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Evans AM. On a Magical Mystery Tour with 8-Bromo-Cyclic ADP-Ribose: From All-or-None Block to Nanojunctions and the Cell-Wide Web. Molecules 2020; 25:E4768. [PMID: 33081414 PMCID: PMC7587525 DOI: 10.3390/molecules25204768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
A plethora of cellular functions are controlled by calcium signals, that are greatly coordinated by calcium release from intracellular stores, the principal component of which is the sarco/endooplasmic reticulum (S/ER). In 1997 it was generally accepted that activation of various G protein-coupled receptors facilitated inositol-1,4,5-trisphosphate (IP3) production, activation of IP3 receptors and thus calcium release from S/ER. Adding to this, it was evident that S/ER resident ryanodine receptors (RyRs) could support two opposing cellular functions by delivering either highly localised calcium signals, such as calcium sparks, or by carrying propagating, global calcium waves. Coincidentally, it was reported that RyRs in mammalian cardiac myocytes might be regulated by a novel calcium mobilising messenger, cyclic adenosine diphosphate-ribose (cADPR), that had recently been discovered by HC Lee in sea urchin eggs. A reputedly selective and competitive cADPR antagonist, 8-bromo-cADPR, had been developed and was made available to us. We used 8-bromo-cADPR to further explore our observation that S/ER calcium release via RyRs could mediate two opposing functions, namely pulmonary artery dilation and constriction, in a manner seemingly independent of IP3Rs or calcium influx pathways. Importantly, the work of others had shown that, unlike skeletal and cardiac muscles, smooth muscles might express all three RyR subtypes. If this were the case in our experimental system and cADPR played a role, then 8-bromo-cADPR would surely block one of the opposing RyR-dependent functions identified, or the other, but certainly not both. The latter seemingly implausible scenario was confirmed. How could this be, do cells hold multiple, segregated SR stores that incorporate different RyR subtypes in receipt of spatially segregated signals carried by cADPR? The pharmacological profile of 8-bromo-cADPR action supported not only this, but also indicated that intracellular calcium signals were delivered across intracellular junctions formed by the S/ER. Not just one, at least two. This article retraces the steps along this journey, from the curious pharmacological profile of 8-bromo-cADPR to the discovery of the cell-wide web, a diverse network of cytoplasmic nanocourses demarcated by S/ER nanojunctions, which direct site-specific calcium flux and may thus coordinate the full panoply of cellular processes.
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Grants
- 01/A/S/07453 Biotechnology and Biological Sciences Research Council
- WT046374 , WT056423, WT070772, WT074434, WT081195AIA, WT212923, WT093147 Wellcome Trust
- PG/10/95/28657 British Heart Foundation
- FS/03/033/15432, FS/05/050, PG/05/128/19884, RG/12/14/29885, PG/10/95/28657 British Heart Foundation
- RG/12/14/29885 British Heart Foundation
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Affiliation(s)
- A Mark Evans
- Centre for Discovery Brain Sciences and Cardiovascular Science, Edinburgh Medical School, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, UK
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2
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Reyes-Corral M, Sørensen NM, Thrasivoulou C, Dasgupta P, Ashmore JF, Ahmed A. Differential Free Intracellular Calcium Release by Class II Antiarrhythmics in Cancer Cell Lines. J Pharmacol Exp Ther 2019; 369:152-162. [PMID: 30655298 DOI: 10.1124/jpet.118.254375] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/02/2019] [Indexed: 12/31/2022] Open
Abstract
Class II antiarrhythmics or β-blockers are antisympathetic nervous system agents that act by blocking β-adrenoceptors. Despite their common clinical use, little is known about the effects of β-blockers on free intracellular calcium (Ca2+ i), an important cytosolic second messenger and a key regulator of cell function. We investigated the role of four chemical analogs, commonly prescribed β-blockers (atenolol, metoprolol, propranolol, and sotalol), on Ca2+ i release and whole-cell currents in mammalian cancer cells (PC3 prostate cancer and MCF7 breast cancer cell lines). We discovered that only propranolol activated free Ca2+ i release with distinct kinetics, whereas atenolol, metoprolol, and sotalol did not. The propranolol-induced Ca2+ i release was significantly inhibited by the chelation of extracellular calcium with ethylene glycol tetraacetic acid (EGTA) and by dantrolene, an inhibitor of the endoplasmic reticulum (ER) ryanodine receptor channels, and it was completely abolished by 2-aminoethoxydiphenyl borate, an inhibitor of the ER inositol-1,4,5-trisphosphate (IP3) receptor channels. Exhaustion of ER stores with 4-chloro-m-cresol, a ryanodine receptor activator, or thapsigargin, a sarco/ER Ca2+ ATPase inhibitor, precluded the propranolol-induced Ca2+ i release. Finally, preincubation of cells with sotalol or timolol, nonselective blockers of β-adrenoceptors, also reduced the Ca2+ i release activated by propranolol. Our results show that different β-blockers have differential effects on whole-cell currents and free Ca2+ i release and that propranolol activates store-operated Ca2+ i release via a mechanism that involves calcium-induced calcium release and putative downstream transducers such as IP3 The differential action of class II antiarrhythmics on Ca2+ i release may have implications on the pharmacology of these drugs.
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Affiliation(s)
- Marta Reyes-Corral
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
| | - Naja M Sørensen
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
| | - Christopher Thrasivoulou
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
| | - Prokar Dasgupta
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
| | - Jonathan F Ashmore
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
| | - Aamir Ahmed
- Centre for Stem Cells and Regenerative Medicine (M.R.-C., A.A.) and MRC Centre for Transplantation (P.D.), King's College London, London, United Kingdom; Sophion Bioscience A/S, Ballerup, Denmark (N.M.S.); and Departments of Cell and Developmental Biology (C.T.) and Neuroscience, Physiology and Pharmacology, and The Ear Institute (J.F.A.), University College London, London, United Kingdom
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Qiao Y, Zheng H, Li L, Zhang J, Li Y, Li S, Zhu R, Zhou J, Zhao S, Jiang Y, Lou H. Terpenoids with vasorelaxant effects from the Chinese liverwort Scapania carinthiaca. Bioorg Med Chem 2018; 26:4320-4328. [PMID: 30049584 DOI: 10.1016/j.bmc.2018.07.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 07/18/2018] [Accepted: 07/20/2018] [Indexed: 12/15/2022]
Abstract
Four new diterpenoids scapanacins A-D (1-4) including one kaurane and three clerodane derivatives, along with eleven known compounds (9-15), were isolated from the Chinese liverwort Scapania carinthiaca J.B. Jack ex Lindb. Their structures were determined based on extensive spectroscopic analyses, and electronic circular dichroism (ECD) calculations. Vasorelaxant activity assays of the clerodane-type diterpenoids 2, and 4-8 revealed that they relaxed 3rd-order rat mesenteric arterioles pre-contracted with norepinephrine (NE). Further assays with scapanacin D (4) confirmed that the vasodilatation was mediated through inhibition of Ca2+ influx via voltage-dependent Ca2+ channels (VDCs), and this Ca2+ channel blocking effect was also confirmed by inhibiting the extracellular Ca2+ influx in MOVAS cells. Besides, very little decrease of the relaxant activity caused by 4 on endothelium-denuded mesenteric arterioles with NE also suggested the vasodilatation was mainly produced by inhibiting Ca2+-induced contraction of smooth muscle. In addition, cytotoxicity testing showed that compounds 1 and 9 with α,β-unsaturated ketone exhibited inhibitory activities against a small panel of human cancer cell lines.
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Affiliation(s)
- Yanan Qiao
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Hongbo Zheng
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Lin Li
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Jiaozhen Zhang
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Yi Li
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Siwen Li
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China
| | - Rongxiu Zhu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250010, China
| | - Jinchuan Zhou
- School of Pharmacy, Linyi University, Linyi 276000, China
| | - Shengtian Zhao
- Central Laboratory, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Yuehua Jiang
- Central Laboratory, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Hongxiang Lou
- Department of Natural Products Chemistry, Key Lab of Chemical Biology of the Ministry of Education, Shandong University, Jinan 250012, China.
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The Modulatory Effect of Ischemia and Reperfusion on Arginine Vasopressin-Induced Arterial Reactions. BIOMED RESEARCH INTERNATIONAL 2016; 2016:3679048. [PMID: 27563664 PMCID: PMC4987452 DOI: 10.1155/2016/3679048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/04/2016] [Accepted: 07/10/2016] [Indexed: 11/17/2022]
Abstract
Aim of the Study. The purpose of this study was to investigate the impact of ischemia and reperfusion on the resistance of arteries to AVP (arginine vasopressin), with a particular emphasis on the role of smooth muscle cells in the action of vasopressin receptors and the role of the cGMP-associated signalling pathway. Materials and Methods. Experiment was performed on the perfunded tail arteries from male Wistar rats. The constriction triggered by AVP after 30 minutes of ischemia and 30 and 90 minutes of reperfusion was analysed. Analogous experiments were also carried out in the presence of 8Br-cGMP. Results. Ischemia reduces and reperfusion increases in a time-dependent manner the arterial reaction to AVP. The presence of 8Br-cGMP causes a significant decrease of arterial reactivity under study conditions. Conclusions. Ischemia and reperfusion modulate arterial contraction triggered by AVP. The effect of 8Br-cGMP on reactions, induced by AVP after ischemia and reperfusion, indicates that signalling pathway associated with nitric oxide (NO) and cGMP regulates the tension of the vascular smooth muscle cells.
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From contraction to gene expression: nanojunctions of the sarco/endoplasmic reticulum deliver site- and function-specific calcium signals. SCIENCE CHINA-LIFE SCIENCES 2016; 59:749-63. [PMID: 27376531 DOI: 10.1007/s11427-016-5071-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/07/2016] [Indexed: 10/21/2022]
Abstract
Calcium signals determine, for example, smooth muscle contraction and changes in gene expression. How calcium signals select for these processes is enigmatic. We build on the "panjunctional sarcoplasmic reticulum" hypothesis, describing our view that different calcium pumps and release channels, with different kinetics and affinities for calcium, are strategically positioned within nanojunctions of the SR and help demarcate their respective cytoplasmic nanodomains. SERCA2b and RyR1 are preferentially targeted to the sarcoplasmic reticulum (SR) proximal to the plasma membrane (PM), i.e., to the superficial buffer barrier formed by PM-SR nanojunctions, and support vasodilation. In marked contrast, SERCA2a may be entirely restricted to the deep, perinuclear SR and may supply calcium to this sub-compartment in support of vasoconstriction. RyR3 is also preferentially targeted to the perinuclear SR, where its clusters associate with lysosome-SR nanojunctions. The distribution of RyR2 is more widespread and extends from this region to the wider cell. Therefore, perinuclear RyR3s most likely support the initiation of global calcium waves at L-SR junctions, which subsequently propagate by calcium-induced calcium release via RyR2 in order to elicit contraction. Data also suggest that unique SERCA and RyR are preferentially targeted to invaginations of the nuclear membrane. Site- and function-specific calcium signals may thus arise to modulate stimulus-response coupling and transcriptional cascades.
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Garcia FADO, Tanae MM, Torres LMB, Lapa AJ, de Lima-Landman MTR, Souccar C. A comparative study of two clerodane diterpenes from Baccharis trimera (Less.) DC. on the influx and mobilization of intracellular calcium in rat cardiomyocytes. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2014; 21:1021-1025. [PMID: 24837474 DOI: 10.1016/j.phymed.2014.04.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 02/21/2014] [Accepted: 04/06/2014] [Indexed: 06/03/2023]
Abstract
Baccharis trimera (Less.) D.C. (Asteraceae) is a medicinal species native to South America and used in Brazilian folk medicine to treat gastrointestinal and liver diseases, kidney disorders and diabetes. The aqueous extract (AE) of the aerial parts of this species presented two mainly constituents: the ent-clerodane diterpene (Fig. 1) and the neo-clerodane diterpene (Fig. 2). The objective of this work was to study their activities on the blockade of Ca(2+)-induced contractions in KCL-depolarized rat portal vein preparations, and on the influx and mobilization of cytosolic calcium in rat cardiomyocytes by fluorescence measurements. The results showed that both the neo- and the ent-clerodane diterpenes reduced the maximal contractions induced by CaCl2, in KCl depolarized rat portal vein preparations, without modifying the EC50. The data on the concentration of cytosolic calcium ([Ca(2+)]c) showed that, while the neo-clerodane diterpene stimulates the mobilization of [Ca(2+)]c in rat cardiomyocytes, this effect was not observed with the ent-clerodane diterpene. On the other hand, the influx of calcium was not altered by the neo-clerodane diterpene, but was reduced in the presence of the ent-clerodane diterpene, indicating that this compound induces a blockade of the voltage-dependent calcium channels.
