Fig. 6.

4-AP alters Ca²⁺ dynamics and SCO in 10 DIV HN cultures. (A) Representative traces of 4-AP–triggered Ca²⁺ responses in HN cultures at 10 DIV. 4-AP produced an immediate intracellular Ca²⁺ rise (Phase I) and concomitant high frequent SCO patterns of low amplitude (Phase II). The integrated Ca²⁺ signals (Phase I responses, area under the curve [AUC]) were calculated from the initial 5 minutes after addition of 4-AP. The Phase II responses were calculated from the 5-minute period between 10 and 15 minutes after addition of 4-AP. (B) 4-AP caused an acute concentration-dependent rise in cytoplasmic Ca²⁺ with an EC₅₀ value of 1.76 μM (1.21–4.54 μM, 95% CI). (C) 4-AP increased SCO frequency with an EC₅₀ value of 2.33 μM (1.30–4.18 μM, 95% CI). (D) 4-AP elicited a concentration-dependent decrease in mean SCO amplitude with an IC₅₀ value of 1.33 μM (1.05–1.74 μM, 95% CI). Each data point represents at least four replicates, and the experiments were repeated in two independent cultures with similar results. Veh, vehicle.