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Hilgers RHP, Das KC. Redox Regulation of K + Channel: Role of Thioredoxin. Antioxid Redox Signal 2024. [PMID: 39099341 DOI: 10.1089/ars.2023.0416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
Significance: Potassium channels regulate the influx and efflux of K+ ions in various cell types that generate and propagate action potential associated with excitation, contraction, and relaxation of various cell types. Although redox active cysteines are critically important for channel activity, the redox regulation of K+ channels by thioredoxin (Trx) has not been systematically reviewed. Recent Advances: Redox regulation of K+ channel is now increasingly recognized as drug targets in the pathological condition of several cardiovascular disease processes. The role of Trx in regulation of these channels and its implication in pathological conditions have not been adequately reviewed. This review specifically focuses on the redox-regulatory role of Trx on K+ channel structure and function in physiological and pathophysiological conditions. Critical Issues: Ion channels, including K+ channel, have been implicated in the functioning of cardiomyocyte excitation-contraction coupling, vascular hyperpolarization, cellular proliferation, and neuronal stimulation in physiological and pathophysiological conditions. Although oxidation-reduction of ion channels is critically important in their function, the role of Trx, redox regulatory protein in regulation of these channels, and its implication in pathological conditions need to be studied to gain further insight into channel function. Future Directions: Future studies need to map all redox regulatory pathways in channel structure and function using novel mouse models and redox proteomic and signal transduction studies, which modulate various currents and altered excitability of relevant cells implicated in a pathological condition. We are yet at infancy of studies related to redox control of various K+ channels and structured and focused studies with novel animal models. Antioxid. Redox Signal. 00, 00-00.
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Affiliation(s)
- Rob H P Hilgers
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Kumuda C Das
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
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Phosphatidylinositol-4,5-Biphosphate (PI(4,5)P 2) Is Required for Rapid Endocytosis in Chromaffin Cells. BIOMED RESEARCH INTERNATIONAL 2020; 2020:9692503. [PMID: 32964048 PMCID: PMC7501565 DOI: 10.1155/2020/9692503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/17/2020] [Indexed: 12/27/2022]
Abstract
Objective Phosphoinositides play a regulatory role in clathrin-mediated endocytosis. However, their involvement in clathrin-independent endocytosis termed rapid endocytosis (RE), which is the mode of vesicle recycling during neurotransmitter release by transient fusion (known as kiss-and-run), has not been investigated. Here, we used patch-clamp recording of whole-cell membrane capacitance in adrenal chromaffin cells (ACC) to monitor changes of RE kinetics in response to pharmacological alteration of phosphatidylinositol-4,5-biphosphate (PI(4,5)P2) level by phenylarsine oxide (PAO) or antibody against phosphatidylinositol 4-kinase (AbPI4K). Results We found that PAO and AbPI4K significantly abrogated RE kinetics. Infusion of PI(4,5)P2 through the patch pipette potentiated RE kinetics and reversed PAO- and AbPI4K-induced blockade of RE. Similarly, the application of the bifunctional thiol dithiothreitol (DTT) to PAO-treated cells completely prevented the inhibitory effect of PAO on RE. These findings indicate that PI(4,5)P2 is implicated in the signaling (mechanistic) process of RE in ACC.
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Johnstone VPA, Hool LC. Glutathionylation of the L-type Ca2+ channel in oxidative stress-induced pathology of the heart. Int J Mol Sci 2014; 15:19203-25. [PMID: 25340983 PMCID: PMC4227269 DOI: 10.3390/ijms151019203] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 01/11/2023] Open
Abstract
There is mounting evidence to suggest that protein glutathionylation is a key process contributing to the development of pathology. Glutathionylation occurs as a result of posttranslational modification of a protein and involves the addition of a glutathione moiety at cysteine residues. Such modification can occur on a number of proteins, and exerts a variety of functional consequences. The L-type Ca2+ channel has been identified as a glutathionylation target that participates in the development of cardiac pathology. Ca2+ influx via the L-type Ca2+ channel increases production of mitochondrial reactive oxygen species (ROS) in cardiomyocytes during periods of oxidative stress. This induces a persistent increase in channel open probability, and the resulting constitutive increase in Ca2+ influx amplifies the cross-talk between the mitochondria and the channel. Novel strategies utilising targeted peptide delivery to uncouple mitochondrial ROS and Ca2+ flux via the L-type Ca2+ channel following ischemia-reperfusion have delivered promising results, and have proven capable of restoring appropriate mitochondrial function in myocytes and in vivo.
