Van Putten M J A M, Padberg M, Tavy D L J
Department of Neurology and Clinical Neurophysiology, Ziekenhuis Leyenburg, Leyweg 275, 2545 CH, The Hague, The Netherlands.
Muscle Nerve. 2002 Dec;26(6):784-90. doi: 10.1002/mus.10274.
To evaluate changes occurring in the neuromuscular junction after injection with botulinum neurotoxin type A (BoTx), three healthy volunteers were injected with 10 U BoTx in the right extensor digitorum brevis muscle. In agreement with previous observations, amplitude of compound muscle action potential (CMAP) decreased to approximately 30% of the initial value at approximately day 8 and slowly returned to baseline values around day 250. Values of the acetylcholine receptor (AChR) open time were determined by spectral analysis of end-plate noise and from single exponential fits to the decay phase of individual miniature end-plate potentials (MEPPs). At baseline, the mean channel open times determined by end-plate noise analysis and the exponential fits were 1.1 +/- 0.2 ms and 1.20 +/- 0.04 ms, respectively. After BoTx injection, initially no end-plate noise could be recorded. From day 9 onwards, however, a gradual recurrence of end-plate noise was observed, with mean channel open times of approximately 2-5 ms, being maximal between days 20 to 140. In addition, the shape of many recorded MEPPs was different from the typical fast rising MEPPs observed at baseline. After day 80, end-plate noise gradually returned to normal and mean channel open times decreased slowly to baseline values. Our findings reflect the changed AChR characteristics of newly formed neuromuscular junctions, which are created after BoTx injection and gradually removed after restoration of the original neuromuscular junctions.
为评估注射A型肉毒杆菌神经毒素（BoTx）后神经肌肉接头处发生的变化，三名健康志愿者在右侧趾短伸肌注射了10 U BoTx。与之前的观察结果一致，复合肌肉动作电位（CMAP）的幅度在大约第8天降至初始值的约30%，并在第250天左右缓慢恢复至基线值。乙酰胆碱受体（AChR）开放时间的值通过终板噪声的频谱分析以及对单个微小终板电位（MEPPs）衰减相的单指数拟合来确定。在基线时，通过终板噪声分析和指数拟合确定的平均通道开放时间分别为1.1 +/- 0.2毫秒和1.20 +/- 0.04毫秒。注射BoTx后，最初无法记录到终板噪声。然而，从第9天起，观察到终板噪声逐渐重现，平均通道开放时间约为2 - 5毫秒，在第20天至140天之间达到最大值。此外，许多记录的MEPPs的形状与基线时观察到的典型快速上升的MEPPs不同。在第80天后，终板噪声逐渐恢复正常，平均通道开放时间缓慢降至基线值。我们的研究结果反映了新形成的神经肌肉接头处AChR特性的变化，这些接头是在注射BoTx后形成的，并在原始神经肌肉接头恢复后逐渐消失。
