ABSTRACT
We studied the effects of in vivo modulation of activity of mitochondrial ATP-dependent potassium channel (mitoKATP) by uridine on the morphofunctional state of mitochondria in rat cardiomyocytes under conditions of acute hypoxia. Preinjection of uridine to animals reduced the number of structurally modified mitochondria, but had practically no effect on their morphogenesis after hypoxia. Uridine in vivo stimulated the formation of micromitochondria and their release into the cytoplasm. The number of "maternal" mitochondria containing three and more new micromitochondria, increased as well. The use of mitoKATP blocker 5-hydroxydecanoate in parallel with uridine abolished its protective effect, as it significantly inhibited the formation of micromitochondria in rat cardiomyocytes after acute hypoxic exposure.
Subject(s)
Hypoxia/metabolism , Myocardium/metabolism , Potassium Channels/metabolism , Uridine/pharmacology , Animals , Cell Hypoxia , Decanoic Acids/antagonists & inhibitors , Decanoic Acids/pharmacology , Hydroxy Acids/antagonists & inhibitors , Hydroxy Acids/pharmacology , Hypoxia/drug therapy , Hypoxia/pathology , Male , Mitochondria, Heart/drug effects , Mitochondria, Heart/metabolism , Mitochondria, Heart/pathology , Myocardium/pathology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , Myocytes, Cardiac/pathology , Potassium Channel Blockers/pharmacology , Rats , Rats, WistarABSTRACT
Hydrogen sulfide (H2S) is a novel gaseous mediator produced by cystathionine-beta-synthase and cystathionine-gamma-lyase in the cardiovascular system, including the heart. Using a rat model of regional myocardial ischemia/reperfusion, we investigated the effects of an H2S donor (sodium hydrogen sulfide [NaHS]) on the infarct size and apoptosis caused by ischemia (25 min) and reperfusion (2 h). Furthermore, we investigated the potential mechanism(s) of the cardioprotective effect(s) afforded by NaHS. Specifically, we demonstrate that NaHS (1) attenuates the increase in caspase 9 activity observed in cardiac myocytes isolated from the area at risk (AAR) of hearts subjected in vivo to regional myocardial I/R and (2) ameliorates the decrease in expression of Bcl-2 within the AAR obtained from rat hearts subjected to regional myocardial I/R. The cardioprotective effects of NaHS were abolished by 5-hydroxydeconoate, a putative mitochondrial adenosine triphosphate-sensitive potassium channel blocker. Furthermore, NaHS attenuated the increase in the I/R-induced (1) phosphorylation of p38 mitogen-activated protein kinase and Jun N-terminal kinase, (2) translocation from the cytosol to the nucleus of the p65 subunit of nuclear factor-kappaB, (3) intercellular adhesion molecule 1 expression, (4) polymorphonuclear leukocyte accumulation, (5) myeloperoxidase activity, (6) malondialdehyde levels, and (7) nitrotyrosine staining determined in the AAR obtained from rat hearts subjected to regional myocardial I/R. In conclusion, we demonstrate that the cardioprotective effect of NaHS is secondary to a combination of antiapoptotic and anti-inflammatory effects. The antiapoptotic effect of NaHS may be in part due to the opening of the putative mitochondrial adenosine triphosphate-sensitive potassium channels.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Apoptosis/drug effects , Cardiotonic Agents/pharmacology , Muscle Proteins/metabolism , Myocardial Reperfusion Injury/prevention & control , Sulfides/pharmacology , Active Transport, Cell Nucleus/drug effects , Animals , Anti-Arrhythmia Agents/antagonists & inhibitors , Anti-Arrhythmia Agents/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/antagonists & inhibitors , Cardiotonic Agents/antagonists & inhibitors , Cell Nucleus/metabolism , Cell Nucleus/pathology , Decanoic Acids/antagonists & inhibitors , Decanoic Acids/pharmacology , Disease Models, Animal , Drug Antagonism , Hydroxy Acids/antagonists & inhibitors , Hydroxy Acids/pharmacology , Male , Malondialdehyde/metabolism , Myocardial Reperfusion Injury/metabolism , Myocardial Reperfusion Injury/pathology , Neutrophils/metabolism , Neutrophils/pathology , Phosphorylation , Rats , Rats, Wistar , Sulfides/antagonists & inhibitors , Tyrosine/analogs & derivatives , Tyrosine/metabolismABSTRACT
We studied the blocking mechanism of 5-hydroxydecanoate, a novel antiarrhythmic agent, on the ATP-sensitive K+ channel in the single ventricular myocytes using the inside-out patch clamp technique. The channel activity in response to 5-hydroxydecanoate varied with each membrane patch corresponding to the sensitivity to ATP. In this condition the exogenous application of cAMP or cAMP-dependent protein kinase (PKA) obviously recovered the ATP-sensitive K+ channel activity after channel deactivation. By contrast, in membrane patches exhibited low sensitivity to ATP, endogenous cAMP-dependent protein kinase inhibitor (PKI) depressed the channel activity and restored the inhibitory action of 5-hydroxydecanoate and ATP on the channel. These results suggest that PKA-PKI system is involved in the regulatory mechanism of gating activity of the ATP-sensitive K+ channel and the blocking action of 5-hydroxydecanoate and ATP appears to be exerted by potentiating the inhibitory action of PKI on the channel.
Subject(s)
Adenosine Triphosphate/antagonists & inhibitors , Anti-Arrhythmia Agents/antagonists & inhibitors , Carrier Proteins/physiology , Decanoic Acids/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Hydroxy Acids/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins , Potassium Channels/drug effects , Adenosine Triphosphate/pharmacology , Animals , Anti-Arrhythmia Agents/pharmacology , Carrier Proteins/pharmacology , Cyclic AMP/pharmacology , Decanoic Acids/pharmacology , Guinea Pigs , Heart Ventricles/drug effects , Hydroxy Acids/pharmacology , Membrane Potentials/drug effects , Protein Kinases/pharmacology , Protein Kinases/physiologyABSTRACT
All acidic non-steroidal anti-inflammatory drugs suppress the activity of microsomal cyclo-oxygenase of arachidonic acid; therefore, these drugs are equipotent inhibitors of prostaglandin and thromboxane generation. A non-acidic anti-inflammatory agent, 1'-(isopropyl-2-indolyl)-3-pyridyl-3-ketone (L 8027), selectively inhibits biosynthesis of thromboxane A2 in blood platelets and in lungs.
