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Chichorro JG, Gambeta E, Baggio DF, Zamponi GW. Voltage-gated Calcium Channels as Potential Therapeutic Targets in Migraine. THE JOURNAL OF PAIN 2024; 25:104514. [PMID: 38522594 DOI: 10.1016/j.jpain.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/06/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024]
Abstract
Migraine is a complex and highly incapacitating neurological disorder that affects around 15% of the general population with greater incidence in women, often at the most productive age of life. Migraine physiopathology is still not fully understood, but it involves multiple mediators and events in the trigeminovascular system and the central nervous system. The identification of calcitonin gene-related peptide as a key mediator in migraine physiopathology has led to the development of effective and highly selective antimigraine therapies. However, this treatment is neither accessible nor effective for all migraine sufferers. Thus, a better understanding of migraine mechanisms and the identification of potential targets are still clearly warranted. Voltage-gated calcium channels (VGCCs) are widely distributed in the trigeminovascular system, and there is accumulating evidence of their contribution to the mechanisms associated with headache pain. Several drugs used in migraine abortive or prophylactic treatment target VGCCs, which probably contributes to their analgesic effect. This review aims to summarize the current evidence of VGGC contribution to migraine physiopathology and to discuss how current pharmacological options for migraine treatment interfere with VGGC function. PERSPECTIVE: Calcitonin gene-related peptide (CGRP) represents a major migraine mediator, but few studies have investigated the relationship between CGRP and VGCCs. CGRP release is calcium channel-dependent and VGGCs are key players in familial migraine. Further studies are needed to determine whether VGCCs are suitable molecular targets for treating migraine.
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Affiliation(s)
- Juliana G Chichorro
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil.
| | - Eder Gambeta
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Darciane F Baggio
- Biological Sciences Sector, Department of Pharmacology, Federal University of Parana, Curitiba, Parana, Brazil
| | - Gerald W Zamponi
- Cumming School of Medicine, Department of Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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2
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Ulgen Temel E, Ozbudak P, Serdaroglu A, Arhan E. Sleep Spindle Alterations in Children With Migraine. Pediatr Neurol 2024; 152:184-188. [PMID: 38301321 DOI: 10.1016/j.pediatrneurol.2023.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/16/2023] [Indexed: 02/03/2024]
Abstract
BACKGROUND The modulation of thalamocortical activity is the most important site of several levels of interference between sleep spindles and migraine. Thalamocortical circuits are responsible for the electrophysiological phenomenon of sleep spindles. Spindle alterations may be used as a beneficial marker in the diagnosis and follow-up of children with migraine. We aimed to formulate the hypothesis that there is a shared mechanism that underlies migraine and sleep spindle activity. METHODS We analyzed the amplitude, frequency, duration, density, and activity of sleep spindles in non-rapid eye movement stage 2 sleep in patients with migraine without aura when compared with healthy control subjects. RESULTS The amplitudes of average, slow, and fast sleep spindles were higher in children with migraine without aura (P = 0.020, 0.013, and 0.033, respectively). The frequency of fast spindles was lower in children with migraines without aura when compared with the control group (P = 0.03). Although not statistically significant, the fast sleep spindle duration in the migraine group was shorter (P = 0.055). Multivariate analysis revealed an increased risk of migraine associated with increased mean spindle amplitude and decreased fast spindle frequency and duration. CONCLUSIONS Our data suggest that spindle alterations may correlate with the vulnerability to develop migraine and may be used as a model for future research about the association between the thalamocortical networks and migraine.
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Affiliation(s)
- Esra Ulgen Temel
- Division of Child Neurology, Cengiz Gökçek Maternity and Children's Hospital, Gaziantep, Turkey
| | - Pinar Ozbudak
- Division of Child Neurology, Etlik City Training and Research Hospital, University of Health Sciences, Ankara, Turkey
| | - Ayse Serdaroglu
- Department of Child Neurology, Gazi University Faculty of Medicine, Ankara, Turkey
| | - Ebru Arhan
- Department of Child Neurology, Gazi University Faculty of Medicine, Ankara, Turkey.
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3
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Lauerer RJ, Lerche H. Voltage-gated calcium channels in genetic epilepsies. J Neurochem 2023. [PMID: 37822150 DOI: 10.1111/jnc.15983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 09/17/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
Voltage-gated calcium channels (VGCC) are abundant in the central nervous system and serve a broad spectrum of functions, either directly in cellular excitability or indirectly to regulate Ca2+ homeostasis. Ca2+ ions act as one of the main connections in excitation-transcription coupling, muscle contraction and excitation-exocytosis coupling, including synaptic transmission. In recent years, many genes encoding VGCCs main α or additional auxiliary subunits have been associated with epilepsy. This review sums up the current state of knowledge on disease mechanisms and provides guidance on disease-specific therapies where applicable.
