[Myocardial ultrastructural changes in rats following different levels of acute +Gz exposure].
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.
Zheng
Jun
J
Clinical Aeromedical Center of PLA, General Hospital of the Air Force, Beijing, China. zhengj3636@sina.com
Liu
Cheng-gang
CG
Ren
Li
L
Xiao
Xiao-guang
XG
Xu
Shu-xuan
SX
Wang
Ping
P
Ji
Gui-ying
GY
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