A noninvasive murine model of hind limb ischemia-reperfusion injury.

BACKGROUND: This study describes a novel murine method of the Controlled Tension Tourniquet (CTT). The CTT applies a measured circumferential tension to hind limbs using a tourniquet attached to digital strain gauges, and is useful for investigating hind limb ischemia reperfusion (IR).
MATERIALS AND METHODS: Mice were subjected to 1, 3, or 6 h of unilateral hind limb ischemia followed by either 4 or 24 h of reperfusion. Blood flow in the ischemic, reperfused, and contralateral limbs was monitored using a Laser Doppler Imager. Edema in the IR limbs was documented by changes in the wet weight to dry weight ratio. Myeloperoxidase and tetrazolium based mitochondrial activity assays indicated neutrophil infiltration and tissue viability, respectively.
RESULTS: During reperfusion following 1, 4, or 6 h, flow stabilized at 100%, 53%, and 23% of baseline levels, respectively. Edema was present all in IR limbs after 4 h of reperfusion, but increased with the duration of ischemia. After 24 h of reperfusion neutrophil infiltration was equivalent in all IR limbs after all intervals of ischemia. After 24 h of reperfusion, tissue viability after 1 h of ischemia was equivalent to sham or contralateral limbs. At 3 or 6 h of ischemia and 24 h reperfusion decreased tissue viability to 40% of sham and contralateral limbs.
CONCLUSIONS: The CTT provides a reproducible, noninvasive model of acute limb ischemia, which reflects the biochemical indices of microvascular injury, inflammation and flow characteristic of reperfusion injury.