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Vörös I, Sághy É, Pohóczky K, Makkos A, Onódi Z, Brenner GB, Baranyai T, Ágg B, Váradi B, Kemény Á, Leszek P, Görbe A, Varga ZV, Giricz Z, Schulz R, Helyes Z, Ferdinandy P. Somatostatin and Its Receptors in Myocardial Ischemia/Reperfusion Injury and Cardioprotection. Front Pharmacol 2021; 12:663655. [PMID: 34803662 PMCID: PMC8602362 DOI: 10.3389/fphar.2021.663655] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 09/09/2021] [Indexed: 12/16/2022] Open
Abstract
Little is known about the role of the neuropeptide somatostatin (SST) in myocardial ischemia/reperfusion injury and cardioprotection. Here, we investigated the direct cardiocytoprotective effect of SST on ischemia/reperfusion injury in cardiomyocyte cultures, as well as the expression of SST and its receptors in pig and human heart tissues. SST induced a bell-shaped, concentration-dependent cardiocytoprotection in both adult rat primary cardiomyocytes and H9C2 cells subjected to simulated ischemia/reperfusion injury. Furthermore, in a translational porcine closed-chest acute myocardial infarction model, ischemic preconditioning increased plasma SST-like immunoreactivity. Interestingly, SST expression was detectable at the protein, but not at the mRNA level in the pig left ventricles. SSTR1 and SSTR2, but not the other SST receptors, were detectable at the mRNA level by PCR and sequencing in the pig left ventricle. Moreover, remote ischemic conditioning upregulated SSTR1 mRNA. Similarly, SST expression was also detectable in healthy human interventricular septum samples at the protein level. Furthermore, SST-like immunoreactivity decreased in interventricular septum samples of patients with ischemic cardiomyopathy. SSTR1, SSTR2, and SSTR5 but not SST and the other SST receptors were detectable at the mRNA level by sequencing in healthy human left ventricles. In addition, in healthy human left ventricle samples, SSTR1 and SSTR2 mRNAs were expressed especially in vascular endothelial and some other cell types as detected by RNA Scope® in situ hybridization. This is the first demonstration that SST exerts a direct cardiocytoprotective effect against simulated ischemia/reperfusion injury. Moreover, SST is expressed in the heart tissue at the peptide level; however, it is likely to be of sensory neural origin since its mRNA is not detectable. SSTR1 and SSTR2 might be involved in the cardioprotective action of SST, but other mechanisms cannot be excluded.
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Affiliation(s)
- Imre Vörös
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- HCEMM-SU Cardiometabolic Immunology Research Group, Budapest, Hungary
| | - Éva Sághy
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Krisztina Pohóczky
- Department of Pharmacology, Faculty of Pharmacy, University of Pécs, Pécs, Hungary
- Szentágothai János Research Center, University of Pécs, Pécs, Hungary
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
| | - András Makkos
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
| | - Zsófia Onódi
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- HCEMM-SU Cardiometabolic Immunology Research Group, Budapest, Hungary
| | - Gábor B. Brenner
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
| | - Tamás Baranyai
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Bence Ágg
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
- Heart and Vascular Center, Semmelweis University, Budapest, Hungary
| | - Barnabás Váradi
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
| | - Ágnes Kemény
- Szentágothai János Research Center, University of Pécs, Pécs, Hungary
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
- Department of Medical Biology, University of Pécs, Pécs, Hungary
| | - Przemyslaw Leszek
- Department of Heart Failure and Transplantology, Cardinal Stefan Wyszyński National Institute of Cardiology, Warszawa, Poland
| | - Anikó Görbe
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
| | - Zoltán V. Varga
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- HCEMM-SU Cardiometabolic Immunology Research Group, Budapest, Hungary
| | - Zoltán Giricz
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
| | - Rainer Schulz
- Institute of Physiology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Zsuzsanna Helyes
- Szentágothai János Research Center, University of Pécs, Pécs, Hungary
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Ferdinandy
- Cardiometabolic Research Group and MTA-SE System Pharmacology Research Group, Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary
- Pharmahungary Group, Szeged, Hungary
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2
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Zhou YX, Ni Y, Liu YB, Liu X. Histone preconditioning protects against obstructive jaundice-induced liver injury in rats. Exp Ther Med 2014; 8:15-20. [PMID: 24944590 PMCID: PMC4061184 DOI: 10.3892/etm.2014.1697] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 03/25/2014] [Indexed: 12/26/2022] Open
Abstract
A major consequence of obstructive jaundice (OJ) in clinical practice is the development of severe liver injury, and at present, no effective treatments have been developed to protect against it. Preconditioning with damage-associated molecular pattern (DAMP) molecules has been demonstrated to protect multiple organs from injury, and histones have been recently identified as DAMP molecules. The aim of the present study was to investigate the protective effect of histone preconditioning against OJ-induced liver injury in rats and the involvement of Toll-like receptors. Rats were administered histone proteins (200 μg/kg; 1 ml) or physiological saline (1 ml) intraperitoneally 24 h prior to being subjected to bile duct ligation (BDL). The serum levels of liver enzymes and bilirubin, as well as the histopathology were analyzed. The mRNA expression of interleukin-6 (IL-6) in the liver tissue was analyzed using quantitative polymerase chain reaction. BDL in the control group caused severe OJ-induced liver injury, as indicated by the significantly elevated levels of liver enzymes and mRNA levels of IL-6, and confirmed by histopathological alterations. However, histone preconditioning significantly ameliorated the OJ-induced liver injury caused by BDL, as shown by an improvement in the levels of liver enzymes, a suppression of IL-6 production, as well as histopathological alterations. Therefore, these results suggested that histone preconditioning is able to protect against OJ-induced liver injury in rats.
