atractyloside and Myocardial-Infarction

Morphine induces myocardial preconditioning (M-PC) via activation of mitochondrial large conductance Ca2+-sensitive potassium (mKCa) channels. An upstream regulator of mKCa channels is protein kinase A (PKA). Furthermore, mKCa channel activation regulates mitochondrial bioenergetics and thereby prevents opening of the mitochondrial permeability transition pore (mPTP). Here, we investigated in the rat heart in vivo whether 1) M-PC is mediated by activation of PKA, and 2) pharmacological opening of the mPTP abolishes the cardioprotective effect of M-PC and 3) M-PC is critically dependent on STAT3 activation, which is located upstream of mPTP within the signalling pathway.. Male Wistar rats were randomised to six groups (each n = 6). All animals underwent 25 minutes of regional myocardial ischemia and 120 minutes of reperfusion. Control animals (Con) were not further treated. Morphine preconditioning was initiated by intravenous administration of 0.3 mg/kg morphine (M-PC). The PKA blocker H-89 (10 μg/kg) was investigated with and without morphine (H-89+M-PC, H-89). We determined the effect of mPTP opening with atractyloside (5 mg/kg) with and without morphine (Atr+M-PC, Atr). Furthermore, the effect of morphine on PKA activity was tested in isolated adult rat cardiomyocytes. In further experiments in isolated hearts we tested the protective properties of morphine in the presence of STAT3 inhibition, and whether pharmacological prevention of the mPTP-opening by cyclosporine A (CsA) is cardioprotective in the presence of STAT3 inhibition.. Morphine reduced infarct size from 64±5% to 39±9% (P<0.05 vs. Con). H-89 completely blocked preconditioning by morphine (64±9%; P<0.05 vs. M-PC), but H-89 itself had not effect on infarct size (61±10%; P>0.05 vs. Con). Also, atractyloside abolished infarct size reduction of morphine completely (65±9%; P<0.05 vs. M-PC) but had no influence on infarct size itself (64±5%; P>0.05 vs. Con). In isolated hearts STAT3 inhibitor Stattic completely abolished morphine-induced preconditioning. Administration of Stattic and mPTP inhibitor cyclosporine A reduced infarct size to 31±6% (Stat+CsA, P<0.05 vs. Con). Cyclosporine A alone reduced infarct size to 26±7% (CsA P<0.05 vs. Con). In cardiomyocytes, PKA activity was increased by morphine.. Our data suggest that morphine-induced cardioprotection is mediated by STAT3-activation and inhibition of mPTP, with STA3 located upstream of mPTP. There is some evidence that protein kinase A is involved within the signalling pathway.

Topics: Animals; Atractyloside; Cardiotonic Agents; Cyclic AMP-Dependent Protein Kinases; Cyclosporine; Energy Metabolism; In Vitro Techniques; Ischemic Preconditioning, Myocardial; Isoquinolines; Male; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Morphine; Myocardial Infarction; Myocardial Ischemia; Myocytes, Cardiac; Random Allocation; Rats, Wistar; Reperfusion; Signal Transduction; STAT3 Transcription Factor; Sulfonamides

Previous studies in our laboratory suggest that an acute inhibition of glycogen synthase kinase 3 (GSK3) by SB-216763 (SB21) is cardioprotective when administered just before reperfusion. However, it is unknown whether the GSK inhibitor SB21 administered 24 h before ischemia is cardioprotective and whether the mechanism involves ATP-sensitive potassium (K(ATP)) channels and the mitochondrial permeability transition pore (MPTP). Male Sprague-Dawley rats were administered the GSK inhibitor SB21 (0.6 mg/kg) or vehicle 24 h before ischemia. Subsequently, the rats were acutely anesthetized with Inactin and underwent 30 min of ischemia and 2 h of reperfusion followed by infarct size determination. Subsets of rats received either the sarcolemmal K(ATP) channel blocker HMR-1098 (6 mg/kg), the mitochondrial K(ATP) channel blocker 5-hydroxydecanoic acid (5-HD; 10 mg/kg), or the MPTP opener atractyloside (5 mg/kg) either 5 min before SB21 administration or 5 min before reperfusion 24 h later. The infarct size was reduced in SB21 compared with vehicle (44 +/- 2% vs. 61 +/- 2%, respectively; P < 0.01). 5-HD administered either before SB21 treatment or 5 min before reperfusion the following day abrogated SB21-induced protection (54 +/- 4% and 61 +/- 2%, respectively). HMR-1098 did not affect the SB21-induced infarct size reduction when administered before the SB21 treatment (43 +/- 1%); however, HMR-1098 partially abrogated the SB21-induced infarct size reduction when administered just before reperfusion 24 h later (52 +/- 1%). The MPTP opening either before SB21 administration or 5 min before reperfusion abrogated the infarct size reduction produced by SB21 (61 +/- 2% and 62 +/- 2%, respectively). Hence, GSK inhibition reduces infarct size when given 24 h before the administration via the opening K(ATP) channels and MPTP closure.

