A comparison of electromyographic and mechanical fatigue properties in motor units of the cat hindlimb
A comparison of electromyographic and mechanical fatigue properties in motor units of the cat hindlimb
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猫后肢运动单位肌电图和机械疲劳特性的比较
DOI：
10.1016/0006-8993(85)91514-8
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发表时间：
1985
期刊：
影响因子：
2.9
通讯作者：
A. Robinson
中科院分区：
文献类型：
--
作者：
H. Clamann;A. Robinson
在猫的腓肠肌内侧（MG）或比目鱼肌（Sol）中分离出单个运动单位。测量每个个体EMG波形的振幅以及全波整流波形下的面积。然后测量运动单元的机械性能，使得每个单元可以根据Burke的标准被分类为FF、FR或S。最后以80 pps的速度连续刺激各单位，记录并比较电反应和机械反应的变化，结果显示MG运动单位的最大强直张力与IEMG呈正相关。在80 pps连续刺激运动单位时，IEMG的电活动有两种类型：（1）IEMG的平稳连续下降是由于神经肌肉接头远端的一个或多个部位发生的电变化;（2）单位肌电波形和IEMG振幅的随机突变，归因于动作电位不能通过轴突分支点传播，导致肌纤维群对刺激的间歇性失效。结果发现，在快速疲劳的运动单位，强直张力下降更迅速，比IEMG，而在缓慢疲劳的运动单位，IEMG下降更迅速，比力。我们得出结论，疲劳的运动单位引起的连续80 pps刺激可以发生在不同的网站在运动单位，疲劳的网站取决于运动单位的属性或运动单位类型。
Single motor units were isolated in medial gastrocnemius (MG) or soleus (Sol) muscles of the cat. Single shocks delivered to the motor axon elicited EMG waveforms which were recorded in the muscle. The amplitude of each individual EMG waveform as well as the area under the full-wave rectified waveform were measured. Mechanical properties of the motor units were then measured so that each unit could be classified as FF, FR or S according to the criteria of Burke. Finally, each unit was stimulated continuously at 80 pulses per second (pps), and changes in electrical and mechanical responses were recorded and compared.IEMG was positively correlated with maximum tetanic tension of motor units in MG. The relationship could be fitted with a parabola showing that ‘large’ motor units produce relatively more electrical activity than do ‘small’ motor units.Two types of electrical changes were seen during continuous stimulation of motor units at 80 pps: (1) a smooth continuous decline in IEMG was attributed to electrical changes occurring at a site or sites distal to the neuromuscular junction; and (2) random, abrupt changes in unit-EMG waveform and hence IEMG amplitude, were attributed to failure of the action potential to propagate past axonal branch points, resulting in the intermittent failure of groups of muscle fibers to respond to stimuli.The rates of decline of electrical and mechanical activity were compared for motor units. It was found that in fast fatiguing motor units, tetanic tension declined more rapidly than did IEMG, while in slowly fatiguing motor units, IEMG declined more rapidly than did force.We conclude that fatigue of motor units induced by continuous 80 pps stimulation can occur at different sites in the motor unit, and that the site of fatigue depends on motor unit properties or motor unit type.
小龙虾轴突分支部位动作电位传播失败的机制。
DOI：
10.1113/jphysiol.1980.sp013202
发表时间：
1980
期刊：
The Journal of physiology
影响因子：
--
作者：
Smith,DO
通讯作者：
Smith,DO