title: [Myocardial ultrastructural changes in rats following different levels of acute +Gz exposure].
abstract: OBJECTIVE
  To observe the effects of different levels of acute +Gz exposure on myocardial ultrastructure of rats and provide experimental basis for further development of anti-G measures.
  
  
  METHODS
  Twenty male Wistar rats were randomly divided into 4 groups (n=5): normal control group, +20 Gz group, +10 Gz group and +5 Gz group. Profile of the centrifuge +Gz exposure was trapezoidal, in which +20 Gz lasted for 30 s, +10 Gz for 1.5 min. +5 Gz exposure was repeated for 3 times with 30 min interval and each for 1.5 min. Myocardial tissue of left ventricle was sampled for transmission electron microscopy 5 h after exposure.
  
  
  RESULTS
  +20 Gz and +10 Gz exposure caused obvious edema of myocardial and endothelial cells, myofibril disorder and injuries of mitochondria and nucleus. Breaks of myocardial fiber, formation of contraction bands and rupture of mitochondria were also observed in +20 Gz group. In +5 Gz group, there was still slight edema of myocardial and endothelial cells, while organic changes of myocardial ultrastructure were not observed.
  
  
  CONCLUSIONS
  High +Gz exposure can cause myocardial ultrastructural injury in rats. Slight reversible injured response can also be observed in myocardial cell after repeated moderate level of +Gz exposure. This indicates that attention should be paid to the study of the effect of high +Gz on heart in pilots.
authors.affiliation: Clinical Aeromedical Center of PLA, General Hospital of the Air Force, Beijing, China. zhengj3636@sina.com
authors.forename: Jun
authors.initials: J
authors.lastname: Zheng
authors.forename: Cheng-gang
authors.initials: CG
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Ren
authors.forename: Xiao-guang
authors.initials: XG
authors.lastname: Xiao
authors.forename: Shu-xuan
authors.initials: SX
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Gui-ying
authors.initials: GY
authors.lastname: Ji
mesh_terms: D000054:Acceleration; D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002498:Centrifugation; D042783:Endothelial Cells / Q000648:ultrastructure*; D018471:Hypergravity / Q000009:adverse effects*; D007424:Intracellular Fluid / Q000502:physiology; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000648:ultrastructure; D009206:Myocardium / Q000166:cytology / Q000648:ultrastructure*; D009210:Myofibrils / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar