Study On The Metabolic Mechanism Of Asymmetrical Dimethylarginine In Impaired Vascular Endothelial Cells Under Oxidative Stress Condition And The Role Of Carvedilol And Captopril

Objective: To investigate the metabolic mechanism of asymmetrical dimethylarginine in the impaired vascular endothelial cell under oxidative stress condition and the role of carvedilol and captopril.Methods: Cultured HUVECs of 3～6th passages were cultured with OFR(0.1mmol/L) and ox-LDL(100mg/L). Both of them were divided into four groups as follows: OFR-conditioned groups intervented with drugs: (1)control group, (2)OFR group,(3)OFR+captopril group(Cap100mg/L),(4)OFR+ carvedi- lol group(CV10μmol/L); ox-LDL-conditioned groups intervented with drugs: (1)control group,(2)ox-LDL group,(3)ox-LDL+captopril group(Cap100mg/L), (4)ox-LDL+carvedilol group(CV10μmol/L). Conditioned medium was collected to detect the concentrations of nitric oxide(NO),L-citrulline and asymmetric dimethylarginine (ADMA) and the activity of nitric oxide synthase(NOS),the expression of dimethylarginine dimethylaminohydrolase(DDAH) was measured by western blotting. Results: (1) Compared with control: the contents of ADMA in medium of cultured HUVECs induced by OFR and ox-LDL were increased significantly in both groups (2.68±0.13 vs 1.06±0.21μmol/L,P<0.01),(2.65±0.12 vs 0.93± 0.09μmol/L,P<0.01); the levels of NO were decreased,OFR group(61.48±2.06 vs 81.36±1.98μmol/L,P<0.01),ox-LDL group(70.12±0.43 vs 80.01±0.56μmol/L, P<0.01); the activity of nitric oxide synthase(NOS) was decreased,OFR group (0.51 ±0.02 vs 0.7±0.03U/ml,P<0.01),ox-LDL group(0.53±0.08 vs 0.71± 0.06U/ml,P<0.01); the concentrations of L-cit were also decreased,OFR group(58.26±1.33 vs 102.42±1.15μmol/L,P<0.01), ox-LDL group (51.26 ± 0.79 vs 102.31 ± 0.87μmol/L,P<0.01); but in both groups the expression of DDAH was different.(2) After interfered with carvedilol or captopril: the levels of NO, the activity of NOS and the concentration of L-cit were increased in OFR-conditioned . the content of ADMA was decreased as follows:(1.99±0.18 vs 2.68±0.13μmol/L,P<0.01),(1.89±0.15 vs 2.68± 0.13μmol/L,P<0.01); There was no statistical significance in the expression of DDAH. The similar results were also showed in ox-LDL-conditioned groups intervented with drugs.Conclusion: (1)The increase of the activity of DDAH is involved in ADMA upregulation in oxidative stress impairment to vascular endothelial cell, but not the expression of DDAH. (2) Both carvedilol and captopril can reduce the level of ADMA by increasing the activity of DDAH to protect vascular endothelial function.