Noninvasive delayed limb ischemic preconditioning attenuates myocardial ischemia-reperfusion injury in rats by a mitochondrial K(ATP) channel-dependent mechanism.
We previously demonstrated in rats that noninvasive delayed limb ischemic preconditioning (LIPC) induced by three cycles of 5-min occlusion and 5-min reperfusion of the left hind limb per day for three days confers the same cardioprotective effect as local ischemic preconditioning of the heart, but the mechanism has not been studied in depth. The aim of this project was to test the hypothesis that delayed LIPC enhances myocardial antioxidative ability during ischemia-reperfusion by a mitochondrial K(ATP) channel (mito K(ATP))-dependent mechanism. Rats were randomized to five groups: ischemia-reperfusion (IR)-control group, myocardial ischemic preconditioning (MIPC) group, LIPC group, IR-5HD group and LIPC-5HD group. The MIPC group underwent local ischemic preconditioning induced by three cycles of 5-min occlusion and 5-min reperfusion of the left anterior descending coronary arteries. The LIPC and LIPC-5HD groups underwent LIPC induced by three cycles of 5-min occlusion and 5-min reperfusion of the left hind limb using a modified blood pressure aerocyst per day for three days. All rats were subjected to myocardial ischemia-reperfusion injury. The IR-5HD and LIPC-5HD groups received the mito K(ATP) channel blocker 5-hydroxydecanoate Na (5-HD) before and during the myocardial ischemia-reperfusion injury. Compared with the IR-control group, both the LIPC and MIPC groups showed an amelioration of ventricular arrhythmia, reduced myocardial infarct size, increased activities of total superoxide dismutase, manganese-superoxide dismutase (Mn-SOD) and glutathione peroxidase, increased expression of Mn-SOD mRNA and decreased xanthine oxidase activity and malondialdehyde concentration. These beneficial effects of LIPC were prevented by 5-HD. In conclusion, delayed LIPC offers similar cardioprotection as local IPC. These results support the hypothesis that the activation of mito K(ATP) channels enhances myocardial antioxidative ability during ischemia-reperfusion, thereby contributing, at least in part, to the anti-arrhythmic and anti-infarct effects of delayed LIPC.
Department of Pharmacology, Tianjin Medical University, Tianjin, China.
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Wu
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Yu
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XH
Zhu
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HJ
Yuan
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Kang
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Jiao
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WZ
Gao
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YX
Liu
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JS
Lou
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000188:drug therapy / Q000517:prevention & control; D003652:Decanoic Acids / Q000494:pharmacology; D005979:Glutathione Peroxidase / Q000096:biosynthesis; D006880:Hydroxy Acids / Q000494:pharmacology; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009203:Myocardial Infarction / Q000188:drug therapy / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000517:prevention & control*; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000096:biosynthesis; D014969:Xanthine Oxidase / Q000096:biosynthesis
D003652:Decanoic Acids; D006880:Hydroxy Acids; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C117780:mitochondrial K(ATP) channel; D008315:Malondialdehyde; C052853:5-hydroxydecanoic acid; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase