Effect and mechanism of calorie restriction-activated Sirt1 in protection of myocardial cells from ischemia/reperfusion injury

AIM To investigate the protection and mechanism of calorie restriction-activated sirtuins 1 (Sirt1) on myocardial cells in ischemia/reperfusion injury (I/RI). METHODSMyocardial cell line H9c2 seeded 5×105/L in a six-well cell culture plate was randomly divided into four groups: control, hypoxia/re-oxygenation (H/R), H/R+CR and H/R+CR+EX527. In control group and hypoxia group, glucose concentration was 4.5 g/L, whereas glucose concentration in low glucose preconditioning group and Sirt1 inhibitor group was 1.5 g/L. DCFH-DA probe was used to detect the level of reactive oxygen species (ROS), methyl thiazolyl tetrazolium (MTT) assay was used to detect cell activity, terminal labeling (TUNEL) staining was used to detect apoptotic levels of cells, and Western blot was used to detect Sirt1 expression and phosphorylation amp activated protein kinase (P-AMPK) protein. RESULTSCompared with those in H/R group, intracellular levels of ROS in H/R+CR group decreased significantly (0.31±0.06 vs. 0.11±0.02, P<0.05) and increased significantly in H/R+CR+EX527 group (0.31±0.06 vs. 0.55±0.06, P<0.05). Compared with those in H/R group, cell activity in H/R+CR group increased significantly (0.23±0.01 vs. 0.64±0.02, P<0.05) and decreased significantly in H/R+CR+EX527 group (0.23±0.01 vs. 0.09±0.005, P<0.05). Compared with those in H/R group, apoptosis levels in H/R+CR group significantly decreased (0.444±0.038 vs. 0.222±0.556, P<0.05) and significantly increased in H/R+CR+EX527 group (0.444±0.038 vs. 0.578±0.0129, P<0.05). Compared with those in H/R group, Sirt1 expression levels significantly increased in H/R+CR group (2.229±0.019 vs. 3.712±0.010, P<0.05) and significantly decreased in H/R+CR+EX527 group (2.229±0.019 vs. 1.603±0.134, P<0.05). Compared with those in H/R group, P-AMPK expression levels in H/R+CR group significantly increased (1.262±0.064 vs. 1.893±0.122, P<0.05) and significantly decreased in H/R+CR+EX527 group (1.262±0.064 vs. 0.734±0.069, P<0.05). CONCLUSIONCalorie-restricted activated Sirt1 may protect myocardial cells from ischemia/reperfusion injury through P-AMPK pathway.