A and B, The expression of HIF‐1α and GLUT1 in cultured ECs. The expression of HIF‐1α and GLUT1 was significantly reduced in the EC isolated from SIRT3 ECKO mice compared with control ECs (*P<0.05 n=4 mice). GLUT4 levels were not significantly altered in EC. C, Glucose uptake in cultured ECs. The glucose uptake was significantly reduced in the ECs isolated from SIRT3 ECKO mice compared with ECs from wild‐type mice (****P<0.0001, n=5 mice). D, Exposure of WT‐ECs to hypoxia for 24 hours resulted in an upregulation of apelin expression. Hypoxia failed to induce apelin expression in the ECs isolated from SIRT3 ECKO mice. The WT‐ECs were isolated from a mouse and used for experiment. E, Treatment of WT‐EC with apelin (1 μmol/L) significantly increased glucose uptake. Apelin‐induced glucose uptake was significantly reduced in the ECs isolated from SIRT3 ECKO mice (n=4 mice, **P<0.01, ***P<0.001). ECKO indicates endothelial‐specific knockout; ECs, endothelial cells; GLUT1, glucose transporter 1; GLUT4, glucose transporter 4; HIF‐1α, hypoxia‐inducible factor‐1α; SIRT3, sirtuin 3; and WT‐ECs, endothelial cells from wild‐type mice.