Attenuation of oxidative reperfusion injury in skeletal muscle by the administration of iron-chelating compounds suggests that ischemia-reperfusion is associated with delocalization of iron with subsequent catalysis of hydroxyl radical generation. To test this hypothesis we examined the extent of iron liberation and lipid peroxidation in a well-established model of high-grade partial hindlimb ischemia and reperfusion. Laparotomy was performed on heparinized male Sprague-Dawley rats with isolation of the infrarenal aorta. Resting membrane potential (Em) and conjugated diene content in hindlimb skeletal muscle were determined along with plasma iron concentration and percent saturation of transferrin in five groups of animals. Baseline animals (n = 6) underwent a 30-minute postoperative stabilization period before data collection; Sham ischemia animals (n = 10) underwent aortic exposure without clamping for 120 minutes; ischemia animals (n = 8) underwent aortic clamping for 120 minutes; sham reperfusion animals (n = 8) underwent aortic exposure without clamping for 150 minutes; reperfusion animals (n = 8) underwent aortic clamping for 120 minutes followed by 30 minutes of reperfusion. Iron delocalization occurred during ischemia, as indicated by a significant rise in percent saturation of transferrin over that of the corresponding sham group (35% +/- 2% vs 25% +/- 2%; p < 0.05) and persisted during reperfusion (39% +/- 5% vs 27% +/- 3%; p < 0.05). Depolarization of resting Em was noted during ischemia (-75.7 +/- 1.7 mV vs - 92.6 +/- 0.4 mV in the corresponding sham group; p < 0.01), with only partial repolarization demonstrated after reperfusion (-82.2 +/- 1.7 mV; p < 0.01 vs all other groups).(ABSTRACT TRUNCATED AT 250 WORDS)