A method for evaluating chemical selectivity of agonists for glutamate receptor channels incorporated in liposomes based on an agonist-induced ion flux measured by ion-selective electrodes

Hanna Radecka, Jun Nakanishi, Ayumi Hirano, Masao Sugawara, Yoshio Umezawa*

*この研究の対応する著者

研究成果: Article査読

10 被引用数 (Scopus)

抄録

A new method for evaluating chemical selectivity of agonists for the NMDA subtype of glutamate receptor (GluR) channels is described. The method is based on the magnitude of Ca2+ release from GluR-incorporated liposomes, which is measured by a Ca2+ ion-selective electrode with a thin-layer mode. The partially purified GluRs from rat whole brain were reconstituted into Ca2+-loaded liposomes. Small aliquots (each 50 μl) of the proteoliposomes, in the presence of an antagonist DNQX for blocking non-NMDA subtype, were subjected to potentiometric measurements of Ca2+ release under stimulation by three kinds of agonists, i.e. NMDA, l-glutamate and l-CCG-IV. The amount of the Ca2+ ion flux through the GluR channel induced by the agonists was found to increase in the order of NMDA<l-glutamate<l-CCG-IV, which was consistent with that of binding affinity of the agonists toward the NMDA subtype. However, the range of selectivity of the relevant agonists was much smaller compared with results based on binding affinities. The present method provides physiologically more relevant values for the agonist selectivity of GluRs as compared to that of the conventional binding assay in the sense that the selectivity is based on the very magnitude of Ca2+ flux through the NMDA receptor, i.e. the extent of signal transduction by a given agonist. The evaluation of agonist selectivity based on Na+ release was also investigated by using a Na+ ion-selective electrode, but agonist-induced Na+ release was not detected, because of low permeability of Na+ through the NMDA subtype. Copyright (C) 1999 Elsevier Science B.V.

本文言語English
ページ(範囲)205-216
ページ数12
ジャーナルJournal of Pharmaceutical and Biomedical Analysis
19
1-2
DOI
出版ステータスPublished - 1999 2
外部発表はい

ASJC Scopus subject areas

  • 分析化学
  • 薬科学
  • 創薬
  • 分光学
  • 臨床生化学

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