Effects of hypokinesia and hypodynamia upon protein turnover in hindlimb muscles of the rat.
Hypokinesia/hypodynamia was induced in the hindlimb muscles of the rat using a suspension technique. This caused differing degrees of atrophy in different muscles, however, this atrophy was reduced in muscles held in a lengthened position. The greatest degree of wasting was observed in the unstretched soleus, a slow postural muscle, where both Type 1 and Type 2a fibers atrophied to the same degree. However, wasting of the gastrocnemius muscle was associated with a reduction in the size of the Type 2b fibers. In both slow postural and fast phasic hindlimb muscles, atrophy was brought about by a reduction in the rate of protein synthesis in conjunction with an elevation in the rate of protein degradation. When inactive muscles were passively stretched, both protein synthesis and degradation were dramatically elevated. Even periods of stretch of as little as 0.5 h.d-1 were found to significantly decrease atrophy in inactive muscles.
Loughna
P T
PT
Department of Anatomy, Royal Veterinary College, University of London, England.
Goldspink
D F
DF
Goldspink
G
G
D000818:Animals; D006614:Hindlimb; D008297:Male; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000378:metabolism*; D009133:Muscular Atrophy / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D013026:Space Flight; D014893:Weightlessness / Q000009:adverse effects*
D009124:Muscle Proteins