Effect of different protocols of ischemic postconditioning on skeletal muscle ischemia/reperfusion injury in a rat model

Peng Long-long; Yang Fu-chun; Bo Zhan-dong; Tan Zhen; Yao Jun; Cheng Jian-wen; Xue Ming-qiang; Zhao Jin-min

doi:10.3969/j.issn.2095-4344.2015.05.015

Abstract：BACKGROUND:Recent studies have shown that ischemic postconditioning can trigger endogenous protection against ischemia/reperfusion injury in various organs including myocardium and skeletal muscle. However, there is variability in protective effects with different protocols and species specificity. <br> OBJECTIVE:To investigate effects of various ischemic postconditioning protocols on rat skeletal muscle ischemia/reperfusion injury and to select an optimal protocol. <br> METHODS:Healthy Adult male Sprague-Dawley rats were randomly al ocated into four groups(n=9):one ischemia/reperfusion injury group and three ischemic postconditioning groups. The rats in ischemia/reperfusion injury group were subjected to 4 hours of main ischemia in the right lower limbs via occlusion of the femoral artery with a clamp, fol owed by 24 hours of reperfusion, and sham surgery in the left lower limbs as self control. The surgical procedures in three ischemic postconditioning groups were same as in ischemia/reperfusion group except additional ischemic postconditioning interventions were applied at the onset of reperfusion after 4 hours of ischemia with three different algorithms respectively:4 cycles of 10 seconds reperfusion/10 seconds ischemia, 4 cycles of 30 seconds reperfusion/30 seconds ischemia, and 4 cycles of 1 minute reperfusion/1 minute ischemia. At the end of 24-hr reperfusion in each group, blood samples were taken from femoral vein for detecting serum lactate dehydrogenase(LDH), and tissue samples from gastrocnemius for measuring wet-dry weight (wet/dry)ratio, enzyme myeloperoxidase and malondialdehyde. Tibialis anterior muscle samples were also col ected for observing the pathological changes in skeletal muscle under electron microscope. RESULTS AND CONCLUSION:The wet/dry ratio was significantly lower in the 30-second reperfusion/30-second ischemia group than in the ischemia/reperfusion injury group (P<0.05). No significant difference was detected between other two ischemic postconditioning groups and ischemia/reperfusion group (P>0.05). Plasma lactate dehydrogenase activity, gastrocnemius myeloperoxidase activity and malondialdehyde contents were lower in the three ischemic postconditioning groups compared to the ischemia/reperfusion injury group (P<0.05). No significant difference was detectable among the three ischemic postconditioning groups. Vacuolar degeneration of skeletal muscle mitochondria, myofibrils structural clarity and integrity of the nucleus were apparently improved in the 30-second reperfusion/30-second ischemia group compared to the ischemia/reperfusion injury group under electron microscope. Ultrastructure changes of the other two ischemic postconditioning groups were improved to different degrees as compared with the ischemia/reperfusion injury group. The results indicate that ischemic postconditioning confers protection against skeletal muscle ischemia/reperfusion injury in the rat model. The protocol of four cycle of 30-second reperfusion/30-second ischemia is optimal, which can be used as a basis for further investigations.