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Bibollet H, Nguyen EL, Miranda DR, Ward CW, Voss AA, Schneider MF, Hernández‐Ochoa EO. Voltage sensor current, SR Ca 2+ release, and Ca 2+ channel current during trains of action potential-like depolarizations of skeletal muscle fibers. Physiol Rep 2023; 11:e15675. [PMID: 37147904 PMCID: PMC10163276 DOI: 10.14814/phy2.15675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 05/07/2023] Open
Abstract
In skeletal muscle, CaV 1.1 serves as the voltage sensor for both excitation-contraction coupling (ECC) and L-type Ca2+ channel activation. We have recently adapted the technique of action potential (AP) voltage clamp (APVC) to monitor the current generated by the movement of intramembrane voltage sensors (IQ ) during single imposed transverse tubular AP-like depolarization waveforms (IQAP ). We now extend this procedure to monitoring IQAP , and Ca2+ currents during trains of tubular AP-like waveforms in adult murine skeletal muscle fibers, and compare them with the trajectories of APs and AP-induced Ca2+ release measured in other fibers using field stimulation and optical probes. The AP waveform remains relatively constant during brief trains (<1 sec) for propagating APs in non-V clamped fibers. Trains of 10 AP-like depolarizations at 10 Hz (900 ms), 50 Hz (180 ms), or 100 Hz (90 ms) did not alter IQAP amplitude or kinetics, consistent with previous findings in isolated muscle fibers where negligible charge immobilization occurred during 100 ms step depolarizations. Using field stimulation, Ca2+ release did exhibit a considerable decline from pulse to pulse during the train, also consistent with previous findings, indicating that the decline of Ca2+ release during a short train of APs is not correlated to modification of charge movement. Ca2+ currents during single or 10 Hz trains of AP-like depolarizations were hardly detectable, were minimal during 50 Hz trains, and became more evident during 100 Hz trains in some fibers. Our results verify predictions on the behavior of the ECC machinery in response to AP-like depolarizations and provide a direct demonstration that Ca2+ currents elicited by single AP-like waveforms are negligible, but can become more prominent in some fibers during short high-frequency train stimulation that elicits maximal isometric force.
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Affiliation(s)
- Hugo Bibollet
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Elton L. Nguyen
- Department of Biological SciencesWright State UniversityDaytonOhioUSA
| | - Daniel R. Miranda
- Department of Biological SciencesWright State UniversityDaytonOhioUSA
| | - Christopher W. Ward
- Department of OrthopedicsUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Andrew A. Voss
- Department of Biological SciencesWright State UniversityDaytonOhioUSA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
| | - Erick O. Hernández‐Ochoa
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMarylandUSA
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Wang X, Dupont C, Grant D, Voss AA, Rich MM. Plateau potentials contribute to myotonia in mouse models of myotonia congenita. Exp Neurol 2023; 361:114303. [PMID: 36563835 PMCID: PMC9892346 DOI: 10.1016/j.expneurol.2022.114303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 12/12/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
It has long been accepted that myotonia (muscle stiffness) in patients with muscle channelopathies is due to myotonic discharges (involuntary firing of action potentials). In a previous study, we identified a novel phenomenon in myotonic muscle: development of plateau potentials, transient depolarizations to near -35 mV lasting for seconds to minutes. In the current study we examined whether plateau potentials contribute to myotonia. A recessive genetic model (ClCadr mice) with complete loss of muscle chloride channel (ClC-1) function was used to model severe myotonia congenita with complete loss of ClC-1 function and a pharmacologic model using anthracene-9-carboxylic acid (9 AC) was used to model milder myotonia congenita with incomplete loss of ClC-1 function. Simultaneous measurements of action potentials and myoplasmic Ca2+ from individual muscle fibers were compared to recordings of whole muscle force generation. In ClCadr muscle both myotonia and plateau potentials lasted 10s of seconds to minutes. During plateau potentials lasting 1-2 min, there was a gradual transition from high to low intracellular Ca2+, suggesting a transition in individual fibers from myotonia to flaccid paralysis in severe myotonia congenita. In 9 AC-treated muscles, both myotonia and plateau potentials lasted only a few seconds and Ca2+ remained elevated during the plateau potentials, suggesting plateau potentials contribute to myotonia without causing weakness. We propose, that in myotonic muscle, there is a novel state in which there is contraction in the absence of action potentials. This discovery provides a mechanism to explain reports of patients with myotonia who suffer from electrically silent muscle contraction lasting minutes.
