破伤风毒素降低 H 反射的局部和下行调节。
Tetanus toxin reduces local and descending regulation of the H-reflex.
出版信息
Muscle Nerve. 2014 Apr;49(4):495-501. doi: 10.1002/mus.23938.
INTRODUCTION
Skeletal muscles that are under the influence of tetanus toxin show an exaggerated reflex response to stretch. We examined which changes in the stretch reflex may underlie the exaggerated response.
METHODS
H-reflexes were obtained from the tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles in rats 7 days after intramuscular injection of tetanus toxin into the TA.
RESULTS
We found effects of the toxin on the threshold, amplitude, and duration of H-waves from the TA. The toxin inhibited rate-dependent depression in the FDB between the stimulation frequencies of 0.5–50 HZ and when a conditioning magnetic stimulus applied to the brain preceded a test electrical stimulus delivered to the plantar nerve.
CONCLUSIONS
Tetanus toxin increased the amplitude of the Hwave and reduced the normal depression of H-wave amplitude that is associated with closely timed stimuli, two phenomena that could contribute to hyperactivity of the stretch reflex.
简介
受破伤风毒素影响的骨骼肌肉对拉伸表现出夸张的反射反应。我们研究了哪些拉伸反射的变化可能是夸张反应的基础。
方法
在肌肉内注射破伤风毒素 7 天后，从大鼠的胫骨前肌 (TA) 和趾短屈肌 (FDB) 中获得 H 反射。
结果
我们发现毒素对 TA 的 H 波的阈值、幅度和持续时间有影响。毒素抑制了 FDB 在刺激频率为 0.5-50 Hz 之间以及当大脑中的条件磁刺激先于施加到足底神经的测试电刺激时的频率依赖性抑制。
结论
破伤风毒素增加了 H 波的幅度，并减少了与时间接近的刺激相关的 H 波幅度的正常抑制，这两个现象可能有助于拉伸反射的过度活跃。
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