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Affiliation(s)
- Victoria P A Johnstone
- School of Anatomy, Physiology and Human Biology, the University of Western Australia, Crawley 6009, WA, Australia.
| | - Livia C Hool
- School of Anatomy, Physiology and Human Biology, the University of Western Australia, Crawley 6009, WA, Australia.
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Zheng MQ, Li X, Tang K, Sharma NM, Wyatt TA, Patel KP, Gao L, Bidasee KR, Rozanski GJ. Pyruvate restores β-adrenergic sensitivity of L-type Ca(2+) channels in failing rat heart: role of protein phosphatase. Am J Physiol Heart Circ Physiol 2013; 304:H1352-60. [PMID: 23504177 DOI: 10.1152/ajpheart.00873.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Oxidative stress plays a major role in the pathogenesis of heart failure, where the contractile response to β-adrenergic stimulation is profoundly depressed. This condition involves L-type Ca(2+) channels, but the mechanisms underlying their impaired adrenergic regulation are unclear. Thus the present study explored the basis for impaired adrenergic control of Ca(2+) channels in a rat infarction model of heart failure. Patch-clamp recordings of L-type Ca(2+) current (I(Ca,L)) from ventricular myocytes isolated from infarcted hearts showed a blunted response to intracellular cAMP that was reversed by treatment with exogenous pyruvate. Biochemical studies showed that basal and cAMP-stimulated protein kinase A activities were similar in infarcted and sham-operated hearts, whereas molecular analysis also found that binding of protein kinase A to the α(1C) subunit of voltage-gated Ca(2+) channel isoform 1.2 was not different between groups. By contrast, protein phosphatase 2A (PP2A) activity and binding to α(1C) were significantly less in infarcted hearts. The PP2A inhibitor okadaic acid markedly increased I(Ca,L) in sham-operated myocytes, but this response was significantly less in myocytes from infarcted hearts. However, pyruvate normalized I(Ca,L) stimulation by okadaic acid, and this effect was blocked by inhibitors of thioredoxin reductase, implicating a functional role for the redox-active thioredoxin system. Our data suggest that blunted β-adrenergic stimulation of I(CaL) in failing hearts results from hyperphosphorylation of Ca(2+) channels secondary to oxidation-induced impairment of PP2A function. We propose that the redox state of Ca(2+) channels or PP2A is controlled by the thioredoxin system which plays a key role in Ca(2+) channel remodeling of the failing heart.
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Affiliation(s)
- Ming-Qi Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Zinc modulation of basal and β-adrenergically stimulated L-type Ca2+ current in rat ventricular cardiomyocytes: consequences in cardiac diseases. Pflugers Arch 2012; 464:459-70. [DOI: 10.1007/s00424-012-1162-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/11/2012] [Accepted: 09/15/2012] [Indexed: 10/27/2022]
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6
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Andersson DC, Fauconnier J, Yamada T, Lacampagne A, Zhang SJ, Katz A, Westerblad H. Mitochondrial production of reactive oxygen species contributes to the β-adrenergic stimulation of mouse cardiomycytes. J Physiol 2011; 589:1791-801. [PMID: 21486840 DOI: 10.1113/jphysiol.2010.202838] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The sympathetic adrenergic system plays a central role in stress signalling and stress is often associated with increased production of reactive oxygen species (ROS). Furthermore, the sympathetic adrenergic system is intimately involved in the regulation of cardiomyocyte Ca2+ handling and contractility. In this study we hypothesize that endogenously produced ROS contribute to the inotropic mechanism of β-adrenergic stimulation in mouse cardiomyocytes. Cytoplasmic Ca2+ transients, cell shortening and ROS production were measured in freshly isolated cardiomyocytes using confocal microscopy and fluorescent indicators. As a marker of oxidative stress, malondialdehyde (MDA) modification of proteins was detected with Western blotting. Isoproterenol (ISO), a β-adrenergic agonist, increased mitochondrial ROS production in cardiomyocytes in a concentration- and cAMP–protein kinase A-dependent but Ca2+-independent manner. Hearts perfused with ISO showed a twofold increase in MDA protein adducts relative to control. ISO increased Ca2+ transient amplitude, contraction and L-type Ca2+ current densities (measured with whole-cell patch-clamp) in cardiomyocytes and these increases were diminished by application of the general antioxidant N-acetylcysteine (NAC) or the mitochondria-targeted antioxidant SS31. In conclusion, increased mitochondrial ROS production plays an integral role in the acute inotropic response of cardiomyocytes to β-adrenergic stimulation. On the other hand, chronically sustained adrenergic stress is associated with the development of heart failure and cardiac arrhythmias and prolonged increases in ROS may contribute to these defects.