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Affiliation(s)
- You-Xing Zhou
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong 518035, P.R. China
| | - Yong Ni
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong 518035, P.R. China
| | - Yi-Bing Liu
- Department of Hepatobiliary Surgery, Longgang District Central Hospital of Shenzhen, Shenzhen, Guangdong 518116, P.R. China
| | - Xiaohong Liu
- Department of Geriatric Psychiatry, Wuxi Mental Health Center, Wuxi, Jiangsu 214151, P.R. China
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3
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Haworth RA, Potter KT, Russell DC. Role of arachidonic acid, lipoxygenase, and mitochondrial depolarization in reperfusion arrhythmias. Am J Physiol Heart Circ Physiol 2010; 299:H165-74. [PMID: 20435853 DOI: 10.1152/ajpheart.00906.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have sought evidence that arachidonic acid (AA) induces mitochondrial depolarization in isolated myocytes by a lipoxygenase (LOX)-dependent mechanism and that such depolarization might contribute to arrhythmogenesis following ischemia-reperfusion injury. A method was developed for measuring mitochondrial depolarization in isolated adult rat myocytes in suspension, using tetramethylrhodamine ethyl ester. The addition of AA to myocytes resulted in mitochondrial depolarization that was inhibited by the LOX inhibitor baicalein, by the reactive oxygen species (ROS) scavenger mercaptoproprionylglycine, and by the anion channel inhibitor diisothiocyanatostilbene-disulfonic acid (DIDS). AA induced mitochondrial uncoupling and mitochondrial ATPase activity in myocytes, but both were insensitive to baicalein. We conclude that the metabolic effect of AA in myocytes puts mitochondria into an energetically compromised state where membrane potential is easily changed by the DIDS-sensitive LOX/ROS-mediated opening of an inner membrane anion channel. In an in vivo anesthetized rat model of coronary artery occlusion, baicalein was found to strongly inhibit arrhythmias induced by ischemia-reperfusion injury. Arrhythmias following ischemia-reperfusion injury have been previously associated with DIDS-sensitive ROS-mediated mitochondrial depolarization, and free fatty acids including AA were previously found to accumulate during such injury. We therefore conclude that arrhythmias following ischemia-reperfusion injury might originate from mitochondrial depolarization mediated by LOX and AA.
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Affiliation(s)
- Robert A Haworth
- Cardiology Section, Medical Service, Wm. S. Middleton Memorial Veterans Hospital, Madison WI 53792, USA.
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4
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Huang C, Liu W, Perry CN, Yitzhaki S, Lee Y, Yuan H, Tsukada YT, Hamacher-Brady A, Mentzer RM, Gottlieb RA. Autophagy and protein kinase C are required for cardioprotection by sulfaphenazole. Am J Physiol Heart Circ Physiol 2009; 298:H570-9. [PMID: 20008275 DOI: 10.1152/ajpheart.00716.2009] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Previously, we showed that sulfaphenazole (SUL), an antimicrobial agent that is a potent inhibitor of cytochrome P4502C9, is protective against ischemia-reperfusion (I/R) injury (Ref. 15). The mechanism, however, underlying this cardioprotection, is largely unknown. With evidence that activation of autophagy is protective against simulated I/R in HL-1 cells, and evidence that autophagy is upregulated in preconditioned hearts, we hypothesized that SUL-mediated cardioprotection might resemble ischemic preconditioning with respect to activation of protein kinase C and autophagy. We used the Langendorff model of global ischemia to assess the role of autophagy and protein kinase C in myocardial protection by SUL during I/R. We show that SUL enhanced recovery of function, reduced creatine kinase release, decreased infarct size, and induced autophagy. SUL also triggered PKC translocation, whereas inhibition of PKC with chelerythrine blocked the activation of autophagy in adult rat cardiomyocytes. In the Langendorff model, chelerythrine suppressed autophagy and abolished the protection mediated by SUL. SUL increased autophagy in adult rat cardiomyocytes infected with GFP-LC3 adenovirus, in isolated perfused rat hearts, and in mCherry-LC3 transgenic mice. To establish the role of autophagy in cardioprotection, we used the cell-permeable dominant-negative inhibitor of autophagy, Tat-Atg5(K130R). Autophagy and cardioprotection were abolished in rat hearts perfused with recombinant Tat-Atg5(K130R). Taken together, these studies indicate that cardioprotection mediated by SUL involves a PKC-dependent induction of autophagy. The findings suggest that autophagy may be a fundamental process that enhances the heart's tolerance to ischemia.
