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Altamura C, Saltarella I, Campanale C, Laghetti P, Desaphy JF. Drug repurposing in skeletal muscle ion channelopathies. Curr Opin Pharmacol 2023; 68:102329. [PMID: 36512979 DOI: 10.1016/j.coph.2022.102329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/26/2022] [Accepted: 11/02/2022] [Indexed: 12/14/2022]
Abstract
Skeletal muscle ion channelopathies are rare genetic diseases mainly characterized by myotonia (muscle stiffness) or periodic paralysis (muscle weakness). Here, we reviewed the available therapeutic options in non-dystrophic myotonias (NDM) and periodic paralyses (PP), which consists essentially in drug repositioning to address stiffness or weakness attacks. Empirical use followed by successful randomized clinical trials eventually led to the orphan drug designation and marketing authorization granting of mexiletine for NDM and dichlorphenamide for PP. Yet, these treatments neither consider the genetic cause of the diseases nor address the individual variability in drug response. Thus, ongoing research aims at the identification of repurposed drugs alternative to mexiletine and dichlorphenamide to allow personalization of treatment. This review highlights how drug repurposing may represent an efficient strategy in rare diseases, allowing reduction of drug development time and costs in a context in which the return on investment may be particularly challenging.
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Affiliation(s)
- Concetta Altamura
- Section of Pharmacology, Department of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Piazza Giulo Cesare, 70124, Bari, Italy
| | - Ilaria Saltarella
- Section of Pharmacology, Department of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Piazza Giulo Cesare, 70124, Bari, Italy
| | - Carmen Campanale
- Section of Pharmacology, Department of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Piazza Giulo Cesare, 70124, Bari, Italy
| | - Paola Laghetti
- Section of Pharmacology, Department of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Piazza Giulo Cesare, 70124, Bari, Italy
| | - Jean-François Desaphy
- Section of Pharmacology, Department of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Piazza Giulo Cesare, 70124, Bari, Italy.
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Albadrani H, Ammar T, Bader M, Renaud JM. Angiotensin 1-7 prevents the excessive force loss resulting from 14- and 28-day denervation in mouse EDL and soleus muscle. J Gen Physiol 2021; 153:212748. [PMID: 34739541 PMCID: PMC8576869 DOI: 10.1085/jgp.201912556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 06/30/2021] [Accepted: 08/11/2021] [Indexed: 11/20/2022] Open
Abstract
Denervation leads to muscle atrophy, which is described as muscle mass and force loss, the latter exceeding expectation from mass loss. The objective of this study was to determine the efficiency of angiotensin (Ang) 1–7 at reducing muscle atrophy in mouse extensor digitorum longus (EDL) and soleus following 14- and 28-d denervation periods. Some denervated mice were treated with Ang 1–7 or diminazene aceturate (DIZE), an ACE2 activator, to increase Ang 1–7 levels. Ang 1–7/DIZE treatment had little effect on muscle mass loss and fiber cross-sectional area reduction. Ang 1–7 and DIZE fully prevented the loss of tetanic force normalized to cross-sectional area and accentuated the increase in twitch force in denervated muscle. However, they did not prevent the shift of the force–frequency relationship toward lower stimulation frequencies. The Ang 1–7/DIZE effects on twitch and tetanic force were completely blocked by A779, a MasR antagonist, and were not observed in MasR−/− muscles. Ang 1–7 reduced the extent of membrane depolarization, fully prevented the loss of membrane excitability, and maintained the action potential overshoot in denervated muscles. Ang 1–7 had no effect on the changes in α-actin, myosin, or MuRF-1, atrogin-1 protein content or the content of total or phosphorylated Akt, S6, and 4EPB. This is the first study that provides evidence that Ang 1–7 maintains normal muscle function in terms of maximum force and membrane excitability during 14- and 28-d periods after denervation.