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Affiliation(s)
- Daniel C Andersson
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden
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7
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Pons-Rejraji H, Bailey JL, Leclerc P. Modulation of bovine sperm signalling pathways: correlation between intracellular parameters and sperm capacitation and acrosome exocytosis. Reprod Fertil Dev 2009; 21:511-24. [PMID: 19383258 DOI: 10.1071/rd07169] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 12/24/2008] [Indexed: 12/23/2022] Open
Abstract
In the present study, the viability, intracellular pH (pHi), cAMP ([cAMP]i), calcium concentration and protein phosphotyrosine content were evaluated in relation to the acrosomal and capacitation status of freshly ejaculated bull spermatozoa. These parameters were evaluated before and after incubation with the capacitation inducer heparin, the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), the phosphotyrosyl-protein phosphatase inhibitors phenylarsine oxide (PAO) and sodium orthovanadate, and hydrogen peroxide. The results obtained were integrated to address the physiological interactions between the different signalling events affecting sperm capacitation and acrosome reaction. As expected, heparin promoted the expression of the 'B' pattern of chlortetracycline binding, increased pHi, [cAMP]i and the phosphotyrosine content of sperm proteins. The effects of heparin were enhanced by IBMX. Both PAO and sodium orthovanadate stimulated protein phosphotyrosine content and acrosomal exocytosis, although only PAO affected pH, Ca2+ and cAMP levels. Intracellular pH was increased while both Ca2+ and [cAMP]i were decreased. Physiological concentrations of H2O2 increased [cAMP]i and promoted acrosomal exocytosis. A significant positive correlation was found between sperm capacitation, protein phosphotyrosine content and stored Ca2+ concentration, whereas the acrosome reaction was correlated with pHi and Ca2+ concentration. This study presents the first global analysis of the major elements individually described during sperm capacitation and acrosome reaction signalling pathways, supported by statistical correlations.
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Affiliation(s)
- Hanae Pons-Rejraji
- Département d'Obstétrique-Gynécologie, Centre de Recherche en Biologie de la Reproduction, Université Laval, Québec, QC G1V 4G2, Canada
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Kojima SI, Ikeda M, Kamikawa Y. Further investigation into the mechanism of tachykinin NK(2) receptor-triggered serotonin release from guinea-pig proximal colon. J Pharmacol Sci 2009; 110:122-6. [PMID: 19423952 DOI: 10.1254/jphs.09032sc] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The effects of the monoamine oxidase A (MAO-A) inhibitor clorgyline, the L-type calcium-channel blocker nicardipine, the syntaxin inhibitor botulinum toxin type C, and the potent thiol-oxidant phenylarsine oxide (PAO) on the selective tachykinin NK(2)-receptor agonist [beta-Ala(8)]-neurokinin A(4-10) [betaAla-NKA-(4-10)]-evoked 5-hydroxytryptamine (5-HT) outflow from colonic enterochromaffin (EC) cells was investigated in vitro using isolated guinea-pig proximal colon. The betaAla-NKA-(4-10)-evoked outflow of 5-HT from clorgyline-treated colonic strips was markedly higher than that from clorgyline-untreated colonic strips. The betaAla-NKA-(4-10)-evoked 5-HT outflow from the clorgyline-treated colonic strips was sensitive to nicardipine or botulinum toxin type C. Moreover, PAO concentration-dependently suppressed the betaAla-NKA-(4-10)-evoked 5-HT outflow from the clorgyline-treated colonic strips. The suppressant action of PAO was reversed by the reducing agent dithiothrietol, but was not blocked by the protein tyrosine kinase inhibitor genistein. These results suggest that the tachykinin NK(2) receptor-triggered 5-HT release from guinea-pig colonic EC cells is mediated by syntaxin-related exocytosis mechanisms and that colonic mucosa MAO-A activity has the important function of modulating the tachykinin NK(2) receptor-triggered 5-HT release. It also appears that PAO-mediated sulfhydryl oxidation plays a role in modulating the tachykinin NK(2) receptor-triggered 5-HT release through a mechanism independent of inhibition of protein tyrosine phosphatase activity.