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Affiliation(s)
- Xueyong Wang
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Chris Dupont
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Delaney Grant
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Andrew A Voss
- Department of Biology, Wright State University, Dayton, OH 45435, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA.
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3
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Idoux R, Bretaud S, Berthier C, Ruggiero F, Jacquemond V, Allard B. Superfast excitation-contraction coupling in adult zebrafish skeletal muscle fibers. J Gen Physiol 2022; 154:213310. [PMID: 35767225 PMCID: PMC9247716 DOI: 10.1085/jgp.202213158] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/15/2022] [Indexed: 12/16/2022] Open
Abstract
The zebrafish has emerged as a very relevant animal model for probing the pathophysiology of human skeletal muscle disorders. This vertebrate animal model displays a startle response characterized by high-frequency swimming activity powered by contraction of fast skeletal muscle fibers excited at extremely high frequencies, critical for escaping predators and capturing prey. Such intense muscle performance requires extremely fast properties of the contractile machinery but also of excitation-contraction coupling, the process by which an action potential spreading along the sarcolemma induces a change in configuration of the dihydropyridine receptors, resulting in intramembrane charge movements, which in turn triggers the release of Ca2+ from the sarcoplasmic reticulum. However, thus far, the fastest Ca2+ transients evoked by vertebrate muscle fibers has been described in muscles used to produce sounds, such as those in the toadfish swim bladder, but not in muscles used for locomotion. By performing intracellular Ca2+ measurements under voltage control in isolated fast skeletal muscle fibers from adult zebrafish and mouse, we demonstrate that fish fast muscle fibers display superfast kinetics of action potentials, intramembrane charge movements, and action potential-evoked Ca2+ transient, allowing fusion and fused sustained Ca2+ transients at frequencies of excitation much higher than in mouse fast skeletal muscle fibers and comparable to those recorded in muscles producing sounds. The present study is the first demonstration of superfast kinetics of excitation-contraction coupling in skeletal muscle allowing superfast locomotor behaviors in a vertebrate.
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Affiliation(s)
- Romane Idoux
- Institut de Physiopathologie et Génétique du Neurone et du Muscle (PGNM), Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5261, INSERM U1315, Faculté de Médecine Rockefeller, Lyon, France
| | - Sandrine Bretaud
- Institut de Génomique Fonctionnelle de Lyon (IGFL), École normale supérieure de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5242, Lyon, France
| | - Christine Berthier
- Institut de Physiopathologie et Génétique du Neurone et du Muscle (PGNM), Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5261, INSERM U1315, Faculté de Médecine Rockefeller, Lyon, France
| | - Florence Ruggiero
- Institut de Génomique Fonctionnelle de Lyon (IGFL), École normale supérieure de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5242, Lyon, France
| | - Vincent Jacquemond
- Institut de Physiopathologie et Génétique du Neurone et du Muscle (PGNM), Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5261, INSERM U1315, Faculté de Médecine Rockefeller, Lyon, France
| | - Bruno Allard
- Institut de Physiopathologie et Génétique du Neurone et du Muscle (PGNM), Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique UMR 5261, INSERM U1315, Faculté de Médecine Rockefeller, Lyon, France,Correspondence to Bruno Allard:
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Watanabe D, Wada M. Orthograde signal of dihydropyridine receptor increases Ca 2+ leakage after repeated contractions in rat fast-twitch muscles in vivo. Am J Physiol Cell Physiol 2021; 320:C806-C821. [PMID: 33596151 DOI: 10.1152/ajpcell.00364.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/10/2021] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to investigate the mechanism underlying sarcoplasmic reticulum (SR) Ca2+ leakage after in vivo contractions. Rat gastrocnemius muscles were electrically stimulated in vivo, and then mechanically skinned fibers and SR microsomes were prepared from the muscles excised 30 min after repeated high-intensity contractions. The mechanically skinned fibers maintained the interaction between dihydropyridine receptors (DHPRs) and ryanodine receptors (RyRs), whereas the SR microsomes did not. Interestingly, skinned fibers from the stimulated muscles showed increased SR Ca2+ leakage, whereas Ca2+ leakage decreased in SR microsomes from the stimulated muscles. To enhance the orthograde signal of DHPRs, SR Ca2+ leakage in the skinned fiber was measured 1) under a continuously depolarized condition and 2) in the presence of nifedipine. As a result, in either of the two conditions, SR Ca2+ leakage in the rested fibers reached a level similar to that in the stimulated fibers. Furthermore, the increased SR Ca2+ leakage from the stimulated fibers was alleviated by treatment with 1 mM tetracaine (Tet) but not by treatment with 3 mM free Mg2+ (3 Mg). Tet exerted a greater inhibitory effect on the DHPR signal to RyR than 3 Mg, although their inhibitory effects on RyR were almost similar. These results suggest that the increased Ca2+ leakage after muscle contractions is mainly caused by the orthograde signal of DHPRs to RyRs.
