后肢制动对肌梭传入放电活动的影响

目的观察后肢制动不同时期单一肌梭感觉末梢放电活动的改变。方法石膏固定建立大鼠后肢制动模型，雌性大鼠随机
分为后肢制动3 d组、7 d组、14 d组及对照组。用空气隔绝法，观察制动不同时期单一肌梭的自发放电、0.05 mg/ml琥珀酰胆碱
灌流及牵拉至伸长位后肌梭放电活动的改变。结果后肢制动3 d肌梭的自发放电活动和对琥珀酰胆碱灌流的反应明显降低
（分别为P<0.01和P<0.05），制动14 d后伸长位肌梭的传入放电频率降低（P<0.01）。单个动作电位时程也随着制动时间的延长
而显著延长（P<0.01）。结论后肢制动可致肌梭的传入放电活动减少，这可能与肌梭自身收缩特性的改变有关。

Changes in muscle spindle afferent discharge activities in rat soleus following hindlimb im-mobilization

Objective To investigate the changes in the afferent discharge activities of the sensory nerve endings in muscle
spindles of rats with hindlimb immobilization. Methods Plaster cast was used immobilize the hindllimbs of rats. Using air-gap
technique, the spontaneous discharge of the muscle spindles and its responses to perfusion with succinylcholine (0.05 mg/ml)
and suspension in an extended position were observed in isolated muscle spindles from rats with hindlimb immobilization for
3, 7, and 14 days. Results The muscle spindles of rat soleus showed a sharp decrease in spontaneous discharge frequency (P<
0.01) and response to succinylcholine perfusion after 3 days of hindlimb immobilization (P<0.05). Significant changes of the
firing rate in an extended position was observed in rats after a 14-day immobilization (P<0.01). The duration of individual
spikes was significantly prolonged following hindlimb immobilization (P<0.01). Conclusion Muscle spindle discharges
decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of
the muscle spindle.