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Affiliation(s)
- Hind Albadrani
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada.,Majmaah University, Department of Medical Laboratory Sciences, Al Majma'ah, Saudi Arabia
| | - T Ammar
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
| | - Michael Bader
- Max-Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.,University of Lübeck, Institute for Biology, Lübeck, Germany.,Charité University Medicine, Berlin, Germany.,German Center for Cardiovascular Research, Berlin, Germany
| | - Jean-Marc Renaud
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
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Uwera F, Ammar T, McRae C, Hayward LJ, Renaud JM. Lower Ca2+ enhances the K+-induced force depression in normal and HyperKPP mouse muscles. J Gen Physiol 2021; 152:151656. [PMID: 32291438 PMCID: PMC7335014 DOI: 10.1085/jgp.201912511] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/18/2020] [Accepted: 03/21/2020] [Indexed: 12/20/2022] Open
Abstract
Hyperkalemic periodic paralysis (HyperKPP) manifests as stiffness or subclinical myotonic discharges before or during periods of episodic muscle weakness or paralysis. Ingestion of Ca2+ alleviates HyperKPP symptoms, but the mechanism is unknown because lowering extracellular [Ca2+] ([Ca2+]e) has no effect on force development in normal muscles under normal conditions. Lowering [Ca2+]e, however, is known to increase the inactivation of voltage-gated cation channels, especially when the membrane is depolarized. Two hypotheses were tested: (1) lowering [Ca2+]e depresses force in normal muscles under conditions that depolarize the cell membrane; and (2) HyperKPP muscles have a greater sensitivity to low Ca2+-induced force depression because many fibers are depolarized, even at a normal [K+]e. In wild type muscles, lowering [Ca2+]e from 2.4 to 0.3 mM had little effect on tetanic force and membrane excitability at a normal K+ concentration of 4.7 mM, whereas it significantly enhanced K+-induced depression of force and membrane excitability. In HyperKPP muscles, lowering [Ca2+]e enhanced the K+-induced loss of force and membrane excitability not only at elevated [K+]e but also at 4.7 mM K+. Lowering [Ca2+]e increased the incidence of generating fast and transient contractures and gave rise to a slower increase in unstimulated force, especially in HyperKPP muscles. Lowering [Ca2+]e reduced the efficacy of salbutamol, a β2 adrenergic receptor agonist and a treatment for HyperKPP, to increase force at elevated [K+]e. Replacing Ca2+ by an equivalent concentration of Mg2+ neither fully nor consistently reverses the effects of lowering [Ca2+]e. These results suggest that the greater Ca2+ sensitivity of HyperKPP muscles primarily relates to (1) a greater effect of Ca2+ in depolarized fibers and (2) an increased proportion of depolarized HyperKPP muscle fibers compared with control muscle fibers, even at normal [K+]e.
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Affiliation(s)
- Francine Uwera
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
| | - Tarek Ammar
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
| | - Callum McRae
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
| | - Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA
| | - Jean-Marc Renaud
- University of Ottawa, Department of Cellular and Molecular Medicine, Ottawa, Ontario, Canada
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Desaphy JF, Altamura C, Vicart S, Fontaine B. Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine. J Neuromuscul Dis 2021; 8:357-381. [PMID: 33325393 PMCID: PMC8203248 DOI: 10.3233/jnd-200582] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. OBJECTIVE This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. METHODS We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. RESULTS For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from CAI compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. CONCLUSIONS These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Savine Vicart
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
