In vivo assessment of muscle membrane properties in the sodium channel myotonias.
Muscle Nerve
; 57(4): 586-594, 2018 04.
Article
en En
| MEDLINE
| ID: mdl-28877545
ABSTRACT
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 57 586-594, 2018.Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Fibras Musculares Esqueléticas
/
Potenciales de la Membrana
/
Miotonía Congénita
Tipo de estudio:
Observational_studies
Límite:
Adult
/
Aged
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Muscle Nerve
Año:
2018
Tipo del documento:
Article
País de afiliación:
Reino Unido