Abstract:

Ultrasound (US) and ultrasound contrast agents’ (UCAs), ability to induce a particular bioeffect, angiogenesis, has been explored as a means of restoring blood flow to ischemic muscle. Determining the progression of the angiogenic response and how the acoustic pressure affects that response are integral to the evaluation of bioeffects, US therapy development, and understanding the physical process. Because UCAs demonstrate an increasing percentage of collapse with increasing US pressure, this study explored the effects with a high percentage of UCA collapse (i.e., high US pressure). Angiogenesis was examined in terms of capillary density in rat gracilis muscle (N=21) using H&E, and two immunohistochemical stains: CD‐31 and CD‐34. Several survival groups (0, 3, 6, 13, 20, and 27 days) were used to determine when the capillary density returned to normal levels. Inflammation cells were also quantified via a color threshold analysis as a percentage of the total section. When compared to the control, high US pressure and UCAs caused capillary density to decrease by 39% and inflammation cells to increase by 30–175% of the inflammation cells at day 0. These values returned to normal levels within 3–6 days. (Work supported by NIH Grant No. R37EB002641.)