Suramin enhances the urinary excretion of VEGF-A in normoglycemic and streptozotocin-induced diabetic rats

BACKGROUND: Vascular endothelial growth factor A (VEGF-A) and P2-receptors (P2Rs) are involved in the pathogenesis of diabetic nephropathy. The processing of VEGF-A by matrix metalloproteinases (MMP) regulates its bioavailability. Since the ATP-induced release of MMP-9 is mediated by P2Rs, we investigated the effect of suramin on VEGF-A excretion in urine and the urinary activity of total MMP and MMP-9. METHODS: The effect of suramin (10 mg/kg, ip) on VEGF-A concentration in serum and its excretion in urine was investigated in streptozotocin (STZ)-induced diabetic rats over a 21-day period. The rats received suramin 7 and 14 days after a single STZ injection (65 mg/kg, ip). A 24-h collection of urine was performed on the day preceding the administration of STZ and the first administration of suramin and on the day before the end of the experiment. The VEGF-A in serum and urine, albumin in urine, and total activity of MMP and MMP-9 in urine were measured using immunoassays. RESULTS: Diabetic rats are characterized by a sixfold higher urinary excretion of VEGF-A. Suramin potentiates VEGF-A urinary excretion by 36% (p = 0.046) in non-diabetic and by 75% (p = 0.0322) in diabetic rats but it did not affect VEGF-A concentration in the serum of non-diabetic and diabetic rats. Urinary albumin excretion as well as total MMP and MMP-9 activity was increased in diabetic rats, but these parameters were not affected by suramin. CONCLUSION: Suramin increases the urinary excretion of VEGF-A in normoglycemia and hyperglycaemia, possibly without the involvement of MMP-9. Suramin may be used as a pharmacological tool enhancing VEGF-A urinary secretion.