title: Similar age-related changes in two regions of muscle with different properties.
abstract: Two regions of the medial gastrocnemius (MG) muscle, with different contractile properties and innervated by different nerve branches, were investigated in male Sprague-Dawley rats at three ages: 2-3 months, 6-7 months and 24-25 months (i.e., the '50% survival age and beyond': a recommended definition of aged rodents derived from lifespan data on a given colony). At the 50% survival age, both regions of the MG showed decreased mass, slowed contraction times and a decreased number of fast-twitch, but not slow-twitch, muscle fibres. The 40% loss of fast-twitch muscle fibres was not reflected in the loss of motoneurones, suggesting that muscle degeneration precedes motoneurone loss at the 50% survival age in the rat.
authors: School of Physical and Occupational Therapy, McGill University, Montreal, Que., Canada.
authors: S
authors: S
authors: Vanden Noven
authors: K L
authors: KL
authors: Seburn
authors: N K
authors: NK
authors: Latham
authors: P F
authors: PF
authors: Gardiner
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002452:Cell Count; D006614:Hindlimb / Q000294:innervation / Q000502:physiology; D006651:Histocytochemistry; D006735:Horseradish Peroxidase; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009121:Muscle Denervation; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D006735:Horseradish Peroxidase