Details

Autor(en) / Beteiligte

• Haddad, F
• Baldwin, K. M
• Tesch, P. A

Titel

Pretranslational markers of contractile protein expression in human skeletal muscle: effect of limb unloading plus resistance exercise

Ist Teil von

• Journal of applied physiology (1985), 2005-01, Vol.98 (1), p.46-52

Ort / Verlag

Bethesda, MD: Am Physiological Soc

Erscheinungsjahr

2005

Quelle

MEDLINE

Beschreibungen/Notizen

• 1 Department of Physiology and Biophysics, University of California, Irvine at Irvine, California; and 2 Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden Submitted 27 May 2004 ; accepted in final form 4 August 2004 Previously, it has been shown that the human ground-based model consisting of unilateral limb suspension (ULLS) induces atrophy and reduced strength of the affected quadriceps muscle group. Resistance exercise (RE) involving concentric-eccentric actions, in the face of ULLS, is effective in ameliorating these deficits. The goal of the present study was to determine whether alterations in contractile protein gene expression, e.g., myosin heavy chain and actin, as studied at the pretranslational level, provide molecular markers concerning the deficits that occur in muscle mass/volume during ULLS, as well as its maintenance in response to ULLS plus RE. Muscle biopsies were obtained from the vastus lateralis muscle of 31 middle-aged men and women before and after 5 wk of ULLS, ULLS plus RE, or RE only. The RE paradigm consisted of 12 sessions of 4 sets of 7 concentric-eccentric knee extensions. Our findings show that there were net deficits in total RNA, total mRNA, and actin and myosin heavy chain mRNA levels of expression after ULLS ( P < 0.05), whereas these alterations were blunted in the two groups receiving RE. Additional observations involving IGF-I and its associated receptor and binding proteins suggest that RE postures the skeletal muscle for signaling processes that favor a greater anabolic state relative to that observed in the ULLS group. Collectively, these findings suggest that molecular markers of contractile protein gene expression serve as useful subcellular indicators for ascertaining the underlying mechanisms regulating alterations in muscle mass in human subjects in response to altered loading states. muscle atrophy; mRNA; myosin; actin; insulin-like growth factor-I Address for reprint requests and other correspondence: F. Haddad, Dept. of Physiology and Biophysics, Univ. of California, Irvine at Irvine, CA 92697 (E-mail: fhaddad{at}uci.edu )