EXTRACELLULAR MAGNESIUM AND CALCIUM REDUCE MYOTONIA IN ISOLATED CLC-1 CHLORIDE CHANNEL-INHIBITED HUMAN MUSCLE

    loading  Checking for direct PDF access through Ovid

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 Nerve51: 65–71, 2015

Related Topics

    loading  Loading Related Articles