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Altarawneh MM, Hanson ED, Betik AC, Petersen AC, Hayes A, McKenna MJ. Effects of testosterone suppression, hindlimb immobilization, and recovery on [ 3H]ouabain binding site content and Na +, K +-ATPase isoforms in rat soleus muscle. J Appl Physiol (1985) 2020; 128:501-513. [PMID: 31854248 DOI: 10.1152/japplphysiol.01077.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the effects of testosterone suppression, hindlimb immobilization, and recovery on skeletal muscle Na+,K+-ATPase (NKA), measured via [3H]ouabain binding site content (OB) and NKA isoform abundances (α1-3, β1-2). Male rats underwent castration or sham surgery plus 7 days of rest, 10 days of unilateral immobilization (cast), and 14 days of recovery, with soleus muscles obtained at each time from cast and noncast legs. Testosterone reduction did not modify OB or NKA isoforms in nonimmobilized control muscles. With sham surgery, OB was lower after immobilization in the cast leg than in both the noncast leg (-26%, P = 0.023) and the nonimmobilized control (-34%, P = 0.001), but OB subsequently recovered. With castration, OB was lower after immobilization in the cast leg than in the nonimmobilized control (-34%, P = 0.001), and remained depressed at recovery (-34%, P = 0.001). NKA isoforms did not differ after immobilization or recovery in the sham group. After castration, α2 in the cast leg was ~60% lower than in the noncast leg (P = 0.004) and nonimmobilized control (P = 0.004) and after recovery remained lower than the nonimmobilized control (-42%, P = 0.039). After immobilization, β1 was lower in the cast than the noncast leg (-26%, P = 0.018), with β2 lower in the cast leg than in the noncast leg (-71%, P = 0.004) and nonimmobilized control (-65%, P = 0.012). No differences existed for α1 or α3. Thus, both OB and α2 decreased after immobilization and recovery in the castration group, with α2, β1, and β2 isoform abundances decreased with immobilization compared with the sham group. Therefore, testosterone suppression in rats impaired restoration of immobilization-induced lowered number of functional NKA and α2 isoforms in soleus muscle.NEW & NOTEWORTHY: The Na+,K+-ATPase (NKA) is vital in muscle excitability and function. In rats, immobilization depressed soleus muscle NKA, with declines in [3H]ouabain binding, which was restored after 14 days recovery. After testosterone suppression by castration, immobilization depressed [3H]ouabain binding, depressed α2, β1, and β2 isoforms, and abolished subsequent recovery in [3H]ouabain binding and α2 isoforms. This may have implications for functional recovery for inactive men with lowered testosterone levels, such as in prostate cancer or aging.
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Affiliation(s)
- Muath M Altarawneh
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Erik D Hanson
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, North Carolina
| | - Andrew C Betik
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Aaron C Petersen
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Alan Hayes
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Australian Institute for Musculoskeletal Science, Victoria University, Melbourne, Australia
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Australia
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Liang P, Mast J, Chen W. Synchronization Modulation of Na/K Pumps Induced Membrane Potential Hyperpolarization in Both Physiological and Hyperkalemic Conditions. J Membr Biol 2019; 252:577-586. [PMID: 31410502 DOI: 10.1007/s00232-019-00080-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/08/2019] [Indexed: 11/29/2022]
Abstract
The capability of the synchronization modulation (SM) technique in enhancing the function of Na/K pumps has been demonstrated in various cells and tissues, including cardiomyocytes, a monolayer of cultured MDCK kidney cells, peripheral blood vessels, and frog skeletal muscles. This study characterized the membrane potential hyperpolarization induced by SM in both physiological and high [K+]o conditions on single skeletal muscle fibers. The results showed that SM could consistently induce membrane potential hyperpolarization by a few millivolts, and this hyperpolarization was not possible in the presence of ouabain. In contrast, the same electrical pulses but with random frequencies, constant frequencies, or synchronization with backward-modulation could not hyperpolarize the membrane potential. Prolonged field application and higher field intensity enhanced the effects of SM-induced hyperpolarization. Finally, the effect of SM was tested on skeletal muscle fibers incubated in a solution with high external potassium. Results showed that the SM electric field could hyperpolarize the membrane potential even if the external K+ concentration was higher than the normal, which implied the therapeutic effects of the SM electric field on the hyperkalemic situation.
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Affiliation(s)
- Pengfei Liang
- Department of Physics, Cellular and Molecular Biophysics Lab, University of South Florida, Tampa, FL, 33620, USA
| | - Jason Mast
- Department of Physics, Cellular and Molecular Biophysics Lab, University of South Florida, Tampa, FL, 33620, USA
| | - Wei Chen
- Department of Physics, Cellular and Molecular Biophysics Lab, University of South Florida, Tampa, FL, 33620, USA.
