Phospholipid peroxidation deacylation and remodeling in postischemic skeletal muscle

Reperfusion of ischemic skeletal muscle is associated with white blood cell (WBC) sequestration and hydroperoxy-conjugated diene (HCF) formation, a marker of free radical-mediated phospholipid peroxidation. The purpose of this study was to define the kinetics of phospholipid fatty acyl peroxidation, deacylation, and remodeling in postischemic skeletal muscle during prolonged reperfusion in vivo, and to determine whether reperfusion with WBC and plasma-depleted blood would attenuate postischemic phospholipid peroxidation and myocyte necrosis. The isolated, paired, canine gracilis muscle model was used. After 5 h of ischemia, muscles underwent unaltered reperfusion or initial reperfusion with WBC-deficient blood cells resuspended in hydroxyethyl starch, followed by return to normal circulation (modified reperfusion). The concentration of native fatty acids and HCDs of linoleic acid extracted from muscle phospholipids was quantified by gas chromatography and positively identified by mass spectrometry. Ischemia and reperfusion resulted in phospholipid deacylation and a selective increase in phospholipid stearic acid content, but had no effect on total phospholipid phosphorus. Modified reperfusion decreased 1) early HCD formation (54%) and 2) postischemic skeletal muscle necrosis (49%). These data suggest that reperfusion results in phospholipid deacylation and remodeling, and that the initial oxidant stress during reperfusion may be a significant determinant of ultimate muscle necrosis.