Topics: Animals; Atractyloside; Benzamides; Blood Gas Analysis; Blood Pressure; Cardiotonic Agents; Glycogen Synthase Kinase 3; Heart Rate; Indoles; KATP Channels; Male; Maleimides; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Ischemia; Potassium Channel Blockers; Rats; Rats, Sprague-Dawley

The anesthetic noble gas, xenon, produces cardioprotection. We hypothesized that other noble gases without anesthetic properties [helium (He), neon (Ne), argon (Ar)] also produce cardioprotection, and further hypothesized that this beneficial effect is mediated by activation of prosurvival signaling kinases [including phosphatidylinositol-3-kinase, extracellular signal-regulated kinase, and 70-kDa ribosomal protein s6 kinase] and inhibition of mitochondrial permeability transition pore (mPTP) opening in vivo.. Rabbits (n = 98) instrumented for hemodynamic measurement and subjected to a 30-min left anterior descending coronary artery (LAD) occlusion and 3 h reperfusion received 0.9% saline (control), three cycles of 70% He-, Ne-, or Ar-30% O2 administered for 5 min interspersed with 5 min of 70% N2-30% O2 before LAD occlusion, or three cycles of brief (5 min) ischemia interspersed with 5 min reperfusion before prolonged LAD occlusion and reperfusion (ischemic preconditioning). Additional groups of rabbits received selective inhibitors of phosphatidylinositol-3-kinase (wortmannin; 0.6 mg/kg), extracellular signal-regulated kinase (PD 098059; 2 mg/kg), or 70-kDa ribosomal protein s6 kinase (rapamycin; 0.25 mg/kg) or mPTP opener atractyloside (5 mg/kg) in the absence or presence of He pretreatment.. He, Ne, Ar, and ischemic preconditioning significantly (P < 0.05) reduced myocardial infarct size [23% +/- 4%, 20% +/- 3%, 22% +/- 2%, 17% +/- 3% of the left ventricular area at risk (mean +/- sd); triphenyltetrazolium chloride staining] versus control (45% +/- 5%). Wortmannin, PD 098059, rapamycin, and atractyloside alone did not affect infarct size, but these drugs abolished He-induced cardioprotection.. The results indicate that noble gases without anesthetic properties produce cardioprotection by activating prosurvival signaling kinases and inhibiting mPTP opening in rabbits.

Topics: Androstadienes; Animals; Argon; Atractyloside; Cardiotonic Agents; Disease Models, Animal; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Heart Ventricles; Helium; Ischemic Preconditioning, Myocardial; Male; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Neon; Noble Gases; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Protein Kinases; Rabbits; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Sirolimus; Wortmannin

Mitochondrial permeability transition (MPT) pores have recently been implicated as a potential mediator of myocardial ischemic injury. Nitric oxide (NO) donors induce a powerful late phase of cardioprotection against ischemia-reperfusion injury; however, the cellular mechanisms involved are poorly understood. The role of MPT pores as a target of cardioprotective signaling pathways activated by NO has never been explored in detail. Thus mice were administered the NO donor diethylenetriamine (DETA)/NO (4 doses of 0.1 mg/kg i.v. each) 24 h before 30 min of coronary artery occlusion followed by 24 h of reperfusion. Infarct size was significantly reduced in DETA/NO-treated mice (30 +/- 2% of risk region in treated mice vs. 50 +/- 2% in control mice; P < 0.05), which demonstrates powerful cardioprotection. To examine the role of MPT pores, mice were administered atractyloside (Atr; 25 mg/kg i.v.), which induces adenine nucleotide translocase-dependent MPT, 20 min before ischemia. Atr blocked the infarct-sparing effects of DETA/NO (infarct size, 58 +/- 1 vs. 30 +/- 2% of risk region in DETA/NO; P < 0.05), whereas Atr alone had no effect. Mitochondria isolated from DETA/NO-treated mice exhibited increased resistance to Ca(2+)-induced swelling by 20 micromol/l CaCl(2) or by the higher concentration of 200 micromol/l, which suggests that cardioprotection involves decreased propensity for MPT. Preincubation of mitochondria from control hearts with 30 nmol/l of the pore inhibitor cyclosporin A prevented swelling by 200 micromol/l CaCl(2), thereby confirming that Ca(2+) induces mitochondrial swelling via MPT. In accordance with the effects on infarct size, administration of Atr to the mice significantly abrogated DETA/NO-induced protection against Ca(2+)-induced mitochondrial swelling. These phenotypic alterations were associated with an increase in the antiapoptotic protein Bcl-2, which suggests that the underlying mechanisms may involve inhibition of cell death by Bcl-2. These data suggest that a critical process during NO donor-induced cardioprotection is to prevent MPT pore opening potentially via targeting of the adenine nucleotide translocator.

