ISCHEMIC PRECONDITIONING (IPC) IS ASSOCIATED WITH ALTERED TEMPORAL AND SUBCELLULAR DISTRIBUTION OF HEXOKINASE ACTIVITY

• Published in: The FASEB journal 2007, Vol.21 (6), p.A1225-A1225
• Main Authors: Zuurbier, Coert Jozef, Gurel, Ebru, Demirci, Cihan, Eerbeek, Otto, Hollmann, Markus
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.6.A1225

Association of hexokinase (HK) with mitochondria preserves mitochondrial integrity and is an important mechanism by which cells can be protected against hypoxic conditions. In the present study we examined how HK activity is distributed over different subcellular fractions before, during and after ischemia and whether IPC is associated with altered HK distribution. Isolated Langendorff‐perfused rat hearts (10 groups of 7 each) were subjected to 35 min ischemia and 30 min reperfusion (control groups); the IPC groups were pretreated with 3 times 5 min ischemia. Hearts were homogenized at 5 min pre‐ischemia (baseline), 5 min and 35 min ischemia, and 5 min and 30 min reperfusion. HK activity was determined with spectrophotometric techniques in the mitochondrial, microsomal and cytosolic fractions and normalized to whole‐cell homogenate HK activity. At baseline, relative HK activity was 33.3 ± 1.1% (mitochondria), 28.7 ± 1.5% (microsomal) and 18.4 ± 1.2% (cytosol). IPC significantly increased HK activity in the mitochondrial fraction at baseline (from 33.3 ± 1.1% to 39.7 ± 2.4%) and at 5 min reperfusion (from 29.4 ± 2.7% to 40.6 ± 3.7%), whereas HK activity was significantly decreased in the cytosolic fraction at 35 min ischemia (from 38.9 ± 3.1% to 28.6 ± 3.2%). These results suggest a role for HK activity in discrete subcellular compartments and at discrete time points in IPC.