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Affiliation(s)
- Chengqun Huang
- BioScience Center, San Diego State University, San Diego, California, USA
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5
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Tsutsumi YM, Patel HH, Huang D, Roth DM. Role of 12-lipoxygenase in volatile anesthetic-induced delayed preconditioning in mice. Am J Physiol Heart Circ Physiol 2006; 291:H979-83. [PMID: 16648187 DOI: 10.1152/ajpheart.00266.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Delayed cardiac protection mediated by 12-lipoxygenase (12-LO) expression and activity has been linked to opioid receptor stimulation. The role of 12-LO in volatile anesthetic-induced delayed cardiac protection has not been determined. We tested the hypothesis that expression and activity of 12-LO mediate delayed cardiac protection induced by isoflurane in the mouse heart in vivo. Mice were pretreated with 1.4% isoflurane for 30 min and allowed to recover for 1, 12, or 24 h. Immunoblot analysis showed isoflurane significantly enhanced 12-LO protein expression at 12 and 24 h after isoflurane exposure, and this induction of 12-LO was confirmed by immunohistochemistry of whole heart sections at 24 h. The induced protein expression appeared to be localized to intercalated disc regions adjoining adjacent cardiac myocytes. Additionally, mice ± isoflurane (24 h previously) were subjected to 30 min coronary artery occlusion followed by 2 h of reperfusion in the presence and absence of a 12-LO inhibitor. Isoflurane reduced infarct size (27.1 ± 2.2% of the area at risk; n = 8) compared with the control group (44.6 ± 3.6%, n = 8). Baicalein (3 mg/kg), a selective 12-LO inhibitor, blocked the delayed protective effects of isoflurane pretreatment on infarct size (40.6 ± 3.6%, n = 8). These data suggest that 12-LO is an important mediator of isoflurane-induced delayed preconditioning.
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Affiliation(s)
- Yasuo M Tsutsumi
- Department of Anesthesiology, University of California, San Diego, CA, USA
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6
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Schäfer SC, Sehrt DN, Kamler M, Jakob H, Lehr HA. Paradoxical attenuation of leukocyte rolling in response to ischemia- reperfusion and extracorporeal blood circulation in inflamed tissue. Am J Physiol Heart Circ Physiol 2005; 289:H330-5. [PMID: 15961377 DOI: 10.1152/ajpheart.00674.2004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In contrast to acute preparations such as the exteriorized mesentery or the cremaster muscle, chronically instrumented chamber models allow one to study the microcirculation under “physiological” conditions, i.e., in the absence of trauma-induced leukocyte rolling along the venular endothelium. To underscore the importance of studying the naive microcirculation, we implanted titanium dorsal skinfold chambers in hamsters and used intravital fluorescence microscopy to study venular leukocyte rolling in response to ischemia-reperfusion injury or extracorporeal blood circulation. The experiments were performed in chambers that fulfilled all well-established criteria for a physiological microcirculation as well as in chambers that showed various extents of leukocyte rolling due to trauma, hemorrhage, or inflammation. In ideal chambers with a physiological microcirculation (<30 rolling leukocytes/mm vessel circumference in 30 s), ischemia-reperfusion injury and extracorporeal blood circulation significantly stimulated leukocyte rolling along the venular endothelium and, subsequently, firm leukocyte adhesion. In contrast, both stimuli failed to elicit leukocyte rolling in borderline chambers (30–100 leukocytes/mm), and in blatantly inflamed chambers with yet higher numbers of rolling leukocytes at baseline (>100 leukocytes/mm), we observed a paradoxical reduction of leukocyte rolling after ischemia-reperfusion injury or extracorporeal blood circulation. A similar effect was observed when we superfused leukotriene B4 (LTB4) onto the chamber tissue. The initial increase in leukocyte rolling in response to an LTB4 challenge was reversed by a second superfusion 90 min later. These observations underscore 1) the benefit of studying leukocyte-endothelial cell interaction in chronically instrumented chamber models and 2) the necessity to strictly adhere to well-established criteria of a physiological microcirculation.
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Affiliation(s)
- Stephan C Schäfer
- Institute of Pathology, University of Mainz Medical Center, Mainz, Germany
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7
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Kohro S, Hogan QH, Warltier DC, Bosnjak ZJ. Protein Kinase C Inhibitors Produce Mitochondrial Flavoprotein Oxidation in Cardiac Myocytes. Anesth Analg 2004; 99:1316-1322. [PMID: 15502023 DOI: 10.1213/01.ane.0000135636.45389.e6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Inhibition of protein kinase C (PKC) antagonizes ischemic preconditioning of myocardium. Opening of mitochondrial adenosine triphosphate (ATP)-dependent potassium (mitoK(ATP)) channels and subsequent oxidation of mitochondria are known to contribute to ischemic preconditioning. We therefore tested the effects of PKC inhibitors on flavoprotein oxidation, measured by flavoprotein fluorescence, as an index of mitoK(ATP) activity in ventricular myocytes from guinea pigs. The PKC inhibitors chelerythrine (1 and 5 microM) and bisindolylmaleimide (100 and 400 nM) strongly increased flavoprotein oxidation in a dose-dependent manner. Specific inhibition of PKC-delta by rottlerin produced persistent flavoprotein oxidation. Inhibition of the production of inositol (1,4,5)-triphosphate by neomycin (0.5 mM) abolished chelerythrine- but not rottlerin-induced flavoprotein oxidation. Inhibition of PKC promotes flavoprotein oxidation via production of inositol (1,4,5)-triphosphate, possibly through the PKC-delta isoform. We speculate that although a certain degree of mitochondrial flavoprotein oxidation causes cardioprotective effects, excessive and/or persistent oxidation abolishes any beneficial actions. Instead of a simple mediator, PKC may act as a regulator of the mitoK(ATP) channel to prevent excessive mitochondrial oxidation.
