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AND FIBRONECTIN WITH CONCOMITANT INCREASE IN NITRIC OXIDE BIOAVAILABILITY
1 Nephrology-Hypertension Section, VA Medical Center and Division of Nephrology and Hypertension and Vascular Biology, University of Miami Miller School of Medicine, Miami, Florida, United States
* To whom correspondence should be addressed. E-mail: MZhou2{at}med.miami.edu.
Clinical and experimental studies have provided evidence suggesting that statins exert renoprotective effects. To investigate the mechanisms by which statins may exert renoprotection, we utilized the hypertensive Dahl salt-sensitive (DS) rat model, which manifests cardiovascular and renal injury linked to increased angiotensin II-dependent activation of NADPH oxidase and decreased nitric oxide (NO) bioavailability. DS rats given high salt diet (4% NaCl) for 10 weeks exhibited hypertension (SBP 200±8 vs. 150±2 mmHg in normal salt diet (0.5% NaCl), P<0.05), glomerulosclerosis, and proteinuria (158%). This was associated with increased renal oxidative stress demonstrated by urinary 8-F2a-isoprostane excretion and NADPH oxidase activity, increased protein expression of transforming growth factor (TGF)-
(63%) and fibronectin (181%), increased mRNA expression of the proinflammatory molecules monocyte chemoattractant protein-1 (MCP-1) and lectin-like oxidized LDL receptor-1 (LOX-1), as well as downregulation of calcium-dependent NO synthase (cNOS) activity (-44%) and NOS3 protein expression. Return to normal salt had no effect on SBP or any of the measured parameters. Atorvastatin (30 mg/kg/day) significantly attenuated proteinuria (-46%) and glomerulosclerosis and normalized renal oxidative stress, TGF-
1, fibronectin, MCP-1 and LOX-1 expression, and NOS activity and expression. Atorvastatin treated rats showed a modest reduction in SBP that remained in the hypertensive range (174±8 mmHg). Atorvastatin combined with removal of high salt normalized SBP and proteinuria. These findings suggest that statins mitigate hypertensive renal injury by restoring the balance among NO, TGF-
1, and oxidative stress and explain the added renoprotective effects observed in clinical studies using statins in addition to inhibitors of the renin-angiotensin system.
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