Abstract
To determine whether systemic nitric oxide production in tourniquet-induced skeletal muscle ischaemia-reper-fusion injury (SMRI) is dependent on release of vascular endothelial growth factor (VEGF), a modulator of nitric oxide cytoprotection in myocardial ischaemia-reperfusion injury.
Mice were randomised (n=10 per group) into: time controls (no tourniquet) and test animals (bilateral hindlimb tourniquet ischaemia). Blood samples were collected in test animals prior to ischaemia and after reper-fusion. In controls, blood samples were collected at the same corresponding time points. Serum VEGF, nitric oxide metabolites (nitrite and nitrate) and the proinflammatory cytokine tumour necrosis factor (TNF)-α (an indicator of systemic inflammation) were determined. At the end of reperfusion, the lungs and muscle (right gastrocnemius) were harvested and tissue injury determined by measuring myeloperoxidase (MPO) activity, a marker of neutrophil infiltration. Data are presented as mean ± SEM and statistical comparison was performed using one-way analysis of variance (ANOVA) with significance attributed to P < 0.05.
In comparison to control animals, muscle (4.9±0.3 versus 4±0.03 units/g of wet tissue; P=0.02) and lung (16.7±1.9 versus 10.4±0.5; P=0.005) MPO activity at the end of repercussion was significantly greater in test animals. The table shows the results with respect to serum cytokine levels and nitricxide metabolites.
These data demonstrate that SMRI results in local and systemic proinflammatory responses. In contrast to myocardial ischaemia-reperfusion injury, nitric oxide production in tourniquet-induced SMRI is VEGF-independent. Alternative mechanisms for nitric oxide production in tourniquet-controlled extremity surgery requires further evaluation.
The abstracts were prepared by Mr Simon Donell. Correspondence should be addressed to him at the Department of Orthopaedics, Norfolk & Norwich Hospital, Level 4, Centre Block, Colney Lane, Norwich NR4 7UY, United Kingdom.
