Lower Risk of Postinfarct Rupture in Mouse Heart Overexpressing β2-Adrenergic Receptors: Importance of Collagen Content

Abstract
This paper addresses whether the enhanced left ventricular (LV) contractility and heart rate, seen in transgenic mice overexpressing β2-adrenergic receptor in the heart, might raise the incidence of LV rupture after myocardial infarct. Transgenic and wild-type mice underwent left coronary artery occlusion. Postinfarct deaths that occurred 1–7 days after surgery were analyzed. Hemodynamics, morphologic parameters, and collagen content in the LV were determined. A significantly lower incidence of LV rupture was observed in transgenic than in wild-type mice 3–5 days after myocardial infarct (2.5 versus 19.7%, p