To study the different ischemic characteristics and compensatory mechanisms of acute or chronic rats hindlimb ischemia.

Three months SD rats with hyperlipemia were used to induce the acute (n = 20) or chronic (n = 20) hindlimb ischemia. Real-time PCR and 2-^△△CT Methods were used to analyze VEGF and HIF-1α in adductor femoris tissue at 6h after femoral artery (FA) occlusion in both groups. Muscle necrosis and inflammation in gastrocnemius were observed at 1 week after FA occlusion. Four weeks after FA occlusion, the ratio of capillary to fibromuscular in ischemic adductorfemoris were counted after immunohistochemical stain. Capability of movement and diameter for ischemic limbs were recorded weekly postoperation.

Acute group showed critical limb ischemia immediately after operation, but Chronic group expressed it at (8.2 ± 0.7) days postsurgical. At 6 h after FA occlusion, the relative quantity of VEGF and HIF-1α were significantly higher than chronic group [(5.57 ± 0.87) vs. (2.49 ± 0.85) and (10.28 ± 1.09) vs. (6.83 ± 1.17), P < 0.05]. At 1 week, acute ischemic gastrocnemius showed more muscle necrosis and inflammation. At 4 week, the ratio of capillary/fibromuscular in acute ischemic adductorfemoris significantly increased than chronic group [(1.37 ± 0.14) vs. (1.18 ± 0.12), P < 0.05]. The acute ischemic limb dysfunction were more severe early after surgical, however, it recovered better at 3 or 4 week postsurgical.

Pathological feature induced by acute or gradual ischemia are different, which cause different compensatory response to ischemia injury. Rats show the better compensation to acute ischemia than to chronic ischemia.