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mitoKATP channel activation in the postanoxic developing heart protects E-C coupling via NO-, ROS-, and PKC-dependent pathways

Sarre, Alexandre
Kucera, Pavel
Raddatz, Eric
Published in American journal of physiology. Heart and circulatory physiology. 2005, vol. 288, no. 4, p. H1611-H1619
Abstract Whereas previous studies have shown that opening of the mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel protects the adult heart against ischemia-reperfusion injury, it remains to be established whether this mechanism also operates in the developing heart. Isolated spontaneously beating hearts from 4-day-old chick embryos were subjected to 30 min of anoxia followed by 60 min of reoxygenation. The chrono-, dromo-, and inotropic disturbances, as well as alterations of the electromechanical delay (EMD), reflecting excitation-contraction (E-C) coupling, were investigated. Production of reactive oxygen species (ROS) in the ventricle was determined using the intracellular fluorescent probe 2',7'-dichlorofluorescin (DCFH). Effects of the specific mitoK(ATP) channel opener diazoxide (Diazo, 50 microM) or the blocker 5-hydroxydecanoate (5-HD, 500 microM), the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 50 microM), the antioxidant N-(2-mercaptopropionyl)glycine (MPG, 1 mM), and the PKC inhibitor chelerythrine (Chel, 5 microM) on oxidative stress and postanoxic functional recovery were determined. Under normoxia, the baseline parameters were not altered by any of these pharmacological agents, alone or in combination. During the first 20 min of postanoxic reoxygenation, Diazo doubled the peak of ROS production and, interestingly, accelerated recovery of ventricular EMD and the PR interval. Diazo-induced ROS production was suppressed by 5-HD, MPG, or L-NAME, but not by Chel. Protection of ventricular EMD by Diazo was abolished by 5-HD, MPG, L-NAME, or Chel, whereas protection of the PR interval was abolished by L-NAME exclusively. Thus pharmacological opening of the mitoK(ATP) channel selectively improves postanoxic recovery of cell-to-cell communication and ventricular E-C coupling. Although the NO-, ROS-, and PKC-dependent pathways also seem to be involved in this cardioprotection, their interrelation in the developing heart can differ markedly from that in the adult myocardium.
Keywords AnimalsAnoxia/metabolismAnti-Arrhythmia Agents/pharmacologyAtrioventricular Node/physiologyChick EmbryoChickensDecanoic Acids/pharmacologyDiazoxide/pharmacologyEnzyme Inhibitors/pharmacologyFree Radical Scavengers/pharmacologyGlycine/analogs & derivatives/pharmacologyHeart/embryologyHydroxy Acids/pharmacologyMembrane Proteins/metabolismMyocardial Reperfusion Injury/metabolismMyocardium/metabolismNG-Nitroarginine Methyl Ester/pharmacologyNitric Oxide/metabolismOxidative Stress/drug effects/physiologyOxygen/pharmacologyPotassium ChannelsProtein Kinase C/antagonists & inhibitors/metabolismReactive Oxygen Species/metabolismSignal Transduction/physiologySulfhydryl Compounds/pharmacologyVasodilator Agents/pharmacology
PMID: 15550517
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SARRE, Alexandre et al. mitoKATP channel activation in the postanoxic developing heart protects E-C coupling via NO-, ROS-, and PKC-dependent pathways. In: American journal of physiology. Heart and circulatory physiology, 2005, vol. 288, n° 4, p. H1611-H1619. doi: 10.1152/ajpheart.00942.2004 https://archive-ouverte.unige.ch/unige:81143

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Deposited on : 2016-03-01

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