Fig. 4.

Permeabilization of astrocytes after 3 h hypoxia in high or normal glucose in “ischemic saline” followed by reoxygenation in normal glucose in normal saline.

Hypoxia–reoxygenation increases rate of Etd⁺ uptake by rat cortical astrocytes in culture, an effect potentiated by high glucose. A. Time-lapse measurements of Etd⁺ uptake under control conditions and starting at 1 h reoxygenation after 3 h hypoxia in 5 mM or 27 mM glucose. Gap 26, a Cx43 hemichannel blocker, applied after 12 min of Etd⁺ uptake measurement greatly reduces uptake after hypoxia in 27 mM glucose. B–D. Fluorescence micrographs of Etd⁺ uptake (10 min exposure to dye) under control conditions (B) and at 1 h reoxygenation after 3 h hypoxia in 5 mM glucose (C) or 27 mM glucose (D). E. Time-lapse measurements of Etd⁺ uptake as in A under control conditions and starting at 1 h reoxygenation after 6 h hypoxia in 5 mM or 27 mM glucose. F–H. Fluorescence micrographs of Etd⁺ uptake (10 min exposure to dye) under control conditions (F) and at 1 h reoxygenation after 6 h hypoxia in 5 mM (G) or 27 mM glucose (H). I. Averaged data normalized to control of Etd⁺ uptake rate measured from the beginning of reoxygenation (time 0) following 3 h hypoxia in 0 mM, 5 mM, or 27 mM glucose. *** P < 0.001, 27 vs. 5 mM glucose; ^††† p < 0.001, 27 vs. 0 mM glucose; ^£££ p < 0.001, 0 vs. 5 mM glucose. (J) Etd⁺ uptake rate as in I following 6 h hypoxia in 0 mM, 5 mM, or 27 mM glucose. *** p < 0.001, ** p < 0.005, * p < 0.05, 27 vs. 5 mM glucose; ^††† p < 0.001, ^†† p < 0.005, ^† p < 0.05, 27 vs. 0 mM; ^£ p < 0.05, 0 vs. 5 mM. K. Etd⁺ uptake rate at 1 h reoxygenation following 3 h or 6 h of hypoxia in different glucose concentrations. *** p < 0.001, * p < 0.05, 27 vs. 0 mM glucose. Each value corresponds to mean ± SE of 20 cells in a representative of five experiments. Bar = 60 μm. From Orellana et al., 2010.