Ultrastructural changes and lipid peroxidation in rat adipomusculocutaneous flap isotransplants after normothermic storage and reperfusion.

Parallel in vivo, histological, and ultrastructural studies were carried out and markers of lipid peroxidation (Schiff's bases [SB] and thiobarbituric-acid-reactive material [TBAR]) were measured in rat adipomusculocutaneous flap isotransplants that had been stored for 0, 2, 4, 6, and 8 hr under normothermic (37 degrees C) conditions and reperfused for specific periods. Flaps stored for 4 hr and treated with intravenous desferrioxamine (DFX) or hypertonic citrate flush (HCA) were also evaluated. In vivo assessment was made after 7 days of reperfusion. Flaps stored for 4 hr eventually exhibited partial necrosis in vivo, and neither DFX or HCA flush increased the area of surviving skin. Electron microscopy revealed extensive storage damage in epidermal, follicle, fat, and smooth muscle cells and in endothelium. HCA significantly preserved fat cells (P = 0.0035) and DFX diminished smooth muscle damage. Reperfusion injury was seen in endothelial cells in the form of swelling that was not prevented by HCA or DFX. Ultrastructural alterations correlated with changes in susceptibility to lipid peroxidation in fat but not in skin. The results of these parallel studies indicate that both free radical-dependent and independent mechanisms operate in ischemia and reperfusion injury in flap tissue and that fat has a greater predisposition to free radical damage than skin.