In vivo assessment of muscle membrane properties in the sodium channel myotonias.

Tan, S Veronica; Z'Graggen, Werner Josef; Hanna, Michael G; Bostock, Hugh (2018). In vivo assessment of muscle membrane properties in the sodium channel myotonias. Muscle & nerve, 57(4), pp. 586-594. John Wiley & Sons 10.1002/mus.25956

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INTRODUCTION The gain-of-function mutations that underlie sodium channel myotonia (SCM) and paramyotonia congenital (PMC) produce differing clinical phenotypes. We used muscle velocity recovery cycles (MVRCs) to investigate membrane properties. METHODS MVRCs and responses to trains of stimuli were compared in patients with SCM (n = 9), PMC (n = 8), and normal controls (n = 26). RESULTS The muscle relative refractory period was reduced in SCM, consistent with faster recovery of the mutant sodium channels from inactivation. Both SCM and PMC showed an increased early supernormality and increased mean supernormality following multiple conditioning stimuli, consistent with slowed sodium channel inactivation. Trains of fast impulses caused a loss of amplitude in PMC, after which only half of the muscle fibers recovered, suggesting that the remainder stayed depolarized by persistent sodium currents. DISCUSSION The differing effects of mutations on sodium channel function can be demonstrated in human subjects in vivo using this technique. Muscle Nerve, 2017.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurosurgery

UniBE Contributor:

Z'Graggen, Werner Josef


600 Technology > 610 Medicine & health




John Wiley & Sons




Nicole Söll

Date Deposited:

09 Jan 2018 11:18

Last Modified:

27 Oct 2019 06:49

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

channelopathy membrane potential myotonia paramyotonia congenita sodium channel velocity recovery cycle




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