Modulation of 45Ca2+ Influx into Cells Stably Expressing Recombinant Human NMDA Receptors by Ligands Acting at Distinct Recognition Sites
- 1 June 1996
- journal article
- Published by Wiley in Journal of Neurochemistry
- Vol. 66 (6) , 2589-2595
- https://doi.org/10.1046/j.1471-4159.1996.66062589.x
Abstract
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.Keywords
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