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Fukutani A, Westerblad H, Jardemark K, Bruton J. Ca 2+ and force during dynamic contractions in mouse intact skeletal muscle fibers. Sci Rep 2024; 14:689. [PMID: 38184730 PMCID: PMC10771458 DOI: 10.1038/s41598-023-51100-5] [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: 09/11/2023] [Accepted: 12/30/2023] [Indexed: 01/08/2024] Open
Abstract
Muscle fiber force production is determined by the excitation frequency of motor nerves, which induce transient increases in cytoplasmic free Ca2+ concentration ([Ca2+]i) and the force-generating capacity of the actomyosin cross-bridges. Previous studies suggest that, in addition to altered cross-bridge properties, force changes during dynamic (concentric or eccentric) contraction might be affected by Ca2+-dependent components. Here we investigated this by measuring [Ca2+]i and force in mouse muscle fibers undergoing isometric, concentric, and eccentric contractions. Intact single muscle fibers were dissected from the flexor digitorum brevis muscle of mice. Fibers were electrically activated isometrically at 30-100 Hz and after reaching the isometric force plateau, they were actively shortened or stretched. We calculated the ratio (relative changes) in force and [Ca2+]i attained in submaximal (30 Hz) and near-maximal (100 Hz) contractions under isometric or dynamic conditions. Tetanic [Ca2+]i was similar during isometric, concentric and eccentric phases of contraction at given stimulation frequencies while the forces were clearly different depending on the contraction types. The 30/100 Hz force ratio was significantly lower in the concentric (44.1 ± 20.3%) than in the isometric (50.3 ± 20.4%) condition (p = 0.005), whereas this ratio did not differ between eccentric and isometric conditions (p = 0.186). We conclude that the larger force decrease by decreasing the stimulation frequency during concentric than during isometric contraction is caused by decreased myofibrillar Ca2+ sensitivity, not by the decreased [Ca2+]i.
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Affiliation(s)
- Atsuki Fukutani
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga, 525-8577, Japan.
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden.
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden
| | - Kent Jardemark
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden
| | - Joseph Bruton
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden
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2
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Mayfield DL, Cronin NJ, Lichtwark GA. Understanding altered contractile properties in advanced age: insights from a systematic muscle modelling approach. Biomech Model Mechanobiol 2023; 22:309-337. [PMID: 36335506 PMCID: PMC9958200 DOI: 10.1007/s10237-022-01651-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 10/14/2022] [Indexed: 11/09/2022]
Abstract
Age-related alterations of skeletal muscle are numerous and present inconsistently, and the effect of their interaction on contractile performance can be nonintuitive. Hill-type muscle models predict muscle force according to well-characterised contractile phenomena. Coupled with simple, yet reasonably realistic activation dynamics, such models consist of parameters that are meaningfully linked to fundamental aspects of muscle excitation and contraction. We aimed to illustrate the utility of a muscle model for elucidating relevant mechanisms and predicting changes in output by simulating the individual and combined effects on isometric force of several known ageing-related adaptations. Simulating literature-informed reductions in free Ca2+ concentration and Ca2+ sensitivity generated predictions at odds qualitatively with the characteristic slowing of contraction speed. Conversely, incorporating slower Ca2+ removal or a fractional increase in type I fibre area emulated expected changes; the former was required to simulate slowing of the twitch measured experimentally. Slower Ca2+ removal more than compensated for force loss arising from a large reduction in Ca2+ sensitivity or moderate reduction in Ca2+ release, producing realistic age-related shifts in the force-frequency relationship. Consistent with empirical data, reductions in free Ca2+ concentration and Ca2+ sensitivity reduced maximum tetanic force only slightly, even when acting in concert, suggesting a modest contribution to lower specific force. Lower tendon stiffness and slower intrinsic shortening speed slowed and prolonged force development in a compliance-dependent manner without affecting force decay. This work demonstrates the advantages of muscle modelling for exploring sources of variation and identifying mechanisms underpinning the altered contractile properties of aged muscle.