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Affiliation(s)
- Francisca Adilfa de Oliveira Garcia
- Department of Pharmacology, School of Medicine of the Federal University of São Paulo (UNIFESP), Rua 3 de Maio, 100, CEP: 04044-020 São Paulo, SP, Brazil.
| | - Mirtes Midori Tanae
- Department of Pharmacology, School of Medicine of the Federal University of São Paulo (UNIFESP), Rua 3 de Maio, 100, CEP: 04044-020 São Paulo, SP, Brazil
| | | | - Antônio José Lapa
- Department of Pharmacology, School of Medicine of the Federal University of São Paulo (UNIFESP), Rua 3 de Maio, 100, CEP: 04044-020 São Paulo, SP, Brazil
| | - Maria Teresa Riggio de Lima-Landman
- Department of Pharmacology, School of Medicine of the Federal University of São Paulo (UNIFESP), Rua 3 de Maio, 100, CEP: 04044-020 São Paulo, SP, Brazil
| | - Caden Souccar
- Department of Pharmacology, School of Medicine of the Federal University of São Paulo (UNIFESP), Rua 3 de Maio, 100, CEP: 04044-020 São Paulo, SP, Brazil
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Villegas R, Martinez NW, Lillo J, Pihan P, Hernandez D, Twiss JL, Court FA. Calcium release from intra-axonal endoplasmic reticulum leads to axon degeneration through mitochondrial dysfunction. J Neurosci 2014; 34:7179-89. [PMID: 24849352 PMCID: PMC4028495 DOI: 10.1523/jneurosci.4784-13.2014] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 02/26/2014] [Accepted: 04/12/2014] [Indexed: 12/30/2022] Open
Abstract
Axonal degeneration represents an early pathological event in neurodegeneration, constituting an important target for neuroprotection. Regardless of the initial injury, which could be toxic, mechanical, metabolic, or genetic, degeneration of axons shares a common mechanism involving mitochondrial dysfunction and production of reactive oxygen species. Critical steps in this degenerative process are still unknown. Here we show that calcium release from the axonal endoplasmic reticulum (ER) through ryanodine and IP3 channels activates the mitochondrial permeability transition pore and contributes to axonal degeneration triggered by both mechanical and toxic insults in ex vivo and in vitro mouse and rat model systems. These data reveal a critical and early ER-dependent step during axonal degeneration, providing novel targets for axonal protection in neurodegenerative conditions.
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MESH Headings
- Animals
- Axons/ultrastructure
- Calcium/metabolism
- Embryo, Mammalian
- Endoplasmic Reticulum/metabolism
- Endoplasmic Reticulum/pathology
- Female
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/ultrastructure
- Imaging, Three-Dimensional
- Male
- Membrane Potential, Mitochondrial/drug effects
- Membrane Potential, Mitochondrial/physiology
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron, Transmission
- Mitochondrial Diseases/pathology
- Mitochondrial Diseases/physiopathology
- Organ Culture Techniques
- Pregnancy
- Rats
- Rats, Sprague-Dawley
- Reactive Oxygen Species/metabolism
- Sciatic Nerve/ultrastructure
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Affiliation(s)
- Rosario Villegas
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile
| | - Nicolas W Martinez
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile
| | - Jorge Lillo
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile
| | - Phillipe Pihan
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile
| | - Diego Hernandez
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 20208, and
| | - Felipe A Court
- Millennium Nucleus for Regenerative Biology, Department of Physiology, Faculty of Biology, Pontificia Universidad Catolica de Chile, Santiago 8331150, Chile, NeuroUnion Biomedical Foundation, Santiago 7630614, Chile
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Longo LD, Goyal R. Cerebral artery signal transduction mechanisms: developmental changes in dynamics and Ca2+ sensitivity. Curr Vasc Pharmacol 2013; 11:655-711. [PMID: 24063382 PMCID: PMC3785013 DOI: 10.2174/1570161111311050008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/12/2012] [Accepted: 07/12/2012] [Indexed: 11/22/2022]
Abstract
As compared to the adult, the developing fetus and newborn infant are at much greater risk for dysregulation of cerebral blood flow (CBF), with complications such as intraventricular and germinal matrix hemorrhage with resultant neurologic sequelae. To minimize this dysregulation and its consequences presents a major challenge. Although in many respects the fundamental signal transduction mechanisms that regulate relaxation and contraction pathways, and thus cerebrovascular tone and CBF in the immature organism are similar to those of the adult, the individual elements, pathways, and roles differ greatly. Here, we review aspects of these maturational changes of relaxation/contraction mechanisms in terms of both electro-mechanical and pharmaco-mechanical coupling, their biochemical pathways and signaling networks. In contrast to the adult cerebrovasculature, in addition to attenuated structure with differences in multiple cytoskeletal elements, developing cerebrovasculature of fetus and newborn differs in many respects, such as a strikingly increased sensitivity to [Ca(2+)]i and requirement for extracellular Ca(2+) for contraction. In essence, the immature cerebrovasculature demonstrates both "hyper-relaxation" and "hypo-contraction". A challenge is to unravel the manner in which these mechanisms are integrated, particularly in terms of both Ca(2+)-dependent and Ca(2+)-independent pathways to increase Ca(2+) sensitivity. Gaining an appreciation of these significant age-related differences in signal mechanisms also will be critical to understanding more completely the vulnerability of the developing cerebral vasculature to hypoxia and other stresses. Of vital importance, a more complete understanding of these mechanisms promises hope for improved strategies for therapeutic intervention and clinical management of intensive care of the premature newborn.
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Affiliation(s)
- Lawrence D Longo
- Center for Perinatal Biology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA.
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9
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Clark JH, Kinnear NP, Kalujnaia S, Cramb G, Fleischer S, Jeyakumar LH, Wuytack F, Evans AM. Identification of functionally segregated sarcoplasmic reticulum calcium stores in pulmonary arterial smooth muscle. J Biol Chem 2010; 285:13542-9. [PMID: 20177054 PMCID: PMC2859515 DOI: 10.1074/jbc.m110.101485] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In pulmonary arterial smooth muscle, Ca(2+) release from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) may induce constriction and dilation in a manner that is not mutually exclusive. We show here that the targeting of different sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCA) and RyR subtypes to discrete SR regions explains this paradox. Western blots identified protein bands for SERCA2a and SERCA2b, whereas immunofluorescence labeling of isolated pulmonary arterial smooth muscle cells revealed striking differences in the spatial distribution of SERCA2a and SERCA2b and RyR1, RyR2, and RyR3, respectively. Almost all SERCA2a and RyR3 labeling was restricted to a region within 1.5 microm of the nucleus. In marked contrast, SERCA2b labeling was primarily found within 1.5 microm of the plasma membrane, where labeling for RyR1 was maximal. The majority of labeling for RyR2 lay in between these two regions of the cell. Application of the vasoconstrictor endothelin-1 induced global Ca(2+) waves in pulmonary arterial smooth muscle cells, which were markedly attenuated upon depletion of SR Ca(2+) stores by preincubation of cells with the SERCA inhibitor thapsigargin but remained unaffected after preincubation of cells with a second SERCA antagonist, cyclopiazonic acid. We conclude that functionally segregated SR Ca(2+) stores exist within pulmonary arterial smooth muscle cells. One sits proximal to the plasma membrane, receives Ca(2+) via SERCA2b, and likely releases Ca(2+) via RyR1 to mediate vasodilation. The other is located centrally, receives Ca(2+) via SERCA2a, and likely releases Ca(2+) via RyR3 and RyR2 to initiate vasoconstriction.
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Affiliation(s)
- Jill H Clark
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
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10
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Abstract
The sarcoplasmic reticulum (SR) of smooth muscles presents many intriguing facets and questions concerning its roles, especially as these change with development, disease, and modulation of physiological activity. The SR's function was originally perceived to be synthetic and then that of a Ca store for the contractile proteins, acting as a Ca amplification mechanism as it does in striated muscles. Gradually, as investigators have struggled to find a convincing role for Ca-induced Ca release in many smooth muscles, a role in controlling excitability has emerged. This is the Ca spark/spontaneous transient outward current coupling mechanism which reduces excitability and limits contraction. Release of SR Ca occurs in response to inositol 1,4,5-trisphosphate, Ca, and nicotinic acid adenine dinucleotide phosphate, and depletion of SR Ca can initiate Ca entry, the mechanism of which is being investigated but seems to involve Stim and Orai as found in nonexcitable cells. The contribution of the elemental Ca signals from the SR, sparks and puffs, to global Ca signals, i.e., Ca waves and oscillations, is becoming clearer but is far from established. The dynamics of SR Ca release and uptake mechanisms are reviewed along with the control of luminal Ca. We review the growing list of the SR's functions that still includes Ca storage, contraction, and relaxation but has been expanded to encompass Ca homeostasis, generating local and global Ca signals, and contributing to cellular microdomains and signaling in other organelles, including mitochondria, lysosomes, and the nucleus. For an integrated approach, a review of aspects of the SR in health and disease and during development and aging are also included. While the sheer versatility of smooth muscle makes it foolish to have a "one model fits all" approach to this subject, we have tried to synthesize conclusions wherever possible.
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Affiliation(s)
- Susan Wray
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Liverpool, Merseyside L69 3BX, United Kingdom.
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The role of intracellular ion channels in regulating cytoplasmic calciumin pulmonary arterial mmooth muscle: which store and where? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:57-76. [PMID: 20204723 DOI: 10.1007/978-1-60761-500-2_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The mobilisation of intracellular Ca(2+) stores plays a pivotal role in the regulation of arterial smooth muscle function, paradoxically during both contraction and relaxation. Moreover, different spatiotemporal Ca(2+) signalling patterns may trigger differential gene expression while mediating the same functional response. These facts alone serve to highlight the importance of the growing body of evidence in support of the view that different Ca(2+) storing organelles may be selected by the discrete or co-ordinated actions of multiple Ca(2+) mobilising messengers. In this respect, it is generally accepted that sarcoplasmic reticulum stores may be mobilised by the ubiquitous messenger inositol 1,4,5 trisphosphate. However, relatively little attention has been paid to the role of Ca(2+) mobilising pyridine nucleotides in arterial smooth muscle, namely cyclic adenosine diphosphate-ribose and nicotinic acid adenine dinucleotide phosphate. This review will, therefore, focus on the role of these novel Ca(2+) mobilising messengers in pulmonary arterial smooth muscle, with particular reference to hypoxic pulmonary vasoconstriction.
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12
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The sarcoplasmic reticulum Ca2+ store arrangement in vascular smooth muscle. Cell Calcium 2009; 46:313-22. [DOI: 10.1016/j.ceca.2009.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 08/28/2009] [Accepted: 09/03/2009] [Indexed: 01/01/2023]
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13
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Kovac JR, Chrones T, Sims SM. Temporal and spatial dynamics underlying capacitative calcium entry in human colonic smooth muscle. Am J Physiol Gastrointest Liver Physiol 2008; 294:G88-98. [PMID: 17975132 DOI: 10.1152/ajpgi.00305.2007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Following smooth muscle excitation and contraction, depletion of intracellular Ca(2+) stores activates capacitative Ca(2+) entry (CCE) to replenish stores and sustain cytoplasmic Ca(2+) (Ca(2+)(i)) elevations. The objectives of the present study were to characterize CCE and the Ca(2+)(i) dynamics underlying human colonic smooth muscle contraction by using tension recordings, fluorescent Ca(2+)-indicator dyes, and patch-clamp electrophysiology. The neurotransmitter acetylcholine (ACh) contracted tissue strips and, in freshly isolated colonic smooth muscle cells (SMCs), caused elevation of Ca(2+)(i) as well as activation of nonselective cation currents. To deplete Ca(2+)(i) stores, the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibitors thapsigargin and cyclopiazonic acid were added to a Ca(2+)-free bathing solution. Under these conditions, addition of extracellular Ca(2+) (3 mM) elicited increased tension that was inhibited by the cation channel blockers SKF-96365 (10 microM) and lanthanum (100 microM), suggestive of CCE. In a separate series of experiments on isolated SMCs, SERCA inhibition generated a gradual and sustained inward current. When combined with high-speed Ca(2+)-imaging techniques, the CCE-evoked rise of Ca(2+)(i) was associated with inward currents carrying Ca(2+) that were inhibited by SKF-96365. Regional specializations in Ca(2+) influx and handling during CCE were observed. Distinct "hotspot" regions of Ca(2+) rise and plateau were evident in 70% of cells, a feature not previously recognized in smooth muscle. We propose that store-operated Ca(2+) entry occurs in hotspots contributing to localized Ca(2+) elevations in human colonic smooth muscle.
