Ligustrazine and the contractile properties of soleus muscle in hindlimb-unloaded rats.

Siyuan Li, Zhe Yang, Yunfang Gao, Guangyue Li, Huiping Wang, Helmut G Hinghofer-Szalkay

Index: Aviat. Space. Environ. Med. 83(11) , 1049-54, (2012)

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Abstract

In this study we investigated the effects of different dosages of ligustrazine (tetramethylpyrazine, Tmp) on soleus function and sarco(endo)plasmatic reticulum Ca(2+)-ATPase (SERCA) activity in 14-d hindlimb-unloaded (HU) rats.Female Sprague-Dawley rats were randomly divided into 4 groups (8 rats in each group): synchronous control (CON); HU plus intragastric water instillation (HU-W); HU plus different dosages of instilled Tmp (high: 42.53 mg x kg(-1), HU-TmpH; low: 21.15 mg x kg(-1), HU-TmpL). Muscle contraction force was examined in the soleus muscle. SERCA activity was assayed according to the released inorganic phosphate content.As expected, in HU-W, soleus peak twitch tension (Pt), peak tetanic tension (P0), time to 50% peak tension (TP50), time to peak tension (TPT), time from peak tension to 50% relaxation (RT50), and SERCA activity decreased, all compared with CON. HU-TmpH Pt and P0 values were 179% and 90% above HU-W, and 187% and 124% above HU-W in HU-TmpL, respectively. TP50 and TPT values were 148% and 80% slower than HU-W with HU-TmpH and 95% and 32% in the HU-TmpL group, respectively. RT50 was slower than HU-W by 21% in HU-TmpH; SERCA activity elevated by 56% with HU-TmpH and by 72% with HU-TmpL.Ligustrazine may alleviate the decrease of muscle contractile force and increase of shortening velocity in atrophied soleus, possibly by means of elevated sarcoplasmic reticulum Ca(2+)-ATPase activity.