Superoxide dismutase and catalase in skin flaps during venous occlusion and reperfusion.

We studied the enzymatic concentrations of superoxide dismutase (SOD) and catalase (CAT) in rabbit abdominal island skin flaps during 8 and 10 hours of venous occlusion followed by 4 hours of reperfusion. A correlation between such enzyme activity at the end of ischemia and flap viability was tested. The results show that the accumulation of blood and blood-derived substances cause enzyme activity to increase considerably during venous occlusion. The amount of increase was similar for both 8- and 10-hour venous occlusion. "True tissue enzyme activity" (corrected for the contribution of blood and blood-derived substances) remained constant during venous occlusion, suggesting that the availability of scavenging enzyme does not correlate with ultimate flap viability. During early reperfusion, however, both SOD and CAT activity decreased, suggesting that membrane damage leads to an increase in membrane permeability and to the loss of intracellular enzymes.