Fig. 2. Mitochondrial membrane potential in cortical astrocytes exposed to OGD and subsequent reintroduction of oxygen and glucose. Mixed cortical cultures were exposed to OGD in the presence of the potentiometric dye TMRE. A, C, Mitochondrial ψ, as TMRE fluorescence, was evaluated in the astrocyte monolayer by confocal microscopy after 40, 50, or 60 min of OGD (A) or during recovery after reintroduction of oxygen and glucose after 60 min of OGD (C). Control cultures were maintained in 21% oxygen and 5.5 mm glucose for 60 min. B, D, The time course of mitochondrial TMRE fluorescence loss in astrocytes during OGD (B) and the recovery of mitochondrial ψ after readdition of oxygen and glucose (D) are shown. Dashed line inB indicates interpolation of TMRE fluorescence changes between 0 and 40 min. Values are mean TMRE fluorescence intensity (as % of control) ± SEM; n > 100 for all conditions from 3 or more independent experiments. *p< 0.05 by ANOVA and Tukey's post hoc analysis.E, Astrocytes were exposed to OGD (60 min) or OGD followed by reintroduction of oxygen plus glucose for an additional 60 or 120 min. Alterations in mitochondrial morphology, visualized by TMRE fluorescence, were apparent after OGD, persisted after reintroduction of O2 plus glucose for 60 min, but had resolved by 120 min after addition of O2 plus glucose. Scale bar: A, C, 20 μm. CTRL, Control; Rep, reperfusion.