Immunohistochemical expression of apoptosis and VEGF expression on random skin flaps in rats treated with hyperbaric oxygen and N-acetylcysteine.

Objective: We sought to investigate the role of hyperbaric oxygen (HBO2), N-acetylcysteine (NAC), and HBO2 plus NAC (HN) on the immunohistochemical expression of caspase-3 and the vascular endothelial growing factor (VEGF) on random skin flaps of rats (modified McFarlane design).

Methods: Thirty-two male Wistar rats were randomly divided into four groups: GS (sham--n = 8); GNAC (N-acetylcysteine--n = 8); GHBO2 (hyperbaric oxygen--n = 8); and GHN (HBO2 plus NAC--n = 8). A rectangular skin flap (2 x 8 cm2) was dissected from the muscular dorsal layer, preserving a cranial pedicle. Polyethylene film was placed over the muscular layer, and an interrupted 3.0 nylon suture fixed the flap into the original place. On the eighth day, full-thickness biopsies (2 x 1 cm2) were collected from the proximal, middle and cranial areas of the skin flap, and in a site away from the flap labeled the control area.

Results: The expression of VEGF in the skin layers (epidermis, dermis, subcutaneous muscles) and vessels showed no significant difference among the groups. Apoptotic cells were significantly increased in the middle area of the flap in all groups. The major increase occurred in GS and GNAC. HBO2 significantly decreased cleaved caspase-3-positive cell numbers in the skin layers and vessels of the three areas.

Conclusions: HBO2 showed a protective effect in the ischemic skin flap that was associated with reduced expression of apoptosis. GNAC and GHN were not associated with lower expression of apoptosis, and poor results were observed in GNAC. The combination of NAC and HBO2 did not show better results than using them separately. The expression of VEGF in skin layers and vessels did not show a significant difference in our modified McFarlane flap model. The results suggest that the diffusion of oxygen through the interstitial space was the determining factor for the more favorable results of HBO2 in the decrease of apoptosis expression.