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Affiliation(s)
- Shu-Ichi Kojima
- Department of Pharmacology, Dokkyo Medical University School of Medicine, Japan.
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Hertelendi Z, Tóth A, Borbély A, Galajda Z, Édes I, Tósaki Á, Papp Z. The peroxynitrite evoked contractile depression can be partially reversed by antioxidants in human cardiomyocytes. J Cell Mol Med 2008; 13:2200-2209. [PMID: 18671759 DOI: 10.1111/j.1582-4934.2008.00445.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In this study, we aimed to determine the contribution of peroxynitrite-dependent sulfhydryl group (SH) oxidation to the contractile dysfunction in permeabilized left ventricular human cardiomyocytes using a comparative approach with the SH-oxidant 2,2'-dithiodipyridine (DTDP). Additionally, different antioxidants: dithiothreitol (DTT), reduced glutathione (GSH) or N-acetyl-L-cysteine (NAC) were employed to test reversibility. Maximal isometric active force production (F(o)) and the maximal turnover rate of the cross-bridge cycle (k(tr,max)) illustrated cardiomyocyte mechanics. SH oxidation was monitored by a semi-quantitative Ellman's assay and by SH-specific protein biotinylation. Both peroxynitrite and DTDP diminished F(o) in a concentration-dependent manner (EC(50,peroxynitrite) = 49 microM; EC(50,DTDP) = 2.75 mM). However, k(tr,max) was decreased only by 2.5-mM DTDP, but not by 50 microM peroxynitrite. The diminution of F(o) to zero by DTDP was paralleled by the complete elimination of the free SH groups, while the peroxynitrite-induced maximal reduction in free SH groups was only to 58 +/- 6% of the control (100%). The diminutions in F(o) and free SH groups evoked by 2.5-mM DTDP were completely reverted by DTT. In contrast, DTT induced only a partial restoration in F(o) (DeltaF(o,): approximately 13%; P < 0.05) despite full reversion in protein SH content after 50 microM peroxynitrite. Although, NAC or DTT were equally effective on F(o) after peroxynitrite exposures, NAC or GSH did not restore F(o) or k(tr,max) after DTDP treatments. Our results revealed that the peroxynitrite-evoked cardiomyocyte dysfunction has a small, but significant component resulting from reversible SH oxidation, and thereby illustrated the potential benefit of antioxidants during cardiac pathologies with excess peroxynitrite production.
