A role for the angiotensin IV/AT(4) system in mediating natriuresis in therat

Angiotensin II (AngII) or Angiotensin IV (AngIV) was infused into the renal artery of anesthetized rats while renal cortical blood flow was measured v ia laser Doppler flowmetry. The infusion of AngII produced a significant el evation in mean arterial pressure (MAP) with an accompanying decrease in co rtical blood flow, glomerular filtration rate (GFR), urine volume, and urin e sodium excretion. The infusion of AngIV induced significant increases in renal cortical blood flow and urine sodium excretion, without altering MAP, GFR, and urine volume. Pretreatment infusion with a specific AT. receptor antagonist, DuP 753, blocked or attenuated the subsequent AngII effects, wh ile pretreatment infusion with the specific AT, receptor antagonist, divali nal-AngIV, blocked the AngIV effects. These results support distinct and op posite roles for AngII and AngIV, i.e. AngII acts: as an anti-natriuretic a gent, while AngIV acts as a natriuretic agent. (C) 2001 Elsevier Science In c. All rights reserved.