The Effects Of Uric Acid On NOS-NO Pathway And ADMA-DDAH System Of Cultured Human Umbilical Vascular Endothelial Cells

Objective:To investigate the effects of uric acid (UA)on NOS-NO Pathway and ADMA-DDAH System of cultured human umbilical vascular endothelial cells.Methods: According to UA concentrations ,cultured HUVECs of 3-6th passage were exposed to uric acid for 24 hour and divided into four groups :control,UA200(UA2), UA400(UA4), UA600(UA6)μmol/L groups, then HUVECs were cultured with uric acid (600μmol/L ) for1,3,5, 7 day. The cellular cultured medium were collected for detecting the concentrations of nitric oxide (NO),L-citrulline(L-cit),asymmetric dimethylarginine (ADMA),angiotensinⅡ(AngII), superoxide dismutase (SOD) and the activity of NO synthase(NOS), the lysis for measuring expression of dimethylarginine dimethylaminohydrolase (DDAH).ADMA was measured by high performance liquid chromatography (HPLC) and DDAH by Western blotting. Results:1.Compered to the control group, the concentrations of NO in UA2, UA4,UA6 groups were increased significantly (15.70±2.29,44.00±5.39,55.56±7.354.7 vs 4±1.22 μmol/L,P<0.01).The activity of NOS(3.79±0.49,4.58±0.67 vs 2.11±0.33U/L,P<0.05),DDAH(L-cit 156.78±4.56,160.78±4.89 vs 102.56±2.32μmol/L,P<0.05) in UA4,UA6 groups were elevated.But the concentrations of ADMA were decreased(0.62±0.042,0. 58±0.046 vs 0.93±0.048μmol/L,P<0.05) and Ang II had no significant change. Nevertheless uric acid had no effects on DDAH expression in different concentrations.The activity of SOD(34.07±3.65,42.07±4.33 vs 22.85±2.71U/L ,P<0.05) were increased in UA4,UA6 groups 2.When HUVECs were exposed to uric acid(600μmol/L) at 1,3,5,7day,compered to the control group, the concentrations of NO(P<0.01),L-citrulline (P<0.05) were increased and the activity of NOS(P<0.05) were elevated in cultured medium. Nevertheless the concentrations of ADMA were reduced(P<0.05),the concentrations AngII and the expression DDAH had no change. But all they had no discrepancy at 1,3,5,7 days except the activity of NOS were decreased at 7 day. Conclusion:1.Uric acid increased the concentrations of NO released from HUVECs in concentration- dependently fasion and non-time-dependently fasion.2.Uric acid increased the concentrations NO via elevating the activity of DDAH and increasing the degradation of NOS competively inhibitor ADMA.3. Uric acid didn't increase the concentrations of Ang II.4.Uric acid can increase the activity of SOD.