Hif-1a expression in the distal side of flaps 48 hours post elevation.

<p><b>(A)</b> Western blot shows significantly higher level of Hif-1a expression in zone IV of the flap in group II, III and IV than that of group I. <b>(B)</b> Immunohistochemistry shows strongly positive staining for Hif-1a in the dermis of flap tissues of the groups without arterial supercharging (group III and IV), compared to that of P2 arterial supercharged groups (group I and II); Red arrow: fibroblasts of positive Hif-1a staining; Black arrow: macrophages/mononuclear neutrophils of positive Hif-1a staining; Bars = 20mm; *: P < 0.05 vs. group I; **: P < 0.01 vs. group I; ^<b>+</b>: P < 0.05 vs. group II; ^<b>++</b>: P < 0.01 vs. group II.