家兔在体胫骨前肌单纤维动作电位及颤抖(jitter)值的测定

MEASUREMENT OF THE SINGLE MUSCLE FIBER ACTION POTENTIALS AND JITTER VALUE IN TIBIALIS ANTERIOR MUSCLES OF RABBITS IN SITU

用自制的jitter数据处理仪配合计算机,采用细胞外引导单纤维动作电位(SF-AP)的方法,观察了家兔在体胫骨前肌SF-AP的特征和在同一运动单位中相邻两条肌纤维重复兴奋时,电位对(potential pair)间隔时间的变异,即颤抖(jitter)。(1)家兔胫骨前肌SF-AP呈光滑先正后负的双相锋电位,其振幅在3mV以上,锋电位持续时间约在1-1.5ms。(2)对7只家兔在体胫骨前肌同一位置引导出来的936个jitter值经自制的jitter数据处理仪及微机统计学处理,均值为31.56μs,百分位数P_(75)-P_(25)为54.99-14.61μs。(3)单肌纤维jitter值的频率直方图多趋于正偏态分布,下限值小于人体骨胳肌正常下限,提示人与家兔骨胳肌SFEMG的jitter值范围略有区别。

With a home--made jitter data. processing board and microcomputer for recordingextracellular single fiber action potential (SF--AP), variations of the time intervals ofthe SF--AP pairs, or the jitters, from two adjacent muscle fibers in the unique motorunit in tibialis' anterior in response to repeated stimuli were measured. The jitter dfstri-bution of 936 recorded from 7 rabbits was positively showed with a percentile value ofP_(75)--P_(25) of 54.99--14.61 μs. The data suggested that the lower limit was smallerthan that of skeletal muscles in normal human and that there exists also some differ-ences in the jitter values of SFEMG between human and rabbit muscles.