Fig. 3.

Source of increased [Ca²⁺]_i during preconditioning hypoxia is intracellular stores. A. [Ca²⁺]_i in CA1 neurons during hypoxic preconditioning in untreated control slices, and in slices pre-treated with a phospholipase C inhibitor (U73122, 1 μM), an IP₃ receptor antagonist xestospongin C (xesto C. 1 μM), the NMDA receptor antagonist a-phosphonovalerate (APV, 10 μM) or low extracellular Ca²⁺ (<0.1 mM). Data are means ±SEM in 8–10 slices. B. Depletion of [Ca²⁺]_i stores with thapsigargin (10 μM) decreases the magnitude of the [Ca²⁺]_I rise in CA1 during hypoxia. * indicates significant (P<0.05) increase in [Ca²⁺]_i compared to hypoxia alone group. Data are means±SD for 6 experiments.