Cardiac insulin-like growth factor I and growth hormone receptor expression in renal hypertension

The aim of the present study was to investigate the role of insulin-like growth factor I in the development of cardiac hypertrophy in two-kidney, one clip hypertension by relating growth hormone receptor and insulin-like growth factor I receptor mRNA levels to insulin-like growth factor I gene transcription using a solution hybridization/RNase protection assay. Two-kidney, one clip hypertension was induced in male Wistar rats, and experiments were performed 2, 4, 7, and 12 days after surgery. Systolic blood pressure was elevated 2, 7, and 12 days after clipping (P<.001). Left ventricular weights were increased 2, 4, 7, and 12 days after surgery (P<.01). Associated with the rise in blood pressure, left ventricular insulin-like growth factor I mRNA was increased 2, 7, and 12 days after surgery (P<.01). Furthermore, growth hormone receptor and insulin-like growth factor I receptor gene expression increased specifically in the left ventricle of renal hypertensive rats (P<.05 and P<.001, respectively). Left ventricular growth hormone receptor mRNA peaked 7 days after induction of renal artery stenosis. These results show that insulin-like growth factor I, growth hormone receptor, and insulin-like growth factor I receptor mRNA increase in the pressure-overloaded left ventricle of two-kidney, one clip rats, suggesting a role for insulin-like growth factor I and the growth hormone/insulin-like growth factor I axis in the development of cardiac hypertrophy.