Is excitation–contraction coupling impaired in myasthenia gravis?
Is excitation–contraction coupling impaired in myasthenia gravis?
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DOI：
10.1016/j.clinph.2007.01.001
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发表时间：
2007-05
影响因子：
4.7
通讯作者：
M. Nakata;S. Kuwabara;N. Kawaguchi;Hirokatsu Takahashi;S. Misawa;K. Kanai;N. Tamura;S. Sawai;M. Motomura;H. Shiraishi;M. Takamori;T. Maruta;H. Yoshikawa;T. Hattori
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文献类型：
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作者：
M. Nakata;S. Kuwabara;N. Kawaguchi;Hirokatsu Takahashi;S. Misawa;K. Kanai;N. Tamura;S. Sawai;M. Motomura;H. Shiraishi;M. Takamori;T. Maruta;H. Yoshikawa;T. Hattori
目的探讨重症肌无力(MG)患者肌肉兴奋-收缩(E-C)偶联功能是否受损。方法对51例全身性MG患者和35例正常人进行腕部正中神经刺激，同步记录拇短展肌复合动作电位(CMAP)和拇指尖端加速计运动相关电位。通过CMAP和运动相关电位的潜伏期差值估计E-C耦合时间(ECCT)。结果MG患者的平均ECCT为2.79±0.1ms，明显长于正常对照组的2.52±0.1ms。在MG患者中，胸腺瘤患者的平均ECCT比无胸腺瘤的患者长(P=0.04)，而FK506(一种免疫抑制剂，也是RyR相关钙释放的增强剂)治疗的患者比没有接受这种治疗的患者的ECCT短(P=0.04)。ECCT与抗AchR、抗RyR、抗Musk抗体无明显相关性。结论MG患者E-C偶联功能受损，尤其是胸腺瘤患者，FK506可能促进E-C偶联。
OBJECTIVETo investigate whether excitation–contraction (E–C) coupling of muscle is impaired in patients with myasthenia gravis (MG).METHODSIn 51 patients with generalized MG and 35 normal subjects, compound muscle action potentials (CMAPs) of the abductor pollicis brevis, and movement-related potentials using an accelerometer placed at the thumb tip were simultaneously recorded after median nerve stimulation at the wrist. The E–C coupling time (ECCT) was estimated by a latency difference between CMAP and movement-related potential. Antibodies against acetylcholine receptor (AChR), ryanodine receptor (RyR), and muscle specific receptor tyrosine kinase (MuSK) were measured by immunoassays.RESULTSThe mean ECCT was significantly longer in patients with MG (mean±SEM; 2.79±0.1ms; p=0.002) than in normal controls (2.52±0.1ms). Among MG patients, the mean ECCT was longer for patients with thymoma than for those without it (P=0.04), and was shorter for patients treated with FK506 (an immunosuppressant and also an enhancer of RyR related Ca2+release) than for those not receiving this treatment (p=0.04). ECCT had no significant correlation with anti-AChR, anti-RyR, or anti-MuSK antibodies.CONCLUSIONSIn MG, E–C coupling appears to be impaired, particularly in patients with thymoma, and FK506 possibly facilitates E–C coupling.SIGNIFICANCEThe functional implication of impaired E–C coupling is not established, but it may contribute to muscle weakness in patients with MG.