士的宁诱导的大鼠离体背根神经节细胞钾电流

Strychnine-induced potassium current in isolated dorsal root ganglion cells of the rat.

作者信息

Aibara K, Oonuma M, Akaike N

机构信息

Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan.

出版信息

Br J Pharmacol. 1991 Feb;102(2):492-6. doi: 10.1111/j.1476-5381.1991.tb12199.x.

DOI:10.1111/j.1476-5381.1991.tb12199.x

PMID:2015426

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1918034/

Abstract

Effects of strychnine (Str) on the dissociated dorsal root ganglion (DRG) cells of the rat have been investigated in whole-cells configuration by a conventional patch-clamp technique. 2. gamma-Aminobutyric acid (GABA)-induced Cl- current (ICl) increased sigmoidally with increasing concentration. The half-maximal response (Ka) was 3 x 10(-5) M and the Hill coefficient was 1.5. Both Str and bicuculline inhibited the GABA-induced ICl in a concentration-dependent manner. 3. Str itself could elicit the current at concentrations over 10(-5) M, at which concentrations the GABA response was completely suppressed. The concentration-response curve for the Str-induced current was bell-shaped, and a nearly maximum response occurred at 3 x 10(-4) M. A transient 'hump' current appeared immediately after the wash-out of external solution containing high concentrations of Str over 3 x 10(-4) M. 4. The Str-induced outward current and a transient 'hump' current were augmented by the removal of extracellular K+ and were suppressed by the substitution of intracellular K+ for Cs+. But the current was not sensitive to extracellular Na+, Ca2+ and Cl-. 5. The reversal potential of Str-induced current (EStr) was -75 mV, which was close to the K+ equilibrium potential (EK = -76.3 mV). The change of EStr for a ten fold change in extracellular K+ concentration was 58 mV, indicating that the membrane behaves like a K+ electrode in the presence of Str. The reversal potential of the 'hump' current was also close to EK. 6. The Str-induced outward current was antagonized by K+ channel blockers such as Ba2+, tetraethylammonium (TEA)-chloride, and 4-aminopyridine (4-AP) in a concentration-dependent manner. 7. The Str-induced K+ current was not affected by internal perfusion of bis(gamma-aminophenoxy)ethane-N, N,N',N-tetraacetic acid (BAPTA), indicating that the Str response does not result in the activation of K+ conductance by the intracellular Ca2+.

摘要

采用传统膜片钳技术的全细胞模式，研究了士的宁（Str）对大鼠离体背根神经节（DRG）细胞的作用。2. γ-氨基丁酸（GABA）诱导的氯离子电流（ICl）随浓度增加呈S形增加。半数最大反应浓度（Ka）为3×10⁻⁵ M，希尔系数为1.5。士的宁和荷包牡丹碱均以浓度依赖方式抑制GABA诱导的ICl。3. 士的宁本身在浓度超过10⁻⁵ M时可引发电流，在此浓度下GABA反应被完全抑制。士的宁诱导电流的浓度-反应曲线呈钟形，在3×10⁻⁴ M时出现近最大反应。在洗脱含有超过3×10⁻⁴ M高浓度士的宁的外部溶液后，立即出现短暂的“驼峰”电流。4. 去除细胞外钾离子可增强士的宁诱导的外向电流和短暂的“驼峰”电流，用铯离子替代细胞内钾离子可抑制该电流。但该电流对细胞外钠离子、钙离子和氯离子不敏感。5. 士的宁诱导电流的反转电位（EStr）为-75 mV，接近钾离子平衡电位（EK = -76.3 mV）。细胞外钾离子浓度变化10倍时EStr的变化为58 mV，表明在士的宁存在下膜表现得像一个钾离子电极。“驼峰”电流的反转电位也接近EK。6. 士的宁诱导的外向电流被钾离子通道阻滞剂如钡离子、氯化四乙铵（TEA）和4-氨基吡啶（4-AP）以浓度依赖方式拮抗。7. 双（γ-氨基苯氧基）乙烷-N，N，N'，N-四乙酸（BAPTA）的内部灌注不影响士的宁诱导的钾离子电流，表明士的宁反应不会通过细胞内钙离子激活钾离子电导。