title: Glucose uptake and glycogen levels are increased in pig heart after repetitive ischemia.
abstract: Repetitive myocardial ischemia increases glucose uptake, but the effect on glycogen is unclear. Thirteen swine instrumented with a hydraulic occluder on the circumflex (Cx) artery underwent 10-min occlusions twice per day for 4 days. After 24 h postfinal ischemia and in the fasted state, echocardiogram and positron emission tomography imaging for blood flow ([(13)N]-ammonia) and 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) uptake were obtained. Tissue was then collected for ATP, creatine phosphate (CP), glycogen, and glucose transporter-4 content, and hexokinase activity. After reperfusion, regional function and CP-to-ATP ratios in the Cx and remote regions were similar. Despite the absence of stunning, the Cx region demonstrated higher glycogen levels (33 +/- 11 vs. 24 +/- 11 micromol/g; P < 0.05), and this increase correlated well with the increase in FDG uptake (r(2) = 0.78; P < 0.01). Hexokinase activity was also increased relative to remote regions (0.62 +/- 0.29 vs. 0.37 +/- 0.19 IU/g; P < 0.05), with no difference in GLUT-4 content. In summary, 24 h after repetitive ischemia, glucose uptake and glycogen levels are increased at a time that functional and bioenergetic markers of stunning have recovered. The significant correlation between glycogen content and FDG accumulation in the postischemic region suggests that increased rates of glucose transport and/or phosphorylation are linked to increased glycogen levels in hearts subjected to repetitive bouts of ischemia.
authors.affiliation: Cardiology Dept., 111C, Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN 55417, USA. mcfal001@tc.umn.edu
authors.forename: Edward O
authors.initials: EO
authors.lastname: McFalls
authors.forename: Bilal
authors.initials: B
authors.lastname: Murad
authors.forename: Jeih-San
authors.initials: JS
authors.lastname: Liow
authors.forename: Mary C
authors.initials: MC
authors.lastname: Gannon
authors.forename: Howard C
authors.initials: HC
authors.lastname: Haspel
authors.forename: Alex
authors.initials: A
authors.lastname: Lange
authors.forename: David
authors.initials: D
authors.lastname: Marx
authors.forename: Joseph
authors.initials: J
authors.lastname: Sikora
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Ward
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000641:Ammonia / Q000493:pharmacokinetics; D000818:Animals; D001692:Biological Transport; D003326:Coronary Circulation / Q000502:physiology; D004452:Echocardiography; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism*; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology; D006593:Hexokinase / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D017202:Myocardial Ischemia / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010725:Phosphocreatine / Q000378:metabolism; D013552:Swine; D014055:Tomography, Emission-Computed
chemical_list: D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D009587:Nitrogen Isotopes; D010725:Phosphocreatine; D019788:Fluorodeoxyglucose F18; D000641:Ammonia; D000255:Adenosine Triphosphate; D006003:Glycogen; D006593:Hexokinase; D005947:Glucose