title: Differences in age-related alterations in muscle contraction properties in rat tongue and hindlimb.
abstract: OBJECTIVE
  Because of differences in muscle architecture and biomechanics, the purpose of this study was to determine whether muscle contractile properties of rat hindlimb and tongue were differentially affected by aging.
  
  
  METHODS
  Deep peroneal and hypoglossal nerves were stimulated in 6 young and 7 old Fischer 344-Brown Norway rats to allow recording of muscle contractile properties of tongue and extensor digitorum longus (EDL) muscle in the hindlimb. In the same animals, the following measurements were made: (a) twitch contraction time (CT; in milliseconds), (b) half decay time (HDT; in milliseconds), (c) maximum twitch force (in grams), (d) tetanic force, and (e) fatigue index determined from repetitive stimulation of the muscles.
  
  
  RESULTS
  No significant differences were observed in young versus old groups in retrusive tongue forces, whereas a significant (p < .05) decrement in EDL tetanic forces was found in old rats. Slower CT in old rats was observed only in the tongue. Old and young groups were not significantly different in fatigue index or HDT for tongue or EDL.
  
  
  CONCLUSIONS
  Old animals generated equivalent maximum tongue forces with stimulation, but they were slower in achieving these forces than young animals. Limb and cranial muscles were not affected equally by aging. As such, information derived from limb muscle studies may not easily generalize to the cranial motor system.
authors.affiliation: University of Wisconsin Clinical Science Center, Madison, WI 53792-7375, USA. connor@surgery.wisc.edu
authors.forename: Nadine P
authors.initials: NP
authors.lastname: Connor
authors.forename: Fumikazu
authors.initials: F
authors.lastname: Ota
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nagai
authors.forename: John A
authors.initials: JA
authors.lastname: Russell
authors.forename: Glen
authors.initials: G
authors.lastname: Leverson
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D006614:Hindlimb / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D014059:Tongue / Q000502:physiology*