Fig. 6. Effect of 30 min of severe hypoxia, with and without 5 min of hypoxic preconditioning, on in situ maximum cardiac performance (N=7–8 per group). Control (open bars), 5 min hypoxic preconditioning (light gray bars), 30 min severe hypoxia (dark gray bars), 5 min hypoxic preconditioning followed by 30 min of severe hypoxia (black bars). Dissimilar letters represent a significant difference (P<0.05) between treatment groups, as determined using one-way ANOVA. Values are means ± S.E.M.