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Affiliation(s)
- Zita Hertelendi
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Attila Borbély
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Zoltán Galajda
- Center of Cardiac Surgery, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - István Édes
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Árpád Tósaki
- Department of Pharmacology, Faculty of Pharmacy, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Zoltán Papp
- Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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10
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Liang H, Li X, Li S, Zheng MQ, Rozanski GJ. Oxidoreductase regulation of Kv currents in rat ventricle. J Mol Cell Cardiol 2008; 44:1062-1071. [PMID: 18455732 PMCID: PMC2492761 DOI: 10.1016/j.yjmcc.2008.03.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 03/03/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
Abstract
Oxidative stress contributes to the arrhythmogenic substrate created by myocardial ischemia-reperfusion partly through a shift in cell redox state, a key modulator of protein function. The activity of many oxidation-sensitive proteins is controlled by oxidoreductase systems that regulate the redox state of cysteine thiol groups, but the impact of these systems on ion channel function is not well defined. Thus, we examined the roles of the thioredoxin and glutaredoxin systems in controlling K(+) channels in the ventricle. An oxidative shift in redox state was elicited in isolated rat ventricular myocytes by brief exposure to diamide, a thiol-specific, membrane-permeable oxidant. Voltage-clamp studies showed that diamide decreased peak outward K(+) current (I(peak)) evoked by depolarizing test pulses by 41% (+60 mV; p<0.05) while steady-state outward current (I(ss)) measured at the end of the test pulse was decreased by 45% (p<0.05). These electrophysiological effects were not prevented by protein kinase C blockers, but the tyrosine kinase inhibitors genistein or lavendustin A blocked the suppression of both K(+) currents by diamide. Moreover, inhibition of I(peak) and I(ss) by diamide was reversed by dichloroacetate and an insulin-mimetic. The effect of dichloroacetate to normalize I(peak) after diamide was blocked by the thioredoxin system inhibitors auranofin or 13-cis-retinoic acid, but I(ss) was not affected by either compound. A pan-specific inhibitor of glutaredoxin and thioredoxin systems, 1,3-bis-(2-chloroethyl)-1-nitrosourea, also blocked the dichloroacetate effect on I(peak) but only partially inhibited the recovery of I(ss). These data suggest that acute regulation of cardiac K(+) channels by oxidoreductase systems is mediated by redox-sensitive tyrosine kinase/phosphatase pathways. The pathways controlling I(peak) channels are targets of the thioredoxin system whereas those regulating I(ss) channels are likely controlled by the glutaredoxin system. Thus, cardiac oxidoreductase systems may be important regulators of ion channels affected by pathogenic oxidative stress.
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Affiliation(s)
- Huixu Liang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Xun Li
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA; Department of Cardiology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu, P.R. China
| | - Shumin Li
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Ming-Qi Zheng
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - George J Rozanski
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA; Center for Redox Biology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
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Karashima Y, Prenen J, Meseguer V, Owsianik G, Voets T, Nilius B. Modulation of the transient receptor potential channel TRPA1 by phosphatidylinositol 4,5-biphosphate manipulators. Pflugers Arch 2008; 457:77-89. [DOI: 10.1007/s00424-008-0493-6] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 03/05/2008] [Indexed: 11/29/2022]
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12
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Liu B, Liang H, Liu L, Zhang H. Phosphatidylinositol 4,5-bisphosphate hydrolysis mediates histamine-induced KCNQ/M current inhibition. Am J Physiol Cell Physiol 2008; 295:C81-91. [PMID: 18448631 DOI: 10.1152/ajpcell.00028.2008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The M-type potassium channel, of which its molecular basis is constituted by KCNQ2-5 homo- or heteromultimers, plays a key role in regulating neuronal excitability and is modulated by many G protein-coupled receptors. In this study, we demonstrate that histamine inhibits KCNQ2/Q3 currents in human embryonic kidney (HEK)293 cells via phosphatidylinositol 4,5-bisphosphate (PIP(2)) hydrolysis mediated by stimulation of H(1) receptor and phospholipase C (PLC). Histamine inhibited KCNQ2/Q3 currents in HEK293 cells coexpressing H(1) receptor, and this effect was totally abolished by H(1) receptor antagonist mepyramine but not altered by H(2) receptor antagonist cimetidine. The inhibition of KCNQ currents was significantly attenuated by a PLC inhibitor U-73122 but not affected by depletion of internal Ca(2+) stores or intracellular Ca(2+) concentration ([Ca(2+)](i)) buffering via pipette dialyzing BAPTA. Moreover, histamine also concentration dependently inhibited M current in rat superior cervical ganglion (SCG) neurons by a similar mechanism. The inhibitory effect of histamine on KCNQ2/Q3 currents was entirely reversible but became irreversible when the resynthesis of PIP(2) was impaired with phosphatidylinsitol-4-kinase inhibitors. Histamine was capable of producing a reversible translocation of the PIP(2) fluorescence probe PLC(delta1)-PH-GFP from membrane to cytosol in HEK293 cells by activation of H(1) receptor and PLC. We concluded that the inhibition of KCNQ/M currents by histamine in HEK293 cells and SCG neurons is due to the consumption of membrane PIP(2) by PLC.
