Expression of vascular endothelial growth factor during the development of cardiac hypertrophy in spontaneously hypertensive rats.

Left ventricular hypertrophy (LVH) is often associated with an impaired maximal coronary blood flow and increases the vulnerability of the heart tissue to ischaemia. In this study, the correlation between coronary blood flow and expression of the vascular endothelial growth factor (VEGF) mRNA was investigated. Using both haemodynamic measurements and analysis of mRNA, we have demonstrated that during development of LVH, in spontaneously hypertensive rats (SHR), an impaired maximal coronary flow at 12 weeks of age is associated with low levels of VEGF mRNA. However, in older SHR (32 weeks) with stabilised hypertrophy and a normal maximal coronary flow response, VEGF mRNA levels are increased 3-fold. These results suggest that the mechanism for the impaired flow, observed in some types of cardiac hypertrophy, might involve an inadequate growth of the coronary vessels due to insufficient activation of the VEGF gene.