]i) can be used to further delineate the intrinsic mechanisms underlying changes in skeletal muscle function. [Ca2+]i measurements are most commonly performed in intact single fibers using ratiometric fluorescent indicators such as indo-1 or fura-2. These Ca2+ indicators are introduced into the fiber by pressure injection or by using the membrane-permeable indo-1 AM, and [Ca2+]i is measured by calculating a ratio of the fluorescence at specific wavelengths emitted for the Ca2+-free and Ca2+-bound forms of the dye. We describe here the procedures for mechanical dissection, and for force and [Ca2+]i measurement in intact single fibers from mouse flexor digitorum brevis (FDB) muscle, which is the most commonly used muscle in studies using intact single fibers. This technique can also be used to isolate intact single fibers from various muscles and from various species. As an alternative to Ca2+ indicators, single fibers can also be loaded with fluorescent indicators to measure, for instance, reactive oxygen species, pH, and [Mg2+], or they can be injected with proteins to change functional properties. The entire protocol, from dissection to the start of an experiment on a single fiber, takes ∼3 h.
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Mizuno S, Arai M, Todoko F, Yamada E, Goto K. Wearing lower-body compression garment with medium pressure impaired exercise-induced performance decrement during prolonged running. PLoS One 2017; 12:e0178620. [PMID: 28562650 PMCID: PMC5451085 DOI: 10.1371/journal.pone.0178620] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 05/16/2017] [Indexed: 11/18/2022] Open
Abstract
Objective To investigate the effect of wearing a lower body compression garment (CG) exerting different pressure levels during prolonged running on exercise-induced muscle damage and the inflammatory response. Methods Eight male participants completed three exercise trials in a random order. The exercise consisted of 120 min of uphill running at 60% of VO2max. The exercise trials included 1) wearing a lower-body CG with 30 mmHg pressure [HIGH]; 2) wearing a lower-body CG with 15 mmHg pressure [MED]; and 3) wearing a lower-body garment with < 5 mmHg pressure [CON]. Heart rate (HR), and rate of perceived exertion for respiration and legs were monitored continuously during exercise. Time-course change in jump height was evaluated before and immediately after exercise. Blood samples were collected to determine blood glucose, lactate, serum creatine kinase, myoglobin, free fatty acids, glycerol, cortisol, and plasma interleukin-6 (IL-6) concentrations before exercise, 60 min of the 120 min exercise period, immediately after exercise, and 60 min after exercise. Results Jump height was significantly higher immediately after the exercise in the MED trial compared with that in the HIGH trial (P = 0.04). Mean HR during the 120 min exercise was significantly lower in the MED trial (162 ± 4 bpm) than that in the CON trial (170 ± 4 bpm, P = 0.01). Plasma IL-6 concentrations increased significantly with exercise in all trials, but the area under the curve during exercise was significantly lower in the MED trial (397 ± 58 pg/ml·120 min) compared with that in the CON trial (670 ± 86 pg/ml·120 min, P = 0.04). Conclusion Wearing a lower body CG exerting medium pressure (approximately 15 mmHg) significantly attenuated decrease in jump performance than that with wearing a lower body CG exerting high pressure (approximately 30 mmHg). Furthermore, exercise-induced increases in HR and the inflammatory response were significantly smaller with CG exerted 15mmHg than that with garment exerted < 5 mmHg.
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Affiliation(s)
- Sahiro Mizuno
- Graduate School of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | | | | | | | - Kazushige Goto
- Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail:
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Matvienko TY, Zavodovskyi DA, Nozdrenko DN, Mishchenko IV, Motuziuk OP, Bogutska KI, Sklyarov YP, Prylutskyy YI. [MUSCLE FATIGUE: FACTORS OF DEVELOPMENT AND WAYS OF CORRECTION]. FIZIOLOHICHNYI ZHURNAL (KIEV, UKRAINE : 1994) 2017; 63:95-104. [PMID: 29975834 DOI: 10.15407/fz63.01.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The data regarding the analysis of the physiological and biochemical mechanisms of muscle fatigue and ways to prevent it are summarized. The effect of the most common endogenous and exogenous antioxidants in the biochemical processes in muscle fatigue was analyzed. It is shown that biocompatible, non-toxic water-soluble C(60) fullerenes, which possess powerful antioxidative properties, promise great prospects in the correction of skeletal muscle fatigue caused by the destructive action of free radicals.
