Na current density at and away from end plates on rat fast- and slow-twitch skeletal muscle fibers.
Na current density at and away from end plates on rat fast- and slow-twitch skeletal muscle fibers.
复制标题
大鼠快肌纤维和慢肌纤维终板处和远离终板的 Na 电流密度。
DOI：
10.1152/ajpcell.1992.262.1.c229
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Ruff,RL
中科院分区：
文献类型：
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作者：
Ruff,RL
用松膜片电压钳技术研究了大鼠快、慢收缩骨骼肌纤维上3个不同区域的Na电流密度和膜电容：1）终板边缘，2）距终板大于200 μ m（连接外），3）终板突触后膜。用胶原酶处理纤维以改善终板的可视化并酶促去除神经末梢。快肌纤维和慢肌纤维上的膜片电容相似，终板上膜片的电容是其他地方膜片的两倍。对于快、慢纤颤纤维，钠电流归一化面积的大小如下：终板大于终板边界大于extrajunctional。对于这两种类型的纤维，钠电流的振幅归一化的膜补丁的电容如下：端板约端板边界大于extrajunctional。在这三个区域中的每一个区域，快缩纤维上的钠电流密度都较大，并且快缩纤维在终板边缘处的钠电流密度比连接外膜处的钠电流密度增加更大。
Na current density and membrane capacitance were studied with the loose patch voltage clamp technique on rat fast- and slow-twitch skeletal muscle fibers at three different regions on the fibers: 1) the end plate border, 2) greater than 200 microns from the end plate (extrajunctional), and 3) on the end plate postsynaptic membrane. Fibers were treated with collagenase to improve visualization of the end plate and to enzymatically remove the nerve terminal. The capacitance of membrane patches was similar on fast- and slow-twitch fibers and patches of membrane on the end plate had twice the capacitance of patches elsewhere. For fast- and slow-twitch fibers, the sizes of the Na current normalized to the area of the patch were as follows: end plate greater than end plate border greater than extrajunctional. For both types of fibers, the amplitudes of the Na current normalized to the capacitance of the membrane patch were as follows: end plate approximately end plate border greater than extrajunctional. At each of the three regions, the Na current densities were larger on fast-twitch fibers and fast-twitch fibers had a larger increase in Na current density at the end plate border compared with extrajunctional membrane.