Gardiner P, Michel R, Olha A, Pettigrew F
Exp Brain Res. 1987;66(3):597-606. doi: 10.1007/BF00270693.
The contractile properties of single motor units of rat plantaris were measured in situ 7 days following muscle partial denervation, achieved by section of radicular nerve L4. Partially denervated muscles weighed less, generated weaker twitch and tetanic forces, and contained denervated fibers, as evidenced by indirect/direct stimulation force ratios less than 1. Fast motor units (over 90% of unit pool) showed elevated twitch and tetanic responses (222% and 171% of controls, respectively) and elevated twitch-to-tetanic force ratios. Although partial denervation did not alter the mean fatiguability of fast motor units, fewer proportions of units remained in the extreme categories of fatigue resistance, with a clustering of units in the intermediate ranges. Slow units, while showing elevated twitch and tetanic responses, did not change in fatiguability. Glycogen depletion of the fibers of two fast motor units in partially denervated muscles revealed the presence of fibers varying in size, and in staining intensities for succinate dehydrogenase and ATPase, within the same motor unit, as a result of motoneurone sprouting.
通过切断L4神经根实现大鼠比目鱼肌部分去神经支配7天后，对其单个运动单位的收缩特性进行了原位测量。部分去神经支配的肌肉重量较轻，产生的单收缩和强直收缩力较弱，并且含有去神经支配的纤维，间接/直接刺激力比值小于1证明了这一点。快肌运动单位（超过单位池的90%）表现出单收缩和强直收缩反应增强（分别为对照组的222%和171%）以及单收缩与强直收缩力比值升高。虽然部分去神经支配并未改变快肌运动单位的平均疲劳性，但处于抗疲劳极端类别的运动单位比例减少，运动单位聚集在中间范围。慢肌运动单位虽然单收缩和强直收缩反应增强，但其疲劳性并未改变。部分去神经支配肌肉中两个快肌运动单位纤维的糖原耗竭表明，由于运动神经元发芽，同一运动单位内存在大小不同以及琥珀酸脱氢酶和ATP酶染色强度不同的纤维。
