Induction of myocardial insulin-like growth factor-I gene expression in left ventricular hypertrophy.

BACKGROUNDLeft ventricular hypertrophy is a generalized adaptation to increased afterload, but the growth factors mediating this response have not been identified. To explore whether the hypertrophic response was associated with changes in local insulin-like growth factor-I (IGF-I) gene regulation, we examined the induction of the cardiac IGF-I gene in three models of systolic hypertension and resultant hypertrophy.METHODS AND RESULTSThe model systems were suprarenal aortic constriction, uninephrectomized spontaneously hypertensive rats (SHR), and uninephrectomized, deoxycorticosterone-treated, saline-fed rats (DOCA salt). Systolic blood pressure reached hypertensive levels at 3 to 4 weeks in all three systems. A differential increase in ventricular weight to body weight (hypertrophy) occurred at 3 weeks in the SHR and aortic constriction models and at 4 weeks in the DOCA salt model. Ventricular IGF-I mRNA was detected by solution hybridization/RNase protection assay. IGF-I mRNA levels increased in all th...