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.