Abstract: Objective To explore the effect of Suramin on Cyclosporine A(CsA)-induced nephrotoxicity in rats and the relevant mechanism.Methods Forty male SD rats were randomly divided into control group,CsA group,CsA+Suramin(low dose) group and CsA+Suramin(high dose)group,with 10 rats in each group.After 5 weeks of administration,24h urine protein,α₁-microglobulin(MG),β₂-MG,N-acetyl-β-D-glucosaminidase(NAG),serum creatinine(SCr),blood urea nitrogen(BUN),uric acid(UA) and cystatin C（Cys C） in 4 groups were detected.The values of creatinine clearance(Ccr) were calculated.Masson trichrome staining was performed to estimate the degree of interstitial fibrosis.The expression of transform growth factor（TGF）-β₁，collagen-Ⅰand fibronectin were determined qualitatively by immunohistochemistry.The corresponding values of average optical density(AOD) of the above indicators were determined.Results The levels of α₁-MG,β₂-MG,NAG,BUN,UA and Cys C in CsA group were higher than those in control group,while the level of Ccr was lower than that in control group（P<0.05）.The levels of α₁-MG,β₂-MG,NAG,BUN,UA and Cys C in CsA+Suramin(low dose) group and CsA+Suramin(high dose)group were lower than that in CsA group,the level of Ccr was higher than that in CsA group（P<0.05）.The degree of interstitial fibrosis and the AOD of TGF-β₁，collagen-Ⅰ，fibronectin in CsA group were higher than those in control group,while the above indicators in CsA+Suramin(low dose) group and CsA+Suramin(high dose)group were lower than those in CsA group（P<0.05）.ConclusionSuramin may probably antagonize the nephrotoxicity induced by CsA.Down regulated expression of TGF-β₁ may probably associated with the mechanism of interstitial fibrosis.

Key words: Cyclosporine A, Suramin, Nephrotoxicity