Xanthine oxidase in critically ischaemic and claudicant limbs: profile of activity during early reperfusion.

Xanthine oxidase activity in blood from the ipsilateral femoral vein, and the relationship between xanthine oxidase production and the products of lipid peroxidation, were studied before operation and for 60 min following release of clamps after successful revascularization in two groups of patients with claudication or critical ischaemia. Before revascularization, detectable levels of xanthine oxidase were found only in patients with critical ischaemia. Clamping during bypass surgery led to release of xanthine oxidase in claudicants, but this activity reduced after 60 min. There was no evidence of lipid peroxidation during this time. Xanthine oxidase activity in brachial vein blood was higher than in femoral vein blood in patients with critical ischaemia before revascularization.