Sitagliptin pretreatment ameliorated hypoxia/reoxygenation (H/R)-induced secretion of high mobility group box 1 (HMGB1) in primary cardiac microvascular endothelial cells (CMECs). Cells were pre-incubated with 100, 200 nM sitagliptin or DMSO vehicle for 12 h, followed by exposure to hypoxia/reoxygenation (H/R) conditions. Secretion of HMGB1 was determined by the ELSA assay (*, P<0.01 vs. vehicle group; #, P<0.01 vs. H/R group; $, P<0.01 vs. H/R+100 nM sitagliptin, n=6).