[Changes in muscle spindle afferent discharge activities in rat soleus following hindlimb immobilization].
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).


CONCLUSIONS
Muscle spindle discharges decrease significantly in rats following hindlimb immobilization, which might be related to reduced contractile properties of the muscle spindle.
Department of Medical Function, Medical College of Hubei University of Arts and Science, Xiangyang 441053, China.E-mail: xuehong_zhao@163.com.
Xuehong
X
Zhao
Wenjing
W
Zhang
Xi
X
Zhou
Yan
Y
Gao
Xiaoli
X
Fan
Guangbin
G
Liu
D000818:Animals; D019417:Hindlimb Suspension; D009470:Muscle Spindles / Q000294:innervation*; D018482:Muscle, Skeletal / Q000294:innervation*; D051381:Rats