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33
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Sparks A, Williams E, Robinson A, Miller P, Bentley DJ, Bridge C, Mc Naughton LR. Sodium bicarbonate ingestion and individual variability in time-to-peak pH. Res Sports Med 2016; 25:58-66. [PMID: 27934546 DOI: 10.1080/15438627.2016.1258645] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This study determined variability in time-to-peak pH after consumption of 300 mg kg-1 of sodium bicarbonate. Seventeen participants (mean ± SD: age 21.38 ± 1.5 years; mass 75.8 ± 5.8 kg; height 176.8 ± 7.6 cm) reported to the laboratory where a resting capillary sample was taken. Then, 300 mg kg-1 of NaHCO3 in 450 ml of flavoured water was ingested. Participants rested for 90 min and repeated blood samples were procured at 10 min intervals for 60 min and then every 5 min until 90 min. Blood pH concentrations were measured. Results suggested that time-to-peak pH (64.41 ± 18.78 min) was variable with a range of 10-85 min and a coefficient of variation of 29.16%. A bimodal distribution occurred, at 65 and 75 min. In conclusion, athletes, when using NaHCO3 as an ergogenic aid, should determine their time-to-peak pH to best utilize the added buffering capacity this substance allows.
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Affiliation(s)
- Andy Sparks
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
| | - Emily Williams
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
| | - Amy Robinson
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
| | - Peter Miller
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
| | - David J Bentley
- b Flinders University, Faculty of Medicine, Nursing and Health Sciences , School of Health Sciences , Adelaide , South Australia , Australia
| | - Craig Bridge
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
| | - Lars R Mc Naughton
- a Department of Sport and Physical Activity , Edge Hill University Exercise Nutrition Research Group, Edge Hill University , Ormskirk , UK
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Li R, Steyn FJ, Stout MB, Lee K, Cully TR, Calderón JC, Ngo ST. Development of a high-throughput method for real-time assessment of cellular metabolism in intact long skeletal muscle fibre bundles. J Physiol 2016; 594:7197-7213. [PMID: 27619319 DOI: 10.1113/jp272988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/07/2016] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS We developed a method that allows for real-time assessment of cellular metabolism in isolated, intact long skeletal muscle fibre bundles from adult mice. This method can be used to study changes in mitochondrial function and fuel utilisation in live skeletal muscle fibre bundles. Our method enables flexibility in experimental design and high-throughput assessment of mitochondrial parameters in isolated skeletal muscle fibre bundles. Extensor digitorum longus (EDL) fibre bundles obtained from chronic high-fat diet fed mice had lower basal oxygen consumption under FCCP-induced maximal respiration, when compared to control chow-fed mice. EDL fibre bundles obtained from chronic high-fat diet fed mice had enhanced mitochondrial oxidation capacity under FCCP-induced maximal respiration, when compared to control chow-fed mice. ABSTRACT Metabolic dysfunction in skeletal muscle contributes to the aetiology and development of muscle diseases and metabolic diseases. As such, assessment of skeletal muscle cellular bioenergetics provides a powerful means to understand the role of skeletal muscle metabolism in disease and to identify possible therapeutic targets. Here, we developed a method that allows for the real-time assessment of cellular respiration in intact skeletal muscle fibre bundles obtained from the extensor digitorum longus (EDL) muscle of adult mice. Using this method, we assessed the contribution of ATP turnover and proton leak to basal mitochondrial oxygen consumption rate (OCR). Our data demonstrate that the mitochondria in EDL fibres are loosely coupled. Moreover, in the presence of carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), we show that palmitate exposure induced comparable peak OCR and higher total OCR in EDL fibre bundles when compared to pyruvate exposure, suggesting that fatty acids might be a more sustainable fuel source for skeletal muscle when mitochondria are driven to maximal respiration. Application of this method to EDL fibre bundles obtained from chronic high-fat diet fed mice revealed lower basal OCR and enhanced mitochondrial oxidation capacity in the presence of FCCP when compared to the chow-diet fed control mice. By using a 96-well microplate format, our method provides a flexible and efficient platform to investigate mitochondrial parameters of intact skeletal muscle fibres obtained from adult mice.
