Extracellular magnesium and calcium reduce myotonia in isolated ClC‐1 chloride channel‐inhibited human muscle |
| |
| Authors: | Martin Skov MSc Frank Vincenzo De Paoli MD PhD Jesper Lausten MD Ole Baekgaard Nielsen PhD Thomas Holm Pedersen PhD |
| |
| Affiliation: | 1. Department of Biomedicine, Aarhus University, Aarhus C, Denmark;2. Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital Skejby, Aarhus, Denmark |
| |
| Abstract: | Introduction: Experimental myotonia induced in rat muscle by ClC‐1 chloride channel‐inhibited has been shown to be related inversely to extracellular concentrations of Mg2+ and Ca2+ ([Mg2+]o and [Ca2+]o) within physiological ranges. Because this implicates a role for [Mg2+]o and [Ca2+]o in the variability of symptoms among myotonia congenita patients, we searched for similar effects of [Mg2+]o and [Ca2+]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 [Mg2+]o or [Ca2+]o were elevated throughout their physiological ranges. These effects of [Mg2+]o and [Ca2+]o were additive and interchangeable. Conclusions: These findings suggest that variations in symptoms in myotonia congenita patients may arise from physiological variations in serum Mg2+ and Ca2+. Muscle Nerve 51 : 65–71, 2015 |
| |
| Keywords: | ClC‐1 extracellular calcium extracellular magnesium human muscle myotonia congenita phenotypic variation |
|
|
