AD-mediated preconditioning activates AMPK, LKB1, and eNOS signaling pathways in the early post-ischemic reperfusion (15 min). Lysates from hearts exposed to 15 min of reperfusion were immunoblotted for phosphorylated and total isoforms of the indicated proteins. A. For each experimental condition, the ratio of phosphorylated/total SIRT-1, eNOS, AMPK and LKB1 proteins are expressed as the mean ± SEM of at least 3 independent experiments (each run in triplicate). Statistical differences between groups were evaluated by one-factor ANOVA followed by Bonferroni correction (*p