Skeletal Muscle Channelopathies and Sodium Channel Dysfunction

Skeletal muscle channelopathies comprise a group of inherited disorders arising from mutations in ion channel genes that regulate muscle fibre excitability. Central to many of these conditions is dysfunction of the Nav1.4 voltage-gated sodium channel, which governs the initiation and propagation of action potentials along the sarcolemma. Perturbations in channel gating or conductance manifest as either hyperexcitability, leading to myotonia and muscle stiffness, or hypoexcitability, causing episodes of periodic paralysis. Beyond classical non-dystrophic myotonias and hypokalemic or hyperkalemic periodic paralysis, recent findings reveal broader roles for sodium channel variants in progressive myopathies and altered muscle development. In addition to genetic heterogeneity, phenotypic variability is influenced by environmental factors, modifier genes and drug sensitivities. Therapeutic strategies have traditionally centred on non-selective sodium channel blockers such as mexiletine, but advances in structure-activity studies and high-resolution channel modelling are paving the way towards more isoform-specific, use-dependent compounds. Ongoing research spans from molecular pathomechanisms and electrophysiological characterisation to clinical natural history studies and novel pharmacogenetic approaches, underscoring the global importance of understanding sodium channel dysfunction for precision management of muscle channelopathies.

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Skeletal Muscle Channelopathies and Sodium Channel Dysfunction publication trend

The graph below shows the total number of articles in skeletal muscle channelopathies and sodium channel dysfunction across all publications each year (not limited to Nature Index journals).

Technical terms

Skeletal muscle channelopathies: Genetic disorders caused by mutations in ion channel genes leading to abnormal muscle excitability.

Nav1.4: The primary voltage-gated sodium channel isoform expressed in skeletal muscle fibres.

Myotonia: Delayed muscle relaxation and stiffness due to membrane hyperexcitability.

Periodic paralysis: Episodic muscle weakness resulting from transient disruptions of ion homeostasis.

Sarcolemma: The plasma membrane of a muscle cell where action potentials are initiated and propagated.

Use-dependent block: A pharmacological property wherein channel blockers preferentially bind to open or inactivated states during high-frequency activity.

References

1. Blockers of Skeletal Muscle Nav1.4 Channels: From Therapy of Myotonic Syndrome to Molecular Determinants of Pharmacological Action and Back. International Journal of Molecular Sciences (2023).
2. Hypokalemic periodic paralysis: a 3-year follow-up study. Journal of Neurology (2023).
3. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells (2021).
4. Therapeutic Approaches to Genetic Ion Channelopathies and Perspectives in Drug Discovery. Frontiers in Pharmacology (2016).
5. Long-Term Safety and Usefulness of Mexiletine in a Large Cohort of Patients Affected by Non-dystrophic Myotonias. Frontiers in Neurology (2020).