Time course of superoxide generation in reperfusion after arterial ischaemia and venous congestion

In order to identify differences in superoxide (O-2(-)) production after re perfusion following arterial ischaemia and venous congestion, we directly q uantified O-2(-) in the venous effluent from reperfused hindlimbs in the ra bbit. Using a total of 20 rabbit hindlimbs, we made hindlimb-reperfusion mo dels by section of both soft tissue and bony structures exclusive of femora l vessels around the thighs and clamping of the artery alone (group A: n = 10) or vein alone (group V: n = 10) by microvascular clamp. A pilot study r evealed that the critical time for venous congestion was 2 h. Accordingly, clamping was performed at 25 degrees C (normothermia) for 2 h. Sham operati ons were performed in the control (n = 7). Venous effluent blood samples fr om the femoral vein proximal to the clamping point were collected before re perfusion, and from 5 to 60 min after reperfusion at 5 min intervals. Efflu ent blood samples were used to quantify O-2(-) using a chemiluminescence me thod using a derivative of luciferin. The time course of O-2(-) production after reperfusion in group A and group V showed significant differences (P < 0.05), compared with the controls. There was no significant difference in the time course of O-2(-) production in group A and that in group V. In th e early reperfusion phase, no difference in O-2(-) production was observed after arterial ischaemia or venous congestion. In future studies, we will t est the contributions of free radicals by setting longer ischaemic times, l onger reperfusion times, and studying secondary ischaemia.