Grimwood S, Gilbert E, Ragan C I, Hutson P H
Merck, Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, England.
J Neurochem. 1996 Jun;66(6):2589-95. doi: 10.1046/j.1471-4159.1996.66062589.x.
A 45Ca2+ influx assay has been used to investigate the pharmacology of stably expressed recombinant human NR1a/NR2A and NR1a/NR2B N-methyl-D-aspartate (NMDA) receptors. Inhibition of glutamate-stimulated 45Ca2+ influx by six glycine-site antagonists and inhibition of glycine-stimulated 45Ca2+ influx by five glutamate-site antagonists revealed no significant differences between affinity values obtained for NR1a/NR2A and NR1a/NR2B receptors. The polyamine site agonist spermine showed differential modulation of glutamate- and glycine-stimulated 45Ca2+ influx for recombinant NMDA receptors, inhibiting and stimulating 45Ca2+ influx into cells expressing NR1a/NR2A receptors (IC50 = 408 microM) and NR1a/NR2B receptors (EC50 = 37.3 microM), respectively. The antagonist ifenprodil was selective for NR1a/NR2B receptors (IC50 = 0.099 microM) compared with NR1a/NR2A receptors (IC50 = 164 microM). The effects of putative polyamine site antagonists, redox agents, ethanol, and Mg2+ and Zn2+ ions were also compared between NR1a/NR2A and NR1a/NR2B receptors. This study demonstrates the use of 45Ca2+ influx as a method for investigating the pharmacology of the numerous modulatory sites that regulate the function of recombinant human NMDA receptors stably expressed in L(tk-) cells.
利用45Ca2+内流测定法研究了稳定表达的重组人NR1a/NR2A和NR1a/NR2B N-甲基-D-天冬氨酸（NMDA）受体的药理学特性。六种甘氨酸位点拮抗剂对谷氨酸刺激的45Ca2+内流的抑制作用以及五种谷氨酸位点拮抗剂对甘氨酸刺激的45Ca2+内流的抑制作用表明，NR1a/NR2A和NR1a/NR2B受体的亲和力值之间没有显著差异。多胺位点激动剂精胺对重组NMDA受体的谷氨酸和甘氨酸刺激的45Ca2+内流表现出不同的调节作用，分别抑制和刺激45Ca2+流入表达NR1a/NR2A受体的细胞（IC50 = 408 microM）和表达NR1a/NR2B受体的细胞（EC50 = 37.3 microM）。与NR1a/NR2A受体（IC50 = 164 microM）相比，拮抗剂ifenprodil对NR1a/NR2B受体具有选择性（IC50 = 0.099 microM）。还比较了NR1a/NR2A和NR1a/NR2B受体之间推定的多胺位点拮抗剂、氧化还原剂、乙醇以及Mg²⁺和Zn²⁺离子的作用。本研究证明了利用45Ca2+内流作为一种方法来研究众多调节位点的药理学特性，这些调节位点调控着在L(tk-)细胞中稳定表达的重组人NMDA受体的功能。