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Ammar T, Lin W, Higgins A, Hayward LJ, Renaud JM. Understanding the physiology of the asymptomatic diaphragm of the M1592V hyperkalemic periodic paralysis mouse. ACTA ACUST UNITED AC 2017; 146:509-25. [PMID: 26621775 PMCID: PMC4664826 DOI: 10.1085/jgp.201511476] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
When muscles become paralyzed in crises of hyperkalemic periodic paralysis, patients do not stop breathing. Here is why. The diaphragm muscle of hyperkalemic periodic paralysis (HyperKPP) patients and of the M1592V HyperKPP mouse model rarely suffers from the myotonic and paralytic symptoms that occur in limb muscles. Enigmatically, HyperKPP diaphragm expresses the mutant NaV1.4 channel and, more importantly, has an abnormally high Na+ influx similar to that in extensor digitorum longus (EDL) and soleus, two hindlimb muscles suffering from the robust HyperKPP abnormalities. The objective was to uncover the physiological mechanisms that render HyperKPP diaphragm asymptomatic. A first mechanism involves efficient maintenance of resting membrane polarization in HyperKPP diaphragm at various extracellular K+ concentrations compared with larger membrane depolarizations in HyperKPP EDL and soleus. The improved resting membrane potential (EM) results from significantly increased Na+ K+ pump electrogenic activity, and not from an increased protein content. Action potential amplitude was greater in HyperKPP diaphragm than in HyperKPP soleus and EDL, providing a second mechanism for the asymptomatic behavior of the HyperKPP diaphragm. One suggested mechanism for the greater action potential amplitude is lower intracellular Na+ concentration because of greater Na+ K+ pump activity, allowing better Na+ current during the action potential depolarization phase. Finally, HyperKPP diaphragm had a greater capacity to generate force at depolarized EM compared with wild-type diaphragm. Action potential amplitude was not different between wild-type and HyperKPP diaphragm. There was also no evidence for an increased activity of the Na+–Ca2+ exchanger working in the reverse mode in the HyperKPP diaphragm compared with the wild-type diaphragm. So, a third mechanism remains to be elucidated to fully understand how HyperKPP diaphragm generates more force compared with wild type. Although the mechanism for the greater force at depolarized resting EM remains to be determined, this study provides support for the modulation of the Na+ K+ pump as a component of therapy to alleviate weakness in HyperKPP.
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Affiliation(s)
- Tarek Ammar
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Wei Lin
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Amanda Higgins
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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8
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Abstract
The NaV1.4 sodium channel is highly expressed in skeletal muscle, where it carries almost all of the inward Na+ current that generates the action potential, but is not present at significant levels in other tissues. Consequently, mutations of SCN4A encoding NaV1.4 produce pure skeletal muscle phenotypes that now include six allelic disorders: sodium channel myotonia, paramyotonia congenita, hyperkalemic periodic paralysis, hypokalemic periodic paralysis, congenital myasthenia, and congenital myopathy with hypotonia. Mutation-specific alternations of NaV1.4 function explain the mechanistic basis for the diverse phenotypes and identify opportunities for strategic intervention to modify the burden of disease.
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Affiliation(s)
- Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA.
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Roy P, Rau F, Ochala J, Messéant J, Fraysse B, Lainé J, Agbulut O, Butler-Browne G, Furling D, Ferry A. Dystrophin restoration therapy improves both the reduced excitability and the force drop induced by lengthening contractions in dystrophic mdx skeletal muscle. Skelet Muscle 2016; 6:23. [PMID: 27441081 PMCID: PMC4952281 DOI: 10.1186/s13395-016-0096-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/11/2016] [Indexed: 12/16/2022] Open
Abstract
Background The greater susceptibility to contraction-induced skeletal muscle injury (fragility) is an important dystrophic feature and tool for testing preclinic dystrophin-based therapies for Duchenne muscular dystrophy. However, how these therapies reduce the muscle fragility is not clear. Methods To address this question, we first determined the event(s) of the excitation-contraction cycle which is/are altered following lengthening (eccentric) contractions in the mdx muscle. Results We found that the immediate force drop following lengthening contractions, a widely used measure of muscle fragility, was associated with reduced muscle excitability. Moreover, the force drop can be mimicked by an experimental reduction in muscle excitation of uninjured muscle. Furthermore, the force drop was not related to major neuromuscular transmission failure, excitation-contraction uncoupling, and myofibrillar impairment. Secondly, and importantly, the re-expression of functional truncated dystrophin in the muscle of mdx mice using an exon skipping strategy partially prevented the reductions in both force drop and muscle excitability following lengthening contractions. Conclusion We demonstrated for the first time that (i) the increased susceptibility to contraction-induced muscle injury in mdx mice is mainly attributable to reduced muscle excitability; (ii) dystrophin-based therapy improves fragility of the dystrophic skeletal muscle by preventing reduction in muscle excitability.