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MESH Headings
- Acetophenones/pharmacology
- Alkaloids
- Animals
- Benzophenanthridines
- Benzopyrans/pharmacology
- Calibration
- Cell Separation
- Female
- Flavoproteins/metabolism
- Guinea Pigs
- In Vitro Techniques
- Indoles/pharmacology
- Inositol 1,4,5-Trisphosphate/antagonists & inhibitors
- Inositol 1,4,5-Trisphosphate/metabolism
- Male
- Maleimides/pharmacology
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/enzymology
- Mitochondria, Heart/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Neomycin/pharmacology
- Oxidation-Reduction
- Phenanthridines/pharmacology
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C-delta
- Protein Synthesis Inhibitors/pharmacology
- Spectrometry, Fluorescence
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Affiliation(s)
- Shinji Kohro
- Departments of *Anesthesiology, †Physiology, ‡Pharmacology, and §Medicine (Division of Cardiovascular Diseases), Medical College of Wisconsin, Milwaukee; and ∥ Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
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8
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Granville DJ, Tashakkor B, Takeuchi C, Gustafsson AB, Huang C, Sayen MR, Wentworth P, Yeager M, Gottlieb RA. Reduction of ischemia and reperfusion-induced myocardial damage by cytochrome P450 inhibitors. Proc Natl Acad Sci U S A 2004; 101:1321-6. [PMID: 14734800 PMCID: PMC337051 DOI: 10.1073/pnas.0308185100] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ischemia and reperfusion both contribute to tissue damage after myocardial infarction. Although many drugs have been shown to reduce infarct size when administered before ischemia, few have been shown to be effective when administered at reperfusion. Moreover, although it is generally accepted that a burst of reactive oxygen species (ROS) occurs at the onset of reperfusion and contributes to tissue damage, the source of ROS and the mechanism of injury is unclear. We now report the finding that chloramphenicol administered at reperfusion reduced infarct size by 60% in a Langendorff isolated perfused rat heart model, and that ROS production was also substantially reduced. Chloramphenicol is an inhibitor of mitochondrial protein synthesis and is also an inhibitor of a subset of cytochrome P450 monooxygenases (CYPs). We could not detect any effect on mitochondrial encoded proteins or mitochondrial respiration in chloramphenicol-perfused hearts, and hypothesized that the effect was caused by inhibition of CYPs. We tested additional CYP inhibitors and found that cimetidine and sulfaphenazole, two CYP inhibitors that have no effect on mitochondrial protein synthesis, were also able to reduce creatine kinase release and infarct size in the Langendorff model. We also showed that chloramphenicol reduced infarct size in an open chest rabbit model of regional ischemia. Taken together, these findings implicate CYPs in myocardial ischemia/reperfusion injury.
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Affiliation(s)
- David J Granville
- Departments of Molecular and Experimental Medicine, Cell Biology, Chemistry, and Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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9
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Murphy E. Primary and secondary signaling pathways in early preconditioning that converge on the mitochondria to produce cardioprotection. Circ Res 2004; 94:7-16. [PMID: 14715531 DOI: 10.1161/01.res.0000108082.76667.f4] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardioprotective mechanisms such as acute or early preconditioning activate several primary signaling pathways that seem to converge on mitochondrial targets, leading to altered cell metabolism and inhibition of apoptosis. Acute preconditioning leads to generation of agonists, which bind to G protein-coupled receptors, and initiates a signaling cascade that involves activation of phosphoinositide-3-kinase, endothelial NO synthase, protein kinase C, glycogen synthase kinase 3beta, mitogen-activated protein kinases, and other signaling pathways. Activation of these signaling pathways along with generation of reactive oxygen species leads to alterations in the activity of key mitochondrial proteins such as mitochondrial ATP-sensitive K(+) channels, the mitochondrial permeability transition pore, and bcl-2 family members. Alterations in these mitochondrial proteins results in altered metabolism and inhibition of cell death, thus resulting in cardioprotection.
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Affiliation(s)
- Elizabeth Murphy
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, Research Triangle Park, NC, USA.
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10
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Yiu SS, Zhao X, Inscho EW, Imig JD. 12-Hydroxyeicosatetraenoic acid participates in angiotensin II afferent arteriolar vasoconstriction by activating L-type calcium channels. J Lipid Res 2003; 44:2391-9. [PMID: 12951362 DOI: 10.1194/jlr.m300183-jlr200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lipoxygenase (LO) metabolite, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], constricts renal vessels, contributes to the vascular response to angiotensin, and has been implicated in cardiovascular and renal diseases. The current studies were performed to determine if renal microvascular 12(S)-HETE production is stimulated by angiotensin and the contribution of L-type calcium channels to the vasoconstriction elicited by 12(S)-HETE. Angiotensin increased renal microvascular 12(S)-HETE production by 64%, whereas cyclooxygenase metabolite production was not altered. Renal microvessels also expressed platelet-type 12-LO and leukocyte-type 12-LO. In the juxtamedullary preparation, afferent arteriolar diameter averaged 21 +/- 1 microm and 12(S)-HETE caused a graded decrease in vessel caliber. The afferent arteriolar response to 12(S)-HETE was abolished during L-type calcium channel inhibition. Renal microvascular smooth muscle cells were studied using fluorescence microscopy. Renal myocyte [Ca2+]i averaged 93 +/- 5 nmol/l. The 12(S)-HETE (5 micromol/l) increased myocyte [Ca2+]i to a peak value of 340 +/- 55 nmol/l. The peak [Ca2+]i response following exposure to 12(S)-HETE was greatly attenuated in the absence of extracellular Ca2+ or calcium channel blockade. These results demonstrate that renal microvascular 12(S)-HETE production is increased in response to angiotensin, and activation of L-type calcium channels is an important mechanism responsible for the afferent arteriolar vasoconstriction elicited by 12(S)-HETE.
