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This Article Full Text Full Text (PDF) Supplemental Tables All Versions of this Article: 107/2/549    most recent 00280.2009v1 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 PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Dalla Libera, L. Articles by Gorza, L. PubMed PubMed Citation Articles by Dalla Libera, L. Articles by Gorza, L.

A transient antioxidant stress response accompanies the onset of disuse atrophy in human skeletal muscle

¹Consiglio Nazionale delle Ricerche-Institute for Neuroscience, and ²Department of Biomedical Sciences, University of Padova, Padova; ³Department of Clinical, Technological and Morphological Sciences, Division of Internal Medicine, University of Trieste, Trieste; and ⁴Division of Internal Medicine, San Bortolo Hospital, Vicenza, Italy

Submitted 16 March 2009 ; accepted in final form 22 May 2009

It is presently unknown whether oxidative stress increases in disused skeletal muscle in humans. Markers of oxidative stress were investigated in biopsies from the vastus lateralis muscle, collected from healthy subjects before [time 0 (T0)], after 1 wk (T8), and after 5 wk (T35) of bed rest. An 18% decrease in fiber cross-sectional area was detected in T35 biopsies (P < 0.05). Carbonylation of muscle proteins significantly increased about twofold at T35 (P < 0.02) and correlated positively with the decrease in fiber cross-sectional area (P = 0.04). Conversely, T8 biopsies showed a significant increase in protein levels of heme oxygenase-1 and glucose-regulated protein-75 (Grp75)/mitochondrial heat shock protein-70, two stress proteins involved in the antioxidant defense (P < 0.05). Heme oxygenase-1 increase, which involved a larger proportion of slow fibers compared with T0, appeared blunted in T35 biopsies. Grp75 protein level increased threefold in T8 biopsies and localized especially in slow fibers (P < 0.025), to decrease significantly in T35 biopsies (P < 0.05). Percent change in Grp75 levels positively correlated with fiber cross-sectional area (P = 0.01). Parallel investigations on rat soleus muscles, performed after 1–15 days of hindlimb suspension, showed that Grp75 protein levels significantly increased after 24 h of unloading (P = 0.02), i.e., before statistically significant evidence of muscle atrophy, to decrease thereafter in relation to the degree of muscle atrophy (P = 0.03). Therefore, in humans as in rodents, disuse muscle atrophy is characterized by increased protein carbonylation and by the blunting of the antioxidant stress response evoked by disuse.

bed rest; protein carbonylation; heme oxygenase-1; glucose-related protein-75; hindlimb suspension