An in vivo model for assessing muscle function during skeletal ischemia-reperfusion injury

Objectives: Acute limb ischemia is associated with a high mortality and amputation rate despite surgical revascularisation, as the ischemia-reperfusion injury that occurs further compromises muscle function. This study's aim was to establish an in vivo assessment of ischemia-reperfusion injury by evaluating muscle function in a rabbit hind-limb model.

Material and Methods: New Zealand White rabbits were anaesthetised; both Mm. tibiales anteriores were dissected and attached to force transducers. Contraction force was measured following twitch (4mA, 10Hz) and tetanic stimulation (4mA, 50Hz). Ischemia was induced by clamping the left A. iliaca comm. and A. femoralis comm. Collaterals were ligated and ischemia was maintained for 210min (n=8). The right hind-limb served as control. Afterwards, clamps were removed in 4 animals, allowing blood reperfusion for 60min. Muscle function was assessed intermittently. Finally, muscle samples were taken to evaluate water content.

Results: All animals survived the procedures and remained hemodynamically stable. Muscle force decreased due to ischemia following twitch (7.3±1.99 to 1.0±0.25cN/g, p<0.001) and tetanic stimulation (15.36±3.06 to 3.94±1.24cN/g, p<0.001). No significant recovery of function impaired by ischemia for 210min was observed after 60min of blood reperfusion (twitch, 1.14±0.18 to 2.1±1.19cN/g, p=0.246, tetanus, 4.72±1.05 to 8.64±3.69cN/g, p=0.145). The reperfused muscles displayed higher water content (76.64±0.86 versus 75.66±0.66% control limb, p=0.017) correlating to tissue oedema and indicating reperfusion injury.

Conclusions: Evaluating anterior tibialis muscle contractility using a force transducer is a reliable method of quantifying ischemia-reperfusion injury in a rabbit hind-limb model. This technique will be employed in further experiments to optimise controlled reperfusion therapy.