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Affiliation(s)
- Pauline Roy
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Fredérique Rau
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Julien Ochala
- Centre of Human and Aerospace Physiological Sciences, King's College London, Guy's Campus, SE3 8TL London, UK
| | - Julien Messéant
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Bodvael Fraysse
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Jeanne Lainé
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Onnik Agbulut
- Biological Adaptation and Ageing, UMR CNRS 8256, Institut de Biologie Paris-Seine (IBPS), UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75005 France
| | - Gillian Butler-Browne
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Denis Furling
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France
| | - Arnaud Ferry
- Groupe Hospitalier Pitié Salpêtrière, Centre de Recherche en Myologie, CNRS, Inserm, UPMC Univ Paris 06, Sorbonne Universités, Paris, F-75013 France ; Sorbonne Paris Cité, Université Paris Descartes, Paris, F-75006 France ; Groupe Hospitalier Pitié-Salpétrière, Institut de Myologie, F-75013 Paris, France
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Abstract
Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K(+) levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are "channelopathies" caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1), and several potassium channels (Kir2.1, Kir2.6, and Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics.
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Affiliation(s)
- Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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11
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Khogali S, Lucas B, Ammar T, Dejong D, Barbalinardo M, Hayward LJ, Renaud JM. Physiological basis for muscle stiffness and weakness in a knock-in M1592V mouse model of hyperkalemic periodic paralysis. Physiol Rep 2015; 3:3/12/e12656. [PMID: 26702073 PMCID: PMC4760441 DOI: 10.14814/phy2.12656] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 11/18/2015] [Indexed: 11/24/2022] Open
Abstract
The mechanisms responsible for the onset and progressive worsening of episodic muscle stiffness and weakness in hyperkalemic periodic paralysis (HyperKPP) are not fully understood. Using a knock‐in HyperKPP mouse model harboring the M1592V NaV1.4 channel mutant, we interrogated changes in physiological defects during the first year, including tetrodotoxin‐sensitive Na+ influx, hindlimb electromyographic (EMG) activity and immobility, muscle weakness induced by elevated [K+]e, myofiber‐type composition, and myofiber damage. In situ EMG activity was greater in HyperKPP than wild‐type gastrocnemius, whereas spontaneous muscle contractions were observed in vitro. We suggest that both the greater EMG activity and spontaneous contractions are related to periods of hyperexcitability during which fibers generate action potentials by themselves in the absence of any stimulation and that these periods are the cause of the muscle stiffness reported by patients. HyperKPP muscles had a greater sensitivity to the K+‐induced force depression than wild‐type muscles. So, an increased interstitial K+ concentration locally near subsets of myofibers as a result of the hyperexcitability likely produced partial loss of force rather than complete paralysis. NaV1.4 channel protein content reached adult level by 3 weeks postnatal in both wild type and HyperKPP and apparent symptoms did not worsen after the first month of age suggesting (i) that the phenotypic behavior of M1592V HyperKPP muscles results from defective function of mutant NaV1.4 channels rather than other changes in protein expression after the first month and (ii) that the lag in onset during the first decade and the progression of human HyperKPP symptoms during adolescence are a function of NaV1.4 channel content.
