Beekley Matthew D, Cullom Damian L, Brechue William F
Department of Physical Education, United States Military Academy, West Point, NY 10996, USA.
Eur J Appl Physiol. 2004 Jan;91(1):105-10. doi: 10.1007/s00421-003-0936-x. Epub 2003 Sep 4.
Acetazolamide (ACZ), a carbonic anhydrase inhibitor, results in altered neuromuscular function secondary to depressed afferent transmission in intact humans. One effect of ACZ is hypercapnia. Thus, to test if the neuromuscular depression observed following ACZ treatment is related to elevated CO(2), human subjects ( n=10) were exposed to 15 min of room air (0% CO(2)) or hypercapnia (7% inspired CO(2)), and neuromuscular function was evaluated. Isometric force (36.8 to 31.1 N) and peak-to-peak electromyographic amplitude (EMG, 1.5 to 1.0 mV) associated with an Achilles tendon tap, and soleus H(max):M(max) ratio (69.0 to 62.2%) were depressed, while EMG latency (34.8 to 39.8 ms) was increased by hypercapnia. Reflex recovery profiles (following a conditioning tap to the contralateral Achilles tendon), motor nerve conduction velocity, amplitude of the maximum M-wave, and peak twitch tension at M(max) were unaltered by hypercapnia. We conclude that elevated CO(2) impairs neuromuscular function through effects on afferent transmission or synaptic integrity between type Ia fibers of the muscle spindle and the alpha motor neuron, without affecting the muscle spindle, efferent conduction or skeletal muscle force-generating capacity.
乙酰唑胺（ACZ）是一种碳酸酐酶抑制剂，在完整人体中，它会因传入神经传递受抑制而导致神经肌肉功能改变。ACZ的一个作用是引起高碳酸血症。因此，为了测试ACZ治疗后观察到的神经肌肉抑制是否与二氧化碳升高有关，对10名人类受试者分别进行15分钟的室内空气（0%二氧化碳）或高碳酸血症（吸入7%二氧化碳）暴露，并评估神经肌肉功能。与跟腱叩击相关的等长肌力（从36.8牛至31.1牛）和肌电图峰峰值幅度（EMG，从1.5毫伏至1.0毫伏）以及比目鱼肌H（最大值）：M（最大值）比值（从69.0%至62.2%）均降低，而高碳酸血症使EMG潜伏期延长（从34.8毫秒至39.8毫秒）。高碳酸血症未改变反射恢复曲线（对侧跟腱进行条件性叩击后）、运动神经传导速度、最大M波幅度以及M（最大值）时的峰值抽搐张力。我们得出结论，二氧化碳升高通过影响传入神经传递或肌梭Ia型纤维与α运动神经元之间的突触完整性来损害神经肌肉功能，而不影响肌梭、传出神经传导或骨骼肌的力量产生能力。
