Akt activation induced by an antioxidant compound during ischemia-reperfusion.
Molecular mechanisms of cardioprotection afforded by modified mexiletine compounds were investigated during ischemia-reperfusion (IR) in Langendorff perfused hearts. Rat hearts were subjected to a global 25 min ischemia followed by reperfusion, either untreated or treated with mexiletine, or three substituted mexiletine derivates (5 muM). A modified mexiletine derivative (H-2693) promoted best the recovery of myocardial energy metabolism (assessed by (31)P NMR spectroscopy) compared to untreated and mexiletine-treated hearts. H-2693 also preserved cardiac contractile function and attenuated the IR-induced lipid peroxidation (TBARS formation) and protein oxidation (carbonyl content). Western blot revealed that H-2693 propagated the phosphorylation of Akt (activation) and its downstream substrate glycogen synthase kinase-3beta (GSK-3beta, inactivation) compared to untreated IR. Parallel treatment with the phosphatidylinositol-3-kinase (upstream activator of Akt) inhibitor wortmannin (100 nM) abolished the beneficial effects of H-2693 on energetics and function, and reduced Akt and GSK-3beta phosphorylation. As a result of the antiapoptotic impacts of Akt activation, H-2693 decreased caspase-3 activity, which was neutralized by wortmannin. Here we first demonstrated that a free radical-entrapping compound could activate the prosurvival Akt pathway beyond its proven ability to scavenge reactive oxygen species. In conclusion, the favorable influence of H-2693 on signaling events during IR may have considerably contributed to its cardioprotective effect.
Toth
Ambrus
A
Department of Biochemistry and Medical Chemistry, University of Pecs Medical School, Pecs, Hungary.
Halmosi
Robert
R
Kovacs
Krisztina
K
Deres
Peter
P
Kalai
Tamas
T
Hideg
Kalman
K
Toth
Kalman
K
Sumegi
Balazs
B
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D017665:Hydroxyl Radical / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008801:Mexiletine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D015394:Molecular Structure; D009200:Myocardial Contraction / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D013481:Superoxides / Q000378:metabolism; D000077191:Wortmannin
D000730:Androstadienes; D000975:Antioxidants; D053148:Caspase 3; D020169:Caspases; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D017665:Hydroxyl Radical; D008801:Mexiletine; D019869:Phosphatidylinositol 3-Kinases; D010725:Phosphocreatine; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011758:Pyrroles; D013481:Superoxides; D000077191:Wortmannin; C487011:2,2,5,5-tetramethyl-N-(1-methyl-2-(2,6-dimethylphenoxy)ethyl)-2,5-dihydro-1H-pyrrole-3-carboxamide; C494920:Akt1 protein, rat; C000605508:Gsk3b protein, rat; C505410:Casp3 protein, rat