Ito I, Maeno T
J Physiol. 1986 Apr;373:115-27. doi: 10.1113/jphysiol.1986.sp016038.
The effects of catechol on various ionic channels of isolated primary afferent neurones of the bull-frog were examined by a single-suction-electrode clamp system, which combined internal perfusion and current or voltage clamp using an electronic switching circuit. Catechol was found to inhibit rather specifically the fast K+ current as does 4-aminopyridine (4-AP). Ca2+, Na+ and slow K+ currents were not affected. Although both 4-AP and catechol were inhibitors of the fast K+ channels, their sites of action were quite different. Catechol was effective when applied on the external surface of the cell membrane whereas 4-AP acted preferably internally. We assumed that a single fast K+ channel has two distinct sites for blockers: the catechol site is exposed to the external medium or situated at the outer orifice of the pore, and the 4-AP site is located within the same channel but is more easily accessible from inside the nerve cell than outside. The 4-AP and catechol sites were not, however, completely separate and independent of each other since a synergistic interaction was observed between catechol and 4-AP.
采用单吸电极钳制系统，结合内部灌流以及利用电子开关电路进行电流或电压钳制，研究了儿茶酚对牛蛙离体初级传入神经元各种离子通道的影响。结果发现，儿茶酚与4 - 氨基吡啶（4 - AP）一样，对快速钾电流具有特异性抑制作用。钙电流、钠电流和慢速钾电流不受影响。虽然4 - AP和儿茶酚都是快速钾通道的抑制剂，但它们的作用位点有很大差异。儿茶酚作用于细胞膜外表面时有效，而4 - AP则优先作用于细胞内部。我们推测，单个快速钾通道有两个不同的阻滞剂作用位点：儿茶酚位点暴露于外部介质，或位于孔道的外口，而4 - AP位点位于同一通道内，但从神经细胞内部比外部更容易接近。然而，4 - AP和儿茶酚位点并非完全相互独立，因为观察到儿茶酚和4 - AP之间存在协同相互作用。
