大鼠结状神经元的河豚毒素抗性钠电流：单价阳离子选择性和二价阳离子阻断 - Suppr | 超能文献

大鼠结状神经元的河豚毒素抗性钠电流：单价阳离子选择性和二价阳离子阻断

Tetrodotoxin-resistant sodium current of rat nodose neurones: monovalent cation selectivity and divalent cation block.

作者信息

Ikeda S R, Schofield G G

机构信息

Section of Electrophysiology, National Institute of Alcohol Abuse and Alcoholism, Rockville, MD 20852.

出版信息

J Physiol. 1987 Aug;389:255-70. doi: 10.1113/jphysiol.1987.sp016656.

DOI:10.1113/jphysiol.1987.sp016656

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1192080/

Abstract

Monovalent cation selectivity and divalent cation sensitivity of the tetrodotoxin (TTX)-resistant Na+ current in dissociated adult rat nodose ganglion neurones were investigated using the whole-cell patch-clamp technique. 2. The TTX-resistant Na+ current was isolated using ion substitution and pharmacological agents. Under these conditions, the current reversal potential shifted 52 mV per tenfold change in external [Na+]. 3. Inorganic and organic monovalent cation permeability ratios (Px/PNa) were determined from changes in reversal potential and the Goldman-Hodgkin-Katz equation. The Px/PNa values determined by the former method were HONH3+, 1.38; Li+, 1.00; H2NNH3+, 0.66; NH4+, 0.28; CH3NH3+, less than 0.13; K+, less than 0.13; Rb+, less than 0.12; Cs+, less than 0.10; (CH3)4N+, less than 0.10. The values determined by either method agreed within 10%. 4. The effects of Cd2+, Co2+, Mn2+ and Ni2+ on the TTX-resistant Na+ current were analysed from peak-conductance values. These ions shifted the activation of the current to more positive potentials and decreased the maximal conductance. At 3 mM concentrations, Cd2+, Ni2+, Co2+ and Mn2+ decreased the maximal conductance 64.6, 50.7, 25.0 and 20.3%, respectively. 5. The results indicate that: (a) the monovalent cation selectivity of the TTX-resistant Na+ current is similar to that of the TTX-sensitive Na+ current in other tissues; and (b) the TTX-resistant Na+ current is less sensitive to divalent cations than the Ca2+ current in these neurones. These observations suggest that the structure determining the monovalent cation permeability of the TTX-resistant Na+ current is similar to that of the TTX-sensitive Na+ current in other tissues, and that the channels carrying the TTX-resistant Na+ current are distinct from those responsible for the Ca2+ current.

摘要

采用全细胞膜片钳技术，研究了成年大鼠离体结节神经节神经元中河豚毒素（TTX）抗性Na⁺电流的单价阳离子选择性和二价阳离子敏感性。2. 利用离子置换和药理试剂分离出TTX抗性Na⁺电流。在这些条件下，电流反转电位随外部[Na⁺]每十倍变化而移动52 mV。3. 根据反转电位的变化和戈德曼-霍奇金- Katz方程确定无机和有机单价阳离子渗透率比值（Px/PNa）。通过前一种方法确定的Px/PNa值为：HONH₃⁺，1.38；Li⁺，1.00；H₂NNH₃⁺，0.66；NH₄⁺，0.28；CH₃NH₃⁺，小于0.13；K⁺，小于0.13；Rb⁺，小于0.12；Cs⁺，小于0.10；(CH₃)₄N⁺，小于0.10。两种方法确定的值在10%以内相符。4. 从峰值电导值分析Cd²⁺、Co²⁺、Mn²⁺和Ni²⁺对TTX抗性Na⁺电流的影响。这些离子将电流的激活向更正的电位移动，并降低最大电导。在3 mM浓度下，Cd²⁺、Ni²⁺、Co²⁺和Mn²⁺分别使最大电导降低64.6%、50.7%、25.0%和20.3%。5. 结果表明：（a）TTX抗性Na⁺电流的单价阳离子选择性与其他组织中TTX敏感性Na⁺电流的相似；（b）TTX抗性Na⁺电流对二价阳离子的敏感性低于这些神经元中的Ca²⁺电流。这些观察结果表明，决定TTX抗性Na⁺电流单价阳离子通透性的结构与其他组织中TTX敏感性Na⁺电流的相似，并且携带TTX抗性Na⁺电流的通道与负责Ca²⁺电流的通道不同。