Changes in muscle spindle afferent discharge activities in rat soleus following hindlimb immobilization / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the changes in the afferent discharge activities of the sensory nerve endings in muscle spindles of rats with hindlimb immobilization.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSION</b>Muscle spindle discharges decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of the muscle spindle.</p>