Effect of TNF-α on production of NO and Activity of eNOS in human umbilical vein endothelial cells

Objective To investigate the effect of TNF-α on production of nitric oxide (NO) and activity of nitric oxide synthase(eNOS) in human umbilical vein endothelial cells(HUVECs). Methods HUVECs were incubated with TNF-α at different concentrations (2-20ng/ml) and different times(2-48h) or pretreatment with L-NMMA or DXM. Nitric oxide production and activity of nitric oxide synthase in HUVECs were measured by NO and NOS assay kits. Results (1) Activity of eNOS was down-regulated by TNF-α in a concentration-dependent manner, while production of NO was upregulated. (2) The activity of eNOS attenuated after long-time treatment with TNF-α, but marked increased production of NO was detected after 24h. (3) The induction of NO by TNF-α can be inhibited by L-NMMA and DXM. Conclusion TNF-α can reduce activity of eNOS and induce iNOS, so that production of NO is increased.