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Affiliation(s)
- Jason R Kovac
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
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McCarron JG, Olson ML. A single luminally continuous sarcoplasmic reticulum with apparently separate Ca2+ stores in smooth muscle. J Biol Chem 2007; 283:7206-18. [PMID: 18096697 DOI: 10.1074/jbc.m708923200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whether or not the sarcoplasmic reticulum (SR) is a continuous, interconnected network surrounding a single lumen or comprises multiple, separate Ca2+ pools was investigated in voltage-clamped single smooth muscle cells using local photolysis of caged compounds and Ca2+ imaging. The entire SR could be depleted or refilled from one small site via either inositol 1,4,5-trisphosphate receptors (IP3R) or ryanodine receptors (RyR) suggesting the SR is luminally continuous and that Ca2+ may diffuse freely throughout. Notwithstanding, regulation of the opening of RyR and IP3R, by the [Ca2+] within the SR, may create several apparent SR elements with various receptor arrangements. IP3R and RyR may appear to exist entirely on a single store, and there may seem to be additional SR elements that express either only RyR or only IP3R. The various SR receptor arrangements and apparently separate Ca2+ storage elements exist in a single luminally continuous SR entity.
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Affiliation(s)
- John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, John Arbuthnott Building, 27 Taylor Street, Glasgow G4 0NR, Scotland, United Kingdom.
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15
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Ng LC, Kyle BD, Lennox AR, Shen XM, Hatton WJ, Hume JR. Cell culture alters Ca2+ entry pathways activated by store-depletion or hypoxia in canine pulmonary arterial smooth muscle cells. Am J Physiol Cell Physiol 2007; 294:C313-23. [PMID: 17977940 DOI: 10.1152/ajpcell.00258.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have shown that, in acutely dispersed canine pulmonary artery smooth muscle cells (PASMCs), depletion of both functionally independent inositol 1,4,5-trisphosphate (IP(3))- and ryanodine-sensitive Ca(2+) stores activates capacitative Ca(2+) entry (CCE). The present study aimed to determine if cell culture modifies intracellular Ca(2+) stores and alters Ca(2+) entry pathways caused by store depletion and hypoxia in canine PASMCs. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured in fura 2-loaded cells. Mn(2+) quench of fura 2 signal was performed to study divalent cation entry, and the effects of hypoxia were examined under oxygen tension of 15-18 mmHg. In acutely isolated PASMCs, depletion of IP(3)-sensitive Ca(2+) stores with cyclopiazonic acid (CPA) did not affect initial caffeine-induced intracellular Ca(2+) transients but abolished 5-HT-induced Ca(2+) transients. In contrast, CPA significantly reduced caffeine- and 5-HT-induced Ca(2+) transients in cultured PASMCs. In cultured PASMCs, store depletion or hypoxia caused a transient followed by a sustained rise in [Ca(2+)](i). The transient rise in [Ca(2+)](i) was partially inhibited by nifedipine, whereas the nifedipine-insensitive transient rise in [Ca(2+)](i) was inhibited by KB-R7943, a selective inhibitor of reverse mode Na(+)/Ca(2+) exchanger (NCX). The nifedipine-insensitive sustained rise in [Ca(2+)](i) was inhibited by SKF-96365, Ni(2+), La(3+), and Gd(3+). In addition, store depletion or hypoxia increased the rate of Mn(2+) quench of fura 2 fluorescence that was also inhibited by these blockers, exhibiting pharmacological properties characteristic of CCE. We conclude that cell culture of canine PASMCs reorganizes IP(3) and ryanodine receptors into a common intracellular Ca(2+) compartment, and depletion of this store or hypoxia activates voltage-operated Ca(2+) entry, reverse mode NCX, and CCE.
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Affiliation(s)
- Lih Chyuan Ng
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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16
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Wang J, Weigand L, Foxson J, Shimoda LA, Sylvester JT. Ca2+ signaling in hypoxic pulmonary vasoconstriction: effects of myosin light chain and Rho kinase antagonists. Am J Physiol Lung Cell Mol Physiol 2007; 293:L674-85. [PMID: 17575009 DOI: 10.1152/ajplung.00141.2007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Antagonists of myosin light chain (MLC) kinase (MLCK) and Rho kinase (ROK) are thought to inhibit hypoxic pulmonary vasoconstriction (HPV) by decreasing the concentration of phosphorylated MLC at any intracellular Ca(2+) concentration ([Ca(2+)](i)) in pulmonary arterial smooth muscle cells (PASMC); however, these antagonists can also decrease [Ca(2+)](i). To determine whether MLCK and ROK antagonists alter Ca(2+) signaling in HPV, we measured the effects of ML-9, ML-7, Y-27632, and HA-1077 on [Ca(2+)](i), Ca(2+) entry, and Ca(2+) release in rat distal PASMC exposed to hypoxia or depolarizing concentrations of KCl. We performed parallel experiments in isolated rat lungs to confirm the inhibitory effects of these agents on pulmonary vasoconstriction. Our results demonstrate that MLCK and ROK antagonists caused concentration-dependent inhibition of hypoxia-induced increases in [Ca(2+)](i) in PASMC and HPV in isolated lungs and suggest that this inhibition was due to blockade of Ca(2+) release from the sarcoplasmic reticulum and Ca(2+) entry through store- and voltage-operated Ca(2+) channels in PASMC. Thus MLCK and ROK antagonists might block HPV by inhibiting Ca(2+) signaling, as well as the actin-myosin interaction, in PASMC. If effects on Ca(2+) signaling were due to decreased phosphorylated myosin light chain concentration, their diversity suggests that MLCK and ROK antagonists may have acted by inhibiting myosin motors and/or altering the cytoskeleton in a manner that prevented achievement of required spatial relationships among the cellular components of the response.
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Affiliation(s)
- Jian Wang
- Division of Pulmonary & Critical Care Medicine, The Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA
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17
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Platoshyn O, Yu Y, Ko EA, Remillard CV, Yuan JXJ. Heterogeneity of hypoxia-mediated decrease in I(K(V)) and increase in [Ca2+](cyt) in pulmonary artery smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2007; 293:L402-16. [PMID: 17526598 DOI: 10.1152/ajplung.00391.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Hypoxic pulmonary vasoconstriction is caused by a rise in cytosolic Ca(2+) ([Ca(2+)](cyt)) in pulmonary artery smooth muscle cells (PASMC) via multiple mechanisms. PASMC consist of heterogeneous phenotypes defined by contractility, proliferation, and apoptosis as well as by differences in expression and function of various genes. In rat PASMC, hypoxia-mediated decrease in voltage-gated K(+) (Kv) currents (I(K(V))) and increase in [Ca(2+)](cyt) were not uniformly distributed in all PASMC tested. Acute hypoxia decreased I(K(V)) and increased [Ca(2+)](cyt) in approximately 46% and approximately 53% of PASMC, respectively. Using combined techniques of single-cell RT-PCR and patch clamp, we show here that mRNA expression level of Kv1.5 in hypoxia-sensitive PASMC (in which hypoxia reduced I(K(V))) was much greater than in hypoxia-insensitive cells (in which hypoxia negligibly affected I(K(V))). These results demonstrate that 1) different PASMC express different Kv channel alpha- and beta-subunits, and 2) the sensitivity of a PASMC to acute hypoxia partially depends on the expression level of Kv1.5 channels; hypoxia reduces whole-cell I(K(V)) only in PASMC that express high level of Kv1.5. In addition, the acute hypoxia-mediated changes in [Ca(2+)](cyt) also vary in different PASMC. Hypoxia increases [Ca(2+)](cyt) only in 34% of cells tested, and the different sensitivity of [Ca(2+)](cyt) to hypoxia was not related to the resting [Ca(2+)](cyt). An intrinsic mechanism within each individual cell may be involved in the heterogeneity of hypoxia-mediated effect on [Ca(2+)](cyt) in PASMC. These data suggest that the heterogeneity of PASMC may partially be related to different expression levels and functional sensitivity of Kv channels to hypoxia and to differences in intrinsic mechanisms involved in regulating [Ca(2+)](cyt).
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Affiliation(s)
- Oleksandr Platoshyn
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0725, USA
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18
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Leblanc N, Ledoux J, Saleh S, Sanguinetti A, Angermann J, O'Driscoll K, Britton F, Perrino BA, Greenwood IA. Regulation of calcium-activated chloride channels in smooth muscle cells: a complex picture is emerging. Can J Physiol Pharmacol 2006; 83:541-56. [PMID: 16091780 DOI: 10.1139/y05-040] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcium-activated chloride channels (ClCa) are ligand-gated anion channels as they have been shown to be activated by a rise in intracellular Ca2+ concentration in various cell types including cardiac, skeletal and vascular smooth muscle cells, endothelial and epithelial cells, as well as neurons. Because ClCa channels are normally closed at resting, free intracellular Ca2+ concentration (approximately 100 nmol/L) in most cell types, they have generally been considered excitatory in nature, providing a triggering mechanism during signal transduction for membrane excitability, osmotic balance, transepithelial chloride movements, or fluid secretion. Unfortunately, the genes responsible for encoding this class of ion channels is still unknown. This review centers primarily on recent findings on the properties of these channels in smooth muscle cells. The first section discusses the functional significance and biophysical and pharmacological properties of ClCa channels in smooth muscle cells, and ends with a description of 2 candidate gene families (i.e., CLCA and Bestrophin) that are postulated to encode for these channels in various cell types. The second section provides a summary of recent findings demonstrating the regulation of native ClCa channels in vascular smooth muscle cells by calmodulin-dependent protein kinase II and calcineurin and how their fine tuning by these enzymes may influence vascular tone.
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Affiliation(s)
- Normand Leblanc
- Department of Pharmacology, Centre of Biomedical Research Excellence (COBRE), University of Nevada School of Medicine, Reno, NV, USA.
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19
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Gómez-Viquez L, Rueda A, García U, Guerrero-Hernández A. Complex effects of ryanodine on the sarcoplasmic reticulum Ca2+ levels in smooth muscle cells. Cell Calcium 2005; 38:121-30. [PMID: 16055184 DOI: 10.1016/j.ceca.2005.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2002] [Revised: 05/19/2005] [Accepted: 06/06/2005] [Indexed: 10/25/2022]
Abstract
We have studied the effects of ryanodine and inhibition of the sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) with thapsigargin, on both [Ca(2+)](i) and the sarcoplasmic reticulum (SR) Ca(2+) level during caffeine-induced Ca(2+) release in single smooth muscle cells. Incubation with 10 microM ryanodine did not inhibit the first caffeine-induced [Ca(2+)](i) response, although it abolished the [Ca(2+)](i) response to a second application of caffeine. To assess whether ryanodine was inducing a permanent depletion of the internal Ca(2+) stores, we measured the SR Ca(2+) level with Mag-Fura-2. The magnitude of the caffeine-induced reduction in the SR Ca(2+) level was not augmented by incubating cells with 1 microM ryanodine. Moreover, on removal of caffeine, the SR Ca(2+) levels partially recovered in 61% of the cells due to the activity of thapsigargin-sensitive SERCA pumps. Unexpectedly, 10 microM ryanodine instead of inducing complete depletion of SR Ca(2+) stores markedly reduced the caffeine-induced SR Ca(2+) response. It was necessary to previously inhibit SERCA pumps with thapsigargin for ryanodine to be able to induce caffeine-triggered permanent depletion of SR Ca(2+) stores. These data suggest that the effect of ryanodine on smooth muscle SR Ca(2+) stores was markedly affected by the activity of SERCA pumps. Our data highlight the importance of directly measuring SR Ca(2+) levels to determine the effect of ryanodine on the internal Ca(2+) stores.
