Sumin Gao1,2, Leyun Zhan3, Zhengchao Yang1, Ruili Shi1, Haobo Li4, Zhengyuan Xia4, Shiying Yuan5, Qing-Ping Wu1, Tingting Wang1, Shanglong Yao1. 1. Department of Anaesthesiology, Institute of Anaesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. 2. Department of Emergency Medicine, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, China. 3. Department of Anaesthesiology, Three Gorges University People's Hospital, Yichang, China. 4. Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China. 5. Department of Critical Care Medicine, Institute of Anaesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Abstract
BACKGROUND: This study aimed to evaluate the protective effect and mechanisms of remote limb ischaemic postconditioning (RIPostC) against myocardial ischaemia/reperfusion (IR) injury. METHODS: Male mice underwent 45 min of coronary artery occlusion followed by 2 h of reperfusion. RIPostC was achieved by three cycles of 5 min of ischaemia and 5 min of reperfusion in the left hind limb at the start of the reperfusion period. After 2 h of cardiac reperfusion, myocardial infarct size, cardiac enzyme release, apoptosis and oxidative stress were assessed. Protein expression and phosphorylation were measured by Western blotting. RESULTS: RIPostC significantly decreased cardiac IR injury, as reflected by reduced infarct size and cellular apoptosis (22.9 ± 3.3% vs 40.9 ± 6.2% and 13.4% ± 3.1% vs 26.2% ± 3.1%, respectively, both P < 0.01) as well as plasma creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) release (21.97 ± 4.08 vs 35.86 ± 2.91 ng/ml and 6.17 ± 0.58 vs 8.37 ± 0.89 U/ml, respectively, both P < 0.01) compared with the IR group. RIPostC significantly increased the phosphorylation of myocardial STAT3, Akt and eNOS (P < 0.01). In addition, RIPostC elevated the nuclear translocation of Nrf2 and the expression of HO-1 and reduced myocardial oxidative stress (P < 0.05). Interestingly, pretreatment with the JAK/STAT3 inhibitor AG490 blocked the cardioprotective effect of RIPostC accompanied by decreased phosphorylation of myocardial STAT3, Akt and eNOS (P < 0.05), decreased nuclear translocation of Nrf2 and expression of HO-1, as well as increased oxidative stress (P < 0.05). CONCLUSION: RIPostC attenuates apoptosis and protects against myocardial IR injury, possibly through the activation of JAK/STAT3-mediated Nrf2-antioxidant signalling.
BACKGROUND: This study aimed to evaluate the protective effect and mechanisms of remote limb ischaemic postconditioning (RIPostC) against myocardial ischaemia/reperfusion (IR) injury. METHODS: Male mice underwent 45 min of coronary artery occlusion followed by 2 h of reperfusion. RIPostC was achieved by three cycles of 5 min of ischaemia and 5 min of reperfusion in the left hind limb at the start of the reperfusion period. After 2 h of cardiac reperfusion, myocardial infarct size, cardiac enzyme release, apoptosis and oxidative stress were assessed. Protein expression and phosphorylation were measured by Western blotting. RESULTS:RIPostC significantly decreased cardiac IR injury, as reflected by reduced infarct size and cellular apoptosis (22.9 ± 3.3% vs 40.9 ± 6.2% and 13.4% ± 3.1% vs 26.2% ± 3.1%, respectively, both P < 0.01) as well as plasma creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) release (21.97 ± 4.08 vs 35.86 ± 2.91 ng/ml and 6.17 ± 0.58 vs 8.37 ± 0.89 U/ml, respectively, both P < 0.01) compared with the IR group. RIPostC significantly increased the phosphorylation of myocardial STAT3, Akt and eNOS (P < 0.01). In addition, RIPostC elevated the nuclear translocation of Nrf2 and the expression of HO-1 and reduced myocardial oxidative stress (P < 0.05). Interestingly, pretreatment with the JAK/STAT3 inhibitor AG490 blocked the cardioprotective effect of RIPostC accompanied by decreased phosphorylation of myocardial STAT3, Akt and eNOS (P < 0.05), decreased nuclear translocation of Nrf2 and expression of HO-1, as well as increased oxidative stress (P < 0.05). CONCLUSION:RIPostC attenuates apoptosis and protects against myocardial IR injury, possibly through the activation of JAK/STAT3-mediated Nrf2-antioxidant signalling.