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Affiliation(s)
- Rui Li
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Frederik J Steyn
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia.,University of Queensland Centre for Clinical Research, Brisbane, Australia
| | - Michael B Stout
- Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA
| | - Kevin Lee
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Tanya R Cully
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Juan C Calderón
- Department of Physiology and Biochemistry, Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
| | - Shyuan T Ngo
- School of Biomedical Sciences, University of Queensland, Brisbane, Australia.,University of Queensland Centre for Clinical Research, Brisbane, Australia.,Queensland Brain Institute, University of Queensland, Brisbane, Australia.,Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Australia
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35
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Evans DR, Boggero IA, Segerstrom SC. The Nature of Self-Regulatory Fatigue and "Ego Depletion": Lessons From Physical Fatigue. PERSONALITY AND SOCIAL PSYCHOLOGY REVIEW 2016; 20:291-310. [PMID: 26228914 PMCID: PMC4788579 DOI: 10.1177/1088868315597841] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Self-regulation requires overriding a dominant response and leads to temporary self-regulatory fatigue. Existing theories of the nature and causes of self-regulatory fatigue highlight physiological substrates such as glucose, or psychological processes such as motivation, but these explanations are incomplete on their own. Historically, theories of physical fatigue demonstrate a similar pattern of useful but incomplete explanations, as recent views of physical fatigue emphasize the roles of both physiological and psychological factors. In addition to accounting for multiple inputs, these newer views also explain how fatigue can occur even in the presence of sufficient resources. Examining these newer theories of physical fatigue can serve as a foundation on which to build a more comprehensive understanding of self-regulatory fatigue that integrates possible neurobiological underpinnings of physical and self-regulatory fatigue, and suggests the possible function of self-regulatory fatigue.
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Affiliation(s)
- Daniel R Evans
- 1 University of Kentucky, Lexington, USA
- 2 Alpert Medical School of Brown University, Providence, RI, USA
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DEBOLD EDWARDP, FITTS ROBERTH, SUNDBERG CHRISTOPHERW, NOSEK THOMASM. Muscle Fatigue from the Perspective of a Single Crossbridge. Med Sci Sports Exerc 2016; 48:2270-2280. [DOI: 10.1249/mss.0000000000001047] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Harper LD, Clifford T, Briggs MA, McNamee G, West DJ, Stevenson E, Russell M. The Effects of 120 Minutes of Simulated Match Play on Indices of Acid-Base Balance in Professional Academy Soccer Players. J Strength Cond Res 2016; 30:1517-24. [DOI: 10.1519/jsc.0000000000001271] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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38
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Toda K, Hitoe S, Takeda S, Shimoda H. Black ginger extract increases physical fitness performance and muscular endurance by improving inflammation and energy metabolism. Heliyon 2016; 2:e00115. [PMID: 27441286 PMCID: PMC4946221 DOI: 10.1016/j.heliyon.2016.e00115] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 04/27/2016] [Accepted: 05/13/2016] [Indexed: 01/23/2023] Open
Abstract
We previously reported that polymethoxyflavones (PMFs) in black ginger (Kaempferia parviflora) extract (KPE) increased energy production by activating AMP-activated protein kinase (AMPK) in C2C12 myoblasts. We herein evaluated the effects of KPE on physical fitness performance and muscular endurance in mice. Male mice were orally administered KPE for 4 weeks, and then forced swimming test, open-field test, inclined plane test, and wire hanging test were performed. KPE significantly increased the swimming time, motility after swimming, and grip strength. IL-6 and TNF-α mRNA expression levels were decreased in the soleus muscle, whereas peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and glycogen synthase mRNA expression levels, mitochondrial number, and glycogen content were increased. These results were in agreement with those obtained for KPE and PMFs in C2C12. Therefore, the activation of AMPK by PMFs may be one of the mechanisms by which KPE improves physical fitness performance and muscular endurance.
