Angotensin II Type 2 Receptors Participate in Reducing Blood Pressure During Angiotensin II Type 1 Receptor Blockade But Do not Affect Cardiovascular Mass and Coronary Hemodynamics

Abstract

P7 This study was designed to determine the role of AT 2 receptors in the beneficial cardiovascular effects of chronic AT 1 antagonism in spontaneously hypertensive rats (SHR). A selective AT 1 receptor antagonist, candesartan (10mg/kg/day) alone (CAND), or in combination with the selective AT 2 receptor antagonist PD 123319 (50g/kg/day) (CAND+PD) was given for 12 weeks to adult male SHR. Control SHR received placebo (PLACEBO) for the same period. Left ventricular coronary blood flow (CBF), flow reserve (CFR) and minimal coronary vascular resistance (MCVR) were measured using radiomicrospheres in 35-week old rats. Mean arterial pressure (MAP), peripheral resistance (TPR), left ventricular weight (LVI), and aortic weight (AWI)were also measured. The grater MAP in CAND+PD group compared with CAND suggests that AT 2 receptor stimulation was responsible, in part for the hypotensive effect of AT 1 receptor antagonism, although they did not contribute to improved coronary hemodynamics and reduced LV and aortic masses after selective AT 1 receptor inhibition.