[Cardioprotection of recombinant human erythropoietin pretreatment on ischemia-reperfused hearts and mechanism thereof: experiment with rats].
OBJECTIVE
To study the cardioprotective effects of recombinant human erythropoietin (rhEPO) on heart with ischemia-reperfusion (I-R) injury and the possible mechanism.


METHODS
156 SD rats, except 36 in the sham operation group, underwent ligation of the left descending coronary artery for 30 minutes and then reperfusion for 3 hours. 108 rats were randomly divided into 3 equal groups IR + rhEPO group (Group C, intraperitoneally injected with rhEPO 5000 U/kg 24 h before IR insult), IR group (Group B), and sham-operation group (Group A). By the end of reperfusion blood sample were collected by cardiac puncture to detect the plasma content of MB isoenzyme of creatine kinase (CK-MB). Before ischemia, after ischemia, and 30, 60, 120, and 180 min after reperfusion the hearts of 6 rats from each group were killed respectively with their hearts taken out. Another 12 rats were randomly divided into Groups B and C as described above to undergo IR insult, and underwent re-ligation, intravenous injection of Evans blue and pathological examination to observe the area of infarct size. Another 18 rats were divided into 3 equal groups: Groups A, B, and C as described above, and then underwent electron microscopy to observe the ultrastructure of the myocardium. Furthermore, another 18 rats were divided into 3 equal groups: Groups A, B, and C as described above to undergo pathological examination of the heart and neutrophil infiltration. Tumor necrosis-alpha (TNF-alpha) and interleukin-6 (IL-6) concentrations of left ventricle were analyzed by ELISA 1 h and 2 h after reperfusion respectively; and nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1) levels were detected by electrophoretic mobility shift assay.


RESULTS
The ratio of infarct size to area at risk (IS%) of Group C was (28.0% +/- 1.3%), significantly lower than that of Group B [(43.3 +/- 2.5)%, P < 0.01]. The plasma CK-MB concentrations of Groups B and C were (2110 +/- 245) U/L and (1689 +/- 138) U/L respectively, both significantly higher than that of Group A [(933 +/- 88) U/L, both P < 0.01], however, the CK-MB level of Group C was significantly lower than that of Group B (P < 0.01). The pathological changes of Group C were remarkably milder than those of Group B. The semi-quantitative scale of Groups B and C were 3.65 +/- 0.51 and 2.37 +/- 0.49 respectively, both significantly higher than that of Group A (1.76 +/- 0.43), and the semi-quantitative scale of Groups C was significantly lower than that of Group B (P < 0.01). The degree of neutrophil infiltration of Group C was remarkably milder than that of Group B. In Group B there were 2 peaks of NF-kappaB expression: 30 min and 180 min after reperfusion, and the AP-1 expression increased 30 min after reperfusion and then gradually decreased. In Group C the expression levels of NF-kappaB and AP-1 increased 30 min after reperfusion in comparison with Group A, and then gradually decreased and were all significantly lower than those of Group B (all P < 0.01). The levels of TNF-alpha and IL-6 1 h after reperfusion of Groups B and C were all significantly higher than those of Group A (all P < 0.01) and the TNF-alpha and IL-6 of Group C were both significantly lower than those of Group B (both P < 0.01).


CONCLUSIONS
RhEPO pretreatment can elicit potent cardioprotection against I-R injury, which may due in part to the suppression of NF-kappaB and AP-1 activation and downregulation of the downstream proinflammatory cytokines.
Liu
Xiao-Ming
XM
Department of Anesthesiology, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
Jia
Zhen
Z
Zhou
Zhi-Qiang
ZQ
Xu
Jian-Guo
JG
D000818:Animals; D004921:Erythropoietin / Q000627:therapeutic use*; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D046529:Microscopy, Electron, Transmission; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D016328:NF-kappa B / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016328:NF-kappa B; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D004921:Erythropoietin