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20
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Evans AM, Wyatt CN, Kinnear NP, Clark JH, Blanco EA. Pyridine nucleotides and calcium signalling in arterial smooth muscle: from cell physiology to pharmacology. Pharmacol Ther 2005; 107:286-313. [PMID: 16005073 DOI: 10.1016/j.pharmthera.2005.03.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2005] [Indexed: 10/25/2022]
Abstract
It is generally accepted that the mobilisation of intracellular Ca2+ stores plays a pivotal role in the regulation of arterial smooth muscle function, paradoxically during both contraction and relaxation. However, the spatiotemporal pattern of different Ca2+ signals that elicit such responses may also contribute to the regulation of, for example, differential gene expression. These findings, among others, demonstrate the importance of discrete spatiotemporal Ca2+ signalling patterns and the mechanisms that underpin them. Of fundamental importance in this respect is the realisation that different Ca2+ storing organelles may be selected by the discrete or coordinated actions of multiple Ca2+ mobilising messengers. When considering such messengers, it is generally accepted that sarcoplasmic reticulum (SR) stores may be mobilised by the ubiquitous messenger inositol 1,4,5 trisphosphate. However, relatively little attention has been paid to the role of Ca2+ mobilising pyridine nucleotides in arterial smooth muscle, namely, cyclic adenosine diphosphate-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP). This review will therefore focus on these novel mechanisms of calcium signalling and their likely therapeutic potential.
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Affiliation(s)
- A Mark Evans
- Division of Biomedical Sciences, School of Biology, Bute Building, University of St. Andrews, St. Andrews, Fife KY16 9TS, UK.
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21
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Xu YJ, Saini HK, Cheema SK, Dhalla NS. Mechanisms of lysophosphatidic acid-induced increase in intracellular calcium in vascular smooth muscle cells. Cell Calcium 2005; 38:569-79. [PMID: 16216324 DOI: 10.1016/j.ceca.2005.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 08/30/2005] [Accepted: 08/30/2005] [Indexed: 11/17/2022]
Abstract
Although lysophosphatidic acid (LPA) is known to cause an increase in intracellular Ca2+ concentration ([Ca2+]i) in vascular smooth muscle cells (VSMCs), the mechanisms of [Ca2+]i mobilization by LPA are not fully understood. In the present study, the effect of LPA on [Ca2+]i mobilization in cultured A10 VSMCs was examined by Fura-2 fluorescence technique. The expression of LPA receptors was studied by immunostaining. LPA was observed to increase [Ca2+]i in a concentration-dependent manner; this increase was dependent on the concentration of extracellular Ca2+. Both sarcolemmal (SL) Na(+)-Ca2+ exchange inhibitors (amiloride, Ni2+ and KB-R7943) and Na(+)-H+ exchange inhibitor (MIA) as well as SL store-operated Ca2+ channel (SOC) antagonists (SK&F 96365, tyrphostin A9 and gadolinium), unlike SL Ca2+ channel antagonists (verapamil and diltiazem), inhibited the LPA-induced increase in [Ca2+]i. In addition, sarcoplasmic reticulum (SR) Ca2+ channel blocker (ryanodine), SR Ca2+ channel opener (caffeine), SR Ca2+ pump ATPase inhibitor (thapsigargin) and inositol 1,4,5-trisphosphate (InsP3) receptor antagonists (xestospongin and 2-aminoethoxydiphenyl borate) were found to inhibit the LPA-induced Ca2+ mobilization. Furthermore, phospholipase C (PLC) inhibitor (U 73122) and protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate) attenuated the LPA-induced increase in [Ca2+]i. These results indicate that Ca2+ mobilization by LPA involves extracellular Ca2+ entry through SL Na(+)-Ca2+ exchanger, Na(+)-H+ exchanger and SL SOCs. In addition, ryanodine-sensitive and InsP(3)-sensitive intracellular Ca2+ pools may be associated with the LPA-induced increase in [Ca2+]i. Furthermore, the LPA-induced [Ca2+]i mobilization in VSMCs seems to be due to the activation of both PLC and PKC.
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Affiliation(s)
- Yan-Jun Xu
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, R3021-351 Tache Avenue, Winnipeg, Man., Canada
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22
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Mauban JRH, Wilkinson K, Schach C, Yuan JXJ. Histamine-mediated increases in cytosolic [Ca2+] involve different mechanisms in human pulmonary artery smooth muscle and endothelial cells. Am J Physiol Cell Physiol 2005; 290:C325-36. [PMID: 16162658 PMCID: PMC1351365 DOI: 10.1152/ajpcell.00236.2005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Agonist stimulation of human pulmonary artery smooth muscle cells (PASMC) and endothelial cells (PAEC) with histamine showed similar spatiotemporal patterns of Ca(2+) release. Both sustained elevation and oscillatory patterns of changes in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) were observed in the absence of extracellular Ca(2+). Capacitative Ca(2+) entry (CCE) was induced in PASMC and PAEC by passive depletion of intracellular Ca(2+) stores with 10 microM cyclopiazonic acid (CPA; 15-30 min). The pyrazole derivative BTP2 inhibited CPA-activated Ca(2+) influx, suggesting that depletion of CPA-sensitive internal stores is sufficient to induce CCE in both PASMC and PAEC. The recourse of histamine-mediated Ca(2+) release was examined after exposure of cells to CPA, thapsigargin, caffeine, ryanodine, FCCP, or bafilomycin. In PASMC bathed in Ca(2+)-free solution, treatment with CPA almost abolished histamine-induced rises in [Ca(2+)](cyt). In PAEC bathed in Ca(2+)-free solution, however, treatment with CPA eliminated histamine-induced sustained and oscillatory rises in [Ca(2+)](cyt) but did not affect initial transient increase in [Ca(2+)](cyt). Furthermore, treatment of PAEC with a combination of CPA (or thapsigargin) and caffeine (and ryanodine), FCCP, or bafilomycin did not abolish histamine-induced transient [Ca(2+)](cyt) increases. These observations indicate that 1) depletion of CPA-sensitive stores is sufficient to cause CCE in both PASMC and PAEC; 2) induction of CCE in PAEC does not require depletion of all internal Ca(2+) stores; 3) the histamine-releasable internal stores in PASMC are mainly CPA-sensitive stores; 4) PAEC, in addition to a CPA-sensitive functional pool, contain other stores insensitive to CPA, thapsigargin, caffeine, ryanodine, FCCP, and bafilomycin; and 5) although the CPA-insensitive stores in PAEC may not contribute to CCE, they contribute to histamine-mediated Ca(2+) release.
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Affiliation(s)
- Joseph R H Mauban
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla 92093-0725, USA
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Thorneloe KS, Nelson MT. Ion channels in smooth muscle: regulators of intracellular calcium and contractility. Can J Physiol Pharmacol 2005; 83:215-42. [PMID: 15870837 DOI: 10.1139/y05-016] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Smooth muscle (SM) is essential to all aspects of human physiology and, therefore, key to the maintenance of life. Ion channels expressed within SM cells regulate the membrane potential, intracellular Ca2+ concentration, and contractility of SM. Excitatory ion channels function to depolarize the membrane potential. These include nonselective cation channels that allow Na+ and Ca2+ to permeate into SM cells. The nonselective cation channel family includes tonically active channels (Icat), as well as channels activated by agonists, pressure-stretch, and intracellular Ca2+ store depletion. Cl--selective channels, activated by intracellular Ca2+ or stretch, also mediate SM depolarization. Plasma membrane depolarization in SM activates voltage-dependent Ca2+ channels that demonstrate a high Ca2+ selectivity and provide influx of contractile Ca2+. Ca2+ is also released from SM intracellular Ca2+ stores of the sarcoplasmic reticulum (SR) through ryanodine and inositol trisphosphate receptor Ca2+ channels. This is part of a negative feedback mechanism limiting contraction that occurs by the Ca2+-dependent activation of large-conductance K+ channels, which hyper polarize the plasma membrane. Unlike the well-defined contractile role of SR-released Ca2+ in skeletal and cardiac muscle, the literature suggests that in SM Ca2+ released from the SR functions to limit contractility. Depolarization-activated K+ chan nels, ATP-sensitive K+ channels, and inward rectifier K+ channels also hyperpolarize SM, favouring relaxation. The expression pattern, density, and biophysical properties of ion channels vary among SM types and are key determinants of electrical activity, contractility, and SM function.
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Affiliation(s)
- Kevin S Thorneloe
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington 05405, USA.
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24
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Wilson SM, Mason HS, Ng LC, Montague S, Johnston L, Nicholson N, Mansfield S, Hume JR. Role of basal extracellular Ca2+ entry during 5-HT-induced vasoconstriction of canine pulmonary arteries. Br J Pharmacol 2005; 144:252-64. [PMID: 15655514 PMCID: PMC1575999 DOI: 10.1038/sj.bjp.0706077] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
1. Measurements of artery contraction, cytosolic [Ca(2+)], and Ca(2+) permeability were made to examine contractile and cytosolic [Ca(2+)] responses of canine pulmonary arteries and isolated cells to 5-hydroxytryptamine (5-HT), and to determine the roles of intracellular Ca(2+) release and extracellular Ca(2+) entry in 5-HT responses. 2. The EC(50) for 5-HT-mediated contractions and cytosolic [Ca(2+)] increases was approximately 10(-7) M and responses were inhibited by ketanserin, a 5-HT(2A)-receptor antagonist. 3. 5-HT induced cytosolic [Ca(2+)] increases were blocked by 20 microM Xestospongin-C and by 2-APB (IC(50)=32 microM inhibitors of InsP(3) receptor activation. 4. 5-HT-mediated contractions were reliant on release of InsP(3) but not ryanodine-sensitive Ca(2+) stores. 5. 5-HT-mediated contractions and cytosolic [Ca(2+)] increases were partially inhibited by 10 microM nisoldipine, a voltage-dependent Ca(2+) channel blocker. 6. Extracellular Ca(2+) removal reduced 5-HT-mediated contractions further than nisoldipine and ablated cytosolic [Ca(2+)] increases and [Ca(2+)] oscillations. Similar to Ca(2+) removal, Ni(2+) reduced cytosolic [Ca(2+)] and [Ca(2+)] oscillations. 7. Mn(2+) quench of fura-2 and voltage-clamp experiments showed that 5-HT failed to activate any significant voltage-independent Ca(2+) entry pathways, including store-operated and receptor-activated nonselective cation channels. Ni(2+) but not nisoldipine or Gd(3+) blocked basal Mn(2+) entry. 8. Voltage-clamp experiments showed that simultaneous depletion of both InsP(3) and ryanodine-sensitive intracellular Ca(2+) stores activates a current with linear voltage dependence and a reversal potential consistent with it being a nonselective cation channel. 5-HT did not activate this current. 9. Basal Ca(2+) entry, rather than CCE, is important to maintain 5-HT-induced cytosolic [Ca(2+)] responses and contraction in canine pulmonary artery.
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Affiliation(s)
- Sean M Wilson
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Helen S Mason
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Lih C Ng
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Stephen Montague
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Louise Johnston
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Neil Nicholson
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Sarah Mansfield
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
| | - Joseph R Hume
- Department of Pharmacology, University of Nevada School of Medicine, Reno, MS 318, NV 89557, U.S.A
- Author for correspondence:
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25
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Ureña J, Smani T, López-Barneo J. Differential functional properties of Ca2+ stores in pulmonary arterial conduit and resistance myocytes. Cell Calcium 2005; 36:525-34. [PMID: 15488602 DOI: 10.1016/j.ceca.2004.05.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 05/12/2004] [Accepted: 05/20/2004] [Indexed: 10/26/2022]
Abstract
In smooth muscle cells, oscillations of intracellular Ca2+ concentration ([Ca2+]i) are controlled by inositol 1,4,5-trisphosphate (InsP3) and ryanodine (Ry) receptors on the sarcoplasmic reticulum (SR). Here we show that these Ca2+ oscillations are regulated differentially by InsP3 and Ry receptors in cells dispersed from the main trunk of the pulmonary artery (conduit myocytes) or from tertiary and quaternary arterial branches (resistance myocytes). Ry receptor antagonists inhibit either spontaneous or ATP-induced Ca2+ oscillations in resistance myocytes but they do not affect the oscillations in most conduit myocytes. In contrast, agents that inhibit InsP3 production or activation of InsP3 receptors do not alter the oscillations is resistance myocytes but block them in conduit myocytes. We have also examined the degree of overlap of Ry- and InsP3-sensitive stores in myocytes along the pulmonary arterial tree. In conduit myocytes, depletion of Ry-sensitive stores with repeated application of caffeine in the presence of Ry or in Ca2+ free solutions did not prevent the ATP-induced Ca2+ release from InsP3-dependent stores. However, responsiveness to ATP was completely abolished in resistance myocytes subjected to the same experimental protocol. Thus, InsP3- and Ry-dependent stores appear to be separated in conduit myocytes but joined in resistance myocytes. These data demonstrate for the first time differential properties of intracellular Ca2+ stores and receptors in myocytes distributed along the pulmonary arterial tree and help to explain the distinct functional responses of large and small pulmonary vessels to vasoactive agents.
