Fig. 3. Effects of imperatorin on PFHxS-induced NMDA receptor activation and Ca²⁺ influx.

(A) Cells were pretreated with MK801 (1 µM), DTZ (10 µM) or NFD (10 µM) and then stimulated with 300 µM of PFHxS or DMSO as a vehicle control for 3 h. Then, the cells were incubated in fresh media for 21 h to detect caspase-3 activity. (B) Cells were pretreated with imperatorin (100 and 500 nM), MK801 (1 µM), DTZ (10 µM) or NFD (10 µM) and then stimulated with 100 µM NMDA or DMSO as a vehicle control for 15 min. Then, the cells were incubated in fresh media for 24 h to detect caspase-3 activity. (C) Cells were treated with 300 µM PFHxS for different times (0~24 h). The level of intracellular Ca²⁺ ([Ca²⁺]_i) was measured. (D) Cells were pretreated with imperatorin (100 and 500 nM), MK801 (1 µM), DTZ (10 µM) or NFD (10 µM) and then stimulated with 300 µM of PFHxS for 1 h to detect intracellular [Ca²⁺]. Data (fold increase) are represented as the mean±SEM of three independent experiments. ^*p<0.05, ^**p<0.01, ^***p<0.001 vs. DMSO. ^###p<0.001 vs. corresponding Control-treated cells (IPT, imperatorin; DTZ, diltiazem; NFD, nifedipine).