The Role Of Reactive Oxygen Species In Hypertensive Renal Injury Of NO-deficient Rat

Background and objectives: Chronic administration with inhibitor of nitric oxide synthase (N(-nitro-L-arginine methyl easter, L-NAME) induces persistent high biood pressure with renal injury, characterized with hypertension, proteinuria, glomerulosclerosis, tubulointersitial fibrosis and inflammation in renal vascular kidney. It was demonstrated that local rennin-angiotensin system (RAS) involve in hypertension and renal injury, which may via increasing production of reactive oxygen species (ROS). This study was designed to investigate the effects of Ebselen, a kind of anti-oxidative drug, on NO-deficient rats. Then we probe to the role of ROS in hypertensive renal injury of NO-deficient rats. Methods: 24 Wistar rats were randomly divided to three groups: C group (Control group), L group (L-NAME 50mg/kg/d), L+E group (L-NAME 50mg/kg/d +Ebselen 30mg/kg/d). We weighed the rats and measured their Systolic blood pressure (SBP) with tail-cuff method every other week. After 8-week-breeding, the rats were killed and blood was collected. The levels of NO, Angiotensin-Convertin(ACE), Angotensin II (AngⅡ), superoxide dismutase (SOD), malondialdehyde (MDA) in plasma and renal cortex were measured. The production of superoxide anion(O2-.) and the levels of AT1 receptor, monocyte chemoattractant protein(MCP-1)expression in renal cortex were determined. Left kidney were processed morphology analysis. Results: (1) L group presented a time-dependent elevation of SBP (124.6±17.4 mmHg, 153.7±16.8 mmHg , 163.0±21.6 mmHg, 169.8±15.1 mmHg, 175.0±12.6 mmHg, 185.0±16.0 mmHg at end of 0, 1, 2, 4, 6, 8 week respectively)compared to Control group at the same time after 1 week (P<0.01). Ebselen did not affect the blood pressure during the early period. But an obviously decrease of blood pressure was deserved at the end of 8th week (P<0.05). (2) L group showed a significantly decreased level of NOx in plasma(16.2±2.56(mol/L vs. 34.25 ± 3.51 (mol/L,P<0.01)and renal cortex(0.42 ±0.17(mol/g prot vs. 1.12±0.25(mol/g prot,P<0.05). NOx levels in plasma and renal cortex were also significant different between L+E and L group (P<0.05).(3) The O2-. production in renal cortex of L group significantly increased (5.82 ±0.42nmol/mg/min in L group vs. 1.35± 0.27 nmol/mg/min in C group, P<0.01). Ebselen prevented the increase(3.12± 0.22 nmol/mg/min in L+E group, P<0.05).(4) The levels of MDA in plasma were higher in L group than Control group.(10.83±1.56 nmol/ml vs. 6.12±1.04nmol/ml,P<0.01).But there was no significant difference between L+E group and L group. The levels of MDA in renal cortex showed a increase in L group.(17.6±1.24nmol/mg prot vs. 6.1±0.52nmol/mg prot,P<0.01). L+E group presented a decreased MDA levels(9.8 ±0.79 nmol/ml)compared to L group. (5) The activity of SOD decreased in plasma of L group,(142.07 ±17.08 U/mg vs. 256.23 ±14.36 U/mg in C group,P<0.01)and Ebselen prevented this decrease(205.32 ±20.14 U/mg in L+E group, P<0.05). A similar alters appeared in renal cortex: The activity of SOD decreased in L group.(186.47 ±21.34U/mg vs. 315.23 ± 25.13 U/mg,P<0.01) and Ebselen prevented its decrease(256.31±18.75 U/mg in L+E group, P<0.05)(6) The concentration of AngⅡin plasma showed no significantly difference among 3 groups respectively.( C group 20.23±7.98 pg/ml, L group 25.68 ±5.32 pg/ml, L+E group 24.08±4.87 pg/ml, P> 0.05)；The levels of Ang II showed an significantly increase in L group compared to C group(96.2±18.3pg/mg prot vs. 45.3± 14.6pg/mg prot , p<0.01 ) and Ebselen prevented this kind of increase in renal cortex. ( L+E group 68.5±12.7 pg/mg prot , P<0.05).(7) A decrease of the activity of ACE was observed in plasma of L and L+E group.(C group 41.2 ± 14.36 nmol/U/min/ml vs. L group 25.89 ± 8.65 nmol/U/ min/ml, and L+E group 25.36 ± 5.36 nmol/U/min/ml, P<0.01)；The ACE activity was increased in renal cortex of L group (34.12±3.71 nmol/U/min/ml vs. C group 18.40±2.65 nmol/U/min/ml, P<0.05)and it was attenuated by Ebselen (24.28±2...