Effect of chronic antioxidant therapy with superoxide dismutase-mimetic drug, tempol, on progression of renal disease in rats with renal mass reduction.

Oxidative stress and inflammation play a major role in the progression of renal damage and antioxidants are potentially useful therapeutic options in chronic renal disease. We investigated if treatment with tempol, a superoxide dismutase mimetic that has beneficial effects in several experimental models of hypertension and acute kidney injury, ameliorates the chronic renal damage resulting in renal mass reduction. Rats with surgical 5/6 nephrectomy were randomly assigned to receive no treatment (CRF group, n = 10) or tempol, 1 mmol/l in the drinking water (CRF-tempol group, n = 10). Sham-operated rats (n = 10) served as controls. All rats were followed for 12 weeks post-nephrectomy. Tempol treatment reduced plasma malondialdehyde (MDA) levels and halved the number of superoxide-positive cells in the remnant kidney; however, the number of hydrogen peroxide-positive cells increased and the overall renal oxidative stress (MDA and nitrotyrosine abundance) and inflammation (interstitial p65 NF-kappaB, macrophage and lymphocyte infiltration) were unchanged. Proteinuria, renal function and glomerular and tubulointerstitial damage in the remnant kidney were similar in the CRF and CRF-tempol groups. In conclusion, tempol administration, at the dose used in these studies, decreased plasma MDA and heightened superoxide dismutation in the kidney, but was incapable of reducing renal oxidative stress or improving renal function or structure in the remnant kidney model.