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

We conclude that (1) hypertension induces significant increases in cardiac IGF-I mRNA and protein that occur coordinately with its onset and early in the development of hypertrophy, (2) IGF-I mRNA levels normalize as the hypertrophic response is established, (3) in comparison to IGF-I, both c-myc and IGF-I receptor genes are differentially controlled in experimental hypertension. These findings suggest that IGF-I may participate in initiating ventricular hypertrophy in response to altered loading conditions. The consistency of these findings in models of high-, moderate-, and low-renin hypertension suggests that they occur independently of the systemic renin-angiotensin endocrine axis.