A Nitric Oxide-Generating Beta-Blocking Agent Prevents Renal Injury in the Rat Remnant Kidney Model

<i>Background:</i> The <i>L-</i>arginine-nitric oxide (NO) pathway plays an important role in the modulation of glomerular disease. We investigated whether β-blocking agents, with and without an NO-generating function, had renoprotective effects in the 5/6 nephrectomized rats (Nx), an animal model of glomerulosclerosis. <i>Methods:</i> Nipradilol, a β-blocker with an ONO₂ group (5, 10 or 15 mg/kg/day) and propranolol, a β-blocker without this group (50 mg/kg/day) were administered for 12 weeks to Nx together with and without nitro-<i>L</i>-arginine methyl ester (L-NAME). We evaluated the effects of both drugs on proteinuria, hypertension, renal function, glomerulosclerosis and urinary excretion of NO metabolites (U_NOx) and cyclic GMP (U_cGMP). <i>Results:</i> Both drugs similarly attenuated the elevated blood pressure in Nx. However, nipradilol, at doses of 10 and 15 mg/kg/day, significantly decreased proteinuria and glomerulosclerosis, while propranolol did not. Nx showed reduced U_NOx in comparison with the sham-operated rats. Nipradilol increased U_NOx and U_cGMP significantly and in a dose- dependent manner, whereas propranolol reduced them to levels lower than those in Nx. Nx receiving L-NAME reduced U_NOx. The addition of nipradilol increased U_NOx and decreased urinary protein excretion and glomerulosclerosis, suggesting that the NO released from the drug contributed to its renoprotective effect. <i>Conclusion:</i> These findings indicate that nipradilol exerts its renoprotective effect through NO generation, and not by lowering blood pressure. The β-adrenergic blocking action per se does not seem to be related to the renoprotective effect of these agents.