title: Reducing mitochondrial bound hexokinase II mediates transition from non-injurious into injurious ischemia/reperfusion of the intact heart.
abstract: Ischemia/reperfusion (I/R) of the heart becomes injurious when duration of the ischemic insult exceeds a certain threshold (approximately ≥20 min). Mitochondrial bound hexokinase II (mtHKII) protects against I/R injury, with the amount of mtHKII correlating with injury. Here, we examine whether mtHKII can induce the transition from non-injurious to injurious I/R, by detaching HKII from mitochondria during a non-injurious I/R interval. Additionally, we examine possible underlying mechanisms (increased reactive oxygen species (ROS), increased oxygen consumption (MVO2) and decreased cardiac energetics) associated with this transition. Langendorff perfused rat hearts were treated for 20 min with saline, TAT-only or 200 nM TAT-HKII, a peptide that translocates HKII from mitochondria. Then, hearts were exposed to non-injurious 15-min ischemia, followed by 30-min reperfusion. I/R injury was determined by necrosis (LDH release) and cardiac mechanical recovery. ROS were measured by DHE fluorescence. Changes in cardiac respiratory activity (cardiac MVO2and efficiency and mitochondrial oxygen tension (mitoPO2) using protoporphyrin IX) and cardiac energetics (ATP, PCr, ∆GATP) were determined following peptide treatment. When exposed to 15-min ischemia, control hearts had no necrosis and 85% recovery of function. Conversely, TAT-HKII treatment resulted in significant LDH release and reduced cardiac recovery (25%), indicating injurious I/R. This was associated with increased ROS during ischemia and reperfusion. TAT-HKII treatment reduced MVO2and improved energetics (increased PCr) before ischemia, without affecting MVO2/RPP ratio or mitoPO2. In conclusion, a reduction in mtHKII turns non-injurious I/R into injurious I/R. Loss of mtHKII was associated with increased ROS during ischemia and reperfusion, but not with increased MVO2or decreased cardiac energetics before damage occurs.
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Rianne
authors.initials: R
authors.lastname: Nederlof
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.|Department of Biology, Faculty of Science, University of Istanbul, 34134, Fatih, Istanbul, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Gürel-Gurevin
authors.affiliation: Department of Physiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Otto
authors.initials: O
authors.lastname: Eerbeek
authors.affiliation: Cardiovascular Research Center, Mt. Sinai School of Medicine, New York, NY, 10029, USA.
authors.forename: Chaoqin
authors.initials: C
authors.lastname: Xie
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: G Sjoerd
authors.initials: GS
authors.lastname: Deijs
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Moritz
authors.initials: M
authors.lastname: Konkel
authors.affiliation: Cardiovascular Research Center, Mt. Sinai School of Medicine, New York, NY, 10029, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Nina C
authors.initials: NC
authors.lastname: Weber
authors.affiliation: Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Cees A
authors.initials: CA
authors.lastname: Schumacher
authors.affiliation: Department of Clinical and Experimental Cardiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Antonius
authors.initials: A
authors.lastname: Baartscheer
authors.affiliation: Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, 's Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands.
authors.forename: Egbert G
authors.initials: EG
authors.lastname: Mik
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Markus W
authors.initials: MW
authors.lastname: Hollmann
authors.affiliation: Cardiovascular Research Center, Mt. Sinai School of Medicine, New York, NY, 10029, USA.
authors.forename: Fadi G
authors.initials: FG
authors.lastname: Akar
authors.affiliation: Laboratory of Experimental Intensive Care and Anesthesiology (L.E.I.C.A.), Department of Anesthesiology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. c.j.zuurbier@amc.uva.nl.
authors.forename: Coert J
authors.initials: CJ
authors.lastname: Zuurbier
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism; D006593:Hexokinase / Q000378:metabolism*; D008297:Male; D008929:Mitochondria, Heart / Q000201:enzymology*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010725:Phosphocreatine / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D006593:Hexokinase
keywords: Hexokinase; Ischemia/reperfusion injury; Oxygen consumption; Reactive oxygen species