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Affiliation(s)
- Shiemaa Khogali
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Brooke Lucas
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Tarek Ammar
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Danica Dejong
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael Barbalinardo
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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12
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Clausen T. Quantification of Na+,K+ pumps and their transport rate in skeletal muscle: functional significance. ACTA ACUST UNITED AC 2014; 142:327-45. [PMID: 24081980 PMCID: PMC3787770 DOI: 10.1085/jgp.201310980] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
During excitation, muscle cells gain Na+ and lose K+, leading to a rise in extracellular K+ ([K+]o), depolarization, and loss of excitability. Recent studies support the idea that these events are important causes of muscle fatigue and that full use of the Na+,K+-ATPase (also known as the Na+,K+ pump) is often essential for adequate clearance of extracellular K+. As a result of their electrogenic action, Na+,K+ pumps also help reverse depolarization arising during excitation, hyperkalemia, and anoxia, or from cell damage resulting from exercise, rhabdomyolysis, or muscle diseases. The ability to evaluate Na+,K+-pump function and the capacity of the Na+,K+ pumps to fill these needs require quantification of the total content of Na+,K+ pumps in skeletal muscle. Inhibition of Na+,K+-pump activity, or a decrease in their content, reduces muscle contractility. Conversely, stimulation of the Na+,K+-pump transport rate or increasing the content of Na+,K+ pumps enhances muscle excitability and contractility. Measurements of [3H]ouabain binding to skeletal muscle in vivo or in vitro have enabled the reproducible quantification of the total content of Na+,K+ pumps in molar units in various animal species, and in both healthy people and individuals with various diseases. In contrast, measurements of 3-O-methylfluorescein phosphatase activity associated with the Na+,K+-ATPase may show inconsistent results. Measurements of Na+ and K+ fluxes in intact isolated muscles show that, after Na+ loading or intense excitation, all the Na+,K+ pumps are functional, allowing calculation of the maximum Na+,K+-pumping capacity, expressed in molar units/g muscle/min. The activity and content of Na+,K+ pumps are regulated by exercise, inactivity, K+ deficiency, fasting, age, and several hormones and pharmaceuticals. Studies on the α-subunit isoforms of the Na+,K+-ATPase have detected a relative increase in their number in response to exercise and the glucocorticoid dexamethasone but have not involved their quantification in molar units. Determination of ATPase activity in homogenates and plasma membranes obtained from muscle has shown ouabain-suppressible stimulatory effects of Na+ and K+.
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Affiliation(s)
- Torben Clausen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
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Lucas B, Ammar T, Khogali S, DeJong D, Barbalinardo M, Nishi C, Hayward LJ, Renaud JM. Contractile abnormalities of mouse muscles expressing hyperkalemic periodic paralysis mutant NaV1.4 channels do not correlate with Na+ influx or channel content. Physiol Genomics 2014; 46:385-97. [PMID: 24714718 DOI: 10.1152/physiolgenomics.00166.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hyperkalemic periodic paralysis (HyperKPP) is characterized by myotonic discharges that occur between episodic attacks of paralysis. Individuals with HyperKPP rarely suffer respiratory distress even though diaphragm muscle expresses the same defective Na(+) channel isoform (NaV1.4) that causes symptoms in limb muscles. We tested the hypothesis that the extent of the HyperKPP phenotype (low force generation and shift toward oxidative type I and IIA fibers) in muscle is a function of 1) the NaV1.4 channel content and 2) the Na(+) influx through the defective channels [i.e., the tetrodotoxin (TTX)-sensitive Na(+) influx]. We measured NaV1.4 channel protein content, TTX-sensitive Na(+) influx, force generation, and myosin isoform expression in four muscles from knock-in mice expressing a NaV1.4 isoform corresponding to the human M1592V mutant. The HyperKPP flexor digitorum brevis muscle showed no contractile abnormalities, which correlated well with its low NaV1.4 protein content and by far the lowest TTX-sensitive Na(+) influx. In contrast, diaphragm muscle expressing the HyperKPP mutant contained high levels of NaV1.4 protein and exhibited a TTX-sensitive Na(+) influx that was 22% higher compared with affected extensor digitorum longus (EDL) and soleus muscles. Surprisingly, despite this high burden of Na(+) influx, the contractility phenotype was very mild in mutant diaphragm compared with the robust abnormalities observed in EDL and soleus. This study provides evidence that HyperKPP phenotype does not depend solely on the NaV1.4 content or Na(+) influx and that the diaphragm does not depend solely on Na(+)-K(+) pumps to ameliorate the phenotype.
