Motoneurone Activity as a Cause of Degeneration in the Soleus Muscle of the Rabbit

The tenotomized soleus muscle of a spinal rabbit does not degenerate unless it is stimulated electrically. If the muscle is stimulated at a frequency of 10 imp./sec., the histological changes occurring resemble those of tenotomized muscles in animals without spinal cord section. No decrease of tension can be found if untenotomized muscles of spinal rabbits are stimulated, indicating that no degeneration is taking place. It is concluded that isotonic contractions without a load are harmful to the structural integrity of the slow soleus muscle.