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Affiliation(s)
- Robert J Lauerer
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University and University Hospital Tuebingen, Tuebingen, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University and University Hospital Tuebingen, Tuebingen, Germany
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4
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Calderon-Rivera A, Gomez K, Loya-López S, Wijeratne EK, Stratton H, Tang C, Duran P, Masterson K, Alsbiei O, Gunatilaka AL, Khanna R. Betulinic acid analogs inhibit N- and T-type voltage-gated calcium channels to attenuate nerve-injury associated neuropathic and formalin models of pain. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2023; 13:100116. [PMID: 36687466 PMCID: PMC9853350 DOI: 10.1016/j.ynpai.2023.100116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/15/2023]
Abstract
Over the past three decades, there has been a significant growth in the use of natural products, with approximately 80% of individuals using them for some aspect of primary healthcare. Our laboratories have identified and studied natural compounds with analgesic effects from dry land plants or their associated fungus during the past ten years. Here, we isolated and characterized thirteen betulin analogs and fifteen betulinic acid analogs for their capacity to prevent calcium influx brought on by depolarization in sensory neurons. The in vitro inhibition of voltage-gated calcium channels by the top drugs was then assessed using whole cell patch clamp electrophysiology. In vivo experiments, conducted at two sites, evaluated the best compound in acute and tonic, neuropathic, inflammatory, post-operative and visceral models of pain. We found that the betulinic acid analog 8 inhibited calcium influx in rat dorsal root ganglion neurons by inhibiting N- (CaV2.2) and T- (CaV3) type voltage-gated calcium channels. Moreover, intrathecal delivery of analog 8 had analgesic activity in both spared nerve injury model of neuropathic pain and acute and tonic pain induced by formalin. The results presented herein highlight the potential antinociceptive properties of betulinic acid analog 8 and set the stage for the development of novel non-opioid pain therapeutics based on the triterpenoid scaffold of betulinic acid.
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Affiliation(s)
- Aida Calderon-Rivera
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
| | - Kimberly Gomez
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
| | - Santiago Loya-López
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
| | - E.M. Kithsiri Wijeratne
- Natural Products Center, School of Natural Resources and the Environment, College of Agriculture and Life Sciences, The University of Arizona, Tucson, AZ, United States
| | - Harrison Stratton
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Cheng Tang
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
| | - Paz Duran
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
| | - Kyleigh Masterson
- NYU Pain Research Center, New York University, New York, NY, United States
| | - Omar Alsbiei
- NYU Pain Research Center, New York University, New York, NY, United States
| | - A.A. Leslie Gunatilaka
- Natural Products Center, School of Natural Resources and the Environment, College of Agriculture and Life Sciences, The University of Arizona, Tucson, AZ, United States
| | - Rajesh Khanna
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, United States
- NYU Pain Research Center, New York University, New York, NY, United States
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5
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Depuydt AS, Rihon J, Cheneval O, Vanmeert M, Schroeder CI, Craik DJ, Lescrinier E, Peigneur S, Tytgat J. Cyclic Peptides as T-Type Calcium Channel Blockers: Characterization and Molecular Mapping of the Binding Site. ACS Pharmacol Transl Sci 2021; 4:1379-1389. [PMID: 34423272 DOI: 10.1021/acsptsci.1c00079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Indexed: 01/18/2023]
Abstract
T-type calcium (CaV3) channels play a crucial role in the generation and propagation of action potentials in excitable cells and are considered potential drug targets for the treatment of neurological and cardiovascular diseases. Given the limited pharmacological repertoire for these channels, there is a great need for novel potent and selective CaV3 channel inhibitors. In this study, we used Xenopus oocytes to heterologously express CaV3.1 channels and characterized the interaction with a small cyclic peptide, PnCS1. Using molecular modeling, PnCS1 was docked into the cryo-electron microscopy structure of the human CaV3.1 channel and molecular dynamics were performed on the resultant complex. The binding site of the peptide was mapped with the involvement of critical amino acids located in the pore region and fenestrations of the channel. More specifically, we found that PnCS1 reclines in the central cavity of the pore domain of the CaV3.1 channel and resides stably between the selectivity filter and the intracellular gate, blocking the conduction pathway of the channel. Using Multiple Attribute Positional Scanning approaches, we developed a series of PnCS1 analogues. These analogues had a reduced level of inhibition, confirming the importance of specific residues and corroborating our modeling. In summary, functional studies of PnCS1 on the CaV3.1 channel combined with molecular dynamics results provide the basis for understanding the molecular interactions of PnCS1 with CaV3.1 and are fundamental to structure-based drug discovery for treating CaV3 channelopathies.
