Is creatine kinase a target for AMP-activated protein kinase in the heart?
Is creatine kinase a target for AMP-activated protein kinase in the heart?
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DOI：
10.1006/jmcc.2002.2062
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发表时间：
2002-09-01
影响因子：
5
通讯作者：
Ingwall, JS
中科院分区：
文献类型：
--
作者：
Ingwall, JS
通过磷酸化靶蛋白，AMP激活的蛋白激酶（AMPK）抑制ATP利用蛋白并激活ATP合成蛋白，从而在诸如缺氧和缺血的条件下增加ATP合成。已经提出AMPK还磷酸化和抑制肌酸激酶（CK），肌酸激酶是催化磷酸基团在肌酸和ADP之间可逆转移的酶。在这里，我们研究的假设，AMPK灭活CK活性在三种条件下，[AMP]和AMP依赖的AMPK速度增加：增加工作量在离体大鼠心脏和活大鼠，缺氧在活大鼠心脏和低流量缺血在离体红细胞灌注大鼠心脏。对于在离体大鼠心脏中改变工作负荷的实验（射血和等容模型），我们还改变了离体心脏可用的可氧化底物以改变[AMP]/[ATP]。用P-31磁化转移法直接测定了大鼠心脏CK反应速度。从P-31 NMR测量确定代谢活性AMP和ATP池，并且我们从Michaelis-Menten关系计算AMP依赖性AMPK速度。我们发现，在常氧条件下，[AMP]和AMPK速度增加。CK和AMPK速度之间的线性关系是正的，而不是反的。在低pO（2）（缺氧和低流量缺血）条件下，CK速度下降2-4倍，而AMP激活的AMPK活性增加幅度不大。该分析说明了AMPK调节心脏的复杂性，（C）2002 Elsevier Science Ltd.保留所有权利。
By phosphorylating target proteins, AMP-activated protein kinase (AMPK) inhibits ATP-utilizing proteins and activates ATP-synthesizing proteins, thereby increasing ATP synthesis under conditions such as hypoxia and ischemia. It has been proposed that AMPK also phosphorylates and inhibits creatine kinase (CK), the enzyme which catalyzes the reversible transfer of a phosphoryl group between creatine and ADP. Here, we examine the hypothesis that AMPK inactivates CK activity under three conditions where [AMP] and AMP-dependent AMPK velocity increase: increased workload both in the isolated rat heart and in the living rat, hypoxia in the living rat heart and low-flow ischemia in the isolated red blood cell perfused rat heart. For the experiments varying workload in the isolated rat heart (both ejecting and isovolumic models), we also changed oxidizable substrate available to the isolated heart in order to vary the [AMP]/[ATP]. CK reaction velocity in the intact rat heart was directly measured using P-31 magnetization transfer. The metabolically active AMP and ATP pools were determined from P-31 NMR measurements and we calculate AMP-dependent AMPK velocity from the Michaelis-Menten relationship. We found that under normoxic conditions where [AMP] and AMPK velocity increase. the linear relationship between CK and AMPK velocities is positive, not inverse. Under conditions of low pO(2) (hypoxia and low-flow ischemia), CK velocity fell 2-4-fold while the increase in AMP-activated AMPK activity was modest. This analysis illustrates the complex nature of AMPK regulation in the heart, (C) 2002 Elsevier Science Ltd. All rights reserved.