Topics: Animals; Atractyloside; Calcium; Cardiotonic Agents; Enzyme Inhibitors; Male; Mice; Mice, Inbred ICR; Mitochondria; Mitochondrial Swelling; Myocardial Infarction; Myocardium; Nitric Oxide; Nitric Oxide Donors; Polyamines; Proto-Oncogene Proteins c-bcl-2; Up-Regulation

The opening of mitochondrial permeability transition pore (PTP) during reperfusion injury of heart has been well demonstrated and thus controlling PTP would attenuate the myocardial damage and cell death. Ursodeoxycholic acid (UDCA) is a hydrophilic bile salt and has been shown to prevent apoptosis in hepatocytes by inhibiting the opening of PTP. Here we demonstrate the role of UDCA in preventing the reperfusion injury of heart through its ability to inhibit PTP. Wistar rats underwent 30 min left coronary artery occlusion (LCA) followed by 180 min reperfusion after treatment with 40 mg/kg per iv infusion of UDCA over 30 min before LCA occlusion. Other groups of rats were treated with PTP agonist atractyloside(5 mg/kg) or PI3 kinase inhibitor wortmannin (16 ug/kg) before UDCA treatment. UDCA treatment prior to LCA occlusion, activated phosphorylation of Akt and Bad. Phosphorylating Bad prevented its translocation in to mitochondria, there by preventing the down regulation of Bcl-2 expression and PTP opening. This was confirmed by reduced cytochrome C release from intramitochondrial space in to the cytosol and hence reduced cell death either by apoptosis (4.8 vs 11.8%, P<0.001, UDCA treated against control group) or necrosis (reduced MI area in UDCA treated group (22.1%) compared to control group(46.4%), P<0.001). In contrast, inhibition of Akt activation with PI3K inhibitor wortmannin or opening the PTP with atractyloside abolished, UDCA mediated cytoprotective effects. Studies on primary culture cardiomyocytes also confirmed our in vivo results of UDCA on cell survival. These results altogether demonstrate that UDCA protect the heart against reperfusion injury by inhibiting the PTP in a PI3K/Akt dependent pathway.

Topics: Adenosine Triphosphate; Androstadienes; Animals; Apoptosis; Atractyloside; bcl-Associated Death Protein; Cell Hypoxia; Cell Survival; Cells, Cultured; Cytochromes c; Male; Mitochondrial Swelling; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Myocytes, Cardiac; Oxygen; Phosphatidylinositol 3-Kinases; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Wistar; Ursodeoxycholic Acid; Wortmannin

Pretreatment with tumor necrosis factor-alpha (TNF-alpha) is known to trigger cardioprotection and it can activate multiple downstream signaling cascades. However, it is not known whether the mitochondrial permeability transition pore and the Ca(2+)-activated K(+) channel (K(Ca) channel) are involved in the TNF-alpha-induced cardioprotection. In the present study, we examined whether TNF-alpha inhibits pore opening and activates the K(Ca) channel in the cardioprotection. In isolated rat hearts subjected to 30 min of regional ischemia and 120 min of reperfusion, pretreatment with 10 U/ml TNF-alpha for 7 min followed by 10 min washout improved the recovery of rate-pressure product (RPP=left ventricular developed pressure x heart rate) and coronary flow (CF) during reperfusion, and reduced the infarct size and release of lactate dehydrogenase (LDH). Administration of 20 micromol/L atractyloside, a pore opener, for the last 5 min of ischemia and first 15 min of reperfusion, and pretreatment with 1 micromol/L paxilline, an inhibitor of the K(Ca) channel, for 5 min before ischemia, attenuated the recovery of RPP and CF, and the reductions of infarct size and release of LDH induced by TNF-alpha. On the other hand, administration of 10 micromol/L NS 1619, an opener of the K(Ca) channel, for 10 min before ischemia, decreased the infarct size and LDH release, and improved contractile functions and CF; these effects were attenuated by atractyloside. Pretreatment with 0.2 micromol/L cyclosporin A for the last 5 min of ischemia and first 15 min of reperfusion showed similar effects to those of TNF-alpha, and they were not attenuated by paxilline. In mitochondria isolated from hearts pretreated with 10 U/ml TNF-alpha for 7 min, a significant inhibition of Ca(2+)-induced swelling was observed. Furthermore, paxilline attenuated the inhibition of Ca(2+)-induced mitochondrial swelling by TNF-alpha. These findings indicate that TNF-alpha protects the myocardium against ischemia and reperfusion injury by inhibiting mitochondrial permeability transition pore opening as well as activating K(Ca) channels, probably the mitochondrial K(Ca) channel, which is upstream from the pore.

