[Daily 4-h standing can prevent soleus atrophy induced by 4 weeks tail suspension in rats].
OBJECTIVE
To observe the effects of intermittent standing in counteracting the soleus atrophy induced by simulated microgravity.


METHODS
Eighteen male Sprague-Dawley rats were randomly assigned to 3 groups: control (CON), four-week tail-suspension (TS), and TS plus daily 4 h standing (TS + STD4). After 4 weeks, bilateral adrenal glands and soleus muscle were dissected and weighed. The left soleus was sectioned with cryostat and stained with ATPase staining. The cross sectional area (CSA) of type I and II fibers and the relative proportion of type I fibers were measured using Leica image analysis system. The right soleus was homogenized and stained with Coomassie Brilliant Blue following electrophoresis on 8% SDS-PAGE under 70 V and < 4 degrees C for 28 h. The Scion image software was used to evaluate the result of the densitometry of different types of MHC.


RESULTS
In TS, wet weights of the soleus, CSA of type I and II fibers, and proportion of type I fibers decreased obviously, as compared with those rats in CON (P<0.01 or P<0.05). The SDS-PAGE showed similar results as by ATPase staining in the proportion of MHC I. Whereas in TS + STD4, there were no significant differences of those parameters compared with those rats in CON.


CONCLUSIONS
Daily 4-h standing fully prevented the soleus atrophy induced by simulated microgravity for 4 wk in rats.
Sun
Biao
B
Feng
Han-zhong
HZ
Zhang
Li-fan
LF
Wang
Yun-ying
YY
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D019417:Hindlimb Suspension; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D009133:Muscular Atrophy / Q000517:prevention & control*; D018995:Myosin Heavy Chains / Q000032:analysis; D009929:Organ Size; D020033:Protein Isoforms; D051381:Rats; D017207:Rats, Sprague-Dawley; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation
D020033:Protein Isoforms; D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains