A Nonpeptide Angiotensin II Type 2 Receptor Agonist Does Not Attenuate Postmyocardial Infarction Left Ventricular Remodeling in Mice

Cardiac overexpression of the angiotensin II type 2 receptor (AT2 R) attenuates left ventricular (LV) remodeling after myocardial infarction (MI) in transgenic mice. We hypothesized that a novel nonpeptide AT2 R agonist, compound 21 (C21), would attenuate post-MI LV remodeling. Fifty-nine mice were studied for 28 days after 1-hour surgical occlusion-reperfusion of the left anterior descending coronary artery. Immediately thereafter, 23 mice received 0.3 mg·kg·d of C21 via Alzet osmotic minipump, 16 received 10 mg·kg·d of the AT1 R antagonist candesartan in drinking water, and 20 were untreated controls. Cardiac magnetic resonance imaging measured ejection fraction (EF), LV end-systolic, and end-diastolic volumes (ESVI and EDVI) indexed to weight serially post MI. Infarct size was measured on day 1 by late gadolinium-enhanced cardiac magnetic resonance imaging. At baseline, heart rate, blood pressure, EDVI, ESVI, and EF were similar between groups. Mean infarct size (42%-45% of LV mass) was similar between groups. C21-treated animals demonstrated adverse LV remodeling (increased EDVI and ESVI at all post-MI time points) compared with control. Candesartan therapy preserved left ventricular EF at day 28 compared with the C21-treated group. Thus, direct stimulation of the AT2 R by C21 at 0.3 mg·kg·d does not attenuate post-MI LV remodeling in reperfused MI in mice.