Postconditioning Protects Skeletal Muscle Against a Long-Lasting Vascular Occlusion

ABSTRACT

Purpose/Aim of the Study: Long-lasting lower limb arterial occlusion is a condition with high incidence and complication rates. With the absence of appropriate treatment to cure advanced complications, mortality rates are high. Postconditioning (PC) might be capable of limiting the degree of ischemic-reperfusion (IR) injuries, thus reducing complications and mortality rates. The aim of this study was to evaluate the impact of postconditioning during the first postoperative day on skeletal muscle after a long-lasting arterial occlusion. Materials and Methods: Male Wistar rats (n = 72) underwent 8 hr of infrarenal aortic occlusion followed by 2, 6, 12, or 24 hr of reperfusion. In one group of each reperfusion period, postconditioning was applied. Muscle samples were collected for histological examinations. Furthermore, muscle fiber viability and muscle wet-to-dry ratio were assessed. Blood samples were taken for creatine-kinase measurements. Results: Postconditioning strongly reduced morphological injury compared to the corresponding ischemic-reperfusion group (p < .001). Serum creatine-kinase levels showed a peak at 6 hr post-ischemia (IR: 6702.2 ± 797.5; PC: 5523.3 ± 769.3 IU/l) and decreased to normal level by the end of the experiment (Sham: 171.5 ± 71.6; IR: 186.2 ± 82.7; PC: 174.2 ± 72.4 IU/l). Creatine-kinase levels were significantly reduced by postconditioning (p_2hr = .028; p_6hr = .06; p_12hr = .042). A marked decrease in viability was observed in the ischemic-reperfusion groups (2 hr: 11.0 ± 4.1; 6 hr: 10.3 ± 3.6; 12 hr: 9.4 ± 3.3; 24 hr: 8.6 ± 2.8%), whereas with postconditioning, viability was preserved (2 hr: 26.4 ± 5.5; 6 hr: 24.6 ± 4.5; 12 hr: 24.5 ± 6.8; 24 hr: 26.2 ± 6.1%; p < .001); moreover, a significant decrease in the wet-to-dry ratio was achieved (p < .001). Conclusion: Postconditioning was able to reduce local complications after a long-lasting lower limb vascular occlusion.

Keywords: :

• acute limb ischemia
• postconditioning
• reperfusion injury
• injury dynamics
• ultrastructure
• viability