Celichowski J, Bichler E
Department of Neurobiology, University School of Physical Education, Poznań, Poland.
J Physiol Pharmacol. 1998 Dec;49(4):597-605.
The time course of fused tetani of three main types of motor units: slow (S), fast resistant (FR) and fast fatigable (FF) was studied in the rat medial gastrocnemius. The rate of tension generation and of the relaxation within a tetanus was measured under isometric conditions. These measurements were performed at three points during both the contraction and relaxation: the beginning, the middle and the end of the phase of changes in tension. Significant differences were found in the rate of tension changes between fast and slow units. Comparison of FF and FR units showed less pronounced differences in their rates of the contraction and the relaxation. Moreover, slow units showed significantly greater slowing of both the contraction and relaxation within a tetanus in relation to the speed of their twitch when compared to fast motor units. The rate of changes in tetanic tension correlated to twitch time parameters and to tension generated during twitch or tetanus. The results point out that the well known difference in the speed of twitch contraction between fast and slow units is also visible in their fused tetani.
在大鼠的内侧腓肠肌中研究了三种主要类型运动单位（慢肌纤维（S）、抗疲劳快肌纤维（FR）和易疲劳快肌纤维（FF））强直收缩的时间进程。在等长条件下测量强直收缩过程中的张力产生速率和松弛速率。这些测量在收缩和松弛过程中的三个时间点进行：张力变化阶段的开始、中间和结束。快肌纤维和慢肌纤维之间的张力变化速率存在显著差异。FF和FR运动单位的收缩和松弛速率差异不太明显。此外，与快肌运动单位相比，慢肌纤维在强直收缩过程中的收缩和松弛减慢程度明显更大。强直张力的变化速率与单收缩时间参数以及单收缩或强直收缩过程中产生的张力相关。结果表明，快肌纤维和慢肌纤维在单收缩速度上的众所周知的差异在它们的强直收缩中也很明显。
