Ameliorated Effects of High Frequency Sinusoidal Vibration Given to Soleus Muscle on H Reflex in Rats Under Tail Suspension / 航天医学与医学工程

ABSTRACT

Objective To observe the changes in excitability of alpha-motoneuron responding to the muscle spindles afferent excitability in the model rats and explore whether the changes in this excitability to be changed as high frequency sinusoidal vibration acted on the soleus muscle.Methods The simulated weightlessness model was created by the tail-suspension.Mechanical vibrations at a frequency of 100 Hz with amplitude of 0.3 mm were acted on soleus muscle.The electromyogram of soleus muscle evoked by electrical stimulation of the sciatic nerve was recorded in control rats and HS rats.Results It was showed that HS and HFV did not influence the tendency of changes in amplitude of H reflex when the stimulation intensity increased.However,after 14-day HS,mean maximal motor response(Mmax)and mean maximal monosynaptic reflex/Mmax(Hmax/Mmax)both significantly decreased,respectively(P0.05).Conclusion It is suggested that HS should lead to the decrease in motoneurons excitability which is resulted from the reduction of muscle spindle afferent.HFV acted on soleus muscle of rats can improve the excitability of alpha-motoneurons in spinal cord during hindlimb suspension.