A transient antioxidant stress response accompanies the onset of disuse atrophy in human skeletal muscle.
Dalla Libera, Luciano ; Ravara, Barbara ; Gobbo, Valerio ; et al. ; - ASI Sponsor
Aug - 2009
ISSN : 8750-7587 ;
journal : Journal of applied physiology (Bethesda, Md. : 1985)

Issue : 2
type: Article Journal

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.

keywords : ASI - Sponsor,Adult,Animals,Antioxidants,Antioxidants: metabolism,Bed Rest,Biopsy,HSP70 Heat-Shock Proteins,HSP70 Heat-Shock Proteins: metabolism,Heme Oxygenase-1,Heme Oxygenase-1: metabolism,Hindlimb Suspension,Humans,Male,Membrane Proteins,Membrane Proteins: metabolism,Muscular Atrophy,Muscular Atrophy: metabolism,Muscular Atrophy: pathology,Oxidative Stress,Protein Carbonylation,Quadriceps Muscle,Quadriceps Muscle: metabolism,Quadriceps Muscle: pathology,Rats,Time Factors,Wistar,Young Adult