Martin Skov

Extracellular magnesium and calcium reduce myotonia in isolated ClC-1 chloride channel-inhibited human muscle

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INTRODUCTION: Experimental myotonia induced in rat muscle by ClC-1 chloride channel-inhibited has been shown to be related inversely to extracellular concentrations of Mg(2+) and Ca(2+) ([Mg(2+) ]o and [Ca(2+) ]o) within physiological ranges. Because this implicates a role for [Mg(2+)]o and [Ca(2+)]o in the variability of symptoms among myotonia congenita patients, we searched for similar effects of [Mg(2+)]o and [Ca(2+)]o on myotonia in human muscle.

METHODS: Bundles of muscle fibers were isolated from abdominal rectus in patients undergoing abdominal surgery. Myotonia was induced by ClC-1 inhibition using 9-anthracene carboxylic acid (9-AC) and was assessed from integrals of force induced by 5-Hz stimulation for 2 seconds.

RESULTS: Myotonia disappeared gradually when [Mg(2+)]o or [Ca(2+)]o were elevated throughout their physiological ranges. These effects of [Mg(2+)]o and [Ca(2+)]o were additive and interchangeable.

CONCLUSIONS: These findings suggest that variations in symptoms in myotonia congenita patients may arise from physiological variations in serum Mg(2+) and Ca(2+).

Original languageEnglish
JournalMuscle & Nerve
Pages (from-to)65-71
Number of pages7
Publication statusPublished - Jan 2015

    Research areas

  • Adult, Aged, Aged, 80 and over, Anthracenes, Area Under Curve, Biophysics, Calcium, Chloride Channels, Dose-Response Relationship, Drug, Electric Stimulation, Female, Humans, In Vitro Techniques, Magnesium, Male, Middle Aged, Muscle Contraction, Muscle Fibers, Skeletal, Myotonia

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