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Chloride channels in myotonia congenita assessed by velocity recovery cycles

Tan, SV; Z'graggen, WJ; Boërio, D; Rayan, DR; Norwood, F; Ruddy, D; Howard, R; ... Bostock, H; + view all (2014) Chloride channels in myotonia congenita assessed by velocity recovery cycles. Muscle & Nerve , 49 (6) pp. 845-857. 10.1002/mus.24069. Green open access

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Abstract

Introduction: Myotonia congenita (MC) is caused by congenital defects in the muscle chloride channel CLC-1. This study used muscle velocity recovery cycles (MVRCs) to investigate how membrane function is affected. Methods: MVRCs and responses to repetitive stimulation were compared between 18 patients with genetically confirmed MC (13 recessive, 7 dominant) and 30 age-matched normal controls. Results: MC patients exhibited increased early supernormality, but treatment with sodium channel blockers prevented this. After multiple conditioning stimuli, late supernormality was enhanced in all MC patients, indicating delayed repolarization. These abnormalities were similar between the MC subtypes, but recessive patients showed a greater drop in amplitude during repetitive stimulation. Discussion: MVRCs indicate that chloride conductance only becomes important when muscle fibers are depolarized. The differential responses to repetitive stimulation suggest that in dominant MC the affected chloride channels are activated by strong depolarization, consistent with a positive shift of the CLC-1 activation curve.

Type: Article
Title: Chloride channels in myotonia congenita assessed by velocity recovery cycles
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/mus.24069
Publisher version: http://dx.doi.org/10.1002/mus.24069
Additional information: © 2013 The Authors. Muscle Nerve published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: Chloride channels, Muscle membrane potential, Muscle velocity recovery cycle, Myotonia congenita, Tibialis anterior muscle
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Department of Neuromuscular Diseases
URI: https://discovery.ucl.ac.uk/id/eprint/1413688
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