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Affiliation(s)
- Daiki Watanabe
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
| | - Masanobu Wada
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
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Figueroa L, Kraeva N, Manno C, Toro S, Ríos E, Riazi S. Abnormal calcium signalling and the caffeine-halothane contracture test. Br J Anaesth 2019; 122:32-41. [PMID: 30579404 PMCID: PMC6334558 DOI: 10.1016/j.bja.2018.08.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/16/2018] [Accepted: 08/06/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The variable clinical presentation of malignant hyperthermia (MH), a disorder of calcium signalling, hinders its diagnosis and management. Diagnosis relies on the caffeine-halothane contracture test, measuring contraction forces upon exposure of muscle to caffeine or halothane (FC and FH, respectively). Patients with above-threshold FC or FH are diagnosed as MH susceptible. Many patients test positive to halothane only (termed 'HH'). Our objective was to determine the characteristics of these HH patients, including their clinical symptoms and features of cytosolic Ca2+ signalling related to excitation-contraction coupling in myotubes. METHODS After institutional ethics committee approval, recruited patients undergoing contracture testing at Toronto's MH centre were assigned to three groups: HH, doubly positive (HS), and negative patients (HN). A clinical index was assembled from musculoskeletal symptoms and signs. An analogous calcium index summarised four measures in cultured myotubes: resting [Ca2+]cytosol, frequency of spontaneous cytosolic Ca2+ events, Ca2+ waves, and cell-wide Ca2+ spikes after electrical stimulation. RESULTS The highest values of both indexes were found in the HH group; the differences in calcium index between HH and the other groups were statistically significant. The principal component analysis confirmed the unique cell-level features of the HH group, and identified elevated resting [Ca2+]cytosol and spontaneous event frequency as the defining HH characteristics. CONCLUSIONS These findings suggest that HH pathogenesis stems from excess Ca2+ leak through sarcoplasmic reticulum channels. This identifies HH as a separate diagnostic group and opens their condition to treatment based on understanding of pathophysiological mechanisms.
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Affiliation(s)
- L Figueroa
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - N Kraeva
- Malignant Hyperthermia Investigation Unit of the University Health Network, Toronto, ON, Canada; Department of Anaesthesia & Pain Management, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
| | - C Manno
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - S Toro
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - E Ríos
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA.
