Affiliation:
1. From the Cardiology Division of the Department of Medicine. University of Alberta, Edmonton, Alberta, Canada
Abstract
Background: We hypothesized that the cardioprotective effect of angiotensin II (AngII) type 1 receptor (AT,R) blockade during in vivo ischemia-reperfusion (IR) might be associated with an increase in AngII type 2 receptor (AT2R) protein, as well as 1,4,5-inositol trisphosphate type 2 receptor (IP3R) and protein kinase C ε, (PKCε) proteins and cyclic guanosine 3',5' monophosphate (cGMP). Methods and Results: We studied the effects of the AT1R blocker, candesartan, on in vivo left ventricular (LV) systolic and diastolic function and remodeling (echocardiogram/Doppler) and hemodynamics during canine reperfused anterior infarction (90-minute ischemia, 120-minute reperfusion), and ex vivo infarct size and AT1R/AT2R, IP3R, and PKCε proteins (immunoblots), and cGMP (enzyme immunoassay). Compared with controls, candesartan (1 mg/kg intravenously over 30-minute preischemia) inhibited the AngII pressor response, decreased preload and afterload, improved LV systolic and diastolic function, limited LV remodeling, decreased infarct size (55% vs 27% risk; P < .000003), markedly increased AT2R, IP3R, and PKCε proteins in the infarct zone, but not the AT,R protein, and increased infarct more than noninfarct cGMP. Conclusions: The overall results suggest that cardioprotective effects of AT1R blockade on acute IR injury might involve AT2R activation and downstream signaling via IP3R, PKCε, and cGMP.
Subject
Pharmacology (medical),Cardiology and Cardiovascular Medicine,Pharmacology