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Active muscle length reduction progressively damages soleus in hindlimb‐suspended rabbits
Author(s) -
Sancesario Giuseppe,
Massa Roberto,
Anzil Archinto P.,
Bernardi Giorgio
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.880150905
Subject(s) - soleus muscle , myofibril , isometric exercise , hindlimb , sarcomere , tenotomy , tonic (physiology) , atrophy , anatomy , chemistry , medicine , endocrinology , skeletal muscle , tendon , myocyte
Abstract This study describes the morphologic changes in rabbit soleus muscle following hindlimb suspension (HS) for 1 to 4 weeks (group A); or following HS with hindfeet passively dorsiflexed, by means of an elastic band, for 1 to 2 weeks (group B). In the latter, elastic band use allowed phasic contractions of foot extensor muscles against resistance and prevented 35% chronic soleus shortening, which occurred in group A animals. In group A, the soleus revealed progressive muscle atrophy and myofibrillar damage. Myofibrils underwent dissolution, muscle regeneration was ineffective, and adipose tissue developed from about 2‐week suspension onward. Conversely, passive dorsiflexon of unloaded hindfeet was essential in maintaining mass and structural muscle integrity in the soleus of group B. It is hereby demonstrated that HS‐induced soleus damage in the rabbit is progressive, and can be prevented, avoiding long‐term shortening of soleus and its phasic unloaded contractions, Soleus sensitivity to unloading conditions, such as HS, tenotomy, and hypogravity, may depend on the particular physiology of this tonic antigravity muscle, engaged mainly in developing long‐lasting isometric contractions in a strectched lenth. © 1992 John Wiley & Sons, Inc.