Evaluation by scintigraphy of hindlimb ischemia in a rat model

The subject of ischemia-reperfusion has commonly been studied in rat hindlimb models. Unfortunately, in these experiments, the ischemia procedures lack standardization. For this reason, the authors evaluated the reliability of rat ischemia models described in the literature using scintigraphy. The study comprised six groups. Each consisted of ten male Wistar rats; five of them underwent methoxy-isobutyl-isonitrile (MIBI) scintigraphy, which is specific for muscle, and the others underwent methylene diphosphanate (MDP) scintigraphy, which is specific for bone. In Group 1, only the iliac artery was ligated; in Group 2, the iliac artery and its branches, except for the superficial epigastric artery, were ligated; in Group 3, the iliac artery and vein were ligated; in Group 4, the iliac artery and all branches, including the superficial epigastric artery, were ligated; in Group 5, in addition to ligation of the iliac artery and its branches, the skin was incised circumferentially around the pelvic girdle; in Group 6, a tourniquet was applied to the limb at the pelvic level. After 2-hr warm ischemia, a radioactive tracer was injected intravenously. In the MIBI group, images were taken at the twentieth minute and second hour after injection, and in the MDP group, at the fifth minute and third hour after injection. The radioactivity in both hind limbs of the animal was measured, and the ratio of the control to the ischemic limb was calculated. In the first five groups, there was no necrosis in the ischemic limb at the end of 2 weeks. The measured radioactivity in the ischemic limb was lower than that of the control limb in all groups. The ratio of activity obtained from the control limb to that of the ischemic limb in the tourniquet group was significantly higher, compared to other groups in both MIBI and MDP evaluations (p < 0.005). Significant ischemia was also seen in the skin incision group (Group 5). A low-flow state was observed in the ischemic limb in Groups 1-4 using both scintigraphic modalities. The tourniquet method (Group 6) provided almost complete limb ischemia, compared to other arterial ligation methods, and it is practical to use for complete ischemia when studying the physiology of replantation or free flaps.