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1. Comparisons were made in vitro at 25 degrees C among soleus and extensor digitorum longus (EDL) muscles from young (2-3 months), adult (9-10 months), and aged (26-27 months) male mice. We tested the hypotheses that, compared with soleus and EDL muscles of young and adult mice, those from aged mice develop decreased maximum tetanic force (P0, mN) and(More)
Maintenance of muscle mass and strength contributes to mobility which impacts on quality of life. Although muscle atrophy, declining strength, and physical frailty are generally accepted as inevitable concomitants of aging, the causes are unknown. Clarification of the mechanisms responsible for these changes would enhance our understanding of the degree to(More)
Contraction-induced injury results in the degeneration and regeneration of muscle fibers. Of the three types of contractions--shortening (concentric), isometric, and lengthening (eccentric)--injury is most likely to occur and the severity of the injury is greatest during lengthening contractions. The magnitude of the injury to muscle fibers may be assessed(More)
Dystrophin is a multidomain protein that links the actin cytoskeleton to laminin in the extracellular matrix through the dystrophin associated protein (DAP) complex. The COOH-terminal domain of dystrophin binds to two components of the DAP complex, syntrophin and dystrobrevin. To understand the role of syntrophin and dystrobrevin, we previously generated a(More)
We tested the hypothesis that after the same amount of contraction-induced injury, skeletal muscles in old mice regenerate less well than muscles in young mice. Extensor digitorum longus (EDL) muscles in young and old mice were exposed to 15 min of lengthening contractions. The amount of injury was evaluated at 3, 7, 14, 28, and 60 days by measurements of(More)
We tested the hypotheses that 1) muscles of old mice are more susceptible to injury than muscles of young and adult mice, and 2) secondary or delayed onset injury results from free radical damage. Extensor digitorum longus muscles were injured in situ by lengthening contractions. Injury was assessed by measurement of maximum isometric tetanic force (Po)(More)
Lengthening (eccentric) contractions result in injury to skeletal muscle fibers. Two hypotheses were tested through lengthening contractions of an in situ muscle preparation: the extent of injury increases with increases in the duration; and the extent of injury increases with increases in the peak force. Mice were anesthetized, and distal tendons of the(More)
We describe a novel phenotype in mice lacking the major antioxidant enzyme, CuZn-superoxide dismutase (Sod1(-/-) mice), namely a dramatic acceleration of age-related loss of skeletal muscle mass. Sod1(-/-) mice are 17 to 20% smaller and have a significantly lower muscle mass than wild-type mice as early as 3 to 4 months of age. Muscle mass in the Sod1(-/-)(More)
As compared with age-matched controls, extensor digitorum longus (EDL) muscles autografted in young rats regenerated significantly greater mass (1.8 times) and developed greater maximum contractile force (2.6 times) than EDL muscles autografted in old rats. A cross-age transplantation study showed that the mass and maximum force of old muscles grafted into(More)
Limb-girdle muscular dystrophy type 2D (LGMD 2D) is an autosomal recessive disorder caused by mutations in the alpha-sarcoglycan gene. To determine how alpha-sarcoglycan deficiency leads to muscle fiber degeneration, we generated and analyzed alpha-sarcoglycan- deficient mice. Sgca-null mice developed progressive muscular dystrophy and, in contrast to other(More)