Effects of physicul stimulation and some growth factors on peripheral nerve regeneration and muscle strophy.

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1) Effects of fixed muscle length during hindlimb suspension were examined. Animals were divided into 3 groups; 1: hindlimb suspension (HS), 2: hindlimb suspension with dorsal flexion (HSD), 3: hindlimb suspension with plantar flexion (HDP). In the tibias anterior, muscle atrophy occurred more severer in the shortened position than in the expanded position. While in the soleus muscle, it occurred more severer in the HS rather than HSP. These findings suggested that muscle atrophy might be depend not only on fixed muscle length but also on some other factors, such as contractile manner.2) Changes of myosin heavy chain (MHC) isoform during the hindlimb suspension were examined in the rat skeletal mus- cle. In he tibialis anterior, MHC isoforms did not change during the hindlimb suspension. In the normal soleus muscle. most of MHC was type I, but after the hindlimb suspension, rate of type I reduced and type IIx, IIa, and IIb appeared. When the electromagnetic stimulation was applied every day during the hindlimb suspension, decrease of type I and ap- pearance of type IIx, IIa and IIb was reduced. These findings suggested that in the soleus muscle, electromagnetic sti- mulation might lighten not only muscle strophy but also immaturelization of myosin heavy chain isoformes.3) Expression of nerve growth factor (NGF) in the peripheral nerve during regeneration was immunohistochemically examined. In the normal nerve, NGF was not noted, but in the crushed nerve. NGF immunoreaction became to be found.When the electromagnetic stimulation was applied to the regenerating nerve, the immunoreaction became stronger. It was said that, the electromagnetic stimulation accelerate the nerve regeneration. One of the reasons for the effect of the stimulation might be the enhancement of the expression of NGF through electromagnetic stimulation.