甘氨酸敏感的N-甲基-D-天冬氨酸受体脱敏动力学的全细胞和单通道分析

Whole cell and single channel analysis of the kinetics of glycine-sensitive N-methyl-D-aspartate receptor desensitization.

作者信息

Parsons C G, Zong X, Lux H D

机构信息

Department of Neurophysiology, Max-Planck Institute for Psychiatry, Planegg-Martinsried, Germany.

出版信息

Br J Pharmacol. 1993 May;109(1):213-21. doi: 10.1111/j.1476-5381.1993.tb13556.x.

DOI:10.1111/j.1476-5381.1993.tb13556.x

PMID:8098640

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2175563/

Abstract

The kinetics of glycine-sensitive, N-methyl-D-aspartate (NMDA) receptor desensitization were investigated in cultured neurones with the patch clamp technique. 2. The degree of fast NMDA-receptor desensitization was inversely related to glycine concentration. Thus, increasing concentrations of glycine from 30 nM to 2.5 microM potentiated desensitized NMDA responses (873% +/- 101%) to a greater degree than peak responses (260% +/- 27%). 3. The desensitization was due to a decrease in the affinity of glycine for the strychnine-insensitive, glycine modulatory site (glycineB site) following activation of the NMDA-receptor complex. Thus, the A50 for glycine in potentiating peak responses (77 nM, 95% confidence limited 58-104 nM) was five fold lower than that for plateau responses (399 nM, 340-468 nM). 4. The rate of desensitization was related to glycine concentration such that a reciprocal plot of desensitization rate (1/tau S-1) against glycine concentration had a slope of 9.5* 10(6) M-1 S-1. 5. Recovery from desensitization following step increases in glycine or L-alanine concentration in the continuous presence of NMDA (200 microM) reflected the association kinetics of the glycineB agonist used. 6. The rate and degree of NMDA receptor desensitization was independent of holding potential. 7. NMDA receptor desensitization was also evident at the single channel level. 8. The glycineB antagonist 7-chlorokynurenic acid (7-Chl-Kyn 3 and 10 microM) concentration-dependently induced an identical form of desensitization in the presence of 1 microM glycine. 9. In contrast, the competitive NMDA antagonist (+/-)-amino-phosphonovaleric acid (APV 30 to 300 microM) concentration-dependently antagonized and slowed the onset kinetics of NMDA responses.

摘要

采用膜片钳技术，在培养的神经元中研究了甘氨酸敏感的N-甲基-D-天冬氨酸（NMDA）受体脱敏的动力学。2. 快速NMDA受体脱敏程度与甘氨酸浓度呈负相关。因此，将甘氨酸浓度从30 nM增加到2.5 μM时，增强脱敏的NMDA反应（873%±101%）的程度大于峰值反应（260%±27%）。3. 脱敏是由于NMDA受体复合物激活后，甘氨酸对士的宁不敏感的甘氨酸调节位点（甘氨酸B位点）的亲和力降低。因此，增强峰值反应时甘氨酸的A50（77 nM，95%置信区间58 - 104 nM）比平台期反应时的A50（399 nM，340 - 468 nM）低五倍。4. 脱敏速率与甘氨酸浓度有关，使得脱敏速率（1/τ s⁻¹）对甘氨酸浓度的倒数图斜率为9.5×10⁶ M⁻¹ s⁻¹。5. 在持续存在NMDA（200 μM）的情况下，甘氨酸或L-丙氨酸浓度阶跃增加后脱敏的恢复反映了所用甘氨酸B激动剂的结合动力学。6. NMDA受体脱敏的速率和程度与钳制电位无关。7. NMDA受体脱敏在单通道水平也很明显。8. 在存在1 μM甘氨酸的情况下，甘氨酸B拮抗剂7-氯犬尿氨酸（7-Chl-Kyn 3和10 μM）浓度依赖性地诱导相同形式的脱敏。9. 相反，竞争性NMDA拮抗剂（±）-氨基膦酸戊酸（APV 30至300 μM）浓度依赖性地拮抗并减慢NMDA反应的起始动力学。