| | - S Riazi
- Malignant Hyperthermia Investigation Unit of the University Health Network, Toronto, ON, Canada; Department of Anaesthesia & Pain Management, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
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6
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Allard B. From excitation to intracellular Ca 2+ movements in skeletal muscle: Basic aspects and related clinical disorders. Neuromuscul Disord 2018; 28:394-401. [DOI: 10.1016/j.nmd.2018.03.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/19/2018] [Accepted: 03/05/2018] [Indexed: 01/18/2023]
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Zullo A, Textor M, Elischer P, Mall S, Alt A, Klingler W, Melzer W. Voltage modulates halothane-triggered Ca 2+ release in malignant hyperthermia-susceptible muscle. J Gen Physiol 2017; 150:111-125. [PMID: 29247050 PMCID: PMC5749113 DOI: 10.1085/jgp.201711864] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 11/16/2017] [Indexed: 12/20/2022] Open
Abstract
Malignant hyperthermia can result from mutations in the ryanodine receptor that favor anesthetic-induced Ca2+ release. Zullo et al. find that membrane potential modulates the effect of the volatile anesthetic halothane on skeletal muscle ryanodine receptors possessing the Y524S mutation. Malignant hyperthermia (MH) is a fatal hypermetabolic state that may occur during general anesthesia in susceptible individuals. It is often caused by mutations in the ryanodine receptor RyR1 that favor drug-induced release of Ca2+ from the sarcoplasmic reticulum. Here, knowing that membrane depolarization triggers Ca2+ release in normal muscle function, we study the cross-influence of membrane potential and anesthetic drugs on Ca2+ release. We used short single muscle fibers of knock-in mice heterozygous for the RyR1 mutation Y524S combined with microfluorimetry to measure intracellular Ca2+ signals. Halothane, a volatile anesthetic used in contracture testing for MH susceptibility, was equilibrated with the solution superfusing the cells by means of a vaporizer system. In the range 0.2 to 3%, the drug causes significantly larger elevations of free myoplasmic [Ca2+] in mutant (YS) compared with wild-type (WT) fibers. Action potential–induced Ca2+ signals exhibit a slowing of their time course of relaxation that can be attributed to a component of delayed Ca2+ release turnoff. In further experiments, we applied halothane to single fibers that were voltage-clamped using two intracellular microelectrodes and studied the effect of small (10-mV) deviations from the holding potential (−80 mV). Untreated WT fibers show essentially no changes in [Ca2+], whereas the Ca2+ level of YS fibers increases and decreases on depolarization and hyperpolarization, respectively. The drug causes a significant enhancement of this response. Depolarizing pulses reveal a substantial negative shift in the voltage dependence of activation of Ca2+ release. This behavior likely results from the allosteric coupling between RyR1 and its transverse tubular voltage sensor. We conclude that the binding of halothane to RyR1 alters the voltage dependence of Ca2+ release in MH-susceptible muscle fibers such that the resting membrane potential becomes a decisive factor for the efficiency of the drug to trigger Ca2+ release.
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Affiliation(s)
- Alberto Zullo
- Institute of Applied Physiology, Ulm University, Ulm, Germany.,CEINGE - Biotecnologie Avanzate, Napoli, Italy.,Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Martin Textor
- Institute of Applied Physiology, Ulm University, Ulm, Germany
| | | | - Stefan Mall
- Institute of Applied Physiology, Ulm University, Ulm, Germany
| | - Andreas Alt
- Institute of Legal Medicine, Ulm University, Ulm, Germany
| | - Werner Klingler
- Department of Neuroanaesthesiology, Ulm University, Günzburg, Germany.,Queensland University of Technology, Brisbane, Australia
| | - Werner Melzer
- Institute of Applied Physiology, Ulm University, Ulm, Germany
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8
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van Bremen T, Send T, Sasse P, Bruegmann T. Spot light on skeletal muscles: optogenetic stimulation to understand and restore skeletal muscle function. J Muscle Res Cell Motil 2017; 38:331-337. [PMID: 28918572 DOI: 10.1007/s10974-017-9481-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/07/2017] [Indexed: 02/04/2023]
Abstract
Damage of peripheral nerves results in paralysis of skeletal muscle. Currently, the only treatment option to restore proper function is electrical stimulation of the innervating nerve or of the skeletal muscles directly. However this approach has low spatial and temporal precision leading to co-activation of antagonistic muscles and lacks cell-type selectivity resulting in pain or discomfort by stimulation of sensible nerves. In contrast to electrical stimulation, optogenetic methods enable spatially confined and cell-type selective stimulation of cells expressing the light sensitive channel Channelrhodopsin-2 with precise temporal control over the membrane potential. Herein we summarize the current knowledge about the use of this technology to control skeletal muscle function with the focus on the direct, non-neuronal stimulation of muscle fibers. The high temporal flexibility of using light pulses allows new stimulation patterns to investigate skeletal muscle physiology. Furthermore, the high spatial precision of focused illumination was shown to be beneficial for selective stimulation of distinct nearby muscle groups. Finally, the cell-type specific expression of the light-sensitive effector proteins in muscle fibers will allow pain-free stimulation and open new options for clinical treatments. Therefore, we believe that direct optogenetic stimulation of skeletal muscles is a very potent method for basic scientists that also harbors several distinct advantages over electrical stimulation to be considered for clinical use in the future.
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Affiliation(s)
- Tobias van Bremen
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany
| | - Thorsten Send
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany.
