Renal function in one-kidney, one clip sodium-restricted rats: influence of enalapril and losartan

Background : Some observations have suggested that the harmful renal effects of angiotensin converting enzyme inhibitors might be partly mediated by non-angiotensin mechanisms under conditions in which a high intraglomerular pressure is required to maintain the glomerular filtration rate. Materials and methods : The effects of enalapril and losartan (10 and 30 mg/kg per 24 h for 6 days, respectively) on arterial pressure and renal function were assessed in one-kidney, one clip hypertensive rats subjected to dietary sodium depletion before treatment. Results : Arterial pressure and renal vascular resistance were reduced to a similar extent in rats treated with enalapril and with losartan. However, the glomerular filtration rate (867±40 μl/min per g kidney weight in untreated rats) decreased to a greater extent in enalapril than in losartan-treated rats (284±29 and 444±32 μl/min per g kidney weight, respectively). In addition, the filtration fraction was reduced in treated compared with untreated rats ; however, it was slightly but significantly lower in enalapril- than in losartan-treated rats. Conclusions : Despite similar final arterial pressure and renal vasodilation, angiotensin converting enzyme inhibitors may exert an effect on intrarenal forces contributing to the regulation of glomerular filtration rate, independently of blockade of the renin-angiotensin system.