Effects of hypoxia on levels of nitric oxide, endothelin-1 and inducible nitric oxide synthase mRNA expression in cultured human umbilical vein endothelial cells

AIM: To observe the effects of hypoxia on the levels of nitric oxide (NO), endothelin (ET-1) and the expression of inducible nitric oxide synthase (iNOS) mRNA in human umbilical vein endothelial cells (HUVECs), and further investigate the mechanism of hypoxic pulmonary hypertension. METHODS: On the basis of the HUVECs culture model, the methods of nitrate reductase and radioimmunoassay were used to determine the changes of NO and ET-1 in the medium secreted by HUVECs, and the expression of iNOS mRNA was analyzed by semi quantitative RT-PCR after exposure to hypoxia (3% O_2) for 6, 12 or 24 h. RESULTS: The contents of NO_2-/NO_3-and ET-1 in hypoxia group in the medium was significantly higher than that in control group at different time points (P0.05). Also, iNOS mRNA expression increased significantly (P0.05). CONCLUSION: Hypoxia stimulates the release of NO and ET-1 from HUVECs, also induces iNOS-mRNA expression. The change of NO may be the result of iNOS mRNA upregulation induced by hypoxia.