Protective effect of SM-19712, a novel and potent endothelin converting enzyme inhibitor, on ischemic acute renal failure in rats

Effects of SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-y l)amino] carbonyl] benzenesulfonamide, monosodium salt), a novel endothelin converting enzyme (ECE) inhibitor, on ischemic acute renal failure (ARF) i n rats were examined in comparison with those of phosphoramidon, a conventi onal ECE inhibitor. ARF was induced by occlusion of the left renal artery a nd vein for 45 min followed by reperfusion, 2 weeks after contralateral nep hrectomy. Renal function in ARF rats markedly decreased at 24 h after reper fusion. Intravenous bolus injection of SM-19712 (3, 10, 30 mg/kg) prior to the occlusion attenuated dose-dependently the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of ARF rats revealed severe renal damages such as tubular necrosis, proteinaceous casts in tubuli and medullary congestion, all of which were dose-dependently att enuated by SM-19712. Protective effects of phosphoramidon (10 mg/kg) on ARF -induced functional and tissue damages were less potent than that of the sa me dose of SM-19712. Endothelin-l (ET-I) content in the kidney after the is chemia/reperfusion was significantly increased, being the maximum level at 6 h after reperfusion, and this elevation was completely suppressed by the higher dose of SM-19712. Our findings support the view that renal ET-1 play s an important role in the development of ischemia/reperfusion-induced rena l injury. SM-19712 may be useful in the treatment of ischemic ARF.