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Loss and renewal of thick myofilaments in glucocorticoid‐treated rat soleus after denervation and reinnervation
Author(s) -
Massa Roberto,
Carpenter Stirling,
Holland Paul,
Karpati George
Publication year - 1992
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880151112
Subject(s) - denervation , myofilament , reinnervation , myosin , myofibril , atrophy , soleus muscle , chemistry , medicine , anatomy , sarcomere , endocrinology , skeletal muscle , myocyte , biochemistry
Denervation of rat soleus muscle and simultaneous administration of high doses of corticosteroids for 7 days caused marked muscle fiber atrophy and selective loss of thick myofilaments from many muscle fibers by light and electron microscopy. Myosin heavy chain/ actin ratios were greatly reduced on polyacrylamide gel electrophoresis. Nerve crush instead of cut permitted reinnervation after 2 weeks and demonstrated the reversibility of the muscle changes within a week after reinnervation. There was formation of new thick filaments and their reintegration into myofibrils without further breakdown, although large areas of Z‐disc streaming appeared. The mechanism of A‐band breakdown remains obscure, but it presumably starts with limited proteolysis and continues with disaggregation of myosin molecules. This is consistent with our observation that the muscle fibers retain a relatively good reactivity to antibodies against myosin heavy chain 1 week after denervation and corticosteroid administration. A syndrome recalling these experiments is seen in severely asthmatic patients receiving corticosteroids and pharmacologically paralyzed for mechanical respiration. © 1992 John Wiley & Sons, Inc.