Role of ADMA-DDAH axis in the vascular endothelial dysfunction induced by uric acid / 中华肾脏病杂志

ABSTRACT

Objective To observe the formation of asymmetric dimethylarginine (ADMA)and the expression of dimethylarginine dimethylaminohydrolase 2 (DDAH-2) of human umbilical vein endothelial cells (HUVECs) stimulated by uric acid (UA), and to explore the role of ADMADDAH axis in the vascular endothelial dysfunction induced by uric acid. Methods HUVECs were cultured in M199 medium supplemented with 10% FBS. Cells were exposed to different concentrations of UA (0, 60, 120 mg/L) for 6 h and 24 h. Under different concentrations and times, the level of ADMA in cell suspension was detected by high performance liquid chromatography (HPLC) technique; the gene and protein expressions of DDAH-2 were detected by RT-PCR and Western blotting; the fluorescence intensity of intracellular 2',7'-dichlorofluorescein (DCF) which represented the productions of ROS was detected by the flow cytometry (FCM). The activity of DDAH-2 in HUVCEs which were exposed to different concentrations of UA (0, 60, 120mg/L) or UA (120 mg/L) +NAC (10 mmol/L) for 24 h was estimated by directly measuring the amount of ADMA metabolized by the enzyme and the role of NAC in the activity was studied.Results The expression of ADMA induced by urid acid was dose-depent and higher at 24 h than that at 6 h in the same dosage (all P＜0.05). The dosage and stimulation time of UA did not have any influence on the expression of intracellular DDAH-2 (all P＞0.05). When HUVECs exposed to UA (120 mg/L) for 24 h, the production of intracellular ROS was significantly increased while the activity of DDAH-2 was decreasesd (all P＜0.05) as compared to 60 mg/L stimulation. This effect could be inhibited by the intervention of anti-oxidant NAC. Conclusions The high UA stimulation on HUVECs can increase the expression of intracellular ROS and inhibit the activity of DDAH-2 which increases the concentration of ADMA by decreasing the degradation of ADMA as well as the formation of NO. DDAH-ADMA axis may participate in the vascular endothelial dysfunction induced by UA.