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Affiliation(s)
- Anne-Sophie Depuydt
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, Leuven 3000, Belgium
| | - Jérôme Rihon
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Olivier Cheneval
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, 4072 Queensland Australia
| | - Michiel Vanmeert
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Christina I Schroeder
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, 4072 Queensland Australia.,National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, United States
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, 4072 Queensland Australia
| | - Eveline Lescrinier
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, Leuven 3000, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, Leuven 3000, Belgium
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Kim HJ, Lee J, Lee GR, Kim N, Lee HI, Kwon M, Kim NY, Park JH, Kang YH, Song HJ, Kim T, Shin DM, Jeong W. Flunarizine inhibits osteoclastogenesis by regulating calcium signaling and promotes osteogenesis. J Cell Physiol 2021; 236:8239-8252. [PMID: 34192358 DOI: 10.1002/jcp.30496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/12/2022]
Abstract
Many bone diseases such as osteoporosis and periodontitis are caused by hyperactivation of osteoclasts. Calcium (Ca2+ ) signals are crucial for osteoclast differentiation and function. Thus, the blockade of Ca2+ signaling may be a strategy for regulating osteoclast activity and has clinical implications. Flunarizine (FN) is a Ca2+ channel antagonist that has been used for reducing migraines. However, the role of FN in osteoclast differentiation and function remains unknown. Here, we investigated whether FN regulates osteoclastogenesis and elucidated the molecular mechanism. FN inhibited osteoclast differentiation along with decreased expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), and attenuated osteoclast maturation and bone resorption. FN inhibition of osteoclast differentiation was restored by ectopic expression of constitutively active NFATc1. FN reduced calcium oscillations and its inhibition of osteoclast differentiation and resorption function was reversed by ionomycin, an ionophore that binds Ca2+ . FN also inhibited Ca2+ /calmodulin-dependent protein kinase IV (CaMKIV) and calcineurin leading to a decrease in the cAMP-responsive element-binding protein-dependent cFos and peroxisome proliferator-activated receptor-γ coactivator 1β expression, and NFATc1 nuclear translocation. These results indicate that FN inhibits osteoclastogenesis via regulating CaMKIV and calcineurin as a Ca2+ channel blocker. In addition, FN-induced apoptosis in osteoclasts and promoted osteogenesis. Furthermore, FN protected lipopolysaccharide- and ovariectomy-induced bone destruction in mouse models, suggesting that it has therapeutic potential for treating inflammatory bone diseases and postmenopausal osteoporosis.
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Affiliation(s)
- Hyun Jin Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Jiae Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Gong-Rak Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Narae Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Hye In Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Minjeong Kwon
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Nam Young Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Jin Ha Park
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Ye Hee Kang
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Hyeong Ju Song
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - TaeSoo Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
| | - Dong Min Shin
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Korea
| | - Woojin Jeong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Korea
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7
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Wan L, Wu W, Jiang S, Wan S, Meng D, Wang Z, Zhang J, Wei L, Yu P. Mibefradil and Flunarizine, Two T-Type Calcium Channel Inhibitors, Protect Mice against Lipopolysaccharide-Induced Acute Lung Injury. Mediators Inflamm 2020; 2020:3691701. [PMID: 33223955 PMCID: PMC7671802 DOI: 10.1155/2020/3691701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/04/2020] [Accepted: 10/21/2020] [Indexed: 12/28/2022] Open
Abstract
Recent studies have illuminated that blocking Ca2+ influx into effector cells is an attractive therapeutic strategy for lung injury. We hypothesize that T-type calcium channel may be a potential therapeutic target for acute lung injury (ALI). In this study, the pharmacological activity of mibefradil (a classical T-type calcium channel inhibitor) was assessed in a mouse model of lipopolysaccharide- (LPS-) induced ALI. In LPS challenged mice, mibefradil (20 and 40 mg/kg) dramatically decreased the total cell number, as well as the productions of TNF-α and IL-6 in bronchoalveolar lavage fluid (BALF). Mibefradil also suppressed total protein concentration in BALF, attenuated Evans blue extravasation, MPO activity, and NF-κB activation in lung tissue. Furthermore, flunarizine, a widely prescripted antimigraine agent with potent inhibition on T-type channel, was also found to protect mice against lung injury. These data demonstrated that T-type calcium channel inhibitors may be beneficial for treating acute lung injury. The important role of T-type calcium channel in the acute lung injury is encouraged to be further investigated.
