Depletion of vascular adaptive mechanisms in hypertension-induced injury of the heart and kidney.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a signalling protein of critical importance for angiogenesis. In an effort to better understand its significance in hypertension-induced injury of the heart and kidney we aimed at studying the changes in its expression in an experimental model and correlated it with capillary density in the myocardium and the renal parenchyma. METHODS: We used two age groups of spontaneously hypertensive rats (6- and 12-month-old), indicative of early and advanced hypertension. VEGF expression was assessed and a semi-quantitative analysis of its immunoreactivity was conducted. Changes in capillary density in the myocardium and kidney were assessed for statistical significance and correlations with VEGF expression were established. RESULTS: We reported stronger VEGF expression in animals with early compared to advanced hypertension in all examined structures. Capillary density decreased significantly at age 12 months compared to 6 months and was significant in all examined structures. A positive correlation was established between capillary density and the expression of VEGF. CONCLUSION: These findings underscore the key significance of VEGF for compensatory angiogenesis and suggest that a statistically significant depletion of these vascular adaptive mechanisms is a major aspect in the cascade of hypertension-induced injury of the heart and kidney (Tab. 3, Fig. 26, Ref. 47).