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Affiliation(s)
- Juan Ureña
- Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología, Hospital Universitario Virgen del Rocío, Edificio de Laboratorios, 2a planta, Universidad de Sevilla, E-41013 Seville, Spain
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Galiano M, Gasparre G, Lippe C, Cassano G. Inositol 1,4,5-trisphosphate and ryanodine receptors mobilize calcium from a common functional pool in human U373 MG cells. Cell Calcium 2005; 36:359-65. [PMID: 15451620 DOI: 10.1016/j.ceca.2004.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2004] [Revised: 02/11/2004] [Accepted: 02/19/2004] [Indexed: 11/30/2022]
Abstract
This investigation concentrates on the change in Ca(2+) concentration ([Ca(2+)]) caused by ryanodine in U373 MG cells. This cell type from a human astrocytoma is a unique cellular model because it only expresses the type 3 ryanodine receptor (RyR3), which is generally the least abundant isoform. In the presence of physiological [Ca(2+)] in the extracellular medium, U373 MG cells are caffeine-insensitive, even after forskolin treatment, and ryanodine-sensitive only when an unusually high concentration (30 microM) is applied. Xestospongin C behaves like thapsigargin and therefore cannot be used as a selective antagonist of inositol 1,4,5-trisphosphate receptors (InsP(3)Rs). After ryanodine challenge, addition of an analog of Substance P (SP), which should deplete InsP(3)-sensitive stores, has no effect on [Ca(2+)](i). After thapsigargin treatment, which unmasks the calcium leak from intracellular stores, neither ryanodine nor SP change [Ca(2+)](i), suggesting that thapsigargin completely depletes the ryanodine-sensitive and the InsP(3)-sensitive stores of U373 MG cells. Finally, in experiments monitoring the [Ca(2+)] in intracellular stores, InsP(3) stimulation of permeabilized cells causes a decrease in [Ca(2+)] that is not affected by subsequent ryanodine treatment. Our results support the conclusion that U373 MG cells express both InsP(3)Rs and RyRs that can individually or in combination mobilize only one functional Ca(2+) pool.
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Affiliation(s)
- Maria Galiano
- Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, 70126 Bari, Italy
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Zhang S, Yuan JXJ, Barrett KE, Dong H. Role of Na+/Ca2+ exchange in regulating cytosolic Ca2+ in cultured human pulmonary artery smooth muscle cells. Am J Physiol Cell Physiol 2004; 288:C245-52. [PMID: 15456699 DOI: 10.1152/ajpcell.00411.2004] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in pulmonary artery smooth muscle cells (PASMC) is an important stimulus for cell contraction, migration, and proliferation. Depletion of intracellular Ca2+ stores opens store-operated Ca2+ channels (SOC) and causes Ca2+ entry. Transient receptor potential (TRP) cation channels that are permeable to Na+ and Ca2+ are believed to form functional SOC. Because sarcolemmal Na+/Ca2+ exchanger has also been implicated in regulating [Ca2+]cyt, this study was designed to test the hypothesis that the Na+/Ca2+ exchanger (NCX) in cultured human PASMC is functionally involved in regulating [Ca2+]cyt by contributing to store depletion-mediated Ca2+ entry. RT-PCR and Western blot analyses revealed mRNA and protein expression for NCX1 and NCKX3 in cultured human PASMC. Removal of extracellular Na+, which switches the Na+/Ca2+ exchanger from the forward (Ca2+ exit) to reverse (Ca2+ entry) mode, significantly increased [Ca2+]cyt, whereas inhibition of the Na+/Ca2+ exchanger with KB-R7943 (10 microM) markedly attenuated the increase in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Store depletion also induced a rise in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Removal of extracellular Na+ or inhibition of the Na+/Ca2+ exchanger with KB-R7943 attenuated the store depletion-mediated Ca2+ entry. Furthermore, treatment of human PASMC with KB-R7943 also inhibited cell proliferation in the presence of serum and growth factors. These results suggest that NCX is functionally expressed in cultured human PASMC, that Ca2+ entry via the reverse mode of Na+/Ca2+ exchange contributes to store depletion-mediated increase in [Ca2+]cyt, and that blockade of the Na+/Ca2+ exchanger in its reverse mode may serve as a potential therapeutic approach for treatment of pulmonary hypertension.
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Affiliation(s)
- Shen Zhang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California, USA
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28
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Garavito-Aguilar ZV, Recio-Pinto E, Corrales AV, Zhang J, Blanck TJJ, Xu F. Differential thapsigargin-sensitivities and interaction of Ca2+ stores in human SH-SY5Y neuroblastoma cells. Brain Res 2004; 1011:177-86. [PMID: 15157804 DOI: 10.1016/j.brainres.2004.03.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2004] [Indexed: 10/26/2022]
Abstract
In human SH-SY5Y neuroblastoma cells, two distinct intracellular Ca2+ stores, a KCl-/caffeine-sensitive and a carbachol-/IP3-sensitive store, were demonstrated previously. In this study, responses of these two intracellular Ca2+ stores to thapsigargin were characterized. Ca2+-release from these stores was evoked either by high K+ (100 mM KCl) or by 1 mM carbachol, and changes in the intracellular Ca2+ level were monitored using Fura-2 fluorimetry. A sequential stimulation protocol (KCl-->carbachol or vice versa) allowed evaluation of the individual contribution of different Ca2+ stores to the evoked intracellular Ca2+ ([Ca2+]i)-transients and the dynamic interaction between them. Thapsigargin (0.05 nM - 20 microM) alone induced a [Ca2+]i-transient. Both the carbachol- and the KCl-evoked [Ca2+]i-transients were inhibited by thapsigargin, but with very different sensitivities. Thapsigargin inhibited the carbachol-evoked [Ca2+]i-transients with (IC50 = 0.353 nM) or without (IC50 = 0.448 nM) a KCl-prestimulation, but an additional small component, with a much lower sensitivity (IC50=4814 nM), was observed in the absence of a KCl-prestimulation. In contrast, the KCl-evoked [Ca2+]i-transients displayed only one component with a very low sensitivity to thapsigargin in both absence (IC50=3343 nM) and presence (IC50=6858 nM) of a carbachol-prestimulation. These findings suggest that the sarco-/endoplasmic reticular Ca2+ ATPases associated with the KCl-/caffeine- and carbachol-/IP3-sensitive intracellular Ca2+ stores differ from each other, either in types or in their post-translational modification. Such difference might play important role in the regulation of neuronal Ca2+ homeostasis.
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Affiliation(s)
- Zayra V Garavito-Aguilar
- Department of Anesthesiology, New York University School of Medicine, 550 First Avenue, Tisch Building, 4th Floor, Room HE-438, New York, NY 10016, USA
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Wier WG, Morgan KG. Alpha1-adrenergic signaling mechanisms in contraction of resistance arteries. Rev Physiol Biochem Pharmacol 2004; 150:91-139. [PMID: 12884052 DOI: 10.1007/s10254-003-0019-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Our goal in this review is to provide a comprehensive, integrated view of the numerous signaling pathways that are activated by alpha(1)-adrenoceptors and control actin-myosin interactions (i.e., crossbridge cycling and force generation) in mammalian arterial smooth muscle. These signaling pathways may be categorized broadly as leading either to thick (myosin) filament regulation or to thin (actin) filament regulation. Thick filament regulation encompasses both "Ca(2+) activation" and "Ca(2+)-sensitization" as it involves both activation of myosin light chain kinase (MLCK) by Ca(2+)-calmodulin and regulation of myosin light chain phosphatase (MLCP) activity. With respect to Ca(2+) activation, adrenergically induced Ca(2+) transients in individual smooth muscle cells of intact arteries are now being shown by high resolution imaging to be sarcoplasmic reticulum-dependent asynchronous propagating Ca(2+) waves. These waves differ from the spatially uniform increases in [Ca(2+)] previously assumed. Similarly, imaging during adrenergic activation has revealed the dynamic translocation, to membranes and other subcellular sites, of protein kinases (e.g., Ca(2+)-activated protein kinases, PKCs) that are involved in regulation of MLCP and thus in "Ca(2+) sensitization" of contraction. Thin filament regulation includes the possible disinhibition of actin-myosin interactions by phosphorylation of CaD, possibly by mitogen-activated protein (MAP) kinases that are also translocated during adrenergic activation. An hypothesis for the mechanisms of adrenergic activation of small arteries is advanced. This involves asynchronous Ca(2+) waves in individual SMC, synchronous Ca(2+) oscillations (at high levels of adrenergic activation), Ca(2+) sparks, "Ca(2+)-sensitization" by PKC and Rho-associated kinase (ROK), and thin filament mechanisms.
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Affiliation(s)
- W G Wier
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
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Roux E, Marhl M. Role of sarcoplasmic reticulum and mitochondria in Ca2+ removal in airway myocytes. Biophys J 2004; 86:2583-95. [PMID: 15041694 PMCID: PMC1304105 DOI: 10.1016/s0006-3495(04)74313-1] [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: 07/02/2003] [Accepted: 12/24/2003] [Indexed: 10/24/2022] Open
Abstract
The aim of this study was to use both a theoretical and experimental approach to determine the influence of the sarco-endoplasmic Ca2+-ATPase (SERCA) activity and mitochondria Ca2+ uptake on Ca2+ homeostasis in airway myocytes. Experimental studies were performed on myocytes freshly isolated from rat trachea. [Ca2+]i was measured by microspectrofluorimetry using indo-1. Stimulation by caffeine for 30 s induced a concentration-graded response characterized by a transient peak followed by a progressive decay to a plateau phase. The decay phase was accelerated for 1-s stimulation, indicating ryanodine receptor closure. In Na2+-Ca2+-free medium containing 0.5 mM La3+, the [Ca2+]i response pattern was not modified, indicating no involvement of transplasmalemmal Ca2+ fluxes. The mathematical model describing the mechanism of Ca2+ handling upon RyR stimulation predicts that after Ca2+ release from the sarcoplasmic reticulum, the Ca2+ is first sequestrated by cytosolic proteins and mitochondria, and pumped back into the sarcoplasmic reticulum after a time delay. Experimentally, we showed that the [Ca2+]i decay after Ca2+ increase was not altered by the SERCA inhibitor cyclopiazonic acid, but was slightly but significantly modified by the mitochondria uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone. The experimental and theoretical results indicate that, although Ca2+ pumping back by SERCA is active, it is not primarily involved in [Ca2+]i decrease that is due, in part, to mitochondrial Ca2+ uptake.
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Affiliation(s)
- Etienne Roux
- Laboratoire de Physiologie Cellulaire Respiratoire, Institut National de la Santé et de Recherche Médicale E 356, Université Victor Segalen Bordeaux 2, 33076 Bordeaux, France.
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Wang J, Shimoda LA, Sylvester JT. Capacitative calcium entry and TRPC channel proteins are expressed in rat distal pulmonary arterial smooth muscle. Am J Physiol Lung Cell Mol Physiol 2003; 286:L848-58. [PMID: 14672922 DOI: 10.1152/ajplung.00319.2003] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammalian homologs of transient receptor potential (TRP) genes in Drosophila encode TRPC proteins, which make up cation channels that play several putative roles, including Ca2+ entry triggered by depletion of Ca2+ stores in endoplasmic reticulum (ER). This capacitative calcium entry (CCE) is thought to replenish Ca2+ stores and contribute to signaling in many tissues, including smooth muscle cells from main pulmonary artery (PASMCs); however, the roles of CCE and TRPC proteins in PASMCs from distal pulmonary arteries, which are thought to be the major site of pulmonary vasoreactivity, remain uncertain. As an initial test of the possibility that TRPC channels contribute to CCE and Ca2+ signaling in distal PASMCs, we measured [Ca2+]i by fura-2 fluorescence in primary cultures of myocytes isolated from rat intrapulmonary arteries (>4th generation). In cells perfused with Ca2+-free media containing cyclopiazonic acid (10 microM) and nifedipine (5 microM) to deplete ER Ca2+ stores and block voltage-dependent Ca2+ channels, restoration of extracellular Ca2+ (2.5 mM) caused marked increases in [Ca2+]i whereas MnCl2 (200 microM) quenched fura-2 fluorescence, indicating CCE. SKF-96365, LaCl3, and NiCl2, blocked CCE at concentrations that did not alter Ca2+ responses to 60 mM KCl (IC50 6.3, 40.4, and 191 microM, respectively). RT-PCR and Western blotting performed on RNA and protein isolated from distal intrapulmonary arteries and PASMCs revealed mRNA and protein expression for TRPC1, -4, and -6, but not TRPC2, -3, -5, or -7. Our results suggest that CCE through TRPC-encoded Ca2+ channels could contribute to Ca2+ signaling in myocytes from distal intrapulmonary arteries.
