Figure 2. In “older” neurons (13-16 DIV), ifenprodil and PEAQX partially inhibited Ca²⁺ influx induced by NMDA. Combined application of ifenprodil and PEAQX completely blocked the [Ca²⁺]_c increase.

The bath solution was supplemented with 1μM tetrodotoxin and 5μM nifedipine. Neurons were loaded with 2.6μM Fura-2AM. Where indicated, (A.) vehicle (0.2% DMSO), ifenprodil (50μM), PEAQX (5μM), or the combination of both ifenprodil (1μM) and PEAQX (0.1μM). NMDA (30μM, plus 10μM glycine) was applied twice for 30 seconds as indicated. The Ca²⁺ influx into neurons was evaluated by measuring amplitude of the increases in [Ca²⁺]_c. [Ca²⁺]_c was calculated using the Grynkiewicz method (Grynkiewicz et al., 1985). The time scale shown in panel D is applicable to traces in A-C. In E, statistical analysis of the Ca²⁺ influx inhibition. Data are mean±SEM, *p<0.05, **p<0.01 compared to vehicle, n=3.