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Updated: Jun 25, 2026
A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion
Published on: July 17, 2012
Ischemic preconditioning affects hexokinase activity and HKII in different subcellular compartments throughout
Ebru Gürel1, Kirsten M Smeele, Otto Eerbeek
1Department of Anaesthesiology, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
Insights
Ischemic preconditioning (IPC) alters hexokinase (HK) activity and distribution in the heart. IPC decreases cytosolic HK activity during ischemia while increasing mitochondrial HK activity before and after reperfusion.
Area of Science:
- Cardiology
- Biochemistry
- Cellular Physiology
Background:
- Hexokinase (HK) is a key glycolytic enzyme implicated in ischemic preconditioning (IPC).
- Understanding HK's role in IPC is crucial for developing cardioprotective strategies.
Purpose of the Study:
- To investigate the effects of IPC on hexokinase activity and protein content (HKI and HKII) in cardiac subcellular fractions.
- To determine the temporal changes in HK activity and protein levels during ischemia-reperfusion following IPC.
Main Methods:
- Isolated Langendorff-perfused rat hearts were used, divided into control and IPC groups.
- IPC involved three cycles of 5-minute ischemia.
- Hearts were subjected to 35 minutes of ischemia and 30 minutes of reperfusion, with analyses at five time points and three subcellular fractions (cytosolic, microsomal, mitochondrial).
Main Results:
- IPC decreased cytosolic HK activity and HKII protein content during ischemia.
- Mitochondrial HK activity was elevated by IPC before ischemia and during reperfusion.
- Mitochondrial HKII protein content increased during reperfusion, suggesting a cellular redistribution of HKII but not HKI.
Conclusions:
- IPC induces a biphasic change in mitochondrial HK activity and a decrease in cytosolic HK activity during ischemia.
- The observed changes in HK activity are associated with alterations in HKII protein content and cellular localization.
- These findings highlight a potential mechanism for HK involvement in cardiac protection during ischemic events.
Abstract:
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.
