Effect of a Specific Endothelin Receptor A Antagonist on mRNA Levels for Extracellular Matrix Components and Growth Factors in Diabetic Glomeruli

We have previously reported that the mRNA levels of extracellular matrix (ECM) components including αl(I), αl(III), and αl(IV) collagen chains, laminin Bl and B2 chains, and growth factors including tumor necrosis factor (TNF)-α, platelet-derived growth factor (PDGF)-B chain, transforming growth factor (TGF)-β, and basic fibroblast growth factor (FGF) all increase with age in diabetic glomeruli. The present study was designed to assess whether glomerular expression of these mRNAs in rat diabetic glomeruli is affected by a specific endothelin receptor A antagonist, FR139317. Diabetes was produced by streptozotocin injection, and animals were divided into four groups: untreated diabetic rats, FR139317-treated diabetic rats, control nondiabetic rats, and FR139317-treated control rats. FR139317 treatment was continued for 24 weeks. FR139317 attenuated the rise in creatinine clearance (P < 0.01) and reduced urinary protein excretion (P < 0.01) in diabetic rats, but did not affect blood pressure. FR139317 attenuated the increases in glomerular mRNA levels of αl(I) (P < 0.01), α1(III) (P < 0.01), and α1(IV) (P < 0.01) collagen chains, laminin B1 (P < 0.01) and B2 (P < 0.01) chains, TNF-α (P < 0.01), PDGF-B (P < 0.01), TGF-β (P < 0.001) and basic FGF (P < 0.01) in diabetic rats. However, FR139317 did not affect these mRNA levels in glomeruli of control rats. These findings suggest that FR139317 may be useful in the treatment of diabetic glomerulopathy by reducing mRNA levels of ECM components and growth factors.