Extracellular magnesium and calcium reduce myotonia in ClC-1 inhibited rat muscle

@article{Skov2013ExtracellularMA,
  title={Extracellular magnesium and calcium reduce myotonia in ClC-1 inhibited rat muscle},
  author={Martin Skov and Anders Riisager and James A. Fraser and Ole Baekgaard Nielsen and Thomas H. Pedersen},
  journal={Neuromuscular Disorders},
  year={2013},
  volume={23},
  pages={489-502}
}
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22 Citations
Highly Influential Citations
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Background Citations
12
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4
Results Citations
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22 Citations

Extracellular magnesium and calcium reduce myotonia in isolated ClC‐1 chloride channel‐inhibited human muscle
TLDR
Findings suggest that variations in symptoms in myotonia congenita patients may arise from physiological variations in serum Mg2+ and Ca2+.
Preclinical pharmacological in vitro investigations on low chloride conductance myotonia: effects of potassium regulation
TLDR
In vitro results of this study suggest that increasing potassium conductivity via activation of voltage-gated potassium channels enhanced the warm-up phenomena, thereby offering a potential therapeutic treatment option for myotonia congenita.
Divalent cation-responsive myotonia and muscle paralysis in skeletal muscle sodium channelopathy
Elevation of extracellular osmolarity improves signs of myotonia congenita in vitro: a preclinical animal study
TLDR
Muscle from mice and ADR (‘arrested development of righting response’) muscle from mice showed a relaxation deficit under physiological conditions compared to wild‐type muscle, mediated by the cation and anion cotransporter, NKCC1 and anti‐myotonic effects of hypertonicity were at least partly antagonized by the application of bumetanide.
Channelopathies of skeletal muscle excitability.
TLDR
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 is provided.
An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies
TLDR
Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.
Inhibiting persistent inward sodium currents prevents myotonia
TLDR
The goal was to identify currents that trigger spontaneous firing of muscle in the setting of reduced ClC‐1 current.
Characterization of the TRPC3 Gene in Myotonic Goats: Further Insight Into Myotonia congenita and Muscular Dystrophy
TLDR
The data indicate that the TRPC3 gene is a potential biomarker to further study Myotonia congenita in Myotonic goats and the interrelationship of the mechanism of calcium signaling in human Mc and MD.
Treatment Updates for Neuromuscular Channelopathies
TLDR
The treatment of skeletal muscle channelopathies combines dietary and lifestyle advice together with pharmacological interventions and the example of the aggregated n-of-1 trial of mexiletine shows that innovative trial design can overcome these hurdles.
The anti‐convulsants lacosamide, lamotrigine, and rufinamide reduce myotonia in isolated human and rat skeletal muscle
TLDR
This study explored whether 3 sodium channel‐modulating anti‐epileptics can reduce myotonia in isolated rat and human muscle.
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References

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TLDR
It is concluded that although changes of extracellular K+ influence both myotonia and the warmup, these changes are unlikely to explain warmup in myotonic patients.
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TLDR
A model myotonia was induced in the muscles in vitro, using either the chloride channel blocker anthracene-9-carboxylic acid or chloride-free Krebs solution, and a possible role for depolarization in preventing/reducing the myotonic response was discussed.
Increased Excitability of Acidified Skeletal Muscle
TLDR
It is concluded that recovery of excitability in K+-depressed muscles induced by muscle acidification is related to reduction in the inhibitory Cl− currents, possibly through inhibition of ClC-1 channels, and acidosis thereby reduces the Na+ current needed to generate and propagate an AP.
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TLDR
The hypothesis that decreased PC1 alone can account for the repetitive action potentials of myotonia is tested with a mathematical model of the muscle membrane and is shown to be valid and to correlate well with clinical observtonia.
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TLDR
It is concluded that the protective effects of acidosis and adrenaline on muscle excitability and force took place via different mechanisms and were additive, and suggests that circulating catecholamines and development of Acidosis during exercise may improve the tolerance of muscles to elevated K+.
Comparatibe actions of mexiletine on sodium channels in nerve, skeletal and cardiac muscle
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TLDR
It is clear that potassium accumulation is not the only reason for the instability of myotonic muscle fibres, and the presence of a surface chloride conductance does stabilize the response of a fibre to constant current or to repetitive stimulation, and its absence could be a sufficient condition for myOTonic behaviour.
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TLDR
The phenotype depends on the mutation type to some extent, but this does not explain the fact that severity varies greatly between heterozygous family members and may even vary with time in the individual patient.
Characteristics of the chloride conductance in muscle fibers of the rat diaphragm
TLDR
Tubular disruption with glycerol lowers apparent GCl but not GK, suggesting that the transverse tubule (T-tubule) system is permeable to Cl- in this species.
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