Gürel Ebru, Smeele Kirsten M, Eerbeek Otto, Koeman Anneke, Demirci Cihan, Hollmann Markus W, Zuurbier Coert J
Department of Anaesthesiology, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
J Appl Physiol (1985). 2009 Jun;106(6):1909-16. doi: 10.1152/japplphysiol.90537.2008. Epub 2009 Feb 19.
The glycolytic enzyme hexokinase (HK) is suggested to play a role in ischemic preconditioning (IPC). In the present study we determined how ischemic preconditioning affects HK activity and HKI and HKII protein content at five different time points and three different subcellular fractions throughout cardiac ischemia-reperfusion. Isolated Langendorff-perfused rat hearts (10 groups of 7 hearts each) were subjected to 35 min ischemia and 30 min reperfusion (control groups); the IPC groups were pretreated with 3 times 5-min ischemia. IPC was without effect on microsomal HK activity, and only decreased cytosolic HK activity at 35 min ischemia, which was mimicked by decreased cytosolic HKII, but not HKI, protein content. In contrast, mitochondrial HK activity at baseline and during reperfusion was elevated by IPC, without changes during ischemia. No effect of IPC on mitochondrial HK I protein content was observed. However, mitochondrial HK II protein content during reperfusion was augmented by IPC, albeit not following the IPC stimulus. It is concluded that IPC results in decreased cytosolic HK activity during ischemia that could be explained by decreased HKII protein content. IPC increased mitochondrial HK activity before ischemia and during reperfusion that was only mimicked by increased HK II protein content during reperfusion. IPC was without effect on the phosphorylation status of HK before ischemia. We conclude that IPC is associated with 1) a biphasic response of increased mitochondrial HK activity before and after ischemia, 2) decreased cytosolic HK activity during ischemia, and 3) cellular redistribution of HKII but not HKI.
糖酵解酶己糖激酶（HK）被认为在缺血预处理（IPC）中发挥作用。在本研究中，我们测定了在心脏缺血-再灌注过程中的五个不同时间点和三个不同亚细胞组分中，缺血预处理如何影响HK活性以及HKI和HKII蛋白含量。将离体Langendorff灌注大鼠心脏（每组7个心脏，共10组）进行35分钟缺血和30分钟再灌注（对照组）；IPC组预先进行3次5分钟缺血预处理。IPC对微粒体HK活性无影响，仅在缺血35分钟时降低胞质HK活性，这与胞质HKII而非HKI蛋白含量降低的情况相似。相比之下，IPC使基线和再灌注期间的线粒体HK活性升高，而在缺血期间无变化。未观察到IPC对线粒体HK I蛋白含量有影响。然而，IPC使再灌注期间的线粒体HK II蛋白含量增加，尽管不是在IPC刺激后立即增加。得出的结论是，IPC导致缺血期间胞质HK活性降低，这可以用HKII蛋白含量降低来解释。IPC使缺血前和再灌注期间的线粒体HK活性增加，这仅与再灌注期间HK II蛋白含量增加的情况相似。IPC对缺血前HK的磷酸化状态无影响。我们得出结论，IPC与以下情况相关：1）缺血前后线粒体HK活性增加的双相反应；2）缺血期间胞质HK活性降低；3）HKII而非HKI的细胞内重新分布。
