Effect of 15 or 60 min of sevoflurane preconditioning on adenosine triphosphate (ATP) concentrations during hypoxia. ATP was measured in the cornus ammonis 1 (CA1 region) of rat hippocampal slices at 5 min of hypoxia. The tissue was treated with 4% sevoflurane (Sevo) in 95% O₂–5% CO₂ for either 15 (A) or 60 (B) min and then the anesthetic was washed out with 95% O₂–5% CO₂ for 5 min (Sevo and Sevo/Hypo groups). At 5 min of hypoxia (Hypo) with 95% N₂–5% CO₂ (Hypoxia and Sevo/Hypo groups) or at an equivalent time period (Normoxia and Sevo groups), the tissue was frozen in liquid nitrogen. The hippocampal slices were lyophilized and the CA1 region was then dissected, weighed, and analyzed using a bioluminescent assay. Values are the mean ± SD (n = 10 rats per group) and are expressed as nmol per mg dry weight. A paired t test indicated that the Hypoxia versus the Sevo/Hypo groups were significantly different from each other as indicated by * (P < 0.001; n = 10 pairs). The normoxia groups (Normoxia vs. Sevo) were not significantly different from each other (P > 0.4; Paired t test; n = 10 pairs).