Angiotensin II Type 2 Receptor Overexpression Preserves Left Ventricular Function After Myocardial Infarction

Abstract
Background— The role of the angiotensin II type 2 receptor (AT2-R) in left ventricular (LV) remodeling may depend on the underlying stimulus. We hypothesized that cardiac AT2-R overexpression in transgenic (TG) mice would attenuate remodeling after myocardial infarction (MI). Methods and Results— Ten wild-type (WT) C57BL/6 mice and 12 TG mice that overexpress the AT2-R in the heart were studied by cardiac MRI at baseline and days 1, 7, and 28 post-MI induced by 1 hour of occlusion of the LAD followed by reperfusion. Short-axis imaging from apex to base was used to determine LV mass index, end-diastolic and end-systolic volume indices (EDVI, ESVI), regional wall thickness and thickening, and ejection fraction (EF). Gadolinium-DTPA was infused 20 minutes before day 1 imaging to assess infarct size. At baseline, heart rate, blood pressure, LV mass index, and EDVI were similar between groups. Baseline ESVI was lower (0.20±0.07 versus 0.45±0.15 μL/g, P<0.001) and EF higher (82.3±4.9% versus 67.7±5.3%, P<0.001)...

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