Insulin-like growth factor-1 overexpression in cardiomyocytes diminishes ex vivo heart functional recovery after acute ischemia

Background:Acute insulin-like growth factor-1 administration has been shown to have beneficial effects in cardiac pathological conditions. The aim of the present study was to assess the structural and ex vivo functional impacts of long-term cardiomyocyte-specific insulin-like growth factor-1 overexpression in hearts of transgenic I?MHC-IGF-1 Ea mice.Methods:Performance of isolated transgenic I?MHC-IGF-1 Ea and littermate wild-type control hearts was compared under baseline conditions and in response to 20-min ischemic insult. Cardiac desmin and laminin expression patterns were determined histologically, and myocardial hydroxyproline was measured to assess collagen content. Results:Overexpression of insulin-like growth factor-1 did not modify expression patterns of desmin or laminin but was associated with a pronounced increase (30 ) in cardiac collagen content (from 3.7 to 4.8 I?g/mg). Baseline myocardial contractile function and coronary flow were unaltered by insulin-like growth factor-1 overexpression. In contrast to prior evidence of acute cardiac protection, insulin-like growth factor-1 overexpression was associated with significant impairment of acute...