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Affiliation(s)
- Shih Shen Yiu
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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11
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Pyle WG, Chen Y, Hofmann PA. Cardioprotection through a PKC-dependent decrease in myofilament ATPase. Am J Physiol Heart Circ Physiol 2003; 285:H1220-8. [PMID: 12763745 DOI: 10.1152/ajpheart.00076.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of myocardial kappa-opioid receptor-protein kinase C (PKC) pathways may improve postischemic contractile function through a myofilament reduction in ATP utilization. To test this, we first examined the effects of PKC inhibitors on kappa-opioid receptor-dependent cardioprotection. The kappa-opioid receptor agonist U50,488H (U50) increased postischemic left ventricular developed pressure and reduced postischemic end-diastolic pressure compared with controls. PKC inhibitors abolished the cardioprotective effects of U50. To determine whether kappa-opioid-PKC-dependent decreases in Ca2+-dependent actomyosin Mg2+-ATPase could account for cardioprotection, we subjected hearts to three separate actomyosin ATPase-lowering protocols. We observed that moderate decreases in myofibrillar ATPase were equally cardioprotective as kappa-opioid receptor stimulation. Immunoblot analysis and confocal microscopy revealed a kappa-opioid-induced increase in myofilament-associated PKC-epsilon, and myofibrillar Ca2+-independent PKC activity was increased after kappa-opioid stimulation. This PKC-myofilament association led to an increase in troponin I and C-protein phosphorylation. Thus we propose PKC-epsilon activation and translocation to the myofilaments causes a decrease in actomyosin ATPase, which contributes to the kappa-opioid receptor-dependent cardioprotective mechanism.
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Affiliation(s)
- W Glen Pyle
- Department of Physiology, University of Tennessee-Memphis, 894 Union Avenue, Memphis, TN 38163, USA
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12
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Patel HH, Fryer RM, Gross ER, Bundey RA, Hsu AK, Isbell M, Eusebi LOV, Jensen RV, Gullans SR, Insel PA, Nithipatikom K, Gross GJ. 12-lipoxygenase in opioid-induced delayed cardioprotection: gene array, mass spectrometric, and pharmacological analyses. Circ Res 2003; 92:676-82. [PMID: 12623876 DOI: 10.1161/01.res.0000065167.52922.f6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
12-lipoxygenase (12-LO) has been shown to be a factor in acute ischemic preconditioning (IPC) in the isolated rat heart; however, no studies have been reported in delayed PC. We characterized the role of 12-LO in an intact rat model of delayed PC induced by a delta-opioid agonist SNC-121 (SNC). Rats were pretreated with SNC and allowed to recover for 24 hours. They were then treated with either baicalein or phenidone, 2 selective 12-LO inhibitors. In addition, SNC-pretreated rats had plasma samples isolated at different times after ischemia-reperfusion for liquid chromatographic-mass spectrometric analysis of the major metabolic product of 12-LO, 12-HETE. Similar studies were conducted with inhibitors. Gene array data showed a significant induction of 12-LO message (P<0.05) after opioid pretreatment. This induction in 12-LO mRNA was confirmed by real-time polymerase chain reaction, and 12-LO protein expression was enhanced by SNC pretreatment at 24 hours relative to vehicle treatment. Both baicalein and phenidone attenuated the protective effects of SNC pretreatment on infarct size (50+/-4% and 42+/-3% versus 29+/-2%, P<0.05, respectively). No significant differences were observed in 12-HETE concentrations between baseline control and SNC-treated rats. However, 12-HETE concentrations were increased significantly at both 15 minutes during ischemia and at 1 hour of reperfusion in the SNC-treated rats compared with controls. Baicalein and phenidone attenuated the increase in 12-HETE at 1 hour of reperfusion. These data suggest that SNC-121 appears to enhance message and subsequently the activity and expression of 12-LO protein during times of stress, resulting in delayed cardioprotection.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/biosynthesis
- Animals
- Arachidonate 12-Lipoxygenase/genetics
- Arachidonate 12-Lipoxygenase/physiology
- Arachidonic Acid/metabolism
- Benzamides/pharmacology
- Blotting, Western
- Cardiotonic Agents/pharmacology
- Enzyme Inhibitors/pharmacology
- Gene Expression Profiling
- Hemodynamics/drug effects
- Ischemic Preconditioning, Myocardial
- Kinetics
- Lipoxygenase Inhibitors
- Male
- Myocardial Reperfusion Injury/enzymology
- Myocardial Reperfusion Injury/genetics
- Myocardial Reperfusion Injury/metabolism
- Myocardial Reperfusion Injury/prevention & control
- Myocardium/enzymology
- Oligonucleotide Array Sequence Analysis
- Piperazines/pharmacology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, delta/agonists
- Reverse Transcriptase Polymerase Chain Reaction
- Spectrometry, Mass, Electrospray Ionization
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Affiliation(s)
- Hemal H Patel
- Medical College of Wisconsin, Department of Pharmacology and Toxicology, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA
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13