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Affiliation(s)
- Kazuya Toda
- Research and Development Division, Oryza Oil and Fat Chemical Co., Ltd., 1 Numata, Kitagata-cho, Ichinomiya, Aichi 493-8001, Japan
| | - Shoketsu Hitoe
- Research and Development Division, Oryza Oil and Fat Chemical Co., Ltd., 1 Numata, Kitagata-cho, Ichinomiya, Aichi 493-8001, Japan
| | - Shogo Takeda
- Research and Development Division, Oryza Oil and Fat Chemical Co., Ltd., 1 Numata, Kitagata-cho, Ichinomiya, Aichi 493-8001, Japan
| | - Hiroshi Shimoda
- Research and Development Division, Oryza Oil and Fat Chemical Co., Ltd., 1 Numata, Kitagata-cho, Ichinomiya, Aichi 493-8001, Japan
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Tanaka Y, Inagaki T, Poole DC, Kano Y. pH buffering of single rat skeletal muscle fibers in the in vivo environment. Am J Physiol Regul Integr Comp Physiol 2016; 310:R926-33. [PMID: 26984893 DOI: 10.1152/ajpregu.00501.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/09/2016] [Indexed: 01/12/2023]
Abstract
Homeostasis of intracellular pH (pHi) has a crucial role for the maintenance of cellular function. Several membrane transporters such as lactate/H(+) cotransporter (MCT), Na(+)/H(+) exchange transporter (NHE), and Na(+)/HCO3 (-) cotransporter (NBC) are thought to contribute to pHi regulation. However, the relative importance of each of these membrane transporters to the in vivo recovery from the low pHi condition is unknown. Using an in vivo bioimaging model, we pharmacologically inhibited each transporter separately and all transporters together and then evaluated the pHi recovery profiles following imposition of a discrete H(+) challenge loaded into single muscle fibers by microinjection. The intact spinotrapezius muscle of adult male Wistar rats (n = 72) was exteriorized and loaded with the fluorescent probe 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein-acetoxymethyl ester (10 μM). A single muscle fiber was then loaded with low-pH solution [piperazine-N,N'-bis(2-ethanesulfonic acid) buffer, pH 6.5, ∼2.33 × 10(-3) μl] by microinjection over 3 s. The rats were divided into groups for the following treatments: 1) no inhibitor (CONT), 2) MCT inhibition (by α-Cyano-4-hydroxyciannamic acid; 4 mM), 3) NHE inhibition (by ethylisopropyl amiloride; 0.5 mM), 4) NBC inhibition (by DIDS; 1 mM), and 5) MCT, NHE, and NBC inhibition (All blockade). The fluorescence ratio (F500 nm/F445 nm) was determined from images captured during 1 min (60 images/min) and at 5, 10, 15, and 20 min after injection. The pHi at 1-2 s after injection significantly decreased from resting pHi (ΔpHi = -0.73 ± 0.03) in CONT. The recovery response profile was biphasic, with an initial rapid and close-to-exponential pHi increase (time constant, τ: 60.0 ± 7.9 s). This initial rapid profile was not affected by any pharmacological blockade but was significantly delayed by carbonic anhydrase inhibition. In contrast, the secondary, more gradual, return toward baseline that restored CONT pHi to 84.2% of baseline was unimpeded by MCT, NHE, and NBC blockade separately but abolished by All blockade (ΔpHi = -0.60 ± 0.07, 72.8% initial pHi, P < 0.05 vs. CONT). After injection of H(+) into, or superfusion onto, an adjacent fiber pHi of the surrounding fibers decreased progressively for the 20-min observation period (∼7.0, P < 0.05 vs. preinjection/superfusion). In conclusion, these results support that, after an imposed H(+) load, the MCT, NHE, and NBC transporters are not involved in the initial rapid phase of pHi recovery. In contrast, the gradual recovery phase was abolished by inhibiting all three membrane transporter systems simultaneously. The alteration of pHi in surrounding fibers suggest that H(+) uptake by neighboring fibers can help alleviate the pH consequences of myocyte H(+) exudation.
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Affiliation(s)
- Yoshinori Tanaka
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan
| | - Tadakatsu Inagaki
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan; Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan; and
| | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Tokyo, Japan;
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Nicholson G, Mcloughlin G, Bissas A, Ispoglou T. Do the acute biochemical and neuromuscular responses justify the classification of strength- and hypertrophy-type resistance exercise? J Strength Cond Res 2016; 28:3188-99. [PMID: 24832969 DOI: 10.1519/jsc.0000000000000519] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This study aimed to examine a wide profile of acute biochemical and neuromuscular responses to strength (STR) and hypertrophy (HYP) resistance exercise (RE). Seven trained men completed an STR workout (4 × 6 repetitions, 85% 1 repetition maximum [1RM], 5-minute rest periods), an HYP workout (4 × 10 repetitions, 70% 1RM, 90-second rest periods), and a control condition (CON) in a randomized crossover design. Peak force (PF), rate of force development (RFD), and muscle activity were quantified before and after exercise during an isometric squat protocol. Blood samples were taken 20, 10, and 0 minutes before and 0, 10, and 60 minutes after exercise to measure the concentration of blood lactate (BL), pH, and a number of electrolytes that were corrected for plasma volume changes. No differences were observed between the workouts for changes in PF, RFD, or muscle activity. Repeated contrasts revealed a greater (p ≤ 0.05) increase in BL concentration and reduction in pH after the HYP protocol than the STR or CON conditions. There were similar but significant (p ≤ 0.05) changes in the concentration of a number of electrolytes after both workouts, and a handful of these changes displayed significant correlations with the PF reductions observed after the HYP condition. Although the STR and HYP workouts were significantly different in terms of intensity, volume, and rest, these differences were only observable in the acid-base responses. The present findings reinforce the need for practitioners to look beyond the classification of RE workouts when aiming to elicit specific physiological responses.