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Affiliation(s)
- Dean L Mayfield
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, USA.
| | - Neil J Cronin
- Neuromuscular Research Centre, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- School of Sport and Exercise, University of Gloucestershire, Cheltenham, UK
| | - Glen A Lichtwark
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia
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Tsuboi Y, Oyama K, Kobirumaki-Shimozawa F, Murayama T, Kurebayashi N, Tachibana T, Manome Y, Kikuchi E, Noguchi S, Inoue T, Inoue YU, Nishino I, Mori S, Ishida R, Kagechika H, Suzuki M, Fukuda N, Yamazawa T. Mice with R2509C-RYR1 mutation exhibit dysfunctional Ca2+ dynamics in primary skeletal myocytes. J Gen Physiol 2022; 154:213526. [PMID: 36200983 PMCID: PMC9546722 DOI: 10.1085/jgp.202213136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 07/22/2022] [Accepted: 09/14/2022] [Indexed: 11/20/2022] Open
Abstract
Type 1 ryanodine receptor (RYR1) is a Ca2+ release channel in the sarcoplasmic reticulum (SR) of the skeletal muscle and plays a critical role in excitation-contraction coupling. Mutations in RYR1 cause severe muscle diseases, such as malignant hyperthermia, a disorder of Ca2+-induced Ca2+ release (CICR) through RYR1 from the SR. We recently reported that volatile anesthetics induce malignant hyperthermia (MH)-like episodes through enhanced CICR in heterozygous R2509C-RYR1 mice. However, the characterization of Ca2+ dynamics has yet to be investigated in skeletal muscle cells from homozygous mice because these animals die in utero. In the present study, we generated primary cultured skeletal myocytes from R2509C-RYR1 mice. No differences in cellular morphology were detected between wild type (WT) and mutant myocytes. Spontaneous Ca2+ transients and cellular contractions occurred in WT and heterozygous myocytes, but not in homozygous myocytes. Electron microscopic observation revealed that the sarcomere length was shortened to ∼1.7 µm in homozygous myocytes, as compared to ∼2.2 and ∼2.3 µm in WT and heterozygous myocytes, respectively. Consistently, the resting intracellular Ca2+ concentration was higher in homozygous myocytes than in WT or heterozygous myocytes, which may be coupled with a reduced Ca2+ concentration in the SR. Finally, using infrared laser-based microheating, we found that heterozygous myocytes showed larger heat-induced Ca2+ transients than WT myocytes. Our findings suggest that the R2509C mutation in RYR1 causes dysfunctional Ca2+ dynamics in a mutant-gene dose-dependent manner in the skeletal muscles, in turn provoking MH-like episodes and embryonic lethality in heterozygous and homozygous mice, respectively.
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Affiliation(s)
- Yoshitaka Tsuboi
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan.,Department of Molecular Physiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Kotaro Oyama
- Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology, Gunma, Japan.,Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
| | | | - Takashi Murayama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Toshiaki Tachibana
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan
| | - Yoshinobu Manome
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan
| | - Emi Kikuchi
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Takayoshi Inoue
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yukiko U Inoue
- Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Shuichi Mori
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ryosuke Ishida
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroyuki Kagechika
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Madoka Suzuki
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, Tokyo, Japan
| | - Toshiko Yamazawa
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan.,Department of Molecular Physiology, The Jikei University School of Medicine, Tokyo, Japan
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Zero AM, Paris MT, Rice CL. Frequency dependent coexistence of muscle fatigue and potentiation assessed by concentric isotonic contractions in human plantar flexors. J Appl Physiol (1985) 2022; 133:490-505. [PMID: 35796610 DOI: 10.1152/japplphysiol.00214.2022] [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: 11/22/2022] Open
Abstract
The purpose was to investigate whether post-activation potentiation (PAP) mitigates power (i.e., torque x angular velocity) loss during dynamic fatiguing contractions and subsequent recovery by enhancing either muscle torque or angular velocity in human plantar flexors. In 12 participants, electrically stimulated (1, 10 and 50 Hz) dynamic contractions were done during a voluntary isotonic fatiguing protocol (20 and 50% voluntary decreases) until a 75% loss in voluntary peak power, and throughout 30 minutes of recovery. At the initial portion of fatigue (20% decrease), power responses of evoked low frequencies (1 and 10 Hz) were enhanced due to PAP (156 and 137%, respectively, P<0.001), while voluntary maximal efforts were depressed due to fatiguing mechanisms. Following the fatiguing task, prolonged low-frequency force depression (PLFFD) was evident by reduced 10:50 Hz peak power ratios (21 - 24%) from 3-min onwards during the 30-min recovery (P<0.005). Inducing PAP with maximal voluntary contractions during PLFFD enhanced the peak power responses of low frequencies (1 and 10 Hz) by 128 - 160 %, P<0.01. This PAP response mitigated the effects of PLFFD as the 1:50 (P<0.05) and 10:50 (P>0.4) Hz peak power ratios were greater or not different from the pre-fatigue values. Additionally, PAP enhanced peak torque more than peak angular velocity during both baseline and fatigue measurements (P<0.03). These results indicate that PAP can ameliorate PLFFD acutely when evaluated during concentric isotonic contractions and that peak torque is enhanced to a greater degree compared to peak angular velocity at baseline and in a fatigued state.
