Effects of adiponectin on HUVECs viability. (a) Effect of adiponectin on endothelial cell death induced by serum starvation in control medium (= 0.5% FCS), induced by VEGF (= 10 ng/mL), in 5 mmol/L glucose medium, 10 mmol/L glucose medium, and 30 mmol/L glucose medium without or with adiponectin (= 30 μg/mL) for 48 hours. Cell viability was quantified with an MTS-based assay. VEGF served as additional control. (b) Role of AMPK in the regulation of adiponectin-induced reduction of endothelial cell death in 5 mmol/L glucose medium, 10 mmol/L glucose medium, and 30 mmol/L glucose medium. HUVECs were transduced with an adenoviral vector expressing β-galactosidase (Ad-βgal) (= control) or with an adenoviral vector expressing dominant-negative AMPKα2 (Ad-dnAMPK). After 24-hour infection, cells were treated for 48 hours with adiponectin (= 30  μg/mL) under serum deprivation conditions. Cell viability was quantified with an MTS-based assay.