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Affiliation(s)
- Gareth Nicholson
- Carnegie School of Sport, Leeds Metropolitan University, Leeds, United Kingdom
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41
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Morales-Alamo D, Losa-Reyna J, Torres-Peralta R, Martin-Rincon M, Perez-Valera M, Curtelin D, Ponce-González JG, Santana A, Calbet JAL. What limits performance during whole-body incremental exercise to exhaustion in humans? J Physiol 2015; 593:4631-48. [PMID: 26250346 DOI: 10.1113/jp270487] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/29/2015] [Indexed: 12/13/2022] Open
Abstract
To determine the mechanisms causing task failure during incremental exercise to exhaustion (IE), sprint performance (10 s all-out isokinetic) and muscle metabolites were measured before (control) and immediately after IE in normoxia (P(IO2) 143 mmHg) and hypoxia (P(IO2): 73 mmHg) in 22 men (22 ± 3 years). After IE, subjects recovered for either 10 or 60 s, with open circulation or bilateral leg occlusion (300 mmHg) in random order. This was followed by a 10 s sprint with open circulation. Post-IE peak power output (W(peak)) was higher than the power output reached at exhaustion during IE (P < 0.05). After 10 and 60 s recovery in normoxia, W(peak) was reduced by 38 ± 9 and 22 ± 10% without occlusion, and 61 ± 8 and 47 ± 10% with occlusion (P < 0.05). Following 10 s occlusion, W(peak) was 20% higher in hypoxia than normoxia (P < 0.05), despite similar muscle lactate accumulation ([La]) and phosphocreatine and ATP reduction. Sprint performance and anaerobic ATP resynthesis were greater after 60 s compared with 10 s occlusions, despite the higher [La] and [H(+)] after 60 s compared with 10 s occlusion recovery (P < 0.05). The mean rate of ATP turnover during the 60 s occlusion was 0.180 ± 0.133 mmol (kg wet wt)(-1) s(-1), i.e. equivalent to 32% of leg peak O2 uptake (the energy expended by the ion pumps). A greater degree of recovery is achieved, however, without occlusion. In conclusion, during incremental exercise task failure is not due to metabolite accumulation or lack of energy resources. Anaerobic metabolism, despite the accumulation of lactate and H(+), facilitates early recovery even in anoxia. This points to central mechanisms as the principal determinants of task failure both in normoxia and hypoxia, with lower peripheral contribution in hypoxia.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - José Losa-Reyna
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Rafael Torres-Peralta
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Department of Sports and Informatics, Pablo de Olavide University, Seville, Spain
| | - Mario Perez-Valera
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - David Curtelin
- Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Emergency Medicine Department, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - Jesús Gustavo Ponce-González
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain.,Clinical Genetics Unit, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Avenida Marítima, del Sur, s/n, 35016, Las Palmas de Gran Canaria, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira s/n, 35017, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
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42
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Physiological and health-related adaptations to low-volume interval training: influences of nutrition and sex. Sports Med 2015; 44 Suppl 2:S127-37. [PMID: 25355187 PMCID: PMC4213388 DOI: 10.1007/s40279-014-0259-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Interval training refers to the basic concept of alternating periods of relatively intense exercise with periods of lower-intensity effort or complete rest for recovery. Low-volume interval training refers to sessions that involve a relatively small total amount of exercise (i.e. ≤10 min of intense exercise), compared with traditional moderate-intensity continuous training (MICT) protocols that are generally reflected in public health guidelines. In an effort to standardize terminology, a classification scheme was recently proposed in which the term 'high-intensity interval training' (HIIT) be used to describe protocols in which the training stimulus is 'near maximal' or the target intensity is between 80 and 100 % of maximal heart rate, and 'sprint interval training' (SIT) be used for protocols that involve 'all out' or 'supramaximal' efforts, in which target intensities correspond to workloads greater than what is required to elicit 100 % of maximal oxygen uptake (VO2max). Both low-volume SIT and HIIT constitute relatively time-efficient training strategies to rapidly enhance the capacity for aerobic energy metabolism and elicit physiological remodeling that resembles changes normally associated with high-volume MICT. Short-term SIT and HIIT protocols have also been shown to improve health-related indices, including cardiorespiratory fitness and markers of glycemic control in both healthy individuals and those at risk for, or afflicted by, cardiometabolic diseases. Recent evidence from a limited number of studies has highlighted potential sex-based differences in the adaptive response to SIT in particular. It has also been suggested that specific nutritional interventions, in particular those that can augment muscle buffering capacity, such as sodium bicarbonate, may enhance the adaptive response to low-volume interval training.
