title: Effects of repeated + Gz forces on masticatory muscles.
abstract: OBJECTIVE
  To study the effects of repeated + Gz forces on masticatory muscles.
  
  
  METHODS
  48 male Wistar rats were randomly divided into 4 groups. Group A was normally fed. Group B was only fixed with rat-kept devices for 5 minutes. Group C was borne + 1 Gz for 5 minutes. Group D was repeatedly exposed + 10 Gz (each for 30 s, onset rate about 0.5 G/s, 5 times/d with + 1 Gz 1 minute intervals, 4 d/wk, 3 weeks in total). The histological changes of the masseter, temporal and lateral pterygoid muscles were observed.
  
  
  RESULTS
  No abnormal changes were observed in Group A, B and C. But pathological changes could be found in group D. The wrench and deformation of muscular fibers, the dissolution of partial myofibril, the swelling of mitochondria, the reduce of hepatin from the masseter and lateral pterygoid muscles could be found.
  
  
  CONCLUSIONS
  Repeated + Gz stresses could induce the damage of masticatory muscles in different degrees.
authors.affiliation: Department of Stomatology, 305 Hospital of PLA, Beijing 100017, China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Sun
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.forename: Yin
authors.initials: Y
authors.lastname: Yin
authors.forename: Liang
authors.initials: L
authors.lastname: Ma
authors.forename: Ping
authors.initials: P
authors.lastname: Du
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
mesh_terms: D000818:Animals; D018471:Hypergravity; D008297:Male; D008406:Masseter Muscle / Q000473:pathology / Q000648:ultrastructure; D008410:Masticatory Muscles / Q000473:pathology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D011626:Pterygoid Muscles / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013703:Temporal Muscle / Q000473:pathology / Q000648:ultrastructure; D013997:Time Factors