Figure 5. Neuronal stimulation in glucose-free conditions is dependent on a run-down in glycolysis.

A, example trace demonstrating that 5 mm lactate and 0.5 mm pyruvate rapidly reverse the initial stimulation evoked by glucose deprivation. Raw discharge frequency from a single fibre is demonstrated (upper) along with frequency histograms (lower). Overdrawn action potentials demonstrate single fibre discrimination (inset). B, mean data showing that the response to glucose deprivation is restored to basal levels by the addition of lactate and pyruvate. Error bars indicate + SEM; *P < 0.05 compared with basal frequency in 11 mm glucose; one-way repeated-measures ANOVA with Dunnett's post hoc comparisons test (n = 9 fibres from 5 CB preparations). C, example trace showing the effect of 1 mm glucose on the response to glucose deprivation. Raw neuronal discharge is shown (upper) along with frequency histograms (lower). Inset: multiple action potentials have been overdrawn to show the single fibre discrimination. D, mean data showing that addition of 1 mm glucose abolishes the response to initial glucose free stimulation. Error bars indicate + SEM; *P < 0.05 compared with the basal frequency in 11 mm glucose; one-way repeated measures ANOVA with Dunnett's post hoc comparisons test (n = 6 fibres from 3 CB preparations). Note: for A–D experiments were performed following 5 min of severe hypoxia, to reduce the initial time to a response in glucose free solution (see earlier).