(a) Intracellular ATP levels in cells exposed to control Basal medium, or glucose-free media containing 10 mM DDG, with or without 5 mM sodium pyruvate, 5 mM L-glutamine, or combination of pyruvate and glutamine. Data are the means ± SEM of 3–5 experiments per group in two astrocytic cultures, normalized to control ATP levels. *p<0.05, vs. control. (b) Kinetics of swelling-activated d-[3H]aspartate release in astrocytes exposed to the same conditions as in (a). Data are the means ± SEM of 6–7 experiments per group performed in two different astrocytic cultures. ***p< 0.001, maximal release values vs. control; ###p < 0.001, integral 20-min release values vs. control. +p<0.05, maximal release values vs. DDG. (left inset) Graphical representation of the relevant metabolic processes. Abbreviations: DDG, 2-deoxy-d-glucose; Gln, glutamine. αKG, α-ketoglutarate; Pyr, pyruvate; TCA, the tricarboxylic acid cycle.