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Affiliation(s)
- Boyi Liu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei Province, China
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13
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Sims C, Reisenweber S, Viswanathan PC, Choi BR, Walker WH, Salama G. Sex, age, and regional differences in L-type calcium current are important determinants of arrhythmia phenotype in rabbit hearts with drug-induced long QT type 2. Circ Res 2008; 102:e86-100. [PMID: 18436794 DOI: 10.1161/circresaha.108.173740] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In congenital and acquired long QT type 2, women are more vulnerable than men to torsade de pointes. In prepubertal rabbits (and children), the arrhythmia phenotype is reversed; however, females still have longer action potential durations than males. Thus, sex differences in K(+) channels and action potential durations alone cannot account for sex-dependent arrhythmia phenotypes. The L-type calcium current (I(Ca,L)) is another determinant of action potential duration, Ca(2+) overload, early afterdepolarizations (EADs), and torsade de pointes. Therefore, sex, age, and regional differences in I(Ca,L) density and in EAD susceptibility were analyzed in epicardial left ventricular myocytes isolated from the apex and base of prepubertal and adult rabbit hearts. In prepubertal rabbits, peak I(Ca,L) at the base was 22% higher in males than females (6.4+/-0.5 versus 5.0+/-0.2 pA/pF; P<0.03) and higher than at the apex (6.4+/-0.5 versus 5.0+/-0.3 pA/pF; P<0.02). Sex differences were reversed in adults: I(Ca,L) at the base was 32% higher in females than males (9.5+/-0.7 versus 6.4+/-0.6 pA/pF; P<0.002) and 28% higher than the apex (9.5+/-0.7 versus 6.9+/-0.5 pA/pF; P<0.01). Apex-base differences in I(Ca,L) were not significant in adult male and prepubertal female hearts. Western blot analysis showed that Ca(v)1.2alpha levels varied with sex, maturity, and apex-base, with differences similar to variations in I(Ca,L); optical mapping revealed that the earliest EADs fired at the base. Single myocyte experiments and Luo-Rudy simulations concur that I(Ca,L) elevation promotes EADs and is an important determinant of long QT type 2 arrhythmia phenotype, most likely by reducing repolarization reserve and by enhancing Ca(2+) overload and the propensity for I(Ca,L) reactivation.
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Affiliation(s)
- Carl Sims
- University of Pittsburgh, School of Medicine, Department of Cell Biology and Physiology, Pittsburgh, PA 15261, USA
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14
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Hool LC. Evidence for the regulation of L-type Ca2+ channels in the heart by reactive oxygen species: mechanism for mediating pathology. Clin Exp Pharmacol Physiol 2008; 35:229-34. [PMID: 18197892 DOI: 10.1111/j.1440-1681.2007.04727.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. It is well recognized that reactive oxygen species (ROS) can activate transduction pathways to mediate pathophysiology. An increase in ROS has been implicated in a number of cardiovascular disorders. Reactive oxygen species regulate cell function through redox modification of target proteins. One of these target proteins is the L-type Ca(2+) channel. 2. There is good evidence that thiol reducing and oxidizing compounds, including hydrogen peroxide, can influence calcium channel function. The evidence for regulation of the channel protein and regulatory proteins by thiol-specific modifying agents and relevance to hypoxia and oxidative stress is presented. 3. Clinical studies suggest that calcium channel antagonists may be beneficial in reducing myocardial injury associated with oxidative stress. The identification of cysteines as possible targets for intervention during hypoxic trigger of arrhythmia or chronic pathological remodelling is discussed.
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Affiliation(s)
- Livia C Hool
- School of Biomedical Biomolecular and Chemical Sciences and The Western Australian Institute for Medical Research, The University of Western Australia, Crawley, Western Australia, Australia.
