Feng Han-zhong, Yu Zhi-bin
Space Med Med Eng (Beijing). 2005 Apr;18(2):89-93.
To observe the effects of nifedipine, a blocker of L-type Ca2+ channel, on soleus weight and expression of myosin heavy chain (MHC) isoforms in control and tail-suspended rats.
Animals were treated with nifedipine at a dose of 10 mg/kg per day in drinking water for 1 or 2 weeks. The expression of MHC isoform protein was observed by SDS-polyacrylamide gel electrophoresis at 4 degrees C. The expression of MHC mRNA was detected by RT-PCR.
The relative weight (muscle weight/body weight) of soleus muscle was decreased by 39.5% and 51.7% in 1 and 2 weeks of tail-suspended group respectively, but no changes in extensor digitorum longus (EDL) weight was found. The relative weight of soleus and EDL in 1 or 2 weeks of nifedipine treated control group showed no changes as compared with the untreated control group. The relative weight of soleus in 1 or 2 weeks of nifedipine treated tail-suspension group decreased by 36.6% or 52.0%, respectively, as compared with control, but there was no difference between tail-suspension group with or without nifedipine treatment. The expression of MHC I, IIa mRNA and protein could be detected in control soleus with or without nifedipine treatment. The expression MHC I, IIa, IIx and IIb mRNA was detected in 1 or 2 weeks of unloaded soleus with or without nifedipine treatment. Nifedipine inhibited the expression of II type MHC mRNA in unloaded soleus and expression of MHC IIa protein in control and unloaded soleus.
Nifedipine can not resist atrophy of unloaded soleus, but inhibit the transition of MHC from slow to fast isoforms at the transcription level.
观察L型钙通道阻滞剂硝苯地平对对照组和尾部悬吊大鼠比目鱼肌重量及肌球蛋白重链（MHC）亚型表达的影响。
动物饮用含10mg/kg硝苯地平的水，持续1或2周。4℃条件下通过SDS-聚丙烯酰胺凝胶电泳观察MHC亚型蛋白的表达，采用RT-PCR检测MHC mRNA的表达。
尾部悬吊组1周和2周时比目鱼肌相对重量（肌肉重量/体重）分别下降39.5%和51.7%，但趾长伸肌（EDL）重量未发现变化。硝苯地平处理的对照组1周或2周时比目鱼肌和EDL的相对重量与未处理的对照组相比无变化。硝苯地平处理的尾部悬吊组1周或2周时比目鱼肌相对重量与对照组相比分别下降36.6%或52.0%，但硝苯地平处理组与未处理组之间无差异。无论是否用硝苯地平处理，对照组比目鱼肌均可检测到MHC I、IIa mRNA和蛋白的表达。无论是否用硝苯地平处理，去负荷比目鱼肌1周或2周时均可检测到MHC I、IIa、IIx和IIb mRNA的表达。硝苯地平抑制去负荷比目鱼肌II型MHC mRNA的表达以及对照组和去负荷比目鱼肌中MHC IIa蛋白的表达。
硝苯地平不能抵抗去负荷比目鱼肌的萎缩，但在转录水平抑制MHC从慢肌型向快肌型的转变。