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43
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Selvin D, Renaud JM. Changes in myoplasmic Ca2+ during fatigue differ between FDB fibers, between glibenclamide-exposed and Kir6.2-/- fibers and are further modulated by verapamil. Physiol Rep 2015; 3:3/3/e12303. [PMID: 25742954 PMCID: PMC4393149 DOI: 10.14814/phy2.12303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
One objective of this study was to document how individual FDB muscle fibers depend on the myoprotection of KATP channels during fatigue. Verapamil, a CaV1.1 channel blocker, prevents large increases in unstimulated force during fatigue in KATP-channel-deficient muscles. A second objective was to determine if verapamil reduces unstimulated [Ca(2+)]i in KATP-channel-deficient fibers. We measured changes in myoplasmic [Ca(2+)] ([Ca(2+)]i) using two KATP-channel-deficient models: (1) a pharmacological approach exposing fibers to glibenclamide, a channel blocker, and (2) a genetic approach using fibers from null mice for the Kir6.2 gene. Fatigue was elicited with one tetanic contraction every sec for 3 min. For all conditions, large differences in fatigue kinetics were observed from fibers which had greater tetanic [Ca(2+)]i at the end than at the beginning of fatigue to fibers which eventually completely failed to release Ca(2+) upon stimulation. Compared to control conditions, KATP-channel-deficient fibers had a greater proportion of fiber with large decreases in tetanic [Ca(2+)]i, fade and complete failure to release Ca(2+) upon stimulation. There was, however, a group of KATP-channel-deficient fibers that had similar fatigue kinetics to those of the most fatigue-resistant control fibers. For the first time, differences in fatigue kinetics were observed between Kir6.2(-/-) and glibenclamide-exposed muscle fibers. Verapamil significantly reduced unstimulated and tetanic [Ca(2+)]i. It is concluded that not all fibers are dependent on the myoprotection of KATP channels and that the decrease in unstimulated force by verapamil reported in a previous studies in glibenclamide-exposed fibers is due to a reduction in Ca(2+) load by reducing Ca(2+) influx through CaV1.1 channels between and during contractions.
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Affiliation(s)
- David Selvin
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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44
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de Aguiar RA, Turnes T, Santos de Oliveira Cruz R, Salvador AF, Caputo F. Repeated sprint performance and metabolic recovery curves: effects of aerobic and anaerobic characteristics. Appl Physiol Nutr Metab 2014; 40:433-40. [PMID: 25853893 DOI: 10.1139/apnm-2014-0431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To examine the influence of aerobic and anaerobic indices on repeated sprint (RS) performance and ability (RSA), 8 sprinters (SPR), 8 endurance runners (END), and 8 active participants (ACT) performed the following tests: (i) incremental test; (ii) 1-min test to determine first decay time constant of pulmonary oxygen uptake off-kinetics and parameters related to anaerobic energy supply, lactate exchange, and removal abilities from blood lactate kinetics; and (iii) RS test (ten 35-m sprints, departing every 20 s) to determine best (RSbest) and mean (RSmean) sprint times and percentage of sprint decrement (%Dec). While SPR had a 98%-100% likelihood of having the fastest RSbest (Cohen's d of 1.8 and 1.4 for ACT and END, respectively) and RSmean (2.1 and 0.9 for ACT and END, respectively), END presented a 97%-100% likelihood of having the lowest %Dec (0.9 and 2.2 for ACT and SPR, respectively). RSmean was very largely correlated with RSbest (r=0.85) and moderately correlated with estimates of anaerobic energy supply (r=-0.40 to -0.49). RSmean adjusted for RSbest (which indirectly reflects RSA) was largely correlated with lactate exchange ability (r=0.55). Our results confirm the importance of locomotor- and anaerobic-related variables to RS performance, and highlight the importance of disposal of selected metabolic by-products to RSA.
