RT Journal Article SR Electronic T1 Stable expression and characterization of recombinant human heteromeric N-methyl-D-aspartate receptor subtypes NMDAR1A/2A and NMDAR1A/2B in mammalian cells. JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 367 OP 378 VO 279 IS 1 A1 M A Varney A1 C Jachec A1 C Deal A1 S D Hess A1 L P Daggett A1 R Skvoretz A1 M Urcan A1 J H Morrison A1 T Moran A1 E C Johnson A1 G Veliçelebi YR 1996 UL http://jpet.aspetjournals.org/content/279/1/367.abstract AB The electrophysiological and pharmacological properties of two mammalian cell lines stably transfected with cDNAs encoding recombinant human N-methyl-D-aspartate (NMDA) receptor subtypes NMDAR1A/2A and NMDAR1A/2B are described. In whole-cell electrophysiological recordings, application of NMDA/glycine elicited inward currents at negative holding potentials in human NMDAR1A/2A (hNMDAR1A/2A)- and hNMDAR1A/2B-expressing cells. The current-voltage relationships determined in both cell lines in the presence and absence of external Mg++ were similar to those observed with recombinant rat NMDA receptors. Power spectra calculated from NMDA/glycine-induced currents for both NMDA receptor-expressing cell lines suggested a kinetically homogeneous population of channels. Immunoprecipitation with an anti-NMDAR1A antibody coprecipitated the corresponding NMDAR2 subunit with the NMDAR1A, suggesting that heteromeric complexes are formed in these stable cell lines. Stimulation of NMDA receptors evoked an increase in intracellular Ca++, which was used to characterize their pharmacological properties. NMDA displayed less intrinsic activity than did glutamate in both NMDA receptor-expressing cell lines and was a 4-fold more potent agonist at hNMDAR1A/2B than hNMDAR1A/2A. NMDA/glycine-evoked increases in Ca++ levels were inhibited by CGS 19755, (+/-)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate, MK-801, ketamine and ifenprodil. (+/-)-3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonate was a 3-fold more potent antagonist at hNMDAR1A/2A than hNMDAR1A/2B, whereas ifenprodil was markedly more selective toward hNMDAR1A/2B, being 250-fold more potent than against hNMDAR1A/2A. These data suggest that cells stably expressing recombinant heteromeric hNMDAR1A/2A and hNMDAR1A/2B represent pharmacologically valid experimental systems to study human NMDA receptors.