Iannaccone S T, Li K X, Sperelakis N
Department of Neurology, University of Cincinnati Medical Center, Ohio 45267.
J Cell Physiol. 1987 Nov;133(2):409-13. doi: 10.1002/jcp.1041330230.
Skeletal muscle explants from normal subjects were established from biopsy material on collagen. Cellular outgrowth appeared within 3-4 days, and fusion of myoblasts was observed in 5-10 days. Multinucleated myotubes were impaled under high optical magnification, at 37 degrees C, with conventional glass microelectrodes. The mean resting potential was -44.4 mV +/- 2.4 (n = 399); -33 +/- 2.3 mV at 9 days (n = 10) vs -48 +/- 2.5 mV (n = 15) at 27 days. The average input resistance (Rin) was 9.7 M omega (n = 83). Action potentials could be elicited by electrical stimulation and had a mean amplitude of 55.9 +/- 2.1 mV with a mean maximum rate of rise (Vmax) of 72.1 +/- 7.5 V/s. The mean overshoot was 13.9 +/- 2.3 mV, and the action potential duration determined at 50% of repolarization (APD50) was 8.0 msec (n = 7). The resting membrane potential showed a depolarization of 23 mV/decade for extracellular potassium ion concentration ([K]o) between 4.5-100 mM. Thus, we have established the normal resting potential and maximum rate of rise of the action potential for human myotubes in culture. We have shown that the values for these are less than those previously reported in cultured avian and rodent cells. In addition, we have shown that the response in our system of the resting potential to change in extracellular potassium concentration is blunted compared to studies using isolated muscle, suggesting an increase in ratio of sodium to potassium permeability. Cultured human muscle cells depolarized in the presence of ouabain.
从正常受试者的活检材料中获取骨骼肌外植体，并将其置于胶原蛋白上。3 - 4天内出现细胞生长，5 - 10天观察到成肌细胞融合。在37℃下，使用传统玻璃微电极在高倍光学显微镜下刺入多核肌管。平均静息电位为-44.4 mV±2.4（n = 399）；9天时为-33±2.3 mV（n = 10），27天时为-48±2.5 mV（n = 15）。平均输入电阻（Rin）为9.7 MΩ（n = 83）。电刺激可诱发动作电位，平均幅度为55.9±2.1 mV，平均最大上升速率（Vmax）为72.1±7.5 V/s。平均超射为13.9±2.3 mV，在复极化50%时测定的动作电位持续时间（APD50）为8.0毫秒（n = 7）。对于细胞外钾离子浓度（[K]o）在4.5 - 100 mM之间，静息膜电位显示每十倍浓度变化有23 mV的去极化。因此，我们确定了培养的人肌管的正常静息电位和动作电位的最大上升速率。我们发现这些值低于先前报道的培养禽和啮齿动物细胞的值。此外，与使用分离肌肉的研究相比，我们发现我们系统中静息电位对细胞外钾浓度变化的反应减弱，表明钠钾通透性比值增加。培养的人肌肉细胞在哇巴因存在下发生去极化。
