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

我们一直对神经细胞、骨骼肌细胞和心肌细胞等可退出细胞之间的可退出性差异感兴趣。因此，采用脂质平面双分子层和膜片钳技术对三种钠离子通道的单通道电流进行了表征，并进行了比较。精确确定了河豚毒素阻断TTX - Na通道的动力学参数。心脏黏液钠通道对TTX的耐受性最强。去神经支配后，骨骼肌钠通道与心脏钠通道一样具有ttx抗性。钠通道蛋白可能作为每种细胞类型特有的同工酶存在，并且很容易转化为另一种同工酶。研究了钠通道激活剂、蛇曲霉毒素和缬草碱对各种钠通道的影响。各类型钠离子通道均表现出相似的可采性。因此，这些结果可以很好地解释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.