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Affiliation(s)
- Limei Wan
- The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou 510080, China
| | - Weibin Wu
- Department of Basic Medicine, Zhaoqing Medical College, Zhaoqing 526020, China
| | - Shunjun Jiang
- Department of Pharmacy, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Shanhe Wan
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Science, Southern Medical University, Guangzhou 510515, China
| | - Dongmei Meng
- Department of Pharmacy, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Zhipeng Wang
- Department of Pharmacy, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Jiajie Zhang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Science, Southern Medical University, Guangzhou 510515, China
| | - Li Wei
- Department of Pharmacy, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Pengjiu Yu
- Department of Pharmacy, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
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8
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Wang W, Mellor RL, Nerbonne JM, Balke CW. Regional differences in the expression of tetrodotoxin-sensitive inward Ca 2+ and outward Cs +/K + currents in mouse and human ventricles. Channels (Austin) 2019; 13:72-87. [PMID: 30704344 PMCID: PMC6380286 DOI: 10.1080/19336950.2019.1568146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Tetrodotoxin (TTX) sensitive inward Ca2+ currents, ICa(TTX), have been identified in cardiac myocytes from several species, although it is unclear if ICa(TTX) is expressed in all cardiac cell types, and if ICa(TTX) reflects Ca2+ entry through the main, Nav1.5-encoded, cardiac Na+ (Nav) channels. To address these questions, recordings were obtained with 2 mm Ca2+ and 0 mm Na+ in the bath and 120 mm Cs+ in the pipettes from myocytes isolated from adult mouse interventricular septum (IVS), left ventricular (LV) endocardium, apex, and epicardium and from human LV endocardium and epicardium. On membrane depolarizations from a holding potential of −100 mV, ICa(TTX) was identified in mouse IVS and LV endocardial myocytes and in human LV endocardial myocytes, whereas only TTX-sensitive outward Cs+/K+ currents were observed in mouse LV apex and epicardial myocytes and human LV epicardial myocytes. The inward Ca2+, but not the outward Cs+/K+, currents were blocked by mm concentrations of MTSEA, a selective blocker of cardiac Nav1.5-encoded Na+ channels. In addition, in Nav1.5-expressing tsA-201 cells, ICa(TTX) was observed in 3 (of 20) cells, and TTX-sensitive outward Cs+/K+ currents were observed in the other (17) cells. The time- and voltage-dependent properties of the TTX-sensitive inward Ca2+ and outward Cs+/K+ currents recorded in Nav1.5-expressing tsA-201 were indistinguishable from native currents in mouse and human cardiac myocytes. Overall, the results presented here suggest marked regional, cell type-specific, differences in the relative ion selectivity, and likely the molecular architecture, of native SCN5A-/Scn5a- (Nav1.5-) encoded cardiac Na+ channels in mouse and human ventricles.
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Affiliation(s)
- Wei Wang
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Rebecca L Mellor
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Jeanne M Nerbonne
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
| | - C William Balke
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
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9
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Song Q, Han X, Xue Y, Song T, Chu X, Zhang X, Zhang Y, Zhang Y, Zhang J, Chu L. Effects of salvianolic acid B on L-type calcium channels and myocardial contractility in isolated rat ventricular myocytes and hERG K + channels expressed in HEK293 cells. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:791-799. [PMID: 28477086 DOI: 10.1007/s00210-017-1381-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 04/28/2017] [Indexed: 02/01/2023]
Abstract
Salvianolic acid B (Sal B), one of the chief water-soluble constituents in Radix Salviae Milthiorrhizae, has often been reported to possess considerable cardiovascular regulatory effects. However, the underlying biochemical and cellular mechanisms of its cardioprotection remain unclear. This study was designed to evaluate the role of Sal B regulation in L-type Ca2+ channel currents (ICa,L) and cell contractility in rat cardiomyocytes and hERG K+ channels expressed in HEK293 cells with the patch-clamp and Ca2+ imaging techniques to clarify its underlying cardioprotective mechanisms. Exposure to Sal B blocked ICa,L with IC50 of 2.07 × 10-5 M, shifted the curves of current and voltage upwards, shifted the curves of activation and inactivation to the left, and significantly inhibited the amplitude of the cell shortening, but the regulatory effects of Sal B on the expressed rapidly activating delayed rectifier potassium current (IKr) did not reach a significant level. These results indicate that the cardioprotective mechanisms of Sal B may be related to the attenuation of calcium overload by directly inhibiting ICa,L and consequently decreasing myocardial contractility without causing drug-induced long QT syndrome (LQTS).
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Affiliation(s)
- Qiongtao Song
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Xue Han
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Yuchong Xue
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Tao Song
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Xi Chu
- The Fourth Hospital of Hebei Medical University, No. 12, Jiankang Road, Shijiazhuang, Hebei, 050011, China
| | - Xuan Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Yuanyuan Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Ying Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China
| | - Jianping Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China. .,Hebei Key Laboratory of Integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, Hebei, 050200, China.
| | - Li Chu
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, Hebei, 050200, China. .,Hebei Key Laboratory of Integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, Hebei, 050200, China.
