Figure 2.

Bergmann glia Ca²⁺ raises during OGD are mediated by Ca²⁺ release from internal stores and Ca²⁺ entry from extracellular space. (A) Bergmann glial cells are loaded with Fluo4 (100 μM) and changes in fluorescence are measured in radial processes during OGD. Averaged ΔF/F values are plotted as a function of time in Ctr (n = 11), after treatment with CPA (20 μM), a blocker of intracellular Ca²⁺ stores refilling (n = 7) or with PPADS (100 μM), a broad-spectrum inhibitor of P2 receptors (n = 8). CPA and PPADS delayed the onset of intracellular Ca²⁺ increase (top) without affecting the onset of I_OGD (bottom). (B) Quantification of the effects of CPA (P = 0.002, n = 6) and PPADS (P = 0.0034, n = 5) on the kinetics of Ca²⁺ raises. (C) Mean and individual values of I_OGD area in control (n = 11), CPA (n = 5, P = 0.59) and in the presence of PPADS (n = 7, P = 0.12). (D) Extracellular Ca²⁺-free solution (+EGTA 5 mM, n = 9) or 2-APB (100 μM, n = 7), a blocker of store operated Ca²⁺ entry, dramatically reduces OGD-induced Ca²⁺ transients observed during OGD (Ctr, n = 11). (E) The time to the fluorescence peak is not affected by these treatments (P = 0.88, n = 5 for Ca²⁺-free solution and P = 0.27, n = 4, for 2-APB when compared to control (n = 8)). Note that the inward current dynamics (D) and the electrical charge (F) are not affected by the absence of extracellular Ca²⁺ (P = 0.51, n = 4) nor by 2-APB (P = 0.73, n = 3). *P < 0.005.