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Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, grid.39381.30Western University, London, ON, Canada
| | - Michael T Paris
- School of Kinesiology, Faculty of Health Sciences, grid.39381.30Western University, London, ON, Canada
| | - Charles L Rice
- Department of Anatomy and Cell Biology, grid.443228.bWestern University, London, Ontario, Canada
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MacDougall KB, Devrome AN, Kristensen AM, MacIntosh BR. Force-frequency relationship during fatiguing contractions of rat medial gastrocnemius muscle. Sci Rep 2020; 10:11575. [PMID: 32665563 PMCID: PMC7360560 DOI: 10.1038/s41598-020-68392-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 06/15/2020] [Indexed: 01/26/2023] Open
Abstract
The force–frequency relationship presents the amount of force a muscle can produce as a function of the frequency of activation. During repetitive muscular contractions, fatigue and potentiation may both impact the resultant contractile response. However, both the apparent fatigue observed, and the potential for activity-dependent potentiation can be affected by the frequency of activation. Thus, we wanted to explore the effects that repetitive stimulation had on the force–frequency relationship. The force–frequency relationship of the rat medial gastrocnemius muscle was investigated during consecutive bouts of increasing fatigue with 20 to 100 Hz stimulation. Force was measured prior to the fatiguing protocol, during each of three levels of fatigue, and after 30 min of recovery. Force at each frequency was quantified relative to the pre-fatigued 100 Hz contractions, as well as the percentage reduction of force from the pre-fatigued level at a given frequency. We observed less reduction in force at low frequencies compared to high frequencies, suggesting an interplay of fatigue and potentiation, in which potentiation can “protect” against fatigue in a frequency-dependent manner. The exact mechanism of fatigue is unknown, however the substantial reduction of force at high frequency suggests a role for reduced force per cross-bridge.
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Affiliation(s)
| | - Andrea N Devrome
- Faculty of Medicine, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | | | - Brian R MacIntosh
- Faculty of Kinesiology, University of Calgary, Calgary, AB, T2N 1N4, Canada.
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Calcium sensitivity during staircase with sequential incompletely fused contractions. J Muscle Res Cell Motil 2020; 42:59-65. [PMID: 31916128 DOI: 10.1007/s10974-019-09572-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/14/2019] [Accepted: 12/27/2019] [Indexed: 10/25/2022]
Abstract
Activity dependent potentiation is thought to result from phosphorylation of the regulatory light chains of myosin, increasing Ca2+ sensitivity. Yet, Ca2+ sensitivity decreases early in a period of intermittent contractions. The purpose of this study was to investigate the early change in Ca2+ sensitivity during intermittent submaximal tetanic contractions. Flexor digitorum brevis muscle fibres were dissected from mice after cervical disarticulation. Fibres were superfused with Tyrode solution at 32 °C. Length was set to yield maximal tetanic force. Indo-1 was microinjected into fibres and allowed to dissipate for 30 min. Fluorescence was measured at 405 and 495 nm wavelength and the ratio was used to estimate [Ca2+]. A control force-Ca2+ relationship was determined with stimulation over a range of frequencies, yielding constants for slope, max force, and half-maximal [Ca2+] (pCa2 +50). Data were collected for sequential contractions at 40 Hz at 2 s intervals. Active force decreased over the first 1-4 contractions then increased. A force-pCa2+ curve was fit to each contraction, using the control values for the Hill slope and max force by adjusting pCa2+50 until the curve passed through the target contraction. Data are presented for three contractions for each fibre: first, maximum shift to the right, and last contraction. There was a significant shift to the right for pCa2+50 (decreased Ca2+ sensitivity), usually early in the series of intermittent contractions, then pCa2 +50 shifted to the left, but remained significantly different from the control value. Although potentiation is associated with increased Ca2+ sensitivity, this increase begins only after Ca2+ sensitivity has decreased and, in most cases, Ca2+ sensitivity does not increase above the control level.