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10
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Song T, Chu X, Zhang X, Song Q, Zhang Y, Zhang Y, Han X, Zhang J, Chu L. Bufalin, a bufanolide steroid from the parotoid glands of the Chinese toad, inhibits L-type Ca2+
channels and contractility in rat ventricular myocytes. Fundam Clin Pharmacol 2017; 31:340-346. [DOI: 10.1111/fcp.12265] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/31/2016] [Accepted: 01/09/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Tao Song
- Hebei Medical University; No. 361, East Zhongshan Road Shijiazhuang 050017 Hebei China
| | - Xi Chu
- The Fourth Hospital of Hebei Medical University; No. 12, Jiankang Road Shijiazhuang 050011 Hebei China
| | - Xuan Zhang
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
| | - Qiongtao Song
- Hebei Medical University; No. 361, East Zhongshan Road Shijiazhuang 050017 Hebei China
| | - Ying Zhang
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
| | - Yuanyuan Zhang
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
| | - Xue Han
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
| | - Jianping Zhang
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
| | - Li Chu
- Hebei Medical University; No. 361, East Zhongshan Road Shijiazhuang 050017 Hebei China
- Hebei University of Chinese Medicine; No. 3, Xingyuan Road Shijiazhuang 050200 Hebei China
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11
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Calcium transport into the cells of the sea urchin larva in relation to spicule formation. Proc Natl Acad Sci U S A 2016; 113:12637-12642. [PMID: 27791140 DOI: 10.1073/pnas.1612017113] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the manner in which the sea urchin larva takes up calcium from its body cavity into the primary mesenchymal cells (PMCs) that are responsible for spicule formation. We used the membrane-impermeable fluorescent dye calcein and alexa-dextran, with or without a calcium channel inhibitor, and imaged the larvae in vivo with selective-plane illumination microscopy. Both fluorescent molecules are taken up from the body cavity into the PMCs and ectoderm cells, where the two labels are predominantly colocalized in particles, whereas the calcium-binding calcein label is mainly excluded from the endoderm and is concentrated in the spicules. The presence of vesicles and vacuoles inside the PMCs that have openings through the plasma membrane directly to the body cavity was documented using high-resolution cryo-focused ion beam-SEM serial imaging. Some of the vesicles and vacuoles are interconnected to form large networks. We suggest that these vacuolar networks are involved in direct sea water uptake. We conclude that the calcium pathway from the body cavity into cells involves nonspecific endocytosis of sea water with its calcium.
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Endothelium- and smooth muscle-dependent vasodilator effects of Citrus aurantium L. var. amara: Focus on Ca(2+) modulation. Biomed Pharmacother 2016; 82:467-71. [PMID: 27470386 DOI: 10.1016/j.biopha.2016.05.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/19/2016] [Accepted: 05/19/2016] [Indexed: 11/20/2022] Open
Abstract
Neroli, the essential oil of Citrus aurantium L. var. amara, is a well-characterized alleviative agent used to treat cardiovascular symptoms. However, because it has been found to have multiple effects, its mechanism of action requires further exploration. We sought to clarify the mechanism underlying the actions of neroli in mouse aorta. In aortic rings from mice precontracted with prostaglandin F2 alpha, neroli induced vasodilation. However, relaxation effect of neroli was decreased in endothelium-denuded ring or pre-incubation with the nitric oxide synthase inhibitor NG-Nitro-l-arginine-methyl ester (L-NAME). And also, neroli-induced relaxation was also partially reversed by 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ), a soluble guanylyl cyclase (sGC) inhibitor. In addition, neroli inhibited extracellular Ca(2+)-dependent, depolarization-induced contraction, an effect that was concentration dependent. Pretreatment with the non-selective cation channel blocker, Ni(2+), attenuated neroli-induced relaxation, whereas the K(+) channel blocker, tetraethylammonium chloride, had no effect. In the presence of verapamil, added to prevent Ca(2+) influx via smooth muscle voltage-gated Ca(2+) channels, neroli-induced relaxation was reduced by the ryanodine receptor (RyR) inhibitor ruthenium red. Our findings further indicate that the endothelial component of neroli-induced vasodilation is partly mediated by the NO-sGC pathway, whereas the smooth muscle component involves modulation of intracellular Ca(2+) concentration through inhibition of cation channel-mediated extracellular Ca(2+) influx and store-operated Ca(2+) release mediated by the RyR signaling pathway.
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Guan S, Ma J, Chu X, Gao Y, Zhang Y, Zhang X, Zhang F, Liu Z, Zhang J, Chu L. Effects of total flavones from Acanthopanax senticosus on L-type calcium channels, calcium transient and contractility in rat ventricular myocytes. Phytother Res 2015; 29:533-9. [PMID: 25586009 DOI: 10.1002/ptr.5278] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 11/28/2014] [Accepted: 12/01/2014] [Indexed: 11/11/2022]
Abstract
Acanthopanax senticosus (Rupr. et Maxim.) Harms (AS), a traditional herbal medicine, has been widely used to treat ischemic heart disease. However, the underlying cellular mechanisms of its benefits to cardiac function remain unclear. The present study examined the effects of total flavones from AS (TFAS) on L-type Ca(2+) channel currents (ICa-L ) using the whole cell patch-clamp technique and on intracellular calcium ([Ca(2+) ]i ) handling and cell contractility in rat ventricular myocytes with the aid of a video-based edge-detection system. Exposure to TFAS resulted in a concentration- and voltage-dependent blockade of ICa-L , with the half-maximal inhibitory concentration (IC50 ) of 283.12 µg/mL and the maximal inhibitory effect of 36.49 ± 1.95%. Moreover, TFAS not only increased the maximum current in the current-voltage relationship but also shifted the activation and inactivation curves of ICa-L toward the hyperpolarizing direction. Meanwhile, TFAS significantly reduced amplitudes of myocyte shortening and [Ca(2+) ]i with an increase in the time to 10% of the peak (Tp) and a decrease in the time to 10% of the baseline (Tr). Thus, the cardioprotective effects of TFAS may be attributed mainly to the attenuation of [Ca(2+) ]i through the direct inhibition of ICa-L in rat ventricular myocytes and consequent negative effect on myocardial contractility.
