Rescue of hypertension-related impairment of angiogenesis by therapeutic ultrasound

We examined the hypothesis that therapeutic ultrasound (TUS) treatment would rescue the hypertension-related inhibition of ischemia-induced angiogenesis. TUS protects against endothelial dysfunction, but it is little known that the effect of TUS treatment on angiogenesis inhibited by hypertension. 20-week-old male spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats (WKYs) were randomly allocated to 4 groups: SHR; TUS treated SHR (SHR-TUS); WKY and TUS treated WKY (WKY-TUS). After undergoing excision of the left femoral artery, the ischemic skeletal muscles were treated with extracorporeal TUS for 9 minutes of daily exposure (frequency of 1 MHz, intensity of 0.3 W/cm(2)) for 14 consecutive days. We found that TUS normalized the blood perfusion in SHR-TUS accompanied by elevated capillary density. Similar results were found in the protein expression of angiogenic factors. TUS treatment also enhanced peripheral capillary density in WKY rats and restored the capillary rarefaction in hypertension by elevating the protein levels of endothelial nitric oxide synthase (eNOS), hypoxic inducible factor-1 alpha (HIF-1 alpha), vascular endothelial growth factor (VEGF) and phosphorylated Akt (p-Akt) in vivo. Our data demonstrated that TUS treatment ameliorated hypertension-related inhibition of ischemia-induced angiogenesis, at least in part, via an NO-dependent manner.