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Zimmermann HB, MacIntosh BR, Dal Pupo J. Does postactivation potentiation (PAP) increase voluntary performance? Appl Physiol Nutr Metab 2019; 45:349-356. [PMID: 31557447 DOI: 10.1139/apnm-2019-0406] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transient increase in torque of an electrically evoked twitch following a voluntary contraction is called postactivation potentiation (PAP). Phosphorylation of myosin regulatory light chains is the most accepted mechanism explaining the enhanced electrically evoked twitch torque. While many authors attribute voluntary postactivation performance enhancement (PAPE) to the positive effects of PAP, few actually confirmed that contraction was indeed potentiated using electrical stimulation (twitch response) at the time that PAPE was measured. Thus, this review aims to investigate if increases in voluntary performance after a conditioning contraction (CC) are related to the PAP phenomenon. For this, studies that confirmed the presence of PAP through an evoked response after a voluntary CC and concurrently evaluated PAPE were reviewed. Some studies reported increases in PAPE when PAP reaches extremely high values. However, PAPE has also been reported when PAP was not present, and unchanged/diminished performance has been identified when PAP was present. This range of observations demonstrates that mechanisms of PAPE are different from mechanisms of PAP. These mechanisms of PAPE still need to be understood and those studying PAPE should not assume that regulatory light chain phosphorylation is the mechanism for such enhanced voluntary performance. Novelty The occurrence of PAP does not necessarily mean that the voluntary performance will be improved. Improvement in voluntary performance is sometimes observed when the PAP level reaches extremely high values. Other mechanisms may be more relevant than that for PAP in the manifestation of acute increases in performance following a conditioning contraction.
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Affiliation(s)
- Haiko Bruno Zimmermann
- Biomechanics Laboratory, Sports Center, Federal University of Santa Catarina, Florianopolis, SC 88040900, Brazil
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Juliano Dal Pupo
- Biomechanics Laboratory, Sports Center, Federal University of Santa Catarina, Florianopolis, SC 88040900, Brazil
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Krüger RL, Aboodarda SJ, Jaimes LM, MacIntosh BR, Samozino P, Millet GY. Fatigue and recovery measured with dynamic properties versus isometric force: effects of exercise intensity. ACTA ACUST UNITED AC 2019; 222:jeb.197483. [PMID: 30890621 DOI: 10.1242/jeb.197483] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/13/2019] [Indexed: 11/20/2022]
Abstract
Although fatigue can be defined as an exercise-related decrease in maximal power or isometric force, most studies have assessed only isometric force. The main purpose of this experiment was to compare dynamic measures of fatigue [maximal torque (T max), maximal velocity (V max) and maximal power (P max)] with measures associated with maximal isometric force [isometric maximal voluntary contraction (IMVC) and maximal rate of force development (MRFD)] 10 s after different fatiguing exercises and during the recovery period (1-8 min after). Ten young men completed six experimental sessions (3 fatiguing exercises×2 types of fatigue measurements). The fatiguing exercises were: 30 s all-out intensity (AI), 10 min at severe intensity (SI) and 90 min at moderate intensity (MI). Relative P max decreased more than IMVC after AI exercise (P=0.005) while the opposite was found after SI (P=0.005) and MI tasks (P<0.001). There was no difference between the decrease in IMVC and T max after the AI exercise, but IMVC decreased more than T max immediately following and during the recovery from the SI (P=0.042) and MI exercises (P<0.001). Depression of MRFD was greater than V max after all fatiguing exercises and during recovery (all P<0.05). Despite the general definition of fatigue, isometric assessment of fatigue is not interchangeable with dynamic assessment following dynamic exercises with large muscle mass of different intensities, i.e. the results from isometric function cannot be used to estimate dynamic function and vice versa. This implies different physiological mechanisms for the various measures of fatigue.
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Affiliation(s)
- Renata L Krüger
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Saied Jalal Aboodarda
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Libia Marcela Jaimes
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | - Pierre Samozino
- Univ Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, F-73000 Chambéry, France
| | - Guillaume Y Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
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