The Effects Of Different Concentration Of TMP On The Contraction Function Of Suspended Rat Soleus Muscle And Preliminary For Its Mechanism

Objectives:1, To observe the effects of different concentrations of TMP on the soleus's contratility and on the sarcoplasmic reticulum Ca2+-ATPase activity in the tail-suspended rat.2, To discuss the possible mechanism of TMP's effects on the soleus's contractility in ratMethods:1, The disuse-atrophy model was achieved by tail-suspension on rat; using PowerLab system and electronic stimulator (SEN.3301) to testify the soleus's contractility in rat.2, The sarcoplasmic reticulum Ca2+-ATPase activity was measured by the Phosphate Determination method.Results:1, Compared with the tail-suspended group:1) both the peak twitch tension (Pt) and peak tetanic tension (Po) of soleus in rat have increased significantly in those groups of intragastric administration with different TMP concentrations; the Pt and P0 have increased 179.02%, 90.29% respectively in the high TMP concentration group, and have increased 186.65%, 123.61% respectively in the low TMP concentration group; there was no significant difference between the high and low TMP concentration groups.2) the time to 50% peak tension (TP50) and time to peak tension (TPT) have incerased notably in those groups of intragastric administration with different TMP concentrations; the TP50 and TPT have rised 148.09% and 80.28% respectively in the high TMP concentration group, and have increased 95.38% and 31.67% respectively in the low TMP concentration group; no significant changes was observed between the high and low TMP concentration groups.3) time from peak tension to 50% relaxation (RTso) has increased 21.36%(P<0.05) in the high TMP concentration group.2, Compared with the tail-suspended group, after intragastric administration with TMP, the sarcoplasmic reticulum Ca2+-ATPase activity of the rat's soleus has increased 55.60%(P <0.01) and 71.84%(P<0.01) in high and low TMP concentration groups respectively; low TMP concentration was more effective than high one on the sarcoplasmic reticulum Ca2+-ATPase activity but was not statistically significant (P>0.05). Conclusions:1, Different concentrations of TMP can effectively alleviate the Tail on the impact caused by muscle atrophy; effective against the Tail on the soleus muscle induced endoplasmic reticulum Ca2+-ATP activity decreased.2, TMP can increase sarcoplasmic reticulum Ca2+-ATP activity, inhibition of muscle fiber type conversion way, against the disuse of the muscle contraction function.