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Abstract
The level of intracellular Ca2+ plays a central role in normal and pathological signaling within and between neurons. These processes involve a cascade of events for locally raising and lowering cytosolic Ca2+. As the mechanisms for age-related alteration in Ca2+ dysregulation have been illuminated, hypotheses concerning Ca2+ homeostasis and brain aging have been modified. The idea that senescence is due to pervasive cell loss associated with elevated resting Ca2+ has been replaced by concepts concerning changes in local Ca2+ levels associated with neural activity. This article reviews evidence for a shift in the sources of intracellular Ca2+ characterized by a diminished role for N-methyl-D-aspartate receptors and an increased role for intracellular stores and voltage-dependent Ca2+ channels. Physiological and biological models are outlined, which relate a shift in Ca2+ regulation with changes in cell excitability and synaptic plasticity, resulting in a functional lesion of the hippocampus.
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Affiliation(s)
- Thomas C Foster
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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16
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Viola HM, Arthur PG, Hool LC. Transient Exposure to Hydrogen Peroxide Causes an Increase in Mitochondria-Derived Superoxide As a Result of Sustained Alteration in L-Type Ca
2+
Channel Function in the Absence of Apoptosis in Ventricular Myocytes. Circ Res 2007; 100:1036-44. [PMID: 17347474 DOI: 10.1161/01.res.0000263010.19273.48] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We sought to understand the effect of a transient exposure of cardiac myocytes to H
2
O
2
at a concentration that did not induce apoptosis. Myocytes were exposed to 30 μmol/L H
2
O
2
for 5 minutes followed by 10 U/mL catalase for 5 minutes to degrade the H
2
O
2
. Cellular superoxide was measured using dihydroethidium. Transient exposure to H
2
O
2
caused a 66.4% increase in dihydroethidium signal compared with controls exposed to only catalase, without activation of caspase 3 or evidence of necrosis. The increase in dihydroethidium signal was attenuated by the mitochondrial inhibitors myxothiazol or carbonyl cyanide
p
-(trifluoromethoxy)phenyl-hydrazone and when calcium uptake by the mitochondria was inhibited with Ru360. We investigated the L-type Ca
2+
channel (
I
Ca-L
) as a source of calcium influx. Nisoldipine, an inhibitor of
I
Ca-L
, attenuated the increase in superoxide. Basal channel activity increased from 5.4 to 8.9 pA/pF. Diastolic calcium was significantly increased in quiescent and contracting myocytes after H
2
O
2
. The response of
I
Ca-L
to β-adrenergic receptor stimulation was used as a functional reporter because decreasing intracellular H
2
O
2
alters the sensitivity of
I
Ca-L
to isoproterenol. H
2
O
2
increased the
K
0.5
required for activation of
I
Ca-L
by isoproterenol from 5.8 to 27.8 nmol/L. This effect and the increase in basal current density persisted for several hours after H
2
O
2
. We propose that extracellular H
2
O
2
is associated with an increase in superoxide from the mitochondria caused by an increase in Ca
2+
influx from
I
Ca-L
. The effect persists because a positive feedback exists among increased basal channel activity, elevated intracellular calcium, and superoxide production by the mitochondria.
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Affiliation(s)
- Helena M Viola
- School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
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17
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Abstract
Calcium plays an integral role in cellular function. It is a well-recognized second messenger necessary for signaling cellular responses, but in excessive amounts can be deleterious to function, causing cell death. The main route by which calcium enters the cytoplasm is either from the extracellular compartment or internal addistores via calcium channels. There is good evidence that calcium channels can respond to pharmacological compounds that reduce or oxidize thiol groups on the channel protein. In addition, reactive oxygen species such as hydrogen peroxide and superoxide that can mediate oxidative pathology also mediate changes in channel function via alterations of thiol groups. This review looks at the structure and function of calcium channels, the evidence that changes in cellular redox state mediate changes in channel function, and the role of redox modification of channels in disease processes. Understanding how redox modification of the channel protein alters channel structure and function is providing leads for the design of therapeutic interventions that target oxidative stress responses.
