Effects of adrenalectomy or RU-486 on rat muscle fibers during hindlimb suspension.
J Appl Physiol (1985)
; 75(6): 2767-73, 1993 Dec.
Article
in En
| MEDLINE
| ID: mdl-8125901
ABSTRACT
The purpose of this study was to investigate the effects of a glucocorticoid antagonist, RU-486, and of adrenalectomy (ADX) on rat skeletal muscle structural properties after 3, 7, and 14 days of hindlimb suspension (H). After H, a significant loss in muscle weight was observed as early as 3 days in soleus (SOL; -10%) and adductor longus (AL; -14%) muscles. In SOL, after only 7 days, a reduction (-14%) in type I fiber percent distribution occurred, accompanied by an increase (+129%) in intermediate type I fibers. Fiber type changes increased depending on the duration of H. In AL muscle, no change occurred after H in the fiber type composition despite a similar degree of muscle atrophy. Treatment with RU-486 or ADX significantly reduced the loss of SOL weight observed after 14 days (-42 and -44%, respectively, vs. -50% for H rats), delayed the SOL atrophy (from 3 to 7 days), and normalized the shift in fiber type distribution induced by H. In SOL, administration of RU-486 (but not ADX) partly prevented the reduction in size induced by H of all the fibers. In AL, neither treatment affected the extent of muscle atrophy, even though the reduction in type IIa fiber size was prevented by RU-486 but not by ADX after 14 days of suspension. ADX or RU-486 administration did not prevent the extensor digitorum longus weight loss observed after 14 days of suspension but allowed a recovery of its normal fiber type composition.(ABSTRACT TRUNCATED AT 250 WORDS)
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Weightlessness
/
Mifepristone
/
Adrenalectomy
/
Muscles
Limits:
Animals
Language:
En
Journal:
J Appl Physiol (1985)
Journal subject:
FISIOLOGIA
Year:
1993
Type:
Article
Affiliation country:
France