Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University School of Medicine, South-1 West-16, Chuo-ku, Sapporo, 060-8543, Japan.
Cardiovasc Drugs Ther. 2010 Dec;24(5-6):401-8. doi: 10.1007/s10557-010-6265-5.
Erythropoietin (EPO) and its non-erythrogenic derivative, carbarmylated EPO (CEPO), have been reported to activate different receptors (homomeric EPO receptor vs. heteromeric receptor consisting of EPO receptor monomer and common β-subunit). The aim of this study was to examine differences between EPO and CEPO in efficacy of cardioprotection against infarction and in activation of pro-survival kinases.
In isolated rat hearts, infarction was induced by global ischemia followed by reperfusion. Infarct size was determined 2 h after reperfusion, and ventricular tissues for immunoblotting were sampled at 5 min after reperfusion.
Pretreatment with EPO (10 units/ml) before ischemia reduced infarct size (% of risk area; %IS/AR) from 47.0 ± 2.1% of the control after 20-min ischemia to 24.7 ± 4.3% and from 62.0 ± 3.0% after 25-min ischemia to 45.5 ± 4.1%. Desialylated EPO (asialoEPO, 100 ng/ml) mimicked the protection by EPO. However, CEPO (100 ng/ml) failed to reduce infarct size after 20-min ischemia (%IS/AR = 47.5 ± 5.9%) and that after 25-min ischemia (%IS/AR = 56.1 ± 4.2%). The infarct size-limiting effect of CEPO was not shown either by increasing CEPO dose to 500 ng/ml or by shortening ischemia to 15 min. Both EPO and CEPO enhanced phosphorylation of cytosolic GSK-3β upon reperfusion. In contrast, phosphorylation of GSK-3β, Akt, and PKC-ε in mitochondria upon reperfusion was significantly enhanced by EPO but not by CEPO.
EPO affords more potent protection against infarction than does CEPO by distinct activation of signaling leading to phosphorylation of pro-survival protein kinases in mitochondria upon reperfusion.
促红细胞生成素（EPO）及其非造血衍生的衍生物，碳化促红细胞生成素（CEPO），已被报道可激活不同的受体（同型 EPO 受体与由 EPO 受体单体和共同β亚基组成的异源受体）。本研究旨在研究 EPO 和 CEPO 在对抗梗死的心脏保护效果以及激活生存相关激酶方面的差异。
在离体大鼠心脏中，通过全缺血后再灌注诱导梗死。再灌注 2 小时后测定梗死面积，并在再灌注 5 分钟时取样心室组织进行免疫印迹。
缺血前用 EPO（10 单位/ml）预处理可使缺血 20 分钟后（缺血/危险区的%；%IS/AR）的梗死面积从 47.0±2.1%减少到 24.7±4.3%，缺血 25 分钟后（缺血/危险区的%；%IS/AR）的梗死面积从 62.0±3.0%减少到 45.5±4.1%。去唾液酸 EPO（asialoEPO，100ng/ml）模拟了 EPO 的保护作用。然而，CEPO（100ng/ml）未能减少缺血 20 分钟后的梗死面积（%IS/AR=47.5±5.9%）和缺血 25 分钟后的梗死面积（%IS/AR=56.1±4.2%）。增加 CEPO 剂量至 500ng/ml 或缩短缺血时间至 15 分钟也未显示出 CEPO 的梗死面积限制作用。EPO 和 CEPO 在再灌注时均增强细胞质 GSK-3β的磷酸化。相比之下，EPO 显著增强了再灌注时线粒体中 GSK-3β、Akt 和 PKC-ε的磷酸化，但 CEPO 没有。
EPO 通过不同的信号激活提供更强的对抗梗死的保护作用，这种激活导致再灌注时线粒体中生存相关蛋白激酶的磷酸化。
