An evaluation of resting arterial ischemia models in the rat hind limb.

Techniques for using the rat hind limb as a model of pure arterial ischemia at rest have not been well defined. Because the rat has no profunda femoral artery, numerous collateral pathways exist to the hind limb, and femoral artery ligation is not an effective method of inducing arterial ischemia. After several anatomic studies, a two stage operation to produce arterial ischemia in the left hind limb was devised. The first stage involved surgical interruption of collateral and re-entrant vessels, and the second stage involved femoral artery ligation. Using Xenon 133 clearance as an estimate of blood flow, reduction in flow to 14, 24, and 37% of the simultaneously measured value in the right hind limb was obtained at 2 hours, 2 days, and 5 days post ligation. Oxygen extraction in the left hind limb doubled both at 2 hours and at 2 days post ligation. Histological evaluation of the anterior compartment musculature after 5 days demonstrated loss of nuclei, degenerating contractile elements, edema, and inflammatory infiltrate. Evaluation of rats that had undergone isolated femoral artery ligation showed a 66% reduction in flow 2 hours after ligation, but no reduction in flow at 5 days, no increase in oxygen extraction, and only nuclear changes on histological exam at five days.