Pyruvate prevents cardiac dysfunction and AMP-activated protein kinase activation by hydrogen peroxide in isolated rat hearts.
Ischemia-reperfusion injury in the heart results in enhanced production of H2O2 and activation of AMP-activated protein kinase (AMPK). Since mutations in AMPK result in cardiovascular dysfunction, we investigated whether the activation of AMPK mediates the H2O2-induced reduction in cardiac mechanical function. Isolated working rat hearts were perfused at 37 degrees C with Krebs-Henseleit solution. Following a 20-minute equilibration period, a single bolus of H2O2 (300 micromol/L) was added and the hearts were perfused for an additional 5 min. H2O2 induced a dramatic and progressive reduction in cardiac function. This was accompanied by rapid and significant activation of AMPK, an increase in Thr-172 phosphorylation of AMPK, and an increase in the creatine to phosphocreatine (Cr/PCr) ratio. Addition of pyruvate (5 mmol/L) to the perfusate prevented the H2O2-mediated reduction in cardiac mechanical dysfunction, activation of myocardial AMPK activity, increase in AMPK phosphorylation and the increase in the Cr/PCr ratio. Hearts challenged with H2O2 (300 micromol/L) in presence of either AMPK inhibitor Compound C (10 micromol/L) or its vehicle (dimethyl sulfoxide (DMSO), 0.1%) showed reduced impairment in cardiac mechanical function. Compound C but not its vehicle significantly inhibited myocardial AMPK activity. Thus, H2O2 induces cardiac dysfunction via both AMPK-dependent and independent mechanisms.
Leon
Hernando
H
Cardiovascular Reserach Group, Department of Pediatrics, University of Alberta, Edmonton, Canada.
Atkinson
Laura L
LL
Sawicka
Jolanta
J
Strynadka
Ken
K
Lopaschuk
Gary D
GD
Schulz
Richard
R
D055372:AMP-Activated Protein Kinases; D000249:Adenosine Monophosphate / Q000502:physiology*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D066298:In Vitro Techniques; D008297:Male; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D015428:Myocardial Reperfusion Injury / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology* / Q000517:prevention & control*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019289:Pyruvic Acid / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; D000249:Adenosine Monophosphate; D019289:Pyruvic Acid; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases