RENAL-FUNCTION IN ONE-KIDNEY, ONE-CLIP SODIUM-RESTRICTED RATS - INFLUENCE OF ENALAPRIL AND LOSARTAN

Background: Some observations have suggested that the harmful renal ef fects of angiotensin converting enzyme inhibitors might be partly medi ated by non-angiotensin mechanisms under conditions in which a high in traglomerular pressure is required to maintain the glomerular filtrati on rate. Materials and methods: The effects of enalapril and losartan (10 and 30 mg/kg per 24 h for 6 days, respectively) on arterial pressu re and renal function were assessed in one-kidney, one clip hypertensi ve rats subjected to dietary sodium depletion before treatment. Result s: Arterial pressure and renal vascular resistance were reduced to a s imilar extent in rats treated with enalapril and with losartan. Howeve r, the glomerular filtration rate (867 +/- 40 mu l/min per g kidney we ight in untreated rats) decreased to a greater extent in enalapril tha n in losartan-treated rats (284 +/- 29 and 444 +/- 32 mu l/min per g k idney weight, respectively). In addition, the filtration fraction was reduced in treated compared with untreated rats; however, it was sligh tly but significantly lower in enalapril- than in losartan-treated rat s. Conclusions: Despite similar final arterial pressure and renal vaso dilation, angiotensin converting enzyme inhibitors may exert an effect on intrarenal forces contributing to the regulation of glomerular fil tration rate, independently of blockade of the renin-angiotensin syste m.