[Effects of simulated weightlessness on ultrastructure of soleus muscle spindle in rats].
OBJECTIVE
To study changes in ultrastructure of soleus muscle spindle induced by simulated weightlessness in rats.


METHODS
Weightlessness was simulated by tail suspension in female rats. The ultrastructure of isolated soleus muscle spindle were observed in 4 d, 7 d, 14 d tail-suspended and 14 d recovered rats.


RESULTS
Chaotic myofibril, hyperplasia of mitochondria, and enlargement of terminal cisterna were found in the ultrastructure of isolated soleus muscle spindle in 4 d tail-suspended rats. The ultrastructure of isolated soleus muscle spindle in 7 d tail-suspended rats showed more distinct changes, while that in 14 d tail-suspended rats showed obvious retrograde changes. The ultrastructure of isolated muscle spindle in 14 d recovered rats after 14 d tail-suspension were similar to that of control group.


CONCLUSIONS
Simulated weightlessness could induce time-related and reversible changes in ultrastructure of soleus muscle spindle in rats.
Wu
Su-di
SD
Department of Physiology, Medical School, Xi'an Jiao-Tong University, Xi'an, China.
Fan
Xiao-li
XL
Tang
Bin
B
Chen
Ming-xia
MX
D000818:Animals; D005260:Female; D019417:Hindlimb Suspension; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000648:ultrastructure*; D009470:Muscle Spindles / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000648:ultrastructure*; D009210:Myofibrils / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D018474:Weightlessness Simulation