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Affiliation(s)
- Shengjiang Guan
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, 050200, Hebei, China; Department of Pharmacy, The Hospital of Hebei University of Chinese Medicine, Shijiazhuang, 050011, Hebei, China
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14
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You J, Moon H, Lee BY, Jin JY, Chang ZE, Kim SY, Park J, Hwang YS, Kim J. Cardiomyocyte sensor responsive to changes in physical and chemical environments. J Biomech 2014; 47:400-9. [DOI: 10.1016/j.jbiomech.2013.11.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 11/05/2013] [Accepted: 11/06/2013] [Indexed: 10/26/2022]
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A selective T-type Ca2+ channel blocker R(-) efonidipine. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:411-21. [PMID: 18278483 DOI: 10.1007/s00210-007-0239-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 11/26/2007] [Indexed: 12/31/2022]
Abstract
Recently, novel compound R(-) efonidipine was reported to selectively block low-voltage-activated (LVA or T-type) Ca2+ channels in peripheral organs. We examined how R(-) efonidipine acts on T-type and high-voltage-activated (HVA) Ca2+ channels in mammalian central nervous system (CNS) neurons. Furthermore, we compared the effects of R(-) efonidipine with those of flunarizine and mibefradil on both T-type and HVA Ca2+ channels in rat hippocampal CA1 neurons by using the nystatin perforated-patch clamp technique. Flunarizine and mibefradil nonselectively inhibited both T-type and HVA Ca2+ channels, though the dose-dependent blocking potency of flunarizine on T-type Ca2+ channels was slightly stronger than that of mibefradil. In contrast, R(-) efonidipine inhibited only T-type Ca2+ channels and did not show any effect on HVA Ca2+ channels. The inhibitory actions of R(-) efonidipine or flunarizine were similar on both Ba2+ and Ca2+ current components passing through T-type Ca2+ channels. In addition, flunarizine but not R(-) efonidipine inhibited voltage-dependent Na+ channels and Ca2+-activated K+ channels. Thus, it appears that R(-) efonidipine is a selective blocker for T-type Ca2+ channels. It could be used as a pharmacological tool in future studies on T-type Ca2+ channels.
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Abstract
Triggered activity in cardiac muscle and intracellular Ca2+ have been linked in the past. However, today not only are there a number of cellular proteins that show clear Ca2+ dependence but also there are a number of arrhythmias whose mechanism appears to be linked to Ca2+-dependent processes. Thus we present a systematic review of the mechanisms of Ca2+ transport (forward excitation-contraction coupling) in the ventricular cell as well as what is known for other cardiac cell types. Second, we review the molecular nature of the proteins that are involved in this process as well as the functional consequences of both normal and abnormal Ca2+ cycling (e.g., Ca2+ waves). Finally, we review what we understand to be the role of Ca2+ cycling in various forms of arrhythmias, that is, those associated with inherited mutations and those that are acquired and resulting from reentrant excitation and/or abnormal impulse generation (e.g., triggered activity). Further solving the nature of these intricate and dynamic interactions promises to be an important area of research for a better recognition and understanding of the nature of Ca2+ and arrhythmias. Our solutions will provide a more complete understanding of the molecular basis for the targeted control of cellular calcium in the treatment and prevention of such.
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Affiliation(s)
- Henk E D J Ter Keurs
- Department of Medicine, Physiology and Biophysics, University of Calgary, Alberta, Canada
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Bostanci MO, Bağirici F, Canan S. A calcium channel blocker flunarizine attenuates the neurotoxic effects of iron. Cell Biol Toxicol 2006; 22:119-25. [PMID: 16528447 DOI: 10.1007/s10565-006-0037-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Accepted: 12/09/2005] [Indexed: 05/07/2023]
Abstract
Iron is a metal highly concentrated in liver and brain tissue, and known to induce neuronal hyperactivity and oxidative stress. It has been established that iron levels rise in the brain in some neurodegenerative diseases such as Parkinson's and Alzheimer's diseases (AD). A body of evidence indicates a link between neuronal death and intracellular excessive calcium accumulation. The aim of the present study was to investigate the effects of a calcium antagonist, flunarizine, on neurotoxicity induced by intracerebroventricular (i.c.v.) iron injection. For this reason rats were divided into three groups as control, iron and iron+flunarizine groups. Animals in iron and iron+flunarizine groups received i.c.v. FeCl(3) injection (200 mM, 2.5 microl), while control rats received the same amount of saline into the cerebral ventricles. Rats in iron+flunarizine group also received i.c.v. flunarizine (1 microM, 2 microl) following FeCl(3) injection. All animals were kept alive for ten days following the operation and animals in iron+flunarizine group received intraperitoneal (i.p.) flunarizine injections once a day (10 mg/kg/day) during this period. After ten days, rats were sacrificed. The total numbers of neurons in hippocampus of all rats were estimated with the latest, unbiased stereological techniques. Findings of the present study suggest that flunarizine may attenuate the neurotoxic effects of iron injection by inhibiting the cellular influx of excessive calcium ions.
