AQP2 and Ureteral obstruction: Reportedly, angiotensin-converting enzyme inhibitors (ACEIs) or Ang II type 1 receptor blockers (ARBs) partly prevent the reduction in GFR and RBF (Frokiaer et al., 1996a) and improve the expression and intracellular trafficking of renal AQP2 and several key sodium transporters in ureteral obstruction (Jensen et al., 2006, 2009; Topcu et al., 2007), indicating that Ang II contributes to the urinary concentrating defect of obstructed kidneys.