The potency of Pb2+ inhibition of glutamate-activated currents mediated by N-methyl-D-aspartate (NMDA) receptors was dependent on the subunits composing the receptors when functionally expressed in Xenopus laevis oocytes. Pb2+ reduced the amplitudes of glutamate-activated currents and shifted the agonist EC50 values of NMDA receptors consisting of different subunit compositions. The IC50 values for Pb2+ ranged from 1.52 to 8.19 μM, with a rank order of potency of NR1b-2A > NR1b-2C > NR1b-2D > NR1b-2AC. For NR1b-2AC NMDA receptors, the IC50 value was dependent on the agonist concentration; at saturating agonist concentrations (300 μM), the IC50 value was 8.19 μM whereas at 3 μM glutamate the IC50 lu va e was 3.39 μM. Pb was a noncompetitive inhibitor of NR1b-2A, NR1b-2C and NR1b-2D NMDA receptors. At low concentrations (<1 μM) Pb2+ potentiated NR1b-2AC NMDA receptors. These data provide further evidence to support the hypothesis that the actions of Pb2+ on NMDA receptors are determined by the receptor subunit composition.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Pharmacology and Experimental Therapeutics|
|State||Published - Sep 1997|
ASJC Scopus subject areas
- Molecular Medicine