Effect of remote limb ischemic postconditioning on level of adiponectin during myocardial ischemia-reperfusion in rats

Objective To evaluate the effect of remote limb ischemic postconditioning on the level of adiponectin during myocardial ischemia-reperfusion (I/R) in rats.Methods Fifty-seven male Sprague-Dawley rats,aged 8 weeks,weighing 250-350 g,were randomly divided into 3 groups (n =19 each):sham operation group (group S); group I/R; remote limb ischemic postconditioning group (group RLIP).Myocardial ischemia was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 180 min reperfusion in urethane-anesthetized rats.In group S,the anterior descending branch was only exposed but not ligated.The animals underwent 10 min ischemia of bilateral hind limbs starting from 20 min of occlusion of the anterior descending branch,followed by reperfusion in RLIP group.The changes in S-T segment were recorded at 30,60,120 and 180 min of reperfusion.At 180 min of reperfusion,the blood samples were taken from the jugular vein for determination of serum levels of creatine kinase MB (CK-MB) and cardiac troponin Ⅰ (cTnⅠ).The animals were then sacrificed and hearts were removed for measurement of myocardial infarct size (IS) and adiponectin contents in myocardial tissues (by ELISA).Results Compared with group S,S-T segment was significantly elevated at each time point,myocardial IS,and serum cTnⅠ and CK-MB levels were increased,and adiponectin contents were decreased in I/R and RLIP groups.Compared with group I/R,elevation of S-T segment was significantly decreased at each time point,myocardial IS,and serum cTnⅠ and CK-MB levels were decreased,and adiponectin contents were increased in RLIP group.Conclusion The mechanism by which remote limb ischemic postconditioning reduces myocardial I/R injury is related to increased level of adiponectin in the myocardium of rats. Key words: Adiponectin ;  Myocardial reperfusion injury ;  Extremities ;  Ischemic postconditioning