Innervation and electrical pulse stimulation - in vitro effects on human skeletal muscle cells
Innervation and electrical pulse stimulation - in vitro effects on human skeletal muscle cells
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DOI：
10.1139/apnm-2019-0575
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发表时间：
2021-04-01
影响因子：
3.4
通讯作者：
Nikolic, Natasa
中科院分区：
文献类型：
--
作者：
Mars, Tomaz;Mis, Katarina;Nikolic, Natasa
骨骼肌收缩诱导的适应性在体内已经得到了很好的表征，但潜在的细胞机制仍未完全了解。培养的人肌管代表了人类骨骼肌的基本模型系统，可以在体外调节，但它们是静止的，除非受到刺激，否则不会收缩。刺激可以通过与胚胎大鼠脊髓共培养体外人肌管的神经支配来实现，或者通过电脉冲刺激（EPS）代替运动神经元的激活来实现。在体外培养的人肌管中，神经支配和EPS两种方法对肌球蛋白重链（myhc）表达和葡萄糖和油酸代谢的影响进行了表征。贴壁的人肌管或受大鼠脊髓节段支配，或暴露于EPS。通过定量聚合酶链反应、免疫印迹和免疫荧光检测myhc的表达模式，同时使用放射性标记底物研究葡萄糖和油酸的代谢。神经支配和EPS促进人肌管向不同纤维类型分化。慢速MyHC-1亚型的表达在神经支配的肌管中减少，而在eps处理的细胞中保持不变。在eps处理的细胞中，两种快速亚型（MyHC-2A和MyHC-2X）的表达都趋于降低。两种方法都诱导了更多的氧化表型，反映在葡萄糖和油酸增加的二氧化碳产量上。新颖性：在人肌管中，神经支配和EPS有利于分化成不同类型的纤维。神经支配和EPS都促进人肌管代谢更多的氧化表型。
Contraction-induced adaptations in skeletal muscles are well characterized in vivo, but the underlying cellular mechanisms are still not completely understood. Cultured human myotubes represent an essential model system for human skeletal muscle that can be modulated ex vivo, but they are quiescent and do not contract unless being stimulated. Stimulation can be achieved by innervation of human myotubes in vitro by co-culturing with embryonic rat spinal cord, or by replacing motor neuron activation by electrical pulse stimulation (EPS). Effects of these two in vitro approaches, innervation and EPS, were characterized with respects to the expression of myosin heavy chains (MyHCs) and metabolism of glucose and oleic acid in cultured human myotubes. Adherent human myotubes were either innervated with rat spinal cord segments or exposed to EPS. The expression pattern of MyHCs was assessed by quantitative polymerase chain reaction, immunoblotting, and immunofluorescence, while the metabolism of glucose and oleic acid were studied using radiolabelled substrates. Innervation and EPS promoted differentiation towards different fiber types in human myotubes. Expression of the slow MyHC-1 isoform was reduced in innervated myotubes, whereas it remained unaltered in EPS-treated cells. Expression of both fast isoforms (MyHC-2A and MyHC-2X) tended to decrease in EPS-treated cells. Both approaches induced a more oxidative phenotype, reflected in increased CO2 production from both glucose and oleic acid.Novelty:Innervation and EPS favour differentiation into different fiber types in human myotubes.Both innervation and EPS promote a metabolically more oxidative phenotype in human myotubes.