| Objective:To study the protective effect of noninvasive delayed limb ischemic preconditioning (NDLIP) against myocardial ischemia reperfusion injury in rats.Methods:Male Wistar rats were randomized into the following groups:The control groups, NDLIP consecutive groups, NDLIP intermittent groups. the control groups, including the sham operation group, the ischemia-reperfusion(I/R)-control group, the myocardial ischemic preconditioning (MIPC) group, the femoral artery ischemic preconditioning (FAIP) group; the NDLIP consecutive groups, including continuously using for1day,3days and7days groups. And each group had a test on the first day, the third day and the fifth day after NDLIP; NDLIP intermittent groups, including1-day NDLIP+1-day interval group,1-day NDLIP+2-day interval group,3-day NDLIP+3-day interval group,3-day NDLIP+5-day interval group. The left ventricular function, ventricular arrhythmia, ST-segment were measured during I/R. Myocardial infarct size, creatine kinase isoenzyme MB (CK-MB), cardiac troponins I (cTnI), heart fatty acid binding protein (H-FABP), glycogen phosphorylase BB (GPBB) and mitochondron respiration chain compound Ⅰ-Ⅳ were determined by ELISA method at the end of experiment;Mn-SOD, MDA and ROS were deteced by spectrophotometer; mitochondrial structure were determined by transmission electron microscopy; Δ Ψ m and ROS were deteced by flowery cell machine; Trx2and TrxR2were measured by western blotting; Trx2mRNA, TrxR2mRNA, miRNA21and miRNA1were measured by real-time quantitative-polymerase chain reaction.Results:1. Effects of NDLIP on changes of cardiac physiological function induced by myocardial I/R injury.The NDLIP consecutive groups:Compared with I/R group, The1st d after3-d NDLIP group, the1st d after7-d NDLIP group could lower the raise degree of ST-segment(P<0.01), onsets of ventricular Premature contraction(VPC) and ventricular tachycardia(VT) were delayed(P<0.01), durations of them were shortened(P<0.01), the three groups attenuated this fall in left ventricular systolic pressure (LVSP) and the maximal rate of rise of left ventricular pressure (dp/dtmax) and the rise in left ventricular end diastolic pressure (LVEDP)(P<0.01). They provided similar cardioprotection to the MIPC and FAIP groups. The3rd d after3-d and7-d NDLIP groups, compared with the I/R group, there were no significant differences in protecting heart against I/R injury.The NDLIP intermittent groups:The1-d NDLIP+1-d INTV group also provided similar cardioprotection to the MIPC and FAIP groups. However, the other groups had no significant differences in protecting heart against I/R injury when compared with the I/R group2. Influence of NDLIP on the infarct size induced by myocardial I/R injury.Compared with I/R group, the1st d after3-d NDLIP group, the1st d after7-d NDLIP group and the1-d NDLIP+1-d INTV group decreased the IS/AAR ratio (P<0.01), and they provided similar cardioprotection to the MIPC and FAIP groups.3. Influence of NDLIP on the biochemistry after myocardial I/R injury.Compared with I/R group, the1st d after3-d NDLIP group, the1st d after7-d NDLIP group and the1-d NDLIP+1-d INTV group could decrease CK-MB, cTnI, H-FABPand GPBB(P<0.01).4. Influence of NDLIP on ROS and mitochondrial functions after myocardial I/R injury.Compared with I/R group, the NDLIP, MIPC and FAIP group could decrease ROS and MDA (P<0.05and P<0.01). Meanwhile, the three groups could elevate Mn-SOD, GSH-PX, and mitochondrial respiratory chain complex Ⅰ-Ⅳ activity (P<0.05and P<0.01).5. Influence of NDLIP on MPTP and mitoKATP after myocardial I/R injury.Compared with I/R group, the NDLIP, MIPC and FAIP group could restrain the open of MPTP and prevent the fall of Δ Ψ m(P<0.05and P<0.01). They all alleviated the swell of mitochondria, maintained the normal structure.6. Influence of NDLIP on Trx2and TrxR2after myocardial I/R injury.Compared with I/R group, the expression of the proteins and mRNA of Trx2and TrxR2was high in NDLIP, MIPC, FAIP and5-HD group(P<0.01). There was no difference in preconditioning groups.7. Influence of NDLIP on miRNA1and miRNA21after myocardial I/R injury.Compared with I/R group, the expression of miRNA1and miRNA21was increased in NDLIP, MIPC, FAIP and5-HD group(P<0.01). There was no difference in preconditioning groups.Conclusions:1. The1st d after3-d NDLIP group, the1st d after7-d NDLIP group and1-day NDLIP+1-day interval group showed an amelioration of ventricular arrhythmia, improved left ventricular function, lower ST-segment elevation, decreased the content of CK-MB, cTnI, H-FABP and GPBB, reduced myocardial infarct size, The protective effects of NDLIP disappeared in72hours, they provided similar cardioprotection to the MIPC and FAIP groups. Considering the results and its potential clinical application, we believed that NDLIP consisted from three cycles of5-minute occlusion and5-minute reperfusion of the left hind limb per day for the cycles of one consecutive day and interval of one day is the optimal strategy.2. NDLIP could decrease ROS and MDA induced by I/R, alleviate oxidation injury, elevate mitochondrial respiratory chain complex I-IVactivity, improve mitochondrial functions.3. NDLIP could restrain the the open of MPTP, enhance the the open of mitoK-ATP, modulating the the open of MPTP and mitoKATP is the one of mechanism of cardioprotection.4. NDLIP could increase the expression of the proteins and mRNA of Trx2and TrxR2after I/R.5. NDLIP could increase the expression of miRNAl and miRNA21after I/R, which are involved cardioprotection. |
PDF Full Text Request