FIGURE 4. Arteriolar diameters over the 10-day observation period within the proximal (A), middle (B), and distal part (C) of control flaps (white circles), heat shock-preconditioned flaps (gray circles), and heat shock-preconditioned flaps treated with SnPP-IX (black circles). Note the dilation response in the proximal area of control and heat shock-preconditioned, but not SnPP-IX-treated flaps, and the prevention of arteriolar constriction in the distal part of heat shock-preconditioned, but not control and SnPP-IX-treated flaps. Data are mean ± SEM. *P < 0.05, **P < 0.001 versus control. ^#P < 0.05, ^##P < 0.001 versus heat shock.