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Affiliation(s)
- M Omer Bostanci
- Department of Physiology, Faculty of Medicine, University of Ondokuz Mayis, 55139, Samsun, Turkey.
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18
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Porzig H. Pharmacological modulation of voltage-dependent calcium channels in intact cells. Rev Physiol Biochem Pharmacol 2006; 114:209-62. [PMID: 2155471 DOI: 10.1007/bfb0031020] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- H Porzig
- Pharmakologisches Institut, Universität Bern, Switzerland
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Sulová Z, Orlický J, Fiala R, Dovinová I, Uhrík B, Seres M, Gibalová L, Breier A. Expression of P-glycoprotein in L1210 cells is linked with rise in sensitivity to Ca2+. Biochem Biophys Res Commun 2005; 335:777-84. [PMID: 16098480 DOI: 10.1016/j.bbrc.2005.07.144] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 07/25/2005] [Indexed: 12/01/2022]
Abstract
L1210/VCR cell line (R) was obtained by adaptation of the L1210 mouse leukaemia cells (S) to vincristine and showed P-glycoprotein (P-gp) mediated multidrug resistance (MDR). R cells were observed to be more sensitive to high external calcium as parental S. More pronounced calcium uptake was observed for R cells. Moreover, differences in intracellular calcium cell localization between S and R cells were found ultrastructurally following a calcium precipitating cytochemical method. In S cells, calcium precipitates were found to be localized predominantly along the cell surface coat and within mitochondria delineating the cristae. In R cells, precipitates were also found inside nuclei, at the border of heterochromatin clumps, and scattered within the cytoplasm. High extracellular calcium did not influence the P-gp mediated extrusion of calcein/AM as P-gp substrate. These results indicate that calcium enters and consequently damages the MDR cells to a higher extent than parental cells.
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Affiliation(s)
- Zdena Sulová
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, 833 34 Bratislava, Slovakia
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Kochegarov AA. Pharmacological modulators of voltage-gated calcium channels and their therapeutical application. Cell Calcium 2003; 33:145-62. [PMID: 12600802 DOI: 10.1016/s0143-4160(02)00239-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Calcium channels (CCs) play an important role in the transduction of action potential to the cytosol. An influx of Ca(2+) is essential for muscle contraction, neurotransmitter, and hormonal release. Level of cytosolic Ca(2+) controls activities of many enzymes and regulatory proteins. Voltage-gated calcium channels (VGCCs) serve as sensors for membrane depolarization. Blood pressure reduction is due to relaxation of actomyosine filaments in vascular smooth muscles. Calcium channel blockers (CCBs) are traditionally used for treatment of cardiovascular diseases. Neurotransmitter release from presynaptic neurons is triggered by Ca(2+) influx. Blockers of neuronal CCs may be applied for pain treatment. Overload of neurons by Ca(2+) is toxic. CCBs may be applied for prevention of some neurodegenerative disorders.
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Affiliation(s)
- Andrei A Kochegarov
- Department of Neurology, UCLA, 695 Charles E. Young Dr. 50, GONDA 5524, Los Angeles, CA 90095, USA.
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De Paoli P, Cerbai E, Koidl B, Kirchengast M, Sartiani L, Mugelli A. Selectivity of different calcium antagonists on T- and L-type calcium currents in guinea-pig ventricular myocytes. Pharmacol Res 2002; 46:491-7. [PMID: 12457621 DOI: 10.1016/s1043661802002360] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Both L- and T-type calcium channels are present in the heart. In cardiac myocytes L-type calcium channels are blocked by the classical calcium channel blockers, while T-type calcium channels are thought to be insensitive to these drugs and to be selectively blocked by mibefradil. We aimed to compare the T/L calcium channel blocking selectivity of several calcium channel blockers by evaluating their effects on both components evoked in the same cell from a holding potential corresponding to the normal physiological value (-90mV). Currents were recorded in single patch-clamped guinea-pig ventricular myocytes, superfused with a Na(+)- and K(+)-free solution to abolish overlapping currents. Two dihydropyridines (amlodipine and lacidipine), verapamil diltiazem and mibefradil were tested; for each compound concentrations equieffective on L-type Ca(2+) current were used. All calcium channel blockers, at concentrations blocking less than 30% of L-type Ca(2+) current, inhibited a significant amount of T-type Ca(2+) current, varying from 0.8% (diltiazem) to 28% (mibefradil). We calculated for each compound the T/L ratio. As expected, mibefradil showed the highest T selectivity; lacidipine and diltiazem resulted to be L selective. Verapamil and amlodipine were not selective. Thus, the calcium channel blockers can be differentiated on the basis of their T/L selectivity.
