title: Effects of long-term losartan and L-arginine treatment on haemodynamics, glomerular filtration, and SOD activity in spontaneously hypertensive rats.
abstract: Recently, it has been reported that losartan, an angiotensin II receptor (ATR) antagonist, depresses the angiotensin II-induced production of superoxide radicals. Also, in spontaneously hypertensive rats (SHR) endothelial dysfunction is associated with decreased nitric oxide (NO) synthesis. In this study, we examined the effects of long-term ATR blockade and L-arginine supplementation on the haemodynamic parameters, glomerular filtration, and oxidative status in SHR. Adult male SHR were treated with losartan (10 mg/kg) and with the NO donor L-arginine (2 g/kg) for 4 weeks. The animals were divided into the following experimental groups: control (n = 7), L-arginine (n = 7), losartan (n = 7), and L-arginine + losartan (n = 7). Mean arterial pressure (MAP), regional blood flow, urea clearance, and activity of superoxide dismutase (SOD) were measured at the end of treatment. MAP was significantly reduced in the losartan group compared with the control group (133.3 +/- 7.3 vs. 161.5 +/- 14.5 mm Hg). Aortic blood flow was significantly higher and aortic vascular resistance was significantly lower in all treated groups than in the control. Urea clearance rose significantly in the L-arginine + losartan group compared with control (393.27 +/- 37.58 vs. 218.68 +/- 42.03 microL x min(-1) x 100 g(-1)) as did the activity of SOD (1668.97 +/- 244.57 vs. 1083.18 +/- 169.96 U/g Hb). Our results suggest that the antihypertensive effect of losartan and L-arginine in SHR is not primarily mediated by increased SOD activity. Also, combined treatment with ATR blockade and L-arginine supplementation has a beneficial effect on renal function that is, at least in part, mediated by increased SOD activity in SHR.
authors.affiliation: Institute for Medical Research, Dr Subotića 4, P.O. Box 102, Belgrade11129, Serbia.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Miloradović
authors.forename: Durdica
authors.initials: D
authors.lastname: Jovović
authors.forename: Nevena
authors.initials: N
authors.lastname: Mihailović-Stanojević
authors.forename: Jelica Grujić
authors.initials: JG
authors.lastname: Milanović
authors.forename: Sladan
authors.initials: S
authors.lastname: Milanović
mesh_terms: D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001012:Aorta, Abdominal / Q000187:drug effects / Q000503:physiopathology; D001120:Arginine / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries / Q000187:drug effects / Q000503:physiopathology; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D006973:Hypertension / Q000188:drug therapy* / Q000201:enzymology / Q000503:physiopathology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D019808:Losartan / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D020030:Nitric Oxide Donors / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D011918:Rats, Inbred SHR; D012039:Regional Blood Flow / Q000187:drug effects; D012077:Renal Artery / Q000187:drug effects / Q000503:physiopathology; D012079:Renal Circulation / Q000187:drug effects; D013482:Superoxide Dismutase / Q000097:blood*; D013997:Time Factors; D014508:Urea / Q000652:urine; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents; D020030:Nitric Oxide Donors; D014508:Urea; D001120:Arginine; D013482:Superoxide Dismutase; D019808:Losartan