Increased Expression of Vascular Endothelial Growth Factor and Capillary Density in Hearts of Spontaneously Hypertensive Rats

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Abstract
Objective: The role of VEGF in vascular remodeling of target organs exposed to chronic hypertension is poorly understood. The authors compared capillary density (CD), capillary‐to‐fiber ratio (C/F), and VEGF mRNA expression in the hearts (left ventricle [LV]), and skeletal muscles (soleus and anterior tibialis [AT]) of 18‐week‐old male spontaneously hypertensive rats (SHR) and age‐matched male Wistar‐Kyoto (WKY) and Sprague‐Dawley (SD) rats. Methods: CD or C/F in LV, soleus, and AT of SHR, WKY, and SD rats was determined by analysis of randomly acquired digital images of cryosections stained with FITC‐conjugated GS‐I lectin. VEGF mRNA expressions in the tissues were determined by Northern blot. Results: VEGF mRNA expressions in LV of SHR were 3.84‐ and 5.05‐fold higher, compared to SD and WKY rats, respectively (n = 6; p < .01). There were no significant differences in VEGF mRNA expression in soleus or AT among SHR, WKY, and SD rats (p > .05). CD in LV of SHR (4975 ± 167) was significantly higher than WKY or SD rats, 4151 ± 169 and 3807 ± 187 mm−2, respectively (p < .05). In LV of SHR, C/F increased (35%) more significantly than CD (increased 20%), compared to WKY rats. CD, or C/F in soleus or AT of SHR was similar to that observed in WKY or SD rats. Conclusions: VEGF expression, CD, and C/F in the heart (LV) of SHR are significantly increased, compared to WKY and SD rats. The data are consistent with the possibility that VEGF may contribute to capillary growth as a compensatory response to hypertension.