Polymorphonuclear leucocytes increase reperfusion injury in skeletal muscle.

Objective: To study the effect of polymorphonuclear leucocytes (PMNLs) on reperfusion injury in rabbit skeletal muscle and to evaluate the role of oxygen-derived free radicals in PMNL-mediated reperfusion injury.

Experimental Design: An isolated rabbit limb perfusion model. Amputated hindlimbs were subjected to 4 hours of ischaemia followed by 2 hours of reperfusion with oxygenated Krebs' buffer.

Setting: Department of experimental surgery.

Animals: 14 rabbits.

Interventions: In group I (n = 8), one limb from each animal was reperfused with PMNL-supplemented buffer while the other limb was reperfused with cell-free buffer (control). In group II (n = 6), SOD and catalase were added to the limb reperfused with PMNL-supplemented buffer while the other limb was reperfused with cell-free buffer without SOD and catalase (control).

Measures: PMNL accumulation as myeloperoxidase (MPO) activity, muscle necrosis as uptake of [Tc99]methylenediphosphonate (MDP), and oedema as increase in muscle water content (MWC). Electron microscopy was performed for histological demonstration of reperfusion injury.

Results: Addition of PMNLs increased MPO activity (p < 0.05) and MDP uptake (p < 0.05) but did not affect MWC. SOD and catalase treatment of limbs perfused with PMNLs prevented the increase in MPO activity (p < 0.05) and reduced MDP uptake (p < 0.05) and MWC (p < 0.05). PMNLs aggravated histological changes seen after reperfusion.

Conclusions: Reperfusion injury in skeletal muscle is, at least partially, mediated by PMNLs. Free radical scavengers reduce PMNL-dependent injury and prevent PMNL accumulation suggesting that oxygen-derived free radicals are mediators of PMNL-dependent injury and/or engaged in the interaction between PMNLs and the microvascular endothelium.