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Dickson EW, Tubbs RJ, Porcaro WA, Lee WJ, Blehar DJ, Carraway RE, Darling CE, Przyklenk K. Myocardial preconditioning factors evoke mesenteric ischemic tolerance via opioid receptors and K(ATP) channels. Am J Physiol Heart Circ Physiol 2002; 283:H22-8. [PMID: 12063270 DOI: 10.1152/ajpheart.01055.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have shown that a reverse-phase concentrate generated from the effluent of preconditioned (PC) rabbit hearts evokes a cardioprotective effect in virgin acceptor hearts. With the use of a model of sustained (1 h) simulated ischemia in isolated, spontaneously contracting rabbit jejunum, our current aims were to 1) determine whether protective factor(s) released from PC hearts can improve ischemic tolerance in noncardiac tissue; and 2) obtain preliminary insight into the mediator(s) involved in triggering and eliciting this remote protection. Recovery of contractile force following reoxygenation (our index of ischemic tolerance) was enhanced in jejunal segments pretreated with concentrate generated from PC hearts (33 +/- 3% of baseline, P < 0.01) versus segments that received no concentrate (21 +/- 2%) and segments treated with concentrate from normoxic hearts (16 +/- 3%; P < 0.01). Protection achieved with PC concentrate was attenuated by coadministration of naloxone or glibenclamide, thereby implicating the involvement of opioids and ATP-sensitive potassium channels. Moreover, evaluation of purified subfractions of the crude PC concentrate identified a specific bioactive fraction that may participate in triggering the improved jejunal ischemic tolerance.
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Affiliation(s)
- Eric W Dickson
- Department of Emergency Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01665, USA.
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14
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McLean PG, Aston D, Sarkar D, Ahluwalia A. Protease-activated receptor-2 activation causes EDHF-like coronary vasodilation: selective preservation in ischemia/reperfusion injury: involvement of lipoxygenase products, VR1 receptors, and C-fibers. Circ Res 2002; 90:465-72. [PMID: 11884377 DOI: 10.1161/hh0402.105372] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activation of protease-activated receptor (PAR)-2 has been proposed to be protective in myocardial ischemia/reperfusion (I/R) injury, an effect possibly related to an action on the coronary vasculature. Therefore, we investigated the effects of PAR2 activation on coronary tone in isolated perfused rat hearts and elucidated the mechanisms of any observed effects. Although having a negligible effect on ventricular contractility, the PAR2 activating peptide SLIGRL produced an endothelium-dependent coronary vasodilatation (ED(50)=3.5 nmol). Following I/R injury, the response to SLIGRL was selectively preserved, whereas the dilator response to acetylcholine was converted to constriction. Trypsin also produced a vasodilator dose-response curve that was biphasic in nature (ED(50-1)=0.36 U, ED(50-2)=38.71 U). Desensitization of PAR2 receptors indicated that the high potency phase was mediated by PAR2. Removal of the endothelium but not treatment with L-NAME (300 micromol/L), indomethacin (5 micromol/L), or oxyhemoglobin (10 micromol/L) inhibited the response to SLIGRL and trypsin. Treatment with the K(+)-channel blockers TEA (10 mmol/L), charybdotoxin (20 nmol/L)/apamin (100 nmol/L), or elevated potassium (20 mmol/L) significantly suppressed responses. Similarly, inhibition of lipoxygenase with nordihydroguaiaretic acid (1 micromol/L), eicosatetraynoic acid (1 micromol/L), or baicalein (10 micromol/L), desensitization of C-fibers using capsaicin (1 micromol/L, 20 minutes), or blockade of vanilloid (VR1) receptors using capsazepine (3 micromol/L) inhibited the responses. This study shows, for the first time, that PAR2 activation causes endothelium-dependent coronary vasodilation that is preserved after I/R injury and is not mediated by NO or prostanoids, but involves the release of an endothelium-derived hyperpolarizing factor (EDHF), possibly a lipoxygenase-derived eicosanoid, and activation of VR1 receptors on sensory C-fibers.
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Affiliation(s)
- Peter G McLean
- Centre for Clinical Pharmacology, Department of Medicine, University College London, UK.
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15
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12-hydroxyeicosatetrenoate (12-HETE) attenuates AMPA receptor-mediated neurotoxicity: evidence for a G-protein-coupled HETE receptor. J Neurosci 2002. [PMID: 11756509 DOI: 10.1523/jneurosci.22-01-00257.2002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
12-hydroxyeicosatetraenoic acid (12-HETE) is a neuromodulator that is synthesized during ischemia. Its neuronal effects include attenuation of calcium influx and glutamate release as well as inhibition of AMPA receptor (AMPA-R) activation. Because 12-HETE reduces ischemic injury in the heart, we examined whether it can also reduce neuronal excitotoxicity. When treated with 12-(S)HETE, cortical neuron cultures subjected to AMPA-R-mediated glutamate toxicity suffered up to 40% less damage than untreated cultures. The protective effect of 12-(S)HETE was concentration-dependent (EC50 = 88 nm) and stereostructurally selective. Maximal protection was conferred by 300 nm 12-(S)HETE; 300 nm 15-(S)HETE was similarly protective, but 300 nm 5-(S)HETE was less effective. The chiral isomer 12-(R)HETE offered no protection; neither did arachidonic acid or 12-(S)hydroperoxyeicosatetraenoic acid. Excitotoxicity was calcium-dependent, and 12-(S)HETE was demonstrated to protect by inactivating N and L (but not P) calcium channels via a pertussis toxin-sensitive mechanism. Calcium imaging demonstrated that 12-(S)HETE also attenuates glutamate-induced calcium influx into neurons via a pertussis toxin-sensitive mechanism, suggesting that it acts via a G-protein-coupled receptor. In addition, 12-(S)HETE stimulates GTPgammaS binding (indicating G-protein activation) and inhibits adenylate cyclase in forskolin-stimulated cultures over the same concentration range as it exerts its anti-excitotoxic and calcium-influx attenuating effects. These studies demonstrate that 12-(S)HETE can protect neurons from excitotoxicity by activating a G(i/o)-protein-coupled receptor, which limits calcium influx through voltage-gated channels.