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany. .,Research Training Group 1873, University of Bonn, 53127, Bonn, Germany.
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9
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Robin G, Allard B. Voltage-gated Ca(2+) influx through L-type channels contributes to sarcoplasmic reticulum Ca(2+) loading in skeletal muscle. J Physiol 2015; 593:4781-97. [PMID: 26383921 DOI: 10.1113/jp270252] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 09/08/2015] [Indexed: 12/15/2022] Open
Abstract
Muscle contraction is triggered by Ca(2+) ions released from the sarcoplasmic reticulum (SR) in response to depolarization of skeletal muscle fibres. Muscle activation is also associated with a voltage-activated trans-sarcolemmal Ca(2+) influx early identified as a current flowing through L-type Ca(2+) channels. Because removal of external Ca(2+) does not impede fibres from contracting, a negligible role was given to this voltage-activated Ca(2+) entry, although the decline of Ca(2+) release is more pronounced in the absence of Ca(2+) during long-lasting activation. Furthermore, it is not clearly established whether Ca(2+) exclusively flows through L-type channels or in addition through a parallel voltage-activated pathway distinct from L-type channels. Here, by monitoring the quenching of fura-2 fluorescence resulting from Mn(2+) influx in voltage-controlled mouse and zebrafish isolated muscle fibres, we show that the L-type current is the only contributor to Ca(2+) influx during long-lasting depolarizations in skeletal muscle. Calibration of the Mn(2+) quenching signal allowed us to estimate a mean Mn(2+) current of 0.31 ± 0.06 A F(-1) flowing through L-type channels during a train of action potentials. Measurements of SR Ca(2+) changes with fluo-5N in response to depolarization revealed that an elevated voltage-activated Ca(2+) current potentiated SR Ca(2+) loading and addition of external Mn(2+) produced quenching of fluo-5N in the SR, indicating that voltage-activated Ca(2+) /Mn(2+) influx contributes to SR Ca(2+) /Mn(2+) loading.
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Affiliation(s)
- Gaëlle Robin
- Université de Lyon, Université Lyon 1, CNRS UMR 5534, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Villeurbanne, France
| | - Bruno Allard
- Université de Lyon, Université Lyon 1, CNRS UMR 5534, Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Villeurbanne, France
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10
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Braubach P, Orynbayev M, Andronache Z, Hering T, Landwehrmeyer GB, Lindenberg KS, Melzer W. Altered Ca(2+) signaling in skeletal muscle fibers of the R6/2 mouse, a model of Huntington's disease. ACTA ACUST UNITED AC 2015; 144:393-413. [PMID: 25348412 PMCID: PMC4210430 DOI: 10.1085/jgp.201411255] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Huntington's disease (HD) is caused by an expanded CAG trinucleotide repeat within the gene encoding the protein huntingtin. The resulting elongated glutamine (poly-Q) sequence of mutant huntingtin (mhtt) affects both central neurons and skeletal muscle. Recent reports suggest that ryanodine receptor-based Ca(2+) signaling, which is crucial for skeletal muscle excitation-contraction coupling (ECC), is changed by mhtt in HD neurons. Consequently, we searched for alterations of ECC in muscle fibers of the R6/2 mouse, a mouse model of HD. We performed fluorometric recordings of action potentials (APs) and cellular Ca(2+) transients on intact isolated toe muscle fibers (musculi interossei), and measured L-type Ca(2+) inward currents on internally dialyzed fibers under voltage-clamp conditions. Both APs and AP-triggered Ca(2+) transients showed slower kinetics in R6/2 fibers than in fibers from wild-type mice. Ca(2+) removal from the myoplasm and Ca(2+) release flux from the sarcoplasmic reticulum were characterized using a Ca(2+) binding and transport model, which indicated a significant reduction in slow Ca(2+) removal activity and Ca(2+) release flux both after APs and under voltage-clamp conditions. In addition, the voltage-clamp experiments showed a highly significant decrease in L-type Ca(2+) channel conductance. These results indicate profound changes of Ca(2+) turnover in skeletal muscle of R6/2 mice and suggest that these changes may be associated with muscle pathology in HD.
