The effects of exogenous H₂O₂ on cell death, reactive oxygen species and glutathione levels in calf pulmonary artery and human umbilical vein endothelial cells

Enhanced oxidative stress contributes to endothelial dysfunction via the apoptotic induction of endothelial cells (ECs). However, the precise molecular mechanisms underlying its important effect remain unclear. Here, we evaluated the effects of exogenous hydrogen peroxide (H₂O₂) on cell growth and death in ECs such as calf pulmonary artery endothelial cells (CPAECs) and human umbilical vein endothelial cells (HUVECs) and investigated its mechanism of action in CPAECs. H₂O₂ inhibited the growth of CPAECs and HUVECs at 24 h with IC₅₀ of approximately 20 and 300 μM, respectively. H₂O₂ induced cell death in both ECs, which was accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨm). H₂O₂-induced CPAEC death occurred via apoptosis, demonstrated by Annexin V-staining cells and Z-VAD (a pan-caspase inhibitor) treatment. H₂O₂ increased superoxide anion levels in HUVECs but not in CPAECs. Treatment with 30 μM H₂O ₂ significantly decreased the activities of superoxide dismutases and catalase in CPAECs. H₂O₂ induced glutathione (GSH) depletion in both ECs. Z-VAD and N-acetyl cysteine (NAC; a well-known antioxidant) attenuated apoptotic cell death and GSH depletion in H ₂O₂-treated CPAECs. In conclusion, H₂O ₂ induced growth inhibition and death in ECs via GSH depletion. HUVECs were relatively resistant to H₂O₂ compared with CPAECs. H₂O₂-induced CPAEC apoptosis required the activation of various caspases.