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Affiliation(s)
- Jian Wang
- Div. of Pulmonary & Critical Care Medicine, The Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Cir., Baltimore, MD 21224, USA
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32
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Villullas IR, Smith AJ, Heavens RP, Simpson PB. Characterisation of a sphingosine 1-phosphate-activated Ca2+ signalling pathway in human neuroblastoma cells. J Neurosci Res 2003; 73:215-26. [PMID: 12836164 DOI: 10.1002/jnr.10636] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Sphingosine 1-phosphate (S1P) has assumed great importance within neuroscience research because of putative links between S1P-sensitive Edg receptors and neuroregeneration, cell survival, and alterations in neurite outgrowth. In the present study, we examined the mechanisms by which the endogenous complement of S1P-sensitive human Edg receptors can elevate Ca(2+) in the human neuroblastoma cell line, SH-SY5Y. Reverse transcriptase-polymersase chain reaction (RT-PCR) confirmed the expression of mRNA for Edg 3, 5, and 8 subtypes of S1P-responsive Edg receptors in SH-SY5Y cells. Neither S1P nor the muscarinic agonist methacholine were able to cause a change in SH-SY5Y cell morphology, whereas retinoic acid caused a range of changes, including an increase in neurite outgrowth, under similar test conditions. Stimulation with S1P resulted in a slowly rising increase in cytosolic Ca(2+) levels. These responses were dependent upon inositol-1,4,5-trisphosphate receptors, thapsigargin-sensitive endoplasmic reticulum, and also intact functional mitochondria. S1P-evoked Ca(2+) responses were similar in mechanism to those of methacholine, which activated a much faster responding, larger amplitude Ca(2+) response. These studies indicate that in an endogenous human expression system, S1P appears to be an efficacious agonist of Edg receptors. Despite its slow time course of response, S1P appears to activate the same single Ca(2+) store in SH-SY5Y cells as is activated by methacholine and other G protein coupled receptors.
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Affiliation(s)
- Israel Ramos Villullas
- Merck Sharp & Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex, United Kingdom
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33
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Gómez-Viquez L, Guerrero-Serna G, García U, Guerrero-Hernández A. SERCA pump optimizes Ca2+ release by a mechanism independent of store filling in smooth muscle cells. Biophys J 2003; 85:370-80. [PMID: 12829491 PMCID: PMC1303092 DOI: 10.1016/s0006-3495(03)74481-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Thapsigargin-sensitive sarco/endoplasmic reticulum Ca(2+) pumps (SERCAs) are involved in maintaining and replenishing agonist-sensitive internal stores. Although it has been assumed that release channels act independently of SERCA pumps, there are data suggesting the opposite. Our aim was to study the relationship between SERCA pumps and the release channels in smooth muscle cells. To this end, we have rapidly blocked SERCA pumps with thapsigargin, to avoid depletion of the internal Ca(2+) stores, and induced Ca(2+) release with either caffeine, to open ryanodine receptors, or acetylcholine, to open inositol 1,4,5-trisphosphate receptors. Blocking SERCA pumps produced smaller and slower agonist-induced [Ca(2+)](i) responses. We determined the Ca(2+) level of the internal stores both indirectly, measuring the frequency of spontaneous transient outward currents, and directly, using Mag-Fura-2, and demonstrated that the inhibition of SERCA pumps did not produce a reduction of the sarco/endoplasmic reticulum Ca(2+) levels to explain the decrease in the agonist-induced Ca(2+) responses. It appears that SERCA pumps are involved in sustaining agonist-induced Ca(2+) release by a mechanism that involves the modulation of Ca(2+) availability in the lumen of the internal stores.
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Boittin FX, Dipp M, Kinnear NP, Galione A, Evans AM. Vasodilation by the calcium-mobilizing messenger cyclic ADP-ribose. J Biol Chem 2003; 278:9602-8. [PMID: 12486132 DOI: 10.1074/jbc.m204891200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In artery smooth muscle, adenylyl cyclase-coupled receptors such as beta-adrenoceptors evoke Ca(2+) signals, which open Ca(2+)-activated potassium (BK(Ca)) channels in the plasma membrane. Thus, blood pressure may be lowered, in part, through vasodilation due to membrane hyperpolarization. The Ca(2+) signal is evoked via ryanodine receptors (RyRs) in sarcoplasmic reticulum proximal to the plasma membrane. We show here that cyclic adenosine diphosphate-ribose (cADPR), by activating RyRs, mediates, in part, hyperpolarization and vasodilation by beta-adrenoceptors. Thus, intracellular dialysis of cADPR increased the cytoplasmic Ca(2+) concentration proximal to the plasma membrane in isolated arterial smooth muscle cells and induced a concomitant membrane hyperpolarization. Smooth muscle hyperpolarization mediated by cADPR, by beta-adrenoceptors, and by cAMP, respectively, was abolished by chelating intracellular Ca(2+) and by blocking RyRs, cADPR, and BK(Ca) channels with ryanodine, 8-amino-cADPR, and iberiotoxin, respectively. The cAMP-dependent protein kinase A antagonist N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide hydrochloride (H89) blocked hyperpolarization by isoprenaline and cAMP, respectively, but not hyperpolarization by cADPR. Thus, cADPR acts as a downstream element in this signaling cascade. Importantly, antagonists of cADPR and BK(Ca) channels, respectively, inhibited beta-adrenoreceptor-induced artery dilation. We conclude, therefore, that relaxation of arterial smooth muscle by adenylyl cyclase-coupled receptors results, in part, from a cAMP-dependent and protein kinase A-dependent increase in cADPR synthesis, and subsequent activation of sarcoplasmic reticulum Ca(2+) release via RyRs, which leads to activation of BK(Ca) channels and membrane hyperpolarization.
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Affiliation(s)
- François-Xavier Boittin
- Division of Biomedical Sciences, School of Biology, Bute Building, University of St Andrews, St Andrews, Fife, KY16 9TS, United Kingdom
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Simpson PB, Villullas IR, Schurov I, Kerby J, Millard R, Haldon C, Beer MS, McAllister G. Native and Recombinant Human Edg4 Receptor-Mediated Ca2+ Signalling. Assay Drug Dev Technol 2002; 1:31-40. [PMID: 15090154 DOI: 10.1089/154065802761001284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have developed an assay system suitable for assessment of compound action on the Edg4 subtype of the widely expressed lysophosphatidic acid (LPA)-responsive Edg receptor family. Edg4 was stably overexpressed in the rat hepatoma cell line Rh 7777, and a Ca(2+)-based FLIPR assay developed for measurement of functional responses. In order to investigate the mechanisms linking Edg4 activation to cytosolic Ca(2+) elevation, we have also studied LPA signalling in a human neuroblastoma cell line that endogenously expresses Edg4. LPA responses displayed similar kinetics and potency in the two cell lines. The Ca(2+) signal generated by activation of LPA-sensitive receptors in these cells is mediated primarily by endoplasmic reticulum. However, there is a substantial inhibition of the LPA response by FCCP, indicating that mitochondria also play a key role in the LPA response. Partial inhibition of the response by cyclosporin A could indicate an active Ca(2+) release role for mitochondria in the LPA response. The inositol 1,4,5-triphosphate receptor antagonist 2-aminoethyl diphenyl borate markedly inhibits, but does not abolish, the Ca(2+) response to LPA, suggesting further complexity to the signalling pathways activated by Edg receptors. In comparing Edg signalling in recombinant and native cells, there is a striking overall similarity in receptor expression pattern, agonist potency, and the effect of modulators on the Ca(2+) response. This indicates that the Edg4-overexpressing Rh7777 cell line is a very useful model system for studying receptor pharmacology and signalling mechanisms, and for investigating the Edg4 receptor's downstream effects.
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Affiliation(s)
- Peter B Simpson
- Merck Sharp & Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK.
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Loukotová J, Kunes J, Zicha J. Gender-dependent difference in cell calcium handling in VSMC isolated from SHR: the effect of angiotensin II. J Hypertens 2002; 20:2213-9. [PMID: 12409960 DOI: 10.1097/00004872-200211000-00021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To investigate gender-dependent difference in the free cytosolic calcium concentration ([Ca2+ ]i ) response to angiotensin II (Ang II) in vascular smooth muscle cells (VSMC) isolated from spontaneously hypertensive rats (SHR). To further evaluate this gender-dependent difference by studying the role of thapsigargin-sensitive intracellular calcium stores and calcium influx in VSMC isolated from male and female SHR. DESIGN AND METHODS Confluent primary cultures of VSMC isolated from male (n = 14) and female (n = 14) SHR aged 10 weeks were used in this study. [Ca2+ ]i was measured by image analysis of single myocytes loaded with Fura-2. [Ca2+ ]i response of VSMC to Ang II was measured in the presence and absence of extracellular Ca2+, to evaluate the influence of Ca2+ influx. To characterize inositol triphosphate (IP3 )-sensitive sarcoplasmic reticulum calcium stores, thapsigargin-sensitive calcium stores were measured in VSMC isolated from SHR of both genders. RESULTS VSMC isolated from male SHR were characterized by an augmented [Ca2+ ]i response to angiotensin II in comparison with VSMC isolated from female SHR. Surprisingly, the thapsigargin-stimulated [Ca2+ ]i rise was found to be significantly greater in VSMC isolated from female SHR compared with VSMC isolated from male SHR. On the other hand, the gender-dependent difference in [Ca2+ ]i response to angiotensin II was abolished in the absence of extracellular calcium. CONCLUSIONS We demonstrated in VSMC isolated from SHR of both genders that a greater [Ca2+ ]i response to angiotensin II in male than female VSMC is dependent on Ca2+ influx.
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Affiliation(s)
- Jana Loukotová
- Institute of Physiology, Academy of Sciences of the Czech Republic and Center for Experimental Research of Cardiovascular Diseases, Prague, Czech Republic.
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Stout MA, Raeymaekers L, De Smedt H, Casteels R. Characterization of Ca2+ release from heterogeneous Ca2+ stores in sarcoplasmic reticulum isolated from arterial and gastric smooth muscle. Can J Physiol Pharmacol 2002; 80:588-603. [PMID: 12117308 DOI: 10.1139/y02-083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+ transport was investigated in vesicles of sarcoplasmic reticulum subfractionated from bovine main pulmonary artery and porcine gastric antrum using digitonin binding and zonal density gradient centrifugation. Gradient fractions recovered at 15-33% sucrose were studied as the sarcoplasmic reticulum component using Fluo-3 fluorescence or 45Ca2+ Millipore filtration. Thapsigargin blocked active Ca2+ uptake and induced a slow Ca2+ release from actively loaded vesicles. Unidirectional 45Ca2+ efflux from passively loaded vesicles showed multicompartmental kinetics. The time course of an initial fast component could not be quantitatively measured with the sampling method. The slow release had a half-time of several minutes. Both components were inhibited by 20 microM ruthenium red and 10 mM Mg2+. Caffeine, inositol 1,4,5-trisphosphate, ATP, and diltiazem accelerated the slow component. A Ca2+ release component activated by ryanodine or cyclic adenosine diphosphate ribose was resolved with Fluo-3. Comparison of tissue responses showed that the fast Ca2+ release was significantly smaller and more sensitive to inhibition by Mg2+ and ruthenium red in arterial vesicles. They released more Ca2+ in response to inositol 1,4,5-trisphosphate and were more sensitive to activation by cyclic adenosine diphosphate ribose. Ryanodine and caffeine, in contrast, were more effective in gastric antrum. In each tissue, the fraction of the Ca2+ store released by sequential application of caffeine and inositol 1,4,5-trisphosphate depended on the order applied and was additive. The results indicate that sarcoplasmic reticulum purified from arterial and gastric smooth muscle represents vesicle subpopulations that retain functional Ca2+ channels that reflect tissue-specific pharmacological modulation. The relationship of these differences to physiological responses has not been determined.
