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BackgroundWhether upper arm remote ischemic postconditioning (RIPostC) exerts protection to kidney in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) remains unknown.MethodsSixty-four patients with STEMI were randomized to PPCI + RIPostC (n=29) and PPCI (n=35) groups. RIPostC consisting of 4 cycles of 5 minutes occlusion/reperfusion by cuff inflation/deflation of the upper arm was started within 1 minute after the first balloon dilatation. Peripheral venous blood samples were collected before PPCI and at 0.5, 8, 24, 48, and 72 hours after PPCI to detect serum creatinine (SCr) and creatine kinase-MB (CK-MB). Acute kidney injury (AKI) rate and estimated glomerular filtration rate (eGFR) were calculated. The transthoracic echocardiography was performed 7 days after PPCI to assess left ventricular ejection fraction (LVEF).ResultsThe patients in the PPCI + RIPostC group had a lower AKI rate compared with those in the PPCI group (P=0.04). The eGFR after PPCI increased in the PPCI + RIPostC group compared to the PPCI group (P<0.01). The peak of CK-MB concentration in the PPCI + RIPostC group was significantly lower than that in the PPCI group (P<0.01). The area under the curve of CK-MB decreased in the PPCI + RIPostC group compared with that in the PPCI group. LVEF in the PPCI + RIPostC group was significantly higher than that in the PPCI group (P=0.04).ConclusionUpper arm RIPostC exerts renal and cardiac protection following cardiac ischemia–reperfusion in patients with STEMI.

Myocardial ischemia and reperfusion (MIR) results in cardiomyocyte apoptosis with severe outcomes, which blocks cardiac tissue recovering from myocardial ischemia diseases. Heat shock protein 70 (HSP70) is one of protective molecule chaperones which could regulate the nucleus translocation of other proteins. In addition, eukaryotic elongation factor 2 (eEF2), which modulates protein translation process, is vital to the recovery of heart during MIR. However, the relationship between HSP70 and eEF2 and its effects on MIR are unclear. The expression and relationship between HSP70 and eEF2 is confirmed by western blot, immunoprecipitation in vitro using cardiomyocyte cell line H9c2 and in vivo rat MIR model. The further investigation was conducted in H9c2 cells with detection for cell-cycle and apoptosis. It is revealed that eEF2 interacted and be regulated by HSP70, which kept eEF2 as dephosphorylated status and preserved the function of eEF2 during MIR. In addition, HSP70 suppressed the nucleus translocation of phosphorylated eEF2, which inhibited cardiomyocyte apoptosis during myocardial reperfusion stage. Furthermore, HSP70 also interacted with C-terminal fragment of eEF2, which could reverse the nucleus translocation and cardiomyocyte apoptosis caused by N-terminal fragment of eEF2. HSP70 draw on advantage and avoid defect of MIR through regulating phosphorylation and nucleus translocation of eEF2.

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