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Affiliation(s)
- Brooke Lucas
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Tarek Ammar
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Shiemaa Khogali
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Danica DeJong
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Michael Barbalinardo
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Cameron Nishi
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Lawrence J Hayward
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada; and
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Cheng CJ, Kuo E, Huang CL. Extracellular potassium homeostasis: insights from hypokalemic periodic paralysis. Semin Nephrol 2014; 33:237-47. [PMID: 23953801 DOI: 10.1016/j.semnephrol.2013.04.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Extracellular potassium makes up only about 2% of the total body's potassium store. The majority of the body potassium is distributed in the intracellular space, of which about 80% is in skeletal muscle. Movement of potassium in and out of skeletal muscle thus plays a pivotal role in extracellular potassium homeostasis. The exchange of potassium between the extracellular space and skeletal muscle is mediated by specific membrane transporters. These include potassium uptake by Na(+), K(+)-adenosine triphosphatase and release by inward-rectifier K(+) channels. These processes are regulated by circulating hormones, peptides, ions, and by physical activity of muscle as well as dietary potassium intake. Pharmaceutical agents, poisons, and disease conditions also affect the exchange and alter extracellular potassium concentration. Here, we review extracellular potassium homeostasis, focusing on factors and conditions that influence the balance of potassium movement in skeletal muscle. Recent findings that mutations of a skeletal muscle-specific inward-rectifier K(+) channel cause hypokalemic periodic paralysis provide interesting insights into the role of skeletal muscle in extracellular potassium homeostasis. These recent findings are reviewed.
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Affiliation(s)
- Chih-Jen Cheng
- Department of Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX 75390-8859, USA
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Abstract
High-frequency tetanic stimulation is associated with an increase in extracellular and T-tubular K(+) and changes of Na(+) and Cl(-) concentrations, membrane depolarization as well as inactivation of voltage-gated Na(+) channels. These alterations are expected to lead to fiber inexcitability, which is largely prevented by mechanisms intrinsic or extrinsic to muscle fibers. They act by adapting electrical membrane properties or by accelerating the reconstitution of ionic homeostasis. The high Cl(-) conductance of muscle fibers supports the K(+) conductance in fast and complete repolarization and creates a mechanism for the fast reuptake of K(+), thereby reducing the T-tubular K(+) accumulation. Excitability is increased by a Ca(2+) and proteinkinase C dependent inhibition of the Cl(-) conductance which is efficient especially in the T-tubular system. Several mediators activate the Na(+)/K(+)-ATPase and thus enhance the restoration of ionic homeostasis. Examples are purines (ATP, ADP), calcitonin-gene related peptide and adrenaline. It is also necessary to adapt the strength of the sarcoplasmic Ca(2+) concentration to the requirements of tetanic contractions. An overwhelming Ca(2+) signal leads to enzymatically driven excitation-contraction uncoupling. This process is most likely driven by the Ca(2+) dependent protease μ-calpain and might lead to the long-lasting fatigue observed after excessive physical activity.
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Abstract
The nondystrophic myotonias and primary periodic paralyses are an important group of genetic muscle diseases characterized by dysfunction of ion channels that regulate membrane excitability. Clinical manifestations vary and include myotonia, hyperkalemic and hypokalemic periodic paralysis, progressive myopathy, and cardiac arrhythmias. The severity of myotonia ranges from severe neonatal presentation causing respiratory compromise through to mild later-onset disease. It remains unclear why the frequency of attacks of paralysis varies greatly or why many patients develop a severe permanent fixed myopathy. Recent detailed characterizations of human genetic mutations in voltage-gated muscle sodium (gene: SCN4A), chloride (gene: CLCN1), calcium (gene: CACNA1S), and inward rectifier potassium (genes: KCNJ2, KCNJ18) channels have resulted in new insights into disease mechanisms, clinical phenotypic variation, and therapeutic options.
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