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Fellner SK, Arendshorst WJ. Store-operated Ca2+ entry is exaggerated in fresh preglomerular vascular smooth muscle cells of SHR. Kidney Int 2002; 61:2132-41. [PMID: 12028453 DOI: 10.1046/j.1523-1755.2002.00383.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Regulation of preglomerular vasomotor tone vessels ultimately control glomerular filtration rate, sodium reabsorption and systemic blood pressure. To gain insight into the complex renal hemodynamic factors that may result in hypertension, we studied calcium signaling pathways. METHODS Fresh, single, preglomerular vascular smooth muscle cells (VSMC) were isolated from 5- to 6-week-old SHR and WKY utilizing a magnetized microsphere/sieving technique. Cytosolic Ca2+ ([Ca2+]i) was measured with fura-2 ratiometric fluorescence. To examine store-operated calcium entry (SOC), VSMC were activated in calcium-free buffer containing nifedipine. To deplete the sarcoplasmic reticulum (SR) of Ca2+, vasopressin-1 receptor agonist [V1R; inositol trisphosphate (IP3)-mediated mobilization], ryanodine (non-IP3 induced mobilization), and cyclopiazonic acid (CPA; Ca2+-ATPase inhibition) were utilized. Addition of external calcium followed by quenching of the fura/Ca2+ signal with Mn2+ permitted assessment of divalent cation entry via SOC. RESULTS V1R caused greater mobilization in SHR than WKY (P < 0.01) as well as greater calcium entry (P < 0.001). Ryanodine and CPA both caused SR calcium depletion that was not statistically different between strains, but absolute calcium entry through SOC was more than double in SHR following either maneuver (P < 0.001). 2-Amino-ethoxybiphenyl borane (2-APB), an inhibitor not only of IP3 receptors, but also of SOC, blocked calcium entry in the ryanodine and CPA experiments independent of IP3. As well, Gd3+, a selective inhibitor of SOC, inhibited the Ca2+ response. We also studied L-channel calcium entry stimulated by V1R. The total calcium response was greater in SHR as was the absolute inhibition by nifedipine. As a percent of the total response, participation of L-type channels sensitive to nifedipine was about 45% in both strains of rat. CONCLUSION Utilizing three separate mechanisms to deplete the SR of Ca2+ in order to activate SOC, we show for the first time, that SOC is exaggerated in preglomerular VSMC of young SHR.
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MESH Headings
- Animals
- Animals, Newborn/metabolism
- Arginine Vasopressin/pharmacology
- Arterioles
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/metabolism
- Calcium Channels, L-Type/metabolism
- Calcium-Transporting ATPases/antagonists & inhibitors
- Indoles/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Kidney Glomerulus/blood supply
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Protein Isoforms/metabolism
- Rats
- Rats, Inbred SHR/metabolism
- Rats, Inbred WKY
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Vasopressin/agonists
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum/enzymology
- Vasopressins/metabolism
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Affiliation(s)
- Susan K Fellner
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, 27599-7545, USA.
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39
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Martin S, Andriambeloson E, Takeda K, Andriantsitohaina R. Red wine polyphenols increase calcium in bovine aortic endothelial cells: a basis to elucidate signalling pathways leading to nitric oxide production. Br J Pharmacol 2002; 135:1579-87. [PMID: 11906973 PMCID: PMC1573266 DOI: 10.1038/sj.bjp.0704603] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
1. The present study investigates the mechanisms by which polyphenolic compounds from red wine elicit Ca(2+) mobilization in bovine aortic endothelial cells (BAECs). Two polyphenol-containing red wine extracts, red wine polyphenolic compounds (RWPC) and Provinols, and delphinidin, an anthocyanin were used. 2. RWPC stimulated a Ca(2+)-dependent release of nitric oxide (NO) from BAECs accounting for the relaxation of endothelium-denuded rat aortic rings as shown by cascade bioassay. 3. RWPC, Provinols and delphinidin increased cytosolic free calcium ([Ca(2+)](i)), by releasing Ca(2+) from intracellular stores and by increasing Ca(2+) entry. 4. The RWPC-induced increase in [Ca(2+)](i) was decreased by exposure to ryanodine (30 microM), whereas Provinols and delphinidin-induced increases in [Ca(2+)](i) were decreased by bradykinin (0.1 microM) and thapsigargin (1 microM) pre-treatment. 5. RWPC, Provinols and delphinidin-induced increases in [Ca(2+)](i) were sensitive to inhibitors of phospholipase C (neomycin, 3 mM; U73122, 3 microM) and tyrosine kinase (herbimycin A, 1 microM). 6. RWPC, Provinols and delphinidin induced herbimycin A (1 microM)-sensitive tyrosine phosphorylation of several intracellular proteins. 7. Provinols released Ca(2+) via both a cholera (CTX) and pertussis toxins (PTX)-sensitive pathway, whereas delphinidin released Ca(2+) only via a PTX-sensitive mechanism. 8. Our data contribute in defining the mechanisms of endothelial NO production caused by wine polyphenols including the increase in [Ca(2+)](i) and the activation of tyrosine kinases. Furthermore, RWPC, Provinols and delphinidin display differences in the process leading to [Ca(2+)](i) increases in endothelial cells illustrating multiple cellular targets of natural dietary polyphenolic compounds.
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Affiliation(s)
- Sophie Martin
- Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur, 67401 Illkirch, France
| | - Emile Andriambeloson
- Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur, 67401 Illkirch, France
| | - Ken Takeda
- Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur, 67401 Illkirch, France
| | - Ramaroson Andriantsitohaina
- Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur, 67401 Illkirch, France
- Author for correspondence:
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40
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Nauli SM, Williams JM, Akopov SE, Zhang L, Pearce WJ. Developmental changes in ryanodine- and IP(3)-sensitive Ca(2+) pools in ovine basilar artery. Am J Physiol Cell Physiol 2001; 281:C1785-96. [PMID: 11698236 DOI: 10.1152/ajpcell.2001.281.6.c1785] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To explore the hypothesis that cerebrovascular maturation alters ryanodine- and inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) pool sizes, we measured total intracellular Ca(2+) with (45)Ca and the fractions of intracellular Ca(2+) released by IP(3) and/or caffeine in furaptra-loaded permeabilized basilar arteries from nonpregnant adult and term fetal (139-141 days) sheep. Ca(2+) mass (nmol/mg dry weight) was similar in adult (1.60 +/- 0.18) and fetal (1.71 +/- 0.16) arteries in the pool sensitive to IP(3) alone but was significantly lower for adult (0.11 +/- 0.01) than for fetal (1.22 +/- 0.11) arteries in the pool sensitive to ryanodine alone. The pool sensitive to both ryanodine and IP(3) was also smaller in adult (0.14 +/- 0.01) than in fetal (0.85 +/- 0.08) arteries. Because the Ca(2+) fraction in the ryanodine-IP(3) pool was small in both adult (5 +/- 1%) and fetal (7 +/- 4%) arteries, the IP(3) and ryanodine pools appear to be separate in these arteries. However, the pool sensitive to neither IP(3) nor ryanodine was 10-fold smaller in adult (0.87 +/- 0.10) than in fetal (8.78 +/- 0.81) arteries, where it accounted for 72% of total intracellular membrane-bound Ca(2+). Thus, during basilar artery maturation, intracellular Ca(2+) mass plummets in noncontractile pools, decreases modestly in ryanodine-sensitive pools, and remains constant in IP(3)-sensitive pools. In addition, age-related increases in IP(3) efficacy must involve factors other than IP(3) pool size alone.
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Affiliation(s)
- S M Nauli
- Department of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California 92350, USA
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41
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Russell MJ, Pelaez NJ, Packer CS, Forster ME, Olson KR. Intracellular and extracellular calcium utilization during hypoxic vasoconstriction of cyclostome aortas. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1506-13. [PMID: 11641122 DOI: 10.1152/ajpregu.2001.281.5.r1506] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoxic vasoconstriction (HV) is an intrinsic response of mammalian pulmonary and cyclostome aortic vascular smooth muscle. The present study examined the utilization of calcium during HV in dorsal aortas (DA) from sea lamprey and New Zealand hagfish. HV was temporally correlated with increased free cytosolic calcium (Ca2+c) in lamprey DA. Extracellular calcium (Ca2+o) did not contribute significantly to HV in lamprey DA, but it accounted for 38.1 +/- 5.3% of HV in hagfish DA. Treatment of lamprey DA with ionomycin, ryanodine, or caffeine added to thapsigargin-reduced HV, whereas HV was augmented by BAY K 8644. Methoxyverapamil (D600) in zero Ca2+o did not affect HV in lamprey DA, nor did it prevent further constriction when Ca2+o was restored during hypoxia in hagfish DA. Removal of extracellular sodium (Na+o) caused a constriction in both species. Lamprey DA relaxed to prehypoxic tension following return to normoxia in zero Na+o, whereas relaxation was inhibited in hagfish DA. Relaxation following HV was inhibited in lamprey DA when Na+o and Ca2+o were removed. These results show that HV is correlated with [Ca2+]c in lamprey DA and that Na+/Ca2+ exchange is used during HV in hagfish but not lamprey DA. Multiple receptor types appear to mediate stored intracellular calcium release in lamprey DA, and L-type calcium channels do not contribute significantly to constriction in either cyclostome.
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Affiliation(s)
- M J Russell
- Indiana University School of Medicine, South Bend Center for Medical Education, University of Notre Dame, Notre Dame 46556, USA
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42
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Flynn ER, Bradley KN, Muir TC, McCarron JG. Functionally separate intracellular Ca2+ stores in smooth muscle. J Biol Chem 2001; 276:36411-8. [PMID: 11477079 DOI: 10.1074/jbc.m104308200] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In smooth muscle, release via the inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)R) and ryanodine receptors (RyR) on the sarcoplasmic reticulum (SR) controls oscillatory and steady-state cytosolic Ca(2+) concentrations ([Ca(2+)](c)). The interplay between the two receptors, itself determined by their organization on the SR, establishes the time course and spatial arrangement of the Ca(2+) signal. Whether or not the receptors are co-localized or distanced from each other on the same store or whether they exist on separate stores will significantly affect the Ca(2+) signal produced by the SR. To date these matters remain unresolved. The functional arrangement of the RyR and Ins(1,4,5)P(3)R on the SR has now been examined in isolated single voltage-clamped colonic myocytes. Depletion of the ryanodine-sensitive store, by repeated application of caffeine, in the presence of ryanodine, abolished the response to Ins(1,4,5)P(3), suggesting that Ins(1,4,5)P(3)R and RyR share a common Ca(2+) store. Ca(2+) release from the Ins(1,4,5)P(3)R did not activate Ca(2+)-induced Ca(2+) release at the RyR. Depletion of the Ins(1,4,5)P(3)-sensitive store, by the removal of external Ca(2+), on the other hand, caused only a small decrease ( approximately 26%) in caffeine-evoked Ca(2+) transients, suggesting that not all RyR exist on the common store shared with Ins(1,4,5)P(3)R. Dependence of the stores on external Ca(2+) for replenishment also differed; removal of external Ca(2+) depleted the Ins(1,4,5)P(3)-sensitive store but caused only a slight reduction in caffeine-evoked transients mediated at RyR. Different mechanisms are presumably responsible for the refilling of each store. Refilling of both Ins(1,4,5)P(3)-sensitive and caffeine-sensitive Ca(2+) stores was inhibited by each of the SR Ca(2+) ATPase inhibitors thapsigargin and cyclopiazonic acid. These results may be explained by the existence of two functionally distinct Ca(2+) stores; the first expressing only RyR and refilled from [Ca(2+)](c), the second expressing both Ins(1,4,5)P(3)R and RyR and dependent upon external Ca(2+) for refilling.
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Affiliation(s)
- E R Flynn
- Neuroscience and Biomedical Systems, Institute of Biomedical and Life Sciences, West Medical Bldg., University of Glasgow, Glasgow G12 8QQ, United Kingdom
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43
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Vallot O, Combettes L, Lompré AM. Functional coupling between the caffeine/ryanodine-sensitive Ca2+ store and mitochondria in rat aortic smooth muscle cells. Biochem J 2001; 357:363-71. [PMID: 11439085 PMCID: PMC1221962 DOI: 10.1042/0264-6021:3570363] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We investigated the role of mitochondria in the agonist-induced and/or caffeine-induced Ca2+ transients in rat aortic smooth muscle cells. We explored the possibility that proliferation modulates the coupling between mitochondria and endoplasmic reticulum. Ca2+ transients induced by either ATP or caffeine were measured in presence or absence of drugs interfering with mitochondrial activity in freshly dissociated cells (day 1) and in subconfluent primary culture (day 12). We found that the mitochondrial inhibitors, rotenone or carbonyl cyanide m-chlorophenylhydrazone, as well as the permeability transition pore inhibitor, cyclosporin A, had no effect on the ATP-induced Ca2+ transient at either day 1 or day 12, but prevented caffeine-induced cytosolic Ca2+ increase at day 12 but not at day 1. Close connections between ryanodine receptors and mitochondria were observed at both day 1 and 12. Thapsigargin (TG) prevented ATP- and caffeine-induced Ca2+ transients at day 1. At day 12, where only 50% of the cells were sensitive to caffeine, TG did not prevent the caffeine-induced Ca2+ transient, and prevented ATP-induced Ca2+ transient in only half of the cells. Together, these data demonstrate that rat aortic smooth muscle cells at day 1 have an ATP- and caffeine-sensitive pool, which is functionally independent but physically closely linked to mitochondria and totally inhibited by TG. At day 12, we propose the existence of two cell populations: half contains IP3 receptors and TG-sensitive Ca2+ pumps only; the other half contains, in addition to the IP3-sensitive pool independent from mitochondria, a caffeine-sensitive pool. This latter pool is linked to mitochondria through the permeability transition pore and is refilled by both TG-sensitive and insensitive mechanisms.
