Figure 1.

REL-1017 concentration-response curve (CRC) was performed in the presence of 10 µM L-glutamate and 10 µM glycine but in the absence of extracellular Mg²⁺ by fluorometric imaging plate reader (FLIPR) Ca²⁺ assay using Chinese hamster ovary (CHO) cell lines expressing the indicated heterodimeric N-methyl-D-aspartate receptors (NMDARs). REL-1017 caused a decrease in the increased intracellular Ca²⁺ elicited by 10 µM L-glutamate with estimated IC₅₀ concentrations of 43 µM, 23 µM, 23 µM, and 68 µM for 2A-, 2B-, 2C-, and 2D-containing NMDARs, respectively. 100 μM REL-1017, the maximal tested concentration, reduced Ca²⁺ influx by 30%, 14%, 15%, and 47% of that evoked by 10 µM L-glutamate for NR1-2A, NR1-2B, NR1-2C, and NR1-2D subtypes, respectively. Fitting parameters for REL-1017 and other known NMDAR blockers, which were tested in identical conditions, are reported in Table 1. Data are mean ± standard error of the mean (SEM), n = 6 per group, and were fitted using the four-parameter logistic equation with GraphPad Prism v8.0. RFU is relative fluorescence units.