Comparison of enalapril and valsartan in cyclosporine A-induced hypertension and nephrotoxicity in spontaneously hypertensive rats on high-sodium diet

1 We compared the effects of the angiotensin converting enzyme (ACE) inhibi tor enalapril and the angiotensin AT(1) receptor antagonist valsartan in cy closporine A (CsA)-induced hypertension and nephrotoxicity in spontaneously hypertensive rats (SHR). 2 SHR (8-9 weeks old) on high-sodium diet were given CsA (5 mg kg(-1)d(-1) s.c.) for 6 weeks. The rats were treated concomitantly either with enalapri l (30 mg kg(-1)d(-1) p.o.) or valsartan (3 or 30 mg kg(-1) d(-1) p.o.). To evaluate the role of bradykinin in the action of enalapril, some rats recei ved a bradykinin B-2 receptor antagonist icatibant (HOE 140, 500 mu g kg(-1 ) d(-1) s.c.) during the last 2 weeks of enalapril treatment. 3 Blood pressure was recorded every second week by tail cuff method. Renal function was measured by serum creatinine, creatinine clearance and urinary excretion of proteins at the end of the experiment. The activity of the re nal kallikrein-kinin system was estimated by urinary kallikrein excretion. 4 CsA caused hypertension, impaired renal function and induced morphologica l nephrotoxicity with glomerular damage and interstitial fibrosis. 5 Enalapril and the lower dose of valsartan attenuated the CsA-induced hype rtension to the same extent, while the higher dose of valsartan totally abo lished it. Icatibant did not reduce the antihypertensive effect of enalapri l. Urinary kallikrein excretion was similar in all groups. Enalapril and va lsartan equally prevented the CsA-induced deterioration of kidney function and morphology. 6 The renin-angiotensin but not the kallikrein-kinin system plays a crucial role in CsA-toxicity during high intake of sodium in SHR.