Figure 8

Effect of TNF-α in tip cells and non-tip cells and effect of DLL4 in total HUVEC populations on mitochondrial respiration and glycolysis. TNF-α (10 ng/ml) treatment of HUVEC cultures reduced maximal respiratory capacity and spare capacity (a) and induced glycolytic activity (b) at 24 h after treatment. TNF-α reduced maximal respiratory capacity and spare capacity in tip cells (d), whereas effects on mitochondrial respiration were not found in non-tip cells (c) at 24 h after treatment. (e) TNF-α in FACS-sorted HUVECs induced glycolysis in non-tip cells (e) and reduced glycolytic capacity in tip cells (f) at 24 h after treatment. (g) HUVECs cultured on DLL4-coated (1 µg/ml) plates showed lower tip cell percentages as compared to those cultured on BSA-coated (1 µg/ml) plates used as a control. DLL4 treatment did not affect mitochondrial respiration (h), but increased basal glycolysis (i) in HUVEC cultures at 24 h after cell addition. OCR and ECAR measurements were represented as fold change compared to control basal OCR and ECAR levels, respectively. Results are shown as means ± SEM of experiments with HUVECs of at least 3 donors. *P < 0.05, **P < 0.01, and ***P < 0.001 as compared to control (Unpaired Student’s t-test).