Allopurinol--a free radical scavenger--reduces reperfusion injury in skeletal muscle.

Reperfusion of ischaemic skeletal muscle may lead to increased vascular permeability, oedema and ultimately muscle necrosis. Oxygen-derived free radicals have been suggested as aetiological factors in reperfusion injury. Amputated rabbit hindlimbs were subjected to 4 h of ischaemia followed by 2 h or reperfusion with Krebs' buffer. One limb from each animal was reperfused with oxygen-saturated buffer (reoxygenated limb) while the other limb was reperfused with nitrogen-saturated buffer (non-reoxygenated limb). Six animals received allopurinol orally 2 days prior to the experiment and ten animals received no treatment. The energy charge dropped from 0.90 to 0.54 during ischaemia and increased to 0.82 after reperfusion with oxygenated perfusate. Oedema was determined by limb weight and water content in muscle biopsies and muscle injury was assessed by uptake of [Tc99]methylenediphosphonate ([Tc99]MDP). The results were expressed in ratios, between the reoxygenated and nonreoxygenated limb. Without allopurinol treatment, the increase in water content and limb weight in reoxygenated limbs exceeded (p less than 0.05) non-reoxygenated limbs (ratios = 1.73 and 1.89, respectively). Allopurinol treatment significantly reduced (p less than 0.05 and p less than 0.02, respectively) the increase in water content and limb weight (ratios = 0.54 and 1.01, respectively). Without treatment, [Tc99]MDP-uptake was greater (p less than 0.05) in reoxygenated limbs than in non-reoxygenated limbs (ratio = 1.60). Allopurinol treatment significantly reduced (p less than 0.002) [Tc99]MDP-uptake in reoxygenated limbs (ratio = 0.80). These results demonstrate that additional injury to ischaemic skeletal muscle occurs during reperfusion with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)