Postconditioning via stuttering reperfusion limits myocardial infarct size in rabbit hearts: role of ERK1/2
Postconditioning via stuttering reperfusion limits myocardial infarct size in rabbit hearts: role of ERK1/2
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DOI：
10.1152/ajpheart.00055.2005
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发表时间：
2005-10-01
影响因子：
4.8
通讯作者：
Przyklenk, K
中科院分区：
文献类型：
--
作者：
Darling, CE;Jiang, R;Przyklenk, K
新出现的证据表明，以断续的方式恢复血流可能会限制致命的心肌缺血-再灌注损伤。然而，这种现象的机制，称为后处理（post-C），仍然不清楚。我们的目的是验证经典的“存活激酶”，磷脂酰肌醇3-激酶（PI 3-激酶）和/或细胞外信号调节激酶（ERK）1/2的激活可能在后C诱导的心脏保护中发挥作用的假设。在方案1中，离体缓冲液灌注的兔心脏经历30分钟的持续冠状动脉闭塞，并随机接受突然再灌注（对照组）或在完全恢复血流之前再灌注30秒和再闭塞30秒的四个周期（C后）。方案2是相同的，除了对照和后处理心脏接受PI 3-激酶抑制剂LY-294002（方案2A）或ERK 1/2拮抗剂PD-98059（方案2B），而在方案3中，在再灌注的前25分钟期间从另外的对照、后处理和非缺血假心脏的再灌注的早期分钟期间获得心肌样品用于评估，通过标准免疫印迹，磷酸化Akt（PI 3-激酶的下游靶）和磷酸化ERK。方案1和2证实，与对照心脏相比，后处理心脏中的梗死面积（通过四唑染色描绘并表示为风险区域的百分比）减少，并且还显示尽管LY-294002治疗，但后C诱导的心脏保护仍得以维持，但被PD-98059废除。这些药理学数据得到了方案3的支持，方案3显示磷酸化ERK的免疫反应性增加，但磷酸化Akt与后C的免疫反应性不增加。因此，我们的研究结果表明，ERK 1/2而不是PI 3-激酶/Akt参与了后C减少梗死面积的作用。
Emerging evidence suggests that restoration of blood flow in a stuttering manner may limit lethal myocardial ischemia-reperfusion injury. However, the mechanisms contributing to this phenomenon, termed postconditioning (post-C), remain poorly defined. Our aim was to test the hypothesis that activation of classic "survival kinases," phosphatidylinositol 3-kinase (PI3-kinase) and/or extracellular signal-regulated kinase (ERK) 1/2, may play a role in post-C-induced cardioprotection. In protocol 1, isolated buffer-perfused rabbit hearts underwent 30 min of sustained coronary artery occlusion and were randomized to receive abrupt reperfusion ( controls) or four cycles of 30 s of reperfusion and 30 s of reocclusion before full restoration of flow (post-C). Protocol 2 was identical except control and postconditioned hearts received the PI3-kinase inhibitor LY-294002 ( protocol 2A) or the ERK1/2 antagonist PD-98059 ( protocol 2B) throughout the first 25 min of reperfusion, whereas in protocol 3, myocardial samples were obtained during the early minutes of reflow from additional control, postconditioned, and nonischemic sham hearts for the assessment, by standard immunoblotting, of phospho-Akt ( downstream target of PI3-kinase) and phospho-ERK. Protocols 1 and 2 corroborated that infarct size ( delineated by tetrazolium staining and expressed as a percent of risk region) was reduced in postconditioned hearts vs. control hearts and also revealed that post-C-induced cardioprotection was maintained despite LY-294002 treatment but was abrogated by PD-98059. These pharmacological data were supported by protocol 3, which showed increased immunoreactivity of phospho-ERK but not phospho-Akt with post-C. Thus our results implicate the involvement of ERK1/2 rather than PI3-kinase/Akt in the reduction of infarct size achieved with post-C.