An association between oxidative stress and muscle atrophy and weakness in vivo is supported by elevated oxidative damage and accelerated loss of muscle mass and force with aging in CuZn-superoxide dismutasedeficient (Sod1 -/-) mice. The purpose was to determine the basis for low specific force (N/cm 2) of gastrocnemius muscles in Sod1 -/- mice and establish the extent to which structural and functional changes in muscles of Sod1 -/- mice resemble those associated with normal aging. We tested the hypothesis that muscle weakness in Sod1 -/-mice is due to functionally denervated fibers by comparing forces during nerve and direct muscle stimulation. No differences were observed for wild-type mice at any age in the forces generated in response to nerve and muscle stimulation. Nerve- and muscle-stimulated forces were also not different for 4-wk-old Sod1 -/- mice, whereas, for 8- and 20-mo-old mice, forces during muscle stimulation were 16 and 30% greater, respectively, than those obtained using nerve stimulation. In addition to functional evidence of denervation with aging, fiber number was not different for Sod1 -/-and wild-type mice at 4 wk, but 50% lower for Sod1 -/- mice by 20 mo, and denervated motor end plates were prevalent in Sod1 -/- mice at both 8 and 20 mo and in WT mice by 28 mo. The data suggest ongoing denervation in muscles of Sod1 -/- mice that results in fiber loss and muscle atrophy. Moreover, the findings support using Sod1 -/- mice to explore mechanistic links between oxidative stress and the progression of deficits in muscle structure and function.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - Nov 1 2011|
- Specific force
ASJC Scopus subject areas
- Physiology (medical)