Comparison of Sodium Channel Currents Between Various Excitable Cells by Planar Lipid Bilayer and Patch Clamp Methods

我们一直对不同兴奋性细胞之间的兴奋性差异感兴趣，如神经、骨骼肌和心肌细胞。因此，本研究采用脂质平面双层膜技术和膜片钳技术对三种钠通道的单通道电流进行了研究。准确地确定了河豚毒素、河豚毒素对钠通道的阻断动力学参数。心脏粘液的NA通道对TTX的抗性最强。失神经支配后，骨骼肌钠通道与心脏钠通道一样具有TTX抗性。Na通道蛋白可能是每种细胞所特有的同工酶，很容易转化为另一种同工酶。此外，还观察了钠通道激动剂、巴曲霉毒素和藜芦碱对各种钠通道的影响。当时，每种类型的钠通道都表现出类似的兴奋性。因此，这些结果可能很好地解释了不同组织之间兴奋性的差异和相似之处。

We have been interested in the differences of exitabilities between various exitable cells such as nerve, skeletal muscle and heart muscle cells. So, the single channel currents of Na channels were characterized to compare between the three type of Na channels by using the lipid planar bilayer and patch clamp techniques. Kinetic parameters in blocking of puffer fish toxin, TTX to Na channels were precisely dicided. Na channel of cardiac mucle was the most resistant to TTX. After denervation, skeletal muscle Na channels became as TTX-resistant as heart Na channels. Na channel protein might exist as an isozyme peculiar to each cell type which is easily able to be transformed to the other kind of isozyme. Effects of Na channel activators, batrachotoxin and veratridine on various Na channels were also examined. Every type of Na channel exhibited similar exitabilities then. Thus, these results might explain well the differences and similarities in excitability between various tissues.