大鼠颈上神经节烟碱电流的整流及失敏

RECTIFICATION AND DESENSITIZATION OF NICOTINIC CURRENTS IN CULTURED RAT CERVICAL GANGLION NEURONS

在培养的新生大鼠颈上神经节交感神经元标本上，用全细胞膜片钳技术研究了烟碱型乙酰胆碱受体（ｎＡＣｈＲ）通道的整流及失敏现象。烟碱激动剂引起的全细胞电流在膜电位为负值时随膜电位呈线性改变，而在膜电位达＋６０ｍＶ时仍不出现外向电流，表现出强烈的内向整流。ｎＡＣｈＲ通道电流存在失敏现象，即持续恒压喷射激动剂所引起的全细胞电流随时间呈指数衰减，不能保持在峰值水平，失敏随激动剂浓度呈量效关系，膜电位的超极化也加剧失敏。

Rectification and desensitization of nicotinic currents in cultured rat superior cervicalganglion neurons were studied using whole-cell voltage-clamp technique. The inward currentsactivated by nicotinic agonists increased linearly within a range of holding potentials(0mV to-80mV by step of-20mV),but no outward currents appeared even at a holding potential of+60mV,thus the nicotinic currents showed intense inward rectification at positive membranepotentials.The nicotinic response declined progressively even in the continued presence ofagonist,a phenomenon was known as desensitization.The rate of the desensitization wasdose-and voltage-dependent.Both increasing of agonist concentration and hyperpolarization ofthe membrane enhanced the desensitization.