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Affiliation(s)
- Peter Braubach
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
| | - Murat Orynbayev
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
| | - Zoita Andronache
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
| | - Tanja Hering
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
| | | | - Katrin S Lindenberg
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
| | - Werner Melzer
- Institute of Applied Physiology and Department of Neurology, Ulm University, D-89081 Ulm, Germany
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11
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Bruegmann T, van Bremen T, Vogt CC, Send T, Fleischmann BK, Sasse P. Optogenetic control of contractile function in skeletal muscle. Nat Commun 2015; 6:7153. [PMID: 26035411 PMCID: PMC4475236 DOI: 10.1038/ncomms8153] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/13/2015] [Indexed: 12/17/2022] Open
Abstract
Optogenetic stimulation allows activation of cells with high spatial and temporal precision. Here we show direct optogenetic stimulation of skeletal muscle from transgenic mice expressing the light-sensitive channel Channelrhodopsin-2 (ChR2). Largest tetanic contractions are observed with 5-ms light pulses at 30 Hz, resulting in 84% of the maximal force induced by electrical stimulation. We demonstrate the utility of this approach by selectively stimulating with a light guide individual intralaryngeal muscles in explanted larynges from ChR2-transgenic mice, which enables selective opening and closing of the vocal cords. Furthermore, systemic injection of adeno-associated virus into wild-type mice provides sufficient ChR2 expression for optogenetic opening of the vocal cords. Thus, direct optogenetic stimulation of skeletal muscle generates large force and provides the distinct advantage of localized and cell-type-specific activation. This technology could be useful for therapeutic purposes, such as restoring the mobility of the vocal cords in patients suffering from laryngeal paralysis.
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Affiliation(s)
- Tobias Bruegmann
- Institute of Physiology I, University of Bonn, Life and Brain Center, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany.,Research Training Group 1873, University of Bonn, 53127 Bonn, Germany
| | - Tobias van Bremen
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Christoph C Vogt
- Institute of Physiology I, University of Bonn, Life and Brain Center, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Thorsten Send
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Bernd K Fleischmann
- Institute of Physiology I, University of Bonn, Life and Brain Center, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Philipp Sasse
- Institute of Physiology I, University of Bonn, Life and Brain Center, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
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12
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Yao LH, Meng W, Song RF, Xiong QP, Sun W, Luo ZQ, Yan WW, Li YP, Li XP, Li HH, Xiao P. Modulation effects of cordycepin on the skeletal muscle contraction of toad gastrocnemius muscle. Eur J Pharmacol 2014; 726:9-15. [PMID: 24447979 DOI: 10.1016/j.ejphar.2014.01.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/20/2013] [Accepted: 01/09/2014] [Indexed: 11/15/2022]
Abstract
Isolated toad gastrocnemius muscle is a typical skeletal muscle tissue that is frequently used to study the motor system because it is an important component of the motor system. This study investigates the effects of cordycepin on the skeletal muscle contractile function of isolated toad gastrocnemius muscles by electrical field stimulation. Results showed that cordycepin (20 mg/l to 100 mg/l) significantly decreased the contractile responses in a concentration-dependent manner. Cordycepin (50 mg/l) also produced a rightward shift of the contractile amplitude-stimulation intensity relationship, as indicated by the increases in the threshold stimulation intensity and the saturation stimulation intensity. However, the most notable result was that the maximum amplitude of the muscle contractile force was significantly increased under cordycepin application (122±3.4% of control). This result suggests that the skeletal muscle contractile function and muscle physical fitness to the external stimulation were improved by the decreased response sensitivity in the presence of cordycepin. Moreover, cordycepin also prevented the repetitive stimulation-induced decrease in muscle contractile force and increased the recovery amplitude and recovery ratio of muscle contraction. However, these anti-fatigue effects of cordycepin on muscle contraction during long-lasting muscle activity were absent in Ca2+-free medium or in the presence of all Ca2+ channels blocker (0.4 mM CdCl2). These results suggest that cordycepin can positively affect muscle performance and provide ergogenic and prophylactic benefits in decreasing skeletal muscle fatigue. The mechanisms involving excitation-coupled Ca2+ influxes are strongly recommended.
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Melzer W. Skeletal muscle fibers: Inactivated or depleted after long depolarizations? ACTA ACUST UNITED AC 2014; 141:517-20. [PMID: 23630336 PMCID: PMC3639573 DOI: 10.1085/jgp.201310997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Werner Melzer
- Institute of Applied Physiology, Ulm University, D-89081 Ulm, Germany.
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