Topics: Animals; Atractyloside; Coronary Circulation; Cyclosporine; In Vitro Techniques; Ion Channels; L-Lactate Dehydrogenase; Male; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Contraction; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Permeability; Potassium Channel Blockers; Potassium Channels, Calcium-Activated; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

Although functional coupling between protein kinase Cepsilon (PKCepsilon) and mitochondria has been implicated in the genesis of cardioprotection, the signal transduction mechanisms that enable this link and the identities of the mitochondrial proteins modulated by PKCepsilon remain unknown. Based on recent evidence that the mitochondrial permeability transition pore may be involved in ischemia/reperfusion injury, we hypothesized that protein-protein interactions between PKCepsilon and mitochondrial pore components may serve as a signaling mechanism to modulate pore function and thus engender cardioprotection. Coimmunoprecipitation and GST-based affinity pull-down from mouse cardiac mitochondria revealed interaction of PKCepsilon with components of the pore, namely voltage-dependent anion channel (VDAC), adenine nucleotide translocase (ANT), and hexokinase II (HKII). VDAC1, ANT1, and HKII were present in the PKCepsilon complex at approximately 2%, approximately 0.2%, and approximately 1% of their total expression, respectively. Moreover, in vitro studies demonstrated that PKCepsilon can directly bind and phosphorylate VDAC1. Incubation of isolated cardiac mitochondria with recombinant PKCepsilon resulted in a significant inhibition of Ca2+-induced mitochondrial swelling, an index of pore opening. Furthermore, cardiac-specific expression of active PKCepsilon in mice, which is cardioprotective, greatly increased interaction of PKCepsilon with the pore components and inhibited Ca2+-induced pore opening. In contrast, cardiac expression of kinase-inactive PKCepsilon did not affect pore opening. Finally, administration of the pore opener atractyloside significantly attenuated the infarct-sparing effect of PKCepsilon transgenesis. Collectively, these data demonstrate that PKCepsilon forms physical interactions with components of the cardiac mitochondrial pore. This in turn inhibits the pathological function of the pore and contributes to PKCepsilon-induced cardioprotection.

Topics: Animals; Atractyloside; Enzyme Inhibitors; Hexokinase; Immunoblotting; Intracellular Membranes; Mice; Mice, Transgenic; Mitochondria, Heart; Mitochondrial ADP, ATP Translocases; Myocardial Infarction; Myocardial Reperfusion Injury; Permeability; Phosphorylation; Porins; Precipitin Tests; Protein Binding; Protein Kinase C; Protein Kinase C-epsilon; Rats; Voltage-Dependent Anion Channel 1; Voltage-Dependent Anion Channels

Reperfusion after a period of ischemia is associated with the formation of reactive oxygen species (ROS) and Ca2+ overload resulting in the opening of a nonspecific pore in the inner membrane of the mitochondria, called the mitochondrial permeability transition pore (PTP), leading to cell damage. Although endogenous antioxidants are activated because of oxidative stress following ischemia, their levels are not high enough to prevent reperfusion injury. Hence there is always a need for exogenous supplement of antioxidants, especially after acute ischemia. Here we demonstrated the effects of the antioxidant 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186) in preventing reperfusion injury of the heart by inhibition of PTP opening. Ischemia (30 min) by left coronary artery (LCA) occlusion and reperfusion (120 min) in Wistar rats after pretreatment with MCI-186 (10 mg/kg iv) infusion starting from 30 min before LCA occlusion resulted in 1) less area of myocardial infarction (19.2% vs. 61.6%), 2) well-maintained myocardial ATP content (P < 0.03 vs. control), 3) decreased mitochondrial swelling and reduced cytochrome c release, 4) increased expression of BCl-2, 5) lower prevalence of apoptotic cells (14.3% vs. 2.9%), and 6) reduced DNA fragmentation in the MCI-186-treated group. These cytoprotective effects of MCI-186 were inhibited on opening PTP before MCI-186 treatment with the PTP activators lonidamine (10 mg/kg iv) or atractyloside (5 mg/kg iv) but failed to inhibit the protective effects exerted by another antioxidant, allopurinol, suggesting that the PTP inhibiting property is specific for MCI-186. These results demonstrate that the radical scavenger MCI-186, by inhibiting the opening of the PTP, prevents necrosis and cytochrome c release and hence pathological apoptosis.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Agents; Antioxidants; Antipyrine; Atractyloside; Blood Pressure; Cytochromes c; DNA Fragmentation; Edaravone; Enzyme Inhibitors; Heart Rate; Indazoles; Male; Mitochondrial Swelling; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Up-Regulation