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16
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Dransfeld O, Rakatzi I, Sasson S, Gruzman A, Schmitt M, Häussinger D, Eckel J. Eicosanoids participate in the regulation of cardiac glucose transport by contribution to a rearrangement of actin cytoskeletal elements. Biochem J 2001; 359:47-54. [PMID: 11563968 PMCID: PMC1222120 DOI: 10.1042/0264-6021:3590047] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Intact actin microfilaments are required for insulin-regulated glucose transporter isoform 4 (GLUT4) translocation to the plasma membrane. Lipoxygenase (LO) metabolites have recently been shown to contribute to the regulation of actin cytoskeleton rearrangement. In the present investigation, ventricular cardiomyocytes were used to study the effects of two structurally different LO inhibitors (esculetin and nordihydroguaiaretic acid) on insulin signalling events, glucose uptake, GLUT4 translocation and the actin network organization. Insulin stimulation increased glucose uptake 3-fold in control cells, whereas LO inhibition completely blocked this effect. This was paralleled by a slight reduction in the insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2. However, inhibition of 12-LO did not affect the association of phosphatidylinositol 3-kinase with IRS-1 and the phosphorylation of Akt/protein kinase B in response to insulin. Addition of 12(S)-hydroxyeicosatetraenoic acid almost completely restored the insulin action in cells exposed to nordihydroguaiaretic acid. Insulin stimulation increased cell surface GLUT4 2-fold in control cells, whereas LO inhibition abrogated the insulin-stimulated GLUT4 translocation. LO inhibition induced a prominent disassembly of actin fibres compared with control cells. In conclusion, we show here that 12(S)-hydroxyeicosatetraenoic acid plays a role in the organization of the actin network in cardiomyocytes. LO inhibition blocks GLUT4 translocation without affecting downstream insulin signalling. These data suggest that LO metabolites participate in the regulation of glucose transport by contributing to a rearrangement of actin cytoskeletal elements.
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Affiliation(s)
- O Dransfeld
- Molecular Cardiology, German Diabetes Research Institute, Auf'm Hennekamp 65, D-40225 Düsseldorf, Germany
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17
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Gabel SA, London RE, Funk CD, Steenbergen C, Murphy E. Leukocyte-type 12-lipoxygenase-deficient mice show impaired ischemic preconditioning-induced cardioprotection. Am J Physiol Heart Circ Physiol 2001; 280:H1963-9. [PMID: 11299195 DOI: 10.1152/ajpheart.2001.280.5.h1963] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the role of 12-lipoxygenase in preconditioning, we examined whether hearts lacking the "leukocyte-type" 12-lipoxygenase (12-LOKO) would be protected by preconditioning. In hearts from wild-type (WT) and 12-LOKO mice, left ventricular developed pressure (LVDP) and (31)P NMR were monitored during treatment (+/-preconditioning) and during global ischemia and reperfusion. Postischemic function (rate-pressure product, percentage of initial value) measured after 20 min of ischemia and 40 min of reperfusion was significantly improved by preconditioning in WT hearts (78 +/- 12% in preconditioned vs. 44 +/- 7% in nonpreconditioned hearts) but not in 12-LOKO hearts (47 +/- 7% in preconditioned vs. 33 +/- 10% in nonpreconditioned hearts). Postischemic recovery of phosphocreatine was significantly better in WT preconditioned hearts than in 12-LOKO preconditioned hearts. Preconditioning significantly reduced the fall in intracellular pH during sustained ischemia in both WT and 12-LOKO hearts, suggesting that attenuation of the fall in pH during ischemia can be dissociated from preconditioning-induced protection. Necrosis was assessed after 25 min of ischemia and 2 h of reperfusion using 2,3,5-triphenyltetrazolium chloride. In WT hearts, preconditioning significantly reduced the area of necrosis (26 +/- 4%) compared with nonpreconditioned hearts (62 +/- 10%) but not in 12-LOKO hearts (85 +/- 3% in preconditioned vs. 63 +/- 11% in nonpreconditioned hearts). Preconditioning resulted in a significant increase in 12(S)-hydroxyeicosatetraenoic acid in WT but not in 12-LOKO hearts. These data demonstrate that 12-lipoxygenase is important in preconditioning.