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MESH Headings
- Adenosine Triphosphate/metabolism
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/metabolism
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium-Transporting ATPases/metabolism
- Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology
- Cell Division/drug effects
- Cell Membrane Permeability/drug effects
- Cell Membrane Permeability/physiology
- Cells, Cultured
- Cyclosporine/pharmacology
- Cytosol/metabolism
- Endoplasmic Reticulum/metabolism
- Male
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Models, Biological
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Rats
- Rats, Wistar
- Rotenone/pharmacology
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/physiology
- Sarcoplasmic Reticulum Calcium-Transporting ATPases
- Thapsigargin/pharmacology
- Time Factors
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Affiliation(s)
- O Vallot
- CNRS EP 1088, IFR-FR 46 Signalisation Cellulaire, Bâtiment 433, Université Paris-Sud, F91405 Orsay, France
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44
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McDaniel SS, Platoshyn O, Wang J, Yu Y, Sweeney M, Krick S, Rubin LJ, Yuan JX. Capacitative Ca(2+) entry in agonist-induced pulmonary vasoconstriction. Am J Physiol Lung Cell Mol Physiol 2001; 280:L870-80. [PMID: 11290510 DOI: 10.1152/ajplung.2001.280.5.l870] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Agonist-induced increases in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in pulmonary artery (PA) smooth muscle cells (SMCs) consist of a transient Ca(2+) release from intracellular stores followed by a sustained Ca(2+) influx. Depletion of intracellular Ca(2+) stores triggers capacitative Ca(2+) entry (CCE), which contributes to the sustained increase in [Ca(2+)](cyt) and the refilling of Ca(2+) into the stores. In isolated PAs superfused with Ca(2+)-free solution, phenylephrine induced a transient contraction, apparently by a rise in [Ca(2+)](cyt) due to Ca(2+) release from the intracellular stores. The transient contraction lasted for 3-4 min until the Ca(2+) store was depleted. Restoration of extracellular Ca(2+) in the presence of phentolamine produced a contraction potentially due to a rise in [Ca(2+)](cyt) via CCE. The store-operated Ca(2+) channel blocker Ni(2+) reduced the store depletion-activated Ca(2+) currents, decreased CCE, and inhibited the CCE-mediated contraction. In single PASMCs, we identified, using RT-PCR, five transient receptor potential gene transcripts. These results suggest that CCE, potentially through transient receptor potential-encoded Ca(2+) channels, plays an important role in agonist-mediated PA contraction.
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Affiliation(s)
- S S McDaniel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California School of Medicine, San Diego, California 92103, USA
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45
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Hubbard MJ. Calcium transport across the dental enamel epithelium. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2001; 11:437-66. [PMID: 11132765 DOI: 10.1177/10454411000110040401] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dental enamel is the most highly calcified tissue in mammals, and its formation is an issue of fundamental biomedical importance. The enamel-forming cells must somehow supply calcium in bulk yet avoid the cytotoxic effects of excess calcium. Disrupted calcium transport could contribute to a variety of developmental defects in enamel, and the underlying cellular machinery is a potential target for drugs to improve enamel quality. The mechanisms used to transport calcium remain unclear despite much progress in our understanding of enamel formation. Here, current knowledge of how enamel cells handle calcium is reviewed in the context of findings from other epithelial calcium-transport systems. In the past, most attention has focused on approaches to boost the poor diffusion of calcium in cytosol. Recent biochemical findings led to an alternative proposal that calcium is routed through high-capacity stores associated with the endoplasmic reticulum. Research areas needing further attention and a working model are also discussed. Calcium-handling mechanisms in enamel cells are more generally relevant to the understanding of epithelial calcium transport, biomineralization, and calcium toxicity avoidance.
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Affiliation(s)
- M J Hubbard
- Department of Biochemistry, University of Otago, Dunedin, New Zealand.
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46
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Abstract
Enamel cells ultimately determine the properties of dental enamel. Surprisingly little is known about enamel cell functions at the biochemical and molecular levels. Understanding of both normal and abnormal enamel formation should benefit from elucidation of this area. This paper reviews our recent efforts to establish microscale biochemical analyses of rat enamel cells, and the ensuing initial findings about their protein phenotype (i.e., proteome) and calcium-handling mechanisms. A perspective of the current status of enamel cell research, and where it might head, is also given.
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Affiliation(s)
- M J Hubbard
- Department of Biochemistry, University of Otago, Dunedin, New Zealand.
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47
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Kochegarov AA, Beylina SI, Matveeva NB, Leontieva GA, Zinchenko VP. Ionomycin and 2,5'-di(tertbutyl)-1,4,-benzohydroquinone elicit Ca2+-induced Ca2+ release from intracellular pools in Physarum polycephalum. Comp Biochem Physiol A Mol Integr Physiol 2001; 128:279-88. [PMID: 11223389 DOI: 10.1016/s1095-6433(00)00306-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcium level in organelles of the slime mold Physarum polycephalum was monitored by chlortetracycline, a low-affinity calcium indicator. It was found that 2,5'-di(tertbutyl)-1,4,-benzohydroquinone (BHQ) at a concentration of 100 microM, but not the highly specific inhibitor of sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), thapsigargin (1-10 microM), elicited calcium release from the CTC-stained intracellular calcium pool. Ionomycin also caused a calcium release (23.7+/-5.1%), which was less than that induced by BHQ (30.1+/-6.0%). Procaine (10 mM), a blocker of ryanodine receptor, completely abolished the responses to BHQ and ionomycin. Another blocker, ryanodine (100 microM), only slightly diminished the responses to ionomycin and BHQ. Apparently, BHQ and ionomycin acting as a Ca2+-ATPase inhibitor and an ionophore, respectively, elicit an increase in [Ca2+]i, which in turn triggers a calcium-induced calcium release (CICR) via the ryanodine receptor. Caffeine, an activator of ryanodine receptor, at a concentration of 25-50 mM produced a Ca2+-release (5.6-16.0%), which was not similar in magnitude to CICR. The response to 25 mM caffeine was only moderately inhibited by 25 mM procaine, and almost completely abolished by 50 mM procaine and 100 microM ryanodine.
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Affiliation(s)
- A A Kochegarov
- Institute of Cell Biophysics of Russian Academy of Sciences, 142292, Moscow Region, Pushchino, Russia
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48
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Alvarez de Sotomayor M, Andriantsitohaina R. Simvastatin and Ca(2+) signaling in endothelial cells: involvement of rho protein. Biochem Biophys Res Commun 2001; 280:486-90. [PMID: 11162544 DOI: 10.1006/bbrc.2000.4144] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor simvastatin is able to produce endothelium-dependent relaxation in addition to its lipid-lowering properties. The underlying mechanisms were investigated in bovine aortic endothelial cells (BAEC). Simvastatin induced an increase in cytosolic calcium ([Ca(2+)](i)) in BAEC, by releasing Ca(2+) from intracellular stores sensitive to thapsigargin and ryanodine, and increasing Ca(2+) entry. Simvastatin response was not altered by the phospholipase A(2) inhibitor ONO-RS-082, or the combination of superoxide dismutase plus catalase. However, the response to simvastatin was reduced by the product of HMG-CoA reductase, mevalonate or by the inhibitor of small G proteins of the Rho family, Clostridium botulinum C3 toxin. Thus, increase in [Ca(2+)](i) involving the activation of Rho protein through mevalonate-dependent pathway is essential for the action of simvastatin and might contribute to its beneficial effects against vascular diseases. This study helps elucidate the mechanisms of endothelial factor generation by simvastatin in BAEC.
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Affiliation(s)
- M Alvarez de Sotomayor
- Departamento de Farmacología, Facultad of Farmacia, Universidad de Sevilla, Seville, 41012, Spain
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49
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Janiak R, Wilson SM, Montague S, Hume JR. Heterogeneity of calcium stores and elementary release events in canine pulmonary arterial smooth muscle cells. Am J Physiol Cell Physiol 2001; 280:C22-33. [PMID: 11121373 DOI: 10.1152/ajpcell.2001.280.1.c22] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To examine the nature of inositol 1,4,5-trisphosphate (IP(3))-sensitive and ryanodine (Ryn)-sensitive Ca(2+) stores in isolated canine pulmonary arterial smooth cells (PASMC), agonist-induced changes in global intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured using fura 2-AM fluorescence. Properties of elementary local Ca(2+) release events were characterized using fluo 3-AM or fluo 4-AM, in combination with confocal laser scanning microscopy. In PASMC, depletion of sarcoplasmic reticulum Ca(2+) stores with Ryn (300 microM) and caffeine (Caf; 10 mM) eliminated subsequent Caf-induced intracellular Ca(2+) transients but had little or no effect on the initial IP(3)-mediated intracellular Ca(2+) transient induced by ANG II (1 microM). Cyclopiazonic acid (CPA; 10 microM) abolished IP(3)-induced intracellular Ca(2+) transients but failed to attenuate the initial Caf-induced intracellular Ca(2+) transient. These results suggest that in canine PASMC, IP(3)-, and Ryn-sensitive Ca(2+) stores are organized into spatially distinct compartments while similar experiments in canine renal arterial smooth muscle cells (RASMC) reveal that these Ca(2+) stores are spatially conjoined. In PASMC, spontaneous local intracellular Ca(2+) transients sensitive to modulation by Caf and Ryn were detected, exhibiting spatial-temporal characteristics similar to those previously described for "Ca(2+) sparks" in cardiac and other types of smooth muscle cells. After depletion of Ryn-sensitive Ca(2+) stores, ANG II (8 nM) induced slow, sustained [Ca(2+)](i) increases originating at sites near the cell surface, which were abolished by depleting IP(3) stores. Discrete quantal-like events expected due to the coordinated opening of IP(3) receptor clusters ("Ca(2+) puffs") were not observed. These data provide new information regarding the functional properties and organization of intracellular Ca(2+) stores and elementary Ca(2+) release events in isolated PASMC.
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MESH Headings
- Angiotensin II/pharmacology
- Aniline Compounds/pharmacology
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Dogs
- Female
- Fluorescent Dyes/pharmacology
- Indoles/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Pulmonary Artery/cytology
- Pulmonary Artery/drug effects
- Pulmonary Artery/metabolism
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- Renal Artery/cytology
- Renal Artery/drug effects
- Renal Artery/metabolism
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/metabolism
- Vasodilator Agents/pharmacology
- Xanthenes/pharmacology
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Affiliation(s)
- R Janiak
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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Martin S, Laude-Lemaire I, Kerbiriou-Nabias D, Freyssinet JM, Martínez MC. Relation between phosphatidylserine exposure and store-operated Ca(2+) entry in stimulated cells. Biochem Biophys Res Commun 2000; 279:639-45. [PMID: 11118338 DOI: 10.1006/bbrc.2000.3980] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A significant increase in intracellular Ca(2+) is required to trigger the remodeling of the cell plasma membrane. Scott syndrome is an extremely rare inherited disorder of the transmembrane migration of phosphatidylserine toward the exoplasmic leaflet in blood cells. We have recently reported a reduced capacitative Ca(2+) entry in Scott cells [Martínez et al. (1999) Biochemistry 38, 10092-10098]. We have investigated here the links between defective phosphatidylserine exposure and Ca(2+) signaling in Scott cells by focusing on the Ca(2+) entry following the emptying of intracellular stores. After depletion of caffeine- or thapsigargin-sensitive stores, Ca(2+) entry was lower in Scott compared to control lymphoblasts. However, the simultaneous depletion of both types of stores restored a normal Ca(2+) influx across the plasma membrane in Scott cells and phosphatidylserine externalization ability was improved concomitantly with capacitative Ca(2+) entry. These observations point to the essential role of capacitative Ca(2+) entry in the control of phosphatidylserine exposure of stimulated cells.
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Affiliation(s)
- S Martin
- Institut d'Hématologie et d'Immunologie, Faculté de Médecine, 4, rue Kirschleger, Strasbourg, 67085, France
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