REN and ischemia: It is well documented that acute UUO is followed by a prompt renal vasodilatation that turns into a persistent vasoconstriction whithin 24 hours.[4–6] The ensuing ischemia is associated with the progressive development of tubular atrophy and interstitial fibrosis that are a proved effect of increased AII release resulting from enhanced Renin production.[2,3] In addition, recent studies have shown that Renin has a fibrogenic effect that is independent of its enzymatic release of AII.