摘要
目的小电导钙激活的钾通道(SK3)介导了动作电位后的后超极化电位的产生,在调节可兴奋细胞的膜电位中起关键作用。使去神经支配和肌强直营养不良患者骨骼肌SK3表达显著上调。本实验拟观察神经对骨骼肌SK3钾通道表达的调节作用。方法在Wistar大鼠,分别通过切断坐骨神经和局部注射河豚毒素(TTX)建立比目鱼肌去神经支配模型,和通过钳夹损伤比目鱼肌神经建立比目鱼肌去神经后神经再支配模型。在体给予去神经比目鱼肌频率为30Hz的电刺激(100脉冲/100 s)。实验结束后,免疫荧光法测定比目鱼肌中SK3钾通道的表达和定位;提取比目鱼肌组织总mRNA和蛋白,逆转录PCR和Western Blot分别检测SK3 mRNA和蛋白水平。结果切断坐骨神经能显著上调比目鱼肌SK3 mRNA和蛋白表达,且分别在术后第6 d和第9 d到达稳定。TTX诱导肌肉瘫痪也能显著上调比目鱼肌SK3 mRNA和蛋白表达。钳夹比目鱼肌神经所造成的暂时神经损伤能诱导SK3蛋白表达上调,而随着神经功能的恢复SK3蛋白表达也随之显著下调。在切断除坐骨神经术后6 d,在体给予电刺激6 d能显著下调比目鱼肌SK3的高表达;而且,在去除坐骨神经的同时给予电刺激则能阻止比目鱼肌SK3表达的上调。结论神经对骨骼肌SK3钾通道表达具有抑制作用,其作用与唤起肌肉活性密切相关。在体电刺激能抑制和防止去神经诱导的骨骼肌SK3蛋白表达上调,可能是改善神经损伤后或相关疾病所致的肌强直症状的有效手段之一。
Objective Small conductance calcium-activated potassium channels (SK3) have been thought to play an important role in excitable cells because they mediate the afterhyperpolarization following action potentials. The SK3 channel was overexpressed in skeletal muscles after denervation and in patients with myotonic dystrophy (DM). The study aims to determine the role of nerve in the modulation of SK3 expression in skeletal muscles. Methods Soleus muscles of Wistar rats were physically denervated by removing the sciatic nerve or chemically denervated by local infusion of tetrodotoxin (TTX). For reinnervation, soleus nerve just outside the soleus muscle was crushed. In the muscle electrical stimulation experiments, the denervated soleus muscles were electrically stimulated (100 pulses at 30 Hz every 100 sec). The mRNA and protein of SK3 in the soleus muscles were determined by reverse transcript-RCR (RT- PCR), immunofluorescence and western blot. Results Denervation upregulated both mRNA and protein expressions of SK3 in the soleus muscles. The mRNA and protein level of SK3 was stable at day 6 and day 9 after the denervation, respectively. Muscle paralysis induced by TTX also significantly upregulated both mRNA and protein expressions of SK3 in the soleus muscles. Reinnervation inhibited the upregulation of SK3 protein expression after the nerve was crushed.Electrical stimulation in vivo could revert the upregulated expression of SK3, and electrical stimulation starting at the time of denervation could prevent the upregulation of SK3 expression. Conclusion Muscle activity may play a key role in the inhibitory effect of nerve on SK3 expression in the skeletal muscles. Electrical stimulation of denervated muscles reverts and prevents the upregulation of SK3 protein expression at the level of transcription, which might be a potential therapeutic implication for DM patients.
出处
《中南药学》
CAS
2007年第1期1-6,共6页
Central South Pharmacy
关键词
去神经支配
电刺激
骨骼肌
小电导钙激活的钾通道(SK3)
denervation
electrical stimulation
skeletal muscle
small-conductance Ca^2+ -activated K^+ channel (SK3)