Excitatory amino acid response in isolated spiral ganglion cells of guinea pig cochlea.
Excitatory amino acid response in isolated spiral ganglion cells of guinea pig cochlea.
复制标题
豚鼠耳蜗离体螺旋神经节细胞的兴奋性氨基酸反应。
作者：
T. Nakagawa;S. Komune;T. Uemura;N. Akaike
1. 采用传统膜片钳技术结合快速给药（Y 管）方法，研究了急性分离的豚鼠螺旋神经节细胞兴奋性氨基酸（EAA）诱导反应的生理和药理特性。 2. L-谷氨酸（Glu）及其激动剂，使君子氨酸（QA）和红藻氨酸（KA）在-70 mV的保持电位（VH）下以浓度依赖性方式诱导内向电流。 Glu的半最大浓度(EC50)值为4.0×10(-4)M，QA为2.3×10(-5)M，KA为1.4×10(-4)M。 Glu、QA 和 KA 的 Hill 系数分别为 0.96、1.00 和 1.56。然而，一种Glu激动剂N-甲基-D-天冬氨酸（NMDA）和另一种兴奋性氨基酸L-天冬氨酸（Asp）即使在含有10（-6）M甘氨酸（Gly）的不含Mg2（+）的外部溶液中也不会诱导任何反应。 3. Glu、QA 和 KA 诱导反应的电流-电压 (I-V) 关系是线性的，并且这些反转电位接近 5 mV。 4. 犬尿酸 (Kyn)、6,7-二氯-3-羟基-2-喹喔啉甲酸 (diCl-HQC) 和喹喔啉二酮如 6-氰基-7-硝基喹喔啉-2,3-二酮 (CNQX) 和 6,7-二硝基-喹喔啉-2,3-二酮 (DNQX) 抑制 Glu-、QA- 和 KA 诱导的电流浓度依赖性方式。抑制效力的顺序为 DNQX = CNQX 大于 diCl-HQC 大于 Kyn。 5. CNQX拮抗Glu-、QA-和KA诱导电流而不影响最大响应，显示无电压依赖性，表明竞争性抑制。（摘要截断为250字）
1. The physiological and pharmacological properties of excitatory amino acid (EAA)-induced responses were investigated in acutely isolated spiral ganglion cells of guinea pig by a conventional patch-clamp technique combined with a rapid drug application (Y-tube) method. 2. L-glutamate (Glu) and its agonists, quisqualate (QA) and kainate (KA), induced inward currents in a concentration-dependent manner at a holding potential (VH) of -70 mV. The values of half-maximal concentration (EC50) were 4.0 x 10(-4) M for Glu, 2.3 x 10(-5) M for QA, and 1.4 x 10(-4) for KA. The Hill coefficients were 0.96, 1.00, and 1.56 for Glu, QA, and KA, respectively. However, one of Glu agonists, N-methyl-D-aspartate (NMDA), and another excitatory amino acid, L-aspartate (Asp), did not induce any responses even in Mg2(+)-free external solution containing 10(-6) M glycine (Gly). 3. The current-voltage (I-V) relationships for the Glu-, QA-, and KA-induced responses were linear, and these reversal potentials were near 5 mV. 4. Kynurenic acid (Kyn), 6,7-dichloro-3-hydroxy-2-quinoxalinecarboxylic acid (diCl-HQC), and quinoxalinediones such as 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 6,7-dinitro-quinoxaline-2,3-dione (DNQX) suppressed the Glu-, QA-, and KA-induced currents in a concentration-dependent manner. The inhibitory potency was in the order of DNQX = CNQX greater than diCl-HQC greater than Kyn. 5. CNQX antagonized the Glu-, QA-, and KA-induced currents without affecting the maximum responses showing no voltage-dependency, indicating the competitive inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)