Effects of simulated weightlessness on myosin heavy chain expression of soleus intrafusal muscle fibers in XXXX .

@entity20932 @entity1885 @entity1573 @entity35 @entity20931
OBJECTIVE: To examine the myosin heavy chain expression in intrafusal fibers in @entity35 soleus muscle before and after simulated weightlessness and to analyse the mechanism involved in muscle spindle deterioration during simulated weightlessness. METHOD: The @entity35 were divided into 3 groups: 7 d, 14 d tail-suspension group and control group. Control and experimental spindles were examined using monoclonal antibodies specific for myosin heavy chains of slow-tonic (ALD58) and fast-twitch (MF30) @entity1573 muscles by the immunoperoxidase reaction utilizing the ABC (avidin- @entity1885 -complex) method. RESULT: The extrafusal muscle fibers did not exhibit immunoreactivity to ALD58 and MF30. Only intrafusal fibers bound these antibodies. The @entity20932 fiber and @entity20931 fiber reacted to ALD58. The @entity20931 fiber and chain fibers stained with MF30. After 7 d suspension the immunoreactivity of the @entity20932 fiber and @entity20931 fiber to ALD58 decreased, while the immunoreactivity of the @entity20931 fiber and chain fibers to MF30 increased. After 14 d suspension the immunoreactivity of the @entity20932 fiber and @entity20931 fiber to ALD58 decreased remarkably, even disappeared. While all of the intrafusal fibers reacted to MF30 and the immunoreactivity increased obviously. CONCLUSION: The expression level and patterns of MHC in intrafusal fibers of @entity35 soleus muscle changed after simulated weightlessness.
