钠离子通道肌强直症中肌肉膜性质的体内评估。
In vivo assessment of muscle membrane properties in the sodium channel myotonias.
机构信息
MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, United Kingdom.
Institute of Neurology, University College London, Queen Square, London, United Kingdom.
出版信息
Muscle Nerve. 2018 Apr;57(4):586-594. doi: 10.1002/mus.25956. Epub 2017 Sep 23.
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.
简介
导致钠离子通道肌强直（SCM）和先天性副肌强直（PMC）的功能获得性突变产生不同的临床表型。我们使用肌肉速度恢复循环（MVRC）来研究膜特性。
方法
比较 SCM（n=9）、PMC（n=8）和正常对照者（n=26）的 MVRC 和刺激串反应。
结果
SCM 的肌肉相对不应期缩短，提示突变型钠离子通道从失活中更快恢复。SCM 和 PMC 均表现出早期超极化增加和多次条件刺激后的平均超极化增加，提示钠离子通道失活减慢。快速冲动串在 PMC 中引起幅度丧失，之后只有一半的肌纤维恢复，表明其余的纤维由于持续的钠离子电流而保持去极化。
讨论
使用该技术可以在体内的人类受试者中证明突变对钠离子通道功能的不同影响。肌肉神经 57：586-594，2018。
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