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Affiliation(s)
- Rafael Alves de Aguiar
- Human Performance Research Group, Santa Catarina State University, Rua Pascoal Simone, 358, Coqueiros. Florianópolis, SC, Brasil. CEP: 88080-350
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45
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Miyamoto N, Kawakami Y. Effect of Pressure Intensity of Compression Short-Tight on Fatigue of Thigh Muscles. Med Sci Sports Exerc 2014; 46:2168-74. [DOI: 10.1249/mss.0000000000000330] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Hostrup M, Kalsen A, Ortenblad N, Juel C, Mørch K, Rzeppa S, Karlsson S, Backer V, Bangsbo J. β2-adrenergic stimulation enhances Ca2+ release and contractile properties of skeletal muscles, and counteracts exercise-induced reductions in Na+-K+-ATPase Vmax in trained men. J Physiol 2014; 592:5445-59. [PMID: 25344552 DOI: 10.1113/jphysiol.2014.277095] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The aim of the present study was to examine the effect of β2-adrenergic stimulation on skeletal muscle contractile properties, sarcoplasmic reticulum (SR) rates of Ca(2+) release and uptake, and Na(+)-K(+)-ATPase activity before and after fatiguing exercise in trained men. The study consisted of two experiments (EXP1, n = 10 males, EXP2, n = 20 males), where β2-adrenoceptor agonist (terbutaline) or placebo was randomly administered in double-blinded crossover designs. In EXP1, maximal voluntary isometric contraction (MVC) of m. quadriceps was measured, followed by exercise to fatigue at 120% of maximal oxygen uptake (V̇O2, max ). A muscle biopsy was taken after MVC (non-fatigue) and at time of fatigue. In EXP2, contractile properties of m. quadriceps were measured with electrical stimulations before (non-fatigue) and after two fatiguing 45 s sprints. Non-fatigued MVCs were 6 ± 3 and 6 ± 2% higher (P < 0.05) with terbutaline than placebo in EXP1 and EXP2, respectively. Furthermore, peak twitch force was 11 ± 7% higher (P < 0.01) with terbutaline than placebo at non-fatigue. After sprints, MVC declined (P < 0.05) to the same levels with terbutaline as placebo, whereas peak twitch force was lower (P < 0.05) and half-relaxation time was prolonged (P < 0.05) with terbutaline. Rates of SR Ca(2+) release and uptake at 400 nm [Ca(2+)] were 15 ± 5 and 14 ± 5% (P < 0.05) higher, respectively, with terbutaline than placebo at non-fatigue, but declined (P < 0.05) to similar levels at time of fatigue. Na(+)-K(+)-ATPase activity was unaffected by terbutaline compared with placebo at non-fatigue, but terbutaline counteracted exercise-induced reductions in maximum rate of activity (Vmax) at time of fatigue. In conclusion, increased contractile force induced by β2-adrenergic stimulation is associated with enhanced rate of Ca(2+) release in humans. While β2-adrenergic stimulation elicits positive inotropic and lusitropic effects on non-fatigued m. quadriceps, these effects are blunted when muscles fatigue.
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Affiliation(s)
- M Hostrup
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Denmark Department of Respiratory Research, Bispebjerg University Hospital, Denmark
| | - A Kalsen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Denmark Department of Respiratory Research, Bispebjerg University Hospital, Denmark
| | - N Ortenblad
- Department of Sports Science and Biomechanics, University of Southern Denmark, Denmark Swedish Winter Sports Research Centre, Mid Sweden University, Sweden
| | - C Juel
- Department of Biology, University of Copenhagen, Denmark
| | - K Mørch
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Denmark
| | - S Rzeppa
- Norwegian Doping Control Laboratory, Oslo University Hospital, Norway
| | - S Karlsson
- Department of Respiratory Research, Bispebjerg University Hospital, Denmark
| | - V Backer
- Department of Respiratory Research, Bispebjerg University Hospital, Denmark
| | - J Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Denmark
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47
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Mitchell JB, Rogers MM, Basset JT, Hubing KA. Fatigue During High-Intensity Endurance Exercise. J Strength Cond Res 2014; 28:1906-14. [DOI: 10.1519/jsc.0000000000000319] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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48
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Kerr JP, Ward CW, Bloch RJ. Dysferlin at transverse tubules regulates Ca(2+) homeostasis in skeletal muscle. Front Physiol 2014; 5:89. [PMID: 24639655 PMCID: PMC3944681 DOI: 10.3389/fphys.2014.00089] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/15/2014] [Indexed: 11/13/2022] Open
Abstract
The class of muscular dystrophies linked to the genetic ablation or mutation of dysferlin, including Limb Girdle Muscular Dystrophy 2B (LGMD2B) and Miyoshi Myopathy (MM), are late-onset degenerative diseases. In lieu of a genetic cure, treatments to prevent or slow the progression of dysferlinopathy are of the utmost importance. Recent advances in the study of dysferlinopathy have highlighted the necessity for the maintenance of calcium handling in altering or slowing the progression of muscular degeneration resulting from the loss of dysferlin. This review highlights new evidence for a role for dysferlin at the transverse (t-) tubule of striated muscle, where it is involved in maintaining t-tubule structure and function.
