IDENTIFICATION OF XANTHINE-OXIDASE ACTIVITY FOLLOWING REPERFUSION IN HUMAN TISSUE

In this series of experiments, we surveyed xanthine oxidase activity a fter microvascular transfer in the venous effluent after reperfusion o f human rectus abdominis muscle (n = 8) and jejunum (n = 4). Enzyme ac tivity was correlated with duration of ischemia and biochemical marker s of cellular injury. Xanthine oxidase (XO) activity was measured spec trofluorometrically using a pterin assay, whereas cellular injury was measured with commercial creatinine phosphokinase activity assay and l ipid peroxidation products using a spectrophotometer. The data demonst rated that XO activity was statistically significantly increased in mu scle flaps kept at room temperature during ischemia compared with musc le flaps that were cooled (p < 0.05). Creatinine phosphokinase activit y was also increased after 15 minutes of reperfusion in muscle flaps t hat were not cooled (p < 0.05). Two of the jejunal free flaps had isch emia times of >1 hour and had elevated XO activity after reperfusion d espite cooling (p < 0.05). Two other jejunal flaps had ischemia times of <1 hour, but in one case, the XO activity was increased before harv est. The other case had no increase in XO activity.