Abstract: AIM: To investigate the effects of angiotensin Ⅱ (Ang Ⅱ) and valsartan on the expression of Ang Ⅱ type 1 receptor (AT₁), Ang Ⅱ type 2 receptor (AT₂) and endothelial nitric oxide synthase (eNOS) and the synthesis of nitric oxide (NO) in human umbilical vein endothelial cells (HUVECs, ECV304 cells).METHODS: Human umbilical vein endothelial cells (HUVECs) were incubated by Ang Ⅱ or valsartan for various periods. The expression of AT₁/AT₂, eNOS and the production of NO were detected. Potential mechanism of the above effects was explored by using the relevant inhibitors of the signal molecules and antioxidants.RESULTS: Both Ang Ⅱ and valsartan significantly inhibited the mRNA and the protein expression of AT₁in HUVECs. The combination of the two drugs caused more significantly inhibitory effects. Ang Ⅱ showed a slightly promotive effect at first and a significantly inhibitory effect afterward on the expression of eNOS and synthesis of NO in HUVECs. MAPK inhibitor reversed the promotive effect whereas valsartan and antioxidant vitamine C significantly reversed the inhibitory effect.CONCLUSION: Valsartan can downregulate the expression of AT₁in HUVECs. Long time action of Ang Ⅱ can significantly inhibit the expression of eNOS and synthesis of NO in endothelial cells, while valsartan can significantly reverse this inhibitory effect.

Key words: angiotensin Ⅱ, valsartan, endothelial cells, receptor, endothelial nitric oxide synthase