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Affiliation(s)
- S A Gabel
- National Institute of Environmental Health Sciences, Research Triangle Park 27709, Durham, North Carolina 27710, USA
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18
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Zink MH, Oltman CL, Lu T, Katakam PV, Kaduce TL, Lee H, Dellsperger KC, Spector AA, Myers PR, Weintraub NL. 12-lipoxygenase in porcine coronary microcirculation: implications for coronary vasoregulation. Am J Physiol Heart Circ Physiol 2001; 280:H693-704. [PMID: 11158968 DOI: 10.1152/ajpheart.2001.280.2.h693] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Noncyclooxygenase metabolites of arachidonic acid (AA) have been proposed to mediate endothelium-dependent vasodilation in the coronary microcirculation. Therefore, we examined the formation and bioactivity of AA metabolites in porcine coronary (PC) microvascular endothelial cells and microvessels, respectively. The major noncyclooxygenase metabolite produced by microvascular endothelial cells was 12(S)-hydroxyeicosatetraenoic acid (HETE), a lipoxygenase product. 12(S)-HETE release was markedly increased by pretreatment with 13(S)-hydroperoxyoctadecadienoic acid but not by the reduced congener 13(S)-hydroxyoctadecadienoic acid, suggesting oxidative upregulation of 12(S)-HETE output. 12(S)-HETE produced potent relaxation and hyperpolarization of PC microvessels (EC(50), expressed as -log[M] = 13.5 +/- 0.5). Moreover, 12(S)-HETE potently activated large-conductance Ca(2+)-activated K(+) currents in PC microvascular smooth muscle cells. In contrast, 12(S)-HETE was not a major product of conduit PC endothelial AA metabolism and did not exhibit potent bioactivity in conduit PC arteries. We suggest that, in the coronary microcirculation, 12(S)-HETE can function as a potent hyperpolarizing vasodilator that may contribute to endothelium-dependent relaxation, particularly in the setting of oxidative stress.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/metabolism
- Animals
- Arachidonate 12-Lipoxygenase/metabolism
- Arachidonic Acid/pharmacokinetics
- Caffeic Acids/pharmacology
- Calcimycin/pharmacology
- Cells, Cultured
- Coronary Circulation/physiology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/enzymology
- Ionophores/pharmacology
- Large-Conductance Calcium-Activated Potassium Channels
- Leukotrienes/pharmacology
- Linoleic Acids/pharmacology
- Lipid Peroxides/pharmacology
- Lipoxygenase Inhibitors/pharmacology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Microcirculation/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Oxidative Stress/physiology
- Potassium Channels/metabolism
- Potassium Channels, Calcium-Activated
- Swine
- Tritium
- Vasoconstrictor Agents/pharmacology
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- M H Zink
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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19
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Abstract
We are on the brink of harnessing the cell's natural defenses against ischemia and reperfusion injury after years of research into the destructive and protective mechanisms involved. Since the discovery of ischemic preconditioning, the surface receptors and signal transduction pathways underlying this phenomenon have been clarified, but many questions remain about the downstream targets that ultimately protect the cell. ATP-sensitive K(+) (K(ATP)) channels are thought to play a role in protection, but their mechanism of action has been unclear. Accumulating evidence now suggests that the location of the K(ATP) channels relevant to cytoprotection may be on the mitochondrial inner membrane instead of on the sarcolemma of the cardiac cell. This review discusses recent findings and unanswered questions about the role of K(ATP) channels in preconditioning and protection.
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Affiliation(s)
- B O'Rourke
- Institute of Molecular Cardiobiology, Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, USA.
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20
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Tong H, Chen W, Steenbergen C, Murphy E. Ischemic preconditioning activates phosphatidylinositol-3-kinase upstream of protein kinase C. Circ Res 2000; 87:309-15. [PMID: 10948065 DOI: 10.1161/01.res.87.4.309] [Citation(s) in RCA: 226] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The present study is designed to test whether phosphatidylinositol 3-kinase (PI3-kinase) has a role in the signaling pathway in ischemic preconditioning (PC) and whether it is proximal or distal to protein kinase C (PKC). Before 20 minutes of global ischemia, Langendorff-perfused rat hearts were perfused for 20 minutes (control); preconditioned with 4 cycles of 5-minute ischemia and 5-minute reflow (PC); treated with either wortmannin (WM) or LY 294002 (LY), each of which is a PI3-kinase inhibitor, for 5 minutes before and throughout PC; treated with 1,2-dioctanoyl-sn-glycerol (DOG), an activator of PKC for 10 minutes (DOG); treated identically to the DOG group except with WM added 10 minutes before and during perfusion with DOG; or treated with either WM or LY for 25 minutes. Recovery of left ventricular developed pressure (LVDP; percentage of initial preischemic LVDP), measured after 30 minutes of reflow, was improved by PC (72+/-2% versus 36+/-4% in control; P<0.001), and this was blocked by WM and LY (41+/-4% and 43+/-5%, respectively; P<0.05 compared with PC). DOG addition improved postischemic LVDP (67+/-6%; P<0.001 compared with control), but in contrast to its effect on PC, WM did not completely eliminate the protective effect of DOG (52+/-4%; P>0.05 compared with DOG; P<0.05 compared with control). PC induced phosphorylation of protein kinase B and translocation of PKC epsilon, and it increased NO production, and these effects were blocked by WM, which suggests a role for PI3-kinase in PC upstream of PKC and NO.
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Affiliation(s)
- H Tong
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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