PRESSOR ACTION OF ANGIOTENSIN-I AT THE VENTROLATERAL MEDULLA - EFFECTOF SELECTIVE ANGIOTENSIN BLOCKADE

In this study we explored the possibility that angiotensin-(1-7) (Ang- (1-7)) is involved in the control of blood pressure at the rostral ven trolateral medulla (RVLM) by determining the effect of angiotensin ant agonists (DuP 753 and A-779) and the effect of the angiotensin convert ing enzyme inhibitor, ramiprilat on the presser action produced by ang iorensin I (Ang I). The presser effect produced by bilateral microinje ction of Ang I into the RVLM of anesthetized rats was not significantl y altered by DuP 753 or by the ACE inhibitor ramiprilat. Conversely, t he Ang-(1-7) antagonist, A-779, reduced significantly the presser effe ct produced by Ang I. These data suggest that in our experimental cond ition Ang I was preferentially converted to Ang-(1-7) at RVLM, or that Ang I and/or one of its fragments acts through a receptor blocked by A-779.