Pyruvate prevents cardiac dysfunction and AMP-activated protein kinase activation by hydrogen peroxide in isolated rat hearts

• Published in: Canadian journal of physiology and pharmacology 2004-06, Vol.82 (6), p.409-416
• Main Authors: Leon, Hernando, Atkinson, Laura L, Sawicka, Jolanta, Strynadka, Ken, Lopaschuk, Gary D, Schulz, Richard
• Format: Article
• Language: English
• Subjects: Adenosine Monophosphate - physiology; AMP-Activated Protein Kinases; Animals; Antioxidants; Biological and medical sciences; Cardiology. Vascular system; Cardiovascular disease; Coronary heart disease; Enzyme Activation - drug effects; Enzyme Activation - physiology; Enzyme Inhibitors - pharmacology; Enzyme Inhibitors - therapeutic use; Heart; Hydrogen peroxide; Hydrogen Peroxide - toxicity; In Vitro Techniques; Male; Medical sciences; Multienzyme Complexes - antagonists & inhibitors; Multienzyme Complexes - metabolism; Myocardial Contraction - drug effects; Myocardial Contraction - physiology; Myocardial Reperfusion Injury - chemically induced; Myocardial Reperfusion Injury - enzymology; Myocardial Reperfusion Injury - physiopathology; Myocardial Reperfusion Injury - prevention & control; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - metabolism; Proteins; Pyruvic Acid - pharmacology; Pyruvic Acid - therapeutic use; Rats; Rats, Sprague-Dawley
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y04-050

Ischemia-reperfusion injury in the heart results in enhanced production of H 2 O 2 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 H 2 O 2 -induced reduction in cardiac mechanical function. Isolated working rat hearts were perfused at 37 °C with Krebs-Henseleit solution. Following a 20-minute equilibration period, a single bolus of H 2 O 2 (300 µmol/L) was added and the hearts were perfused for an additional 5 min. H 2 O 2 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 H 2 O 2 -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 H 2 O 2 (300 µmol/L) in presence of either AMPK inhibitor Compound C (10 µmol/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, H 2 O 2 induces cardiac dysfunction via both AMPK-dependent and independent mechanisms.Key words: oxidative stress, AMPK, antioxidant, isolated rat heart, pyruvate.