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Affiliation(s)
- Jaclyn P Kerr
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Christopher W Ward
- Department of Organizational Systems and Adult Health, University of Maryland School of Nursing Baltimore, MD, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
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49
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Nelson CR, Fitts RH. Effects of low cell pH and elevated inorganic phosphate on the pCa-force relationship in single muscle fibers at near-physiological temperatures. Am J Physiol Cell Physiol 2014; 306:C670-8. [PMID: 24452378 DOI: 10.1152/ajpcell.00347.2013] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intense muscle contraction induces high rates of ATP hydrolysis with resulting increases in Pi, H(+), and ADP, factors thought to induce fatigue by interfering with steps in the cross-bridge cycle. Force inhibition is less at physiological temperatures; thus the role of low pH in fatigue has been questioned. Effects of pH 6.2 and collective effects with 30 mM Pi on the pCa-force relationship were assessed in skinned fast and slow rat skeletal muscle fibers at 15 and 30°C. At 30°C, pH 6.2 + 30 mM Pi significantly depressed peak force in all fiber types, with the greatest effect in type IIx fibers. Across fiber types, Ca(2+) sensitivity was depressed by low pH and low pH + high Pi, with the greater effect at 30°C. For type IIx fibers at 30°C, half-maximal activation (pCa50) was 5.36 at pH 6.2 (no added Pi) and 4.98 at pH 6.2 + 30 mM Pi compared with 6.58 in the control condition (pH 7, no added Pi). At 30°C, n2, reflective of thick filament cooperativity, was unchanged by low cell pH but was depressed from 5.02 to 2.46 in type IIx fibers with pH 6.2 + 30 mM Pi. With acidosis, activation thresholds of all fiber types required higher free Ca(2+) at 15 and 30°C. With the exception of type IIx fibers, the Ca(2+) required to reach activation threshold increased further with added Pi. In conclusion, it is clear that fatigue-inducing effects of low cell pH and elevated Pi at near-physiological temperatures are substantial.
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Affiliation(s)
- Cassandra R Nelson
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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50
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Siegler JC, Marshall PWM, Raftry S, Brooks C, Dowswell B, Romero R, Green S. The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling. J Appl Physiol (1985) 2013; 115:1634-40. [DOI: 10.1152/japplphysiol.00688.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this investigation was to assess the influence of sodium bicarbonate supplementation on maximal force production, rate of force development (RFD), and muscle recruitment during repeated bouts of high-intensity cycling. Ten male and female ( n = 10) subjects completed two fixed-cadence, high-intensity cycling trials. Each trial consisted of a series of 30-s efforts at 120% peak power output (maximum graded test) that were interspersed with 30-s recovery periods until task failure. Prior to each trial, subjects consumed 0.3 g/kg sodium bicarbonate (ALK) or placebo (PLA). Maximal voluntary contractions were performed immediately after each 30-s effort. Maximal force (Fmax) was calculated as the greatest force recorded over a 25-ms period throughout the entire contraction duration while maximal RFD (RFDmax) was calculated as the greatest 10-ms average slope throughout that same contraction. Fmax declined similarly in both the ALK and PLA conditions, with baseline values (ALK: 1,226 ± 393 N; PLA: 1,222 ± 369 N) declining nearly 295 ± 54 N [95% confidence interval (CI) = 84–508 N; P < 0.006]. RFDmax also declined in both trials; however, a differential effect persisted between the ALK and PLA conditions. A main effect of condition was observed across the performance time period, with RFDmax on average higher during ALK (ALK: 8,729 ± 1,169 N/s; PLA: 7,691 ± 1,526 N/s; mean difference between conditions 1,038 ± 451 N/s, 95% CI = 17–2,059 N/s; P < 0.048). These results demonstrate a differential effect of alkalosis on maximum force vs. maximum rate of force development during a whole body fatiguing task.
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Affiliation(s)
| | | | - Sean Raftry
- Sport and Exercise Science, School of Science and Health, and
| | - Cristy Brooks
- Sport and Exercise Science, School of Science and Health, and
| | - Ben Dowswell
- Sport and Exercise Science, School of Science and Health, and
| | - Rick Romero
- Sport and Exercise Science, School of Science and Health, and
| | - Simon Green
- Sport and Exercise Science, School of Science and Health, and
- School of Medicine, University of Western Sydney Campbelltown Campus, Sydney, Australia
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