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Affiliation(s)
- Livia C Hool
- Discipline of Physiology, School of Biomedical, Biomolecular, and Chemical Sciences, The University of Western Australia, Crawley, Western Australia.
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18
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Burlando B, Viarengo A. Ca2+ is mobilized by hydroxyl radical but not by superoxide in RTH-149 cells: The oxidative switching-on of Ca2+ signaling. Cell Calcium 2005; 38:507-13. [PMID: 16140374 DOI: 10.1016/j.ceca.2005.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 06/23/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
Differential effects of superoxide and hydroxyl radical on intracellular calcium were investigated in trout hepatoma cells (RTH-149). [Ca2+]i variations were recorded using confocal imaging, fluo-3 loading, and exposure to various mixtures consisting of hypoxanthine/xanthine oxidase (HX/XO), and of sub-stimulatory concentrations of H2O2 and Cu2+ . No [Ca2+]i variation was found with HX/XO, a slight [Ca2+]i rise with a mixture of Cu2+ and HX/XO, a sustained rise with Cu2+ and H2O2, and the highest rise with Cu2+, H2O2 and HX/XO. Fluorimetric assay using dihydrorhodamine 123 revealed a correlation between the oxidizing power of a mixture and its effect on [Ca2+]i. The [Ca2+]i rise induced by Cu2+, H2O2 and HX/XO, was partially reduced in Ca2+ free medium or in the presence of SOD, converted into Ca2+ transient by verapamil, and almost abolished by the PLC inhibitor U73122 or in the presence of the hydroxyl radical quencher TEMPOL. Data indicate that Ca2+ is mobilized by hydroxyl radical but not by superoxide. The mechanism consists of PLC activation causing intracellular Ca2+ release, while Ca2+ entry potentiates Ca2+ release thus leading to sustained [Ca2+]i rise. A role of hydroxyl radicals in the oxidative switching-on of Ca2+ signaling is discussed.
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Affiliation(s)
- Bruno Burlando
- DISAV, Università del Piemonte Orientale, Via Bellini 25 G, 15100 Alessandria, Italy.
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19
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Kyselovic J, Martinka P, Batova Z, Gazova A, Godfraind T. Calcium channel blocker inhibits Western-type diet-evoked atherosclerosis development in ApoE-deficient mice. J Pharmacol Exp Ther 2005; 315:320-8. [PMID: 16020630 DOI: 10.1124/jpet.105.089847] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium channel blockers slow the progression of atherosclerosis. The purpose of the present experiments was to examine the action of lacidipine in a condition that accelerates the development of atherosclerosis in order to test the hypothesis that the protective action of lacidipine in atherosclerosis is unrelated to the reduction of blood pressure. Male ApoE-deficient mice (6 weeks old) were exposed either to normal chow (ND) or to a Western-type diet (WD, adjusted calorie diet containing 42% from fat) for 8 weeks. Western-type diet induced a reduction of nitric oxide (NO)-mediated endothelium-dependent relaxation to acetylcholine (Max relaxation % = 55.8 +/- 2 for ND and 46.6 +/- 2 for WD, n = 8, p < 0.05). Dose-relaxation curves to S-nitroso-N-acetylpenicillamine (SNAP) NO donor were also significantly rightward-shifted (n = 7, ANOVA, p < 0.01) in WD compared with ND arteries. Chronic treatment of WD mice with lacidipine (1 and 3 mg/kg/day) increased significantly the acetylcholine-evoked relaxation (to 76.6 +/- 3.5%, n = 6, ANOVA, p < 0.001) and prevented the loss of responsiveness to SNAP in mice exposed to WD. Plasma renin activity and endothelin-1 plasma levels as well as thiobarbituric acid-reactive substance levels in kidneys were significantly lower in WD mice treated with lacidipine than in untreated ones. In mice exposed to WD lacidipine reduced extension of atherosclerotic lesions, renal injury and increase in blood pressure. Experimental data indicate that inhibition of Western-type diet-evoked alterations is related to both antioxidant and vasoactive properties of lacidipine.
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Affiliation(s)
- Jan Kyselovic
- Department of Pharmacology, Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic
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