FIGURE 2.

Identification of receptors involved in high or low 4-AP/bic preconditioning. Cortical neuron cultures were subjected to (A) high 4-AP/bic preconditioning (2.5 mm 4-AP with 50 μm bicuculline) (light bars) or control wash (dark bars) in the absence (labeled antagonist-free) or presence of a receptor antagonist for 48 h, followed by a 24-h recovery and then exposure to 65–80 min OGD, with assessment of the % PI-uptake performed 24 h later. B, cultures were treated as described in A, except preconditioning was accomplished using low 4-AP/bic (20 μm 4-AP with 50 μm bicuculline). Antagonists examined were a Na⁺ channel blocker, tetrodotoxin (1 μm TTX; n = 18); an NMDA receptor antagonist, memantine (12.5 μm; n = 9–15); an l-type voltage-gated Ca²⁺ channel antagonist, nifedipine (5 μm; n = 9); memantine plus nifedipine (n = 12); and an AMPA receptor antagonist, NBQX (10 μm; n = 12). Brackets denote a significant difference (p < 0.05) between indicated conditions using an ANOVA.