Erythropoietin affords additional cardioprotection to preconditioned hearts by enhanced phosphorylation of glycogen synthase kinase-3β
Erythropoietin affords additional cardioprotection to preconditioned hearts by enhanced phosphorylation of glycogen synthase kinase-3β
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DOI：
10.1152/ajpheart.00837.2005
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发表时间：
2006-08-01
影响因子：
4.8
通讯作者：
Shimamoto, Kazuaki
中科院分区：
文献类型：
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作者：
Nishihara, Masahiro;Miura, Tetsuji;Shimamoto, Kazuaki
本研究的目的是确定促红细胞生成素(EPO)是否通过促进Akt、STAT3或糖原合成酶-3β(GSK-3β)的磷酸化而对预适应心肌提供额外的心脏保护。缺血5min/再灌流5min的预适应(PC)和EPO(5,000 U/kg iv)可使大鼠在体心肌缺血20min后的心肌梗死面积(AS%)由56.5±1.8%降至25.2+/-2.1%，EPO(5,000 U/kg)静注后降至36.2+/-2.8%。蛋白激酶C抑制剂白屈菜红碱(5 mg/kg)显著抑制PC诱导的保护作用，而磷脂酰肌醇-3-激酶抑制剂Wortmannin(15µg/kg)则轻微减弱PC诱导的保护作用。对于EPO诱导的保护，则观察到相反的抑制模式。PC和EPO联合应用可使IS/AR进一步降低至8.9+/-1.9%，白屈菜红碱和Wortmannin可抑制这一保护作用。PC和EPO对心肌梗死面积的相加作用反映在其对再灌流5min时磷酸化GSK-3β水平的影响，而对磷酸化Akt或磷酸化STAT3水平的影响不明显。为了模拟磷酸化对GSK-3β活性的抑制作用，在缺血前或再灌流前5分钟给予GSK-3β抑制剂SB-216763(SB)。缺血前注射(%IS/AR=40.4+/-2.2%，Sb 0.6 mg/kg和1.2 mg/kg Sb，%IS/AR=34.0+/-1.8%)和预灌注组(%IS/AR=32.0+/-2.0%，1.2 mg/kg Sb)均能显著缩小心肌梗死面积。这些结果提示EPO和PC在再灌流时通过Akt依赖和非依赖机制对GSK-3β的附加磷酸化而发挥附加的限制梗塞面积的作用。
The aim of this study was to determine whether erythropoietin (EPO) affords additional cardioprotection to the preconditioned myocardium by enhanced phosphorylation of Akt, STAT3, or glycogen synthase kinase-3 beta (GSK-3 beta). Preconditioning (PC) with 5-min ischemia/5-min reperfusion and EPO (5,000 U/kg iv) reduced infarct size (as % of area at risk, % IS/AR) after 20-min ischemia in rat hearts in situ from 56.5 +/- 1.8% to 25.2 +/- 2.1% and to 36.2 +/- 2.8%, respectively. PC-induced protection was significantly inhibited by a protein kinase C inhibitor, chelerythrine (5 mg/kg), and slightly blunted by a phosphatidylinositol-3-kinase inhibitor, wortmannin (15 mu g/kg). The opposite pattern of inhibition was observed for EPO-induced protection. The combination of PC and EPO further reduced % IS/AR to 8.9 +/- 1.9%, and this protection was inhibited by chelerythrine and wortmannin. The additive effects of PC and EPO on infarct size were mirrored by their effects on the level of phosphorylated GSK-3 beta at 5 min after reperfusion but not their effects on the level of phospho-Akt or phospho-STAT3. To mimic phosphorylation-induced inhibition of GSK-3 beta activity, SB-216763 (SB), a GSK-3 beta inhibitor, was administered before ischemia or 5 min before reperfusion. Infarct size was significantly reduced by preischemic injection (% IS/AR = 40.4 +/- 2.2% by 0.6 mg/kg SB and 34.0 +/- 1.8% by 1.2 mg/kg SB) and also by prereperfusion injection (% IS/AR = 32.0 +/- 2.0% by 1.2 mg/kg SB). These results suggest that EPO and PC afford additive infarct size-limiting effects by additive phosphorylation of GSK-3 beta at the time of reperfusion by Akt-dependent and -independent mechanisms.