HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by McClung, J. M. Articles by Carson, J. A. Search for Related Content PubMed PubMed Citation Articles by McClung, J. M. Articles by Carson, J. A.

RhoA expression during recovery from skeletal muscle disuse

¹Department of Exercise Science, Integrative Muscle Biology Laboratory, School of Public Health, University of South Carolina, Columbia 29208; and ²Department of Biology and Physical Sciences, Benedict College, Columbia, South Carolina 29204

Submitted 22 September 2003 ; accepted in final form 21 November 2003

Functional overload and anabolic steroid administration induce signaling pathways that regulate skeletal muscle RhoA expression. The purpose of this study was to determine RhoA and associated protein expression at the onset of disuse and after a brief period of reloading. Male Sprague-Dawley rats were randomly assigned to cage control (Con), 3 days of hindlimb suspension (Sus), or 3 days of hindlimb suspension with 12 h of reloading (12-h Reload). The reloading stimuli consisted of 12 h of resumed normal locomotion after 3 days of hindlimb suspension. Plantaris muscle-to-body weight (mg/g) ratio decreased 17% from Con with Sus but returned to Con with 12-h Reload, increasing 13% from Sus. Sus decreased RhoA protein concentration 46%, whereas 12-h Reload induced a 24% increase compared with Sus. The ratio of cytosolic- to membrane-associated RhoA protein was not changed with either Sus or 12-h Reload. RhoA mRNA concentration was decreased 48% by Sus, and 12-h Reload induced a 170% increase from Sus. ₁-Integrin protein, a transmembrane protein associated with RhoA activation, was not altered by Sus but increased 155% with 12-h Reload. Although ₁-integrin mRNA was not altered by Sus, it increased 70% from Con with 12-h Reload. Rho family member Cdc42 protein associated with the muscle membrane was decreased 60% with Sus, and 12-h Reload induced a 172% increase compared with Sus. In conclusion, decreased RhoA protein expression and mRNA abundance are early adaptations to disuse but recover rapidly after normal locomotion is resumed.

hypertrophic signaling; muscle growth; muscle wasting; mechanotransduction; muscle atrophy

This article has been cited by other articles:

				J. M. McClung, M. A. Whidden, A. N. Kavazis, D. J. Falk, K. C. DeRuisseau, and S. K. Powers Redox regulation of diaphragm proteolysis during mechanical ventilation Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2008; 294(5): R1608 - R1617. [Abstract] [Full Text] [PDF]

				J. M. McClung, J. M. Davis, M. A. Wilson, E. C. Goldsmith, and J. A. Carson Estrogen status and skeletal muscle recovery from disuse atrophy J Appl Physiol, June 1, 2006; 100(6): 2012 - 2023. [Abstract] [Full Text] [PDF]

				T. A. Washington, J. M. Reecy, R. W. Thompson, L. L. Lowe, J. M. McClung, and J. A. Carson Lactate dehydrogenase expression at the onset of altered loading in rat soleus muscle J Appl Physiol, October 1, 2004; 97(4): 1424 - 1430. [Abstract] [Full Text] [PDF]