Pharmacological analysis of recombinant NR1a/2A and NR1a/2B NMDA receptors using the whole-cell patch-clamp method

N-methyl-D-aspartate receptors (NMDARs) are ligand-gated ion channels belonging to the family of ionotropic glutamate receptors. Functional NMDARs are heterotetrameric assemblies of NR1 subunits with at least one type of NR2 subunits. Various combinations of these subunits form distinct NMDAR subtypes involved in a variety of physiological and pathological processes. Several pharmaceutical companies search subunit-selective drugs for curing various neurological diseases and having favorable side-effect profile. We applied the whole-cell patch-clamp technique for testing NR2B subunit-specific drugs in HEK cells transiently or stably expressing different types of NMDAR subunits. In stable cell lines, we applied an inducible mammalian expression system; cDNAs of NR1 and either NR2A or NR2B subunits were inserted into an ecdyson-inducible mammalian expression vector and were introduced into HEK293 cells. These expression systems proved to be suitable to analyze precisely the subtype selectivity of newly synthesized NR2B-selective NMDAR antagonists by using whole-cell patch-clamp technique.