To test this hypothesis, losartan as a selective antagonist of angiotensin-II (Ang-II) type-1 (AT1) receptor is used in this study since it is well-known that Ang-II,14-16 through its AT1-receptor increases renal arteriolar constriction to reduce RBF and GFR in ureteral obstruction.7,17 Consequently, the present study was designed to investigate the effects of losartan alone and combined with a-tocopherol on changes in haemodynamics, solutes excretion, urine-concentrating ability, acid-base excretion and oxidative balance at the early hours following release of 24-h UUO in both POK and NOK. Here, AGTR1 is linked to Ureteral obstruction.