useful for AIPGMEE 2016 1 With unilateral ureteral obstruction, renal blood flow increases during the first 1 to 2 hours. It begins to decrease at 3 to 4 hours and markedly declines after 5 hours of obstruction. 2 The increase in renal blood flow in unilateral ureteral obstruction is a result of relaxation of afferent arterials in which PGE2 and nitrous oxide play a role. 3 Reduction in whole-kidney GFR after prolonged obstruction is due to afferent arteriolar vaso-constriction mediated by the renin-angiotensin system.
Thus angiotensin II is an important mediator of reduced renal blood flow in the second and third phases of ureteral obstruction. Moreover, thromboxane A2 may also contribute. 4 In bilateral ureteral obstruction, there is a modest increase in renal blood flow lasting approximately 2 hours, followed by a profound decline in renal blood flow. 5 In unilateral…
