Effect of hypertension on arterial structure and wound repair at the microvascular anastomosis site using stroke-prone spontaneously hypertensive rats (SHRSP)

Abstract

Different processes of microvascular wound healing under hypertension in comparison to normotension have been suspected. To explore these differences at the site of anastomotic wound repair, we performed microvascular anastomoses of the femoral arteries in 12-week-old, stroke-prone hypertensive rats (SHRSP) whose maximum blood pressure reached 238 mm Hg and in normotensive age-matched Wistar Kyoto (WKY) rats. Morphologic changes under hypertension were examined via light microscopy. The arrangement and number of endothelial cells were examined using the en face silver staining technique. The plasma activity levels of factor XIII were also measured in each group. Transitional healing at the microvascular anastomosis site was evaluated via scanning electron microscopy. The extent of endothelial migration over the exposed media around the needle holes was determined using a computerized graphic analysis system. Histologic cross sections demonstrated a thickened media, with altered shape and arrangement of the smooth muscle cell nuclei in SHRSP arteries compared with WKY arteries. En face silver staining showed small and spindle-shaped endothelial cells with an irregular cell arrangement and distribution in SHRSP arteries relative to WKY arteries. Factor XIII was increased 36% over baseline in SHRSP rats postoperatively; this was significantly higher than the increase in WKY rats (P < 0.05). Although both SHRSP and WKY arteries had similar wound healing responses to microvascular anastomosis, endothelial cell migration over the exposed media was significantly accelerated in the SHRSP rats.