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Affiliation(s)
- Petra De Paoli
- Department of Preclinical and Clinical Pharmacology, Centre of Molecular Medicine, University of Firenze, Viale G. Pieraccini 6, 50139 Firenze, Italy
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Abstract
T-type calcium channels play critical roles in cellular excitability and have been implicated in the pathogenesis of a variety of neurological disorders including epilepsy. Although there have been reports that certain neuroleptics that primarily target D2 dopamine receptors and are used to treat psychoses may also interact with T-type Ca channels, there has been no systematic examination of this phenomenon. In the present paper we provide a detailed analysis of the effects of several widely used neuroleptic agents on a family of exogenously expressed neuronal T-type Ca channels (alpha1G, alpha1H, and alpha1I subtypes). Among the neuroleptics tested, the diphenylbutylpiperidines pimozide and penfluridol were the most potent T-type channel blockers with Kd values (approximately 30-50 nm and approximately 70-100 nm, respectively), in the range of their antagonism of the D2 dopamine receptor. In contrast, the butyrophenone haloperidol was approximately 12- to 20-fold less potent at blocking the various T-type Ca channels. The diphenyldiperazine flunarizine was also less potent compared with the diphenylbutylpiperadines and preferentially blocked alpha1G and alpha1I T-type channels compared with alpha1H. The various neuroleptics did not significantly affect T-type channel activation or kinetic properties, although they shifted steady-state inactivation profiles to more negative values, indicating that these agents preferentially bind to channel inactivated states. Overall, our findings indicate that T-type Ca channels are potently blocked by a subset of neuroleptic agents and suggest that the action of these drugs on T-type Ca channels may significantly contribute to their therapeutic efficacy.
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Castilho RF, Hansson O, Brundin P. Improving the survival of grafted embryonic dopamine neurons in rodent models of Parkinson's disease. PROGRESS IN BRAIN RESEARCH 2001; 127:203-31. [PMID: 11142029 DOI: 10.1016/s0079-6123(00)27011-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- R F Castilho
- Section for Neuronal Survival, Wallenberg Neuroscience Center, Department of Physiological Sciences, Lund University, Sölvegatan 17, S-223 62 Lund, Sweden
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24
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Abstract
Calcium channels are critical to normal cardiac function. They are involved in the generation and conduction of the action potential and in contraction. Three surface membrane channels have been identified. The L-type Ca channel is most abundant and is responsible for Ca entry into the cell that triggers contraction. T-type Ca channels are most prevalent in the conduction system and are probably involved in automaticity. A newly described TTX-sensitive calcium current may be important in "boosting" or enhancing conduction and contraction. The main intracellular Ca channel resides in the sarcoplasmic reticulum and is responsible for the release of the Ca that activates contraction. Oscillatory behavior of this channel influences the sarcolemmal membrane, causing delayed aftercontractions and arrhythmias such as those seen in digoxin toxicity. The on-going molecular characterization of these channels will enhance our knowledge of their normal function and dysfunction in disease states, leading to the development of new therapeutic agents to treat arrhythmias and contractile dysfunction.
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Affiliation(s)
- S R Shorofsky
- Departments of Physiology and Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Brundin P, Karlsson J, Emgård M, Schierle GS, Hansson O, Petersén A, Castilho RF. Improving the survival of grafted dopaminergic neurons: a review over current approaches. Cell Transplant 2000; 9:179-95. [PMID: 10811392 DOI: 10.1177/096368970000900205] [Citation(s) in RCA: 274] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neural transplantation is developing into a therapeutic alternative in Parkinson's disease. A major limiting factor is that only 3-20% of grafted dopamine neurons survive the procedure. Recent advances regarding how and when the neurons die indicate that events preceding actual tissue implantation and during the first week thereafter are crucial, and that apoptosis plays a pivotal role. Triggers that may initiate neuronal death in grafts include donor tissue hypoxia and hypoglycemia, mechanical trauma, free radicals, growth factor deprivation, and excessive extracellular concentrations of excitatory amino acids in the host brain. Four distinct phases during grafting that can involve cell death have been identified: retrieval of the embryo; dissection and preparation of the donor tissue; implantation procedure followed by the immediate period after graft injection; and later stages of graft maturation. During these phases, cell death processes involving free radicals and caspase activation (leading to apoptosis) may be triggered, possibly involving an increase in intracellular calcium. We review different approaches that reduce cell death and increase survival of grafted neurons, typically by a factor of 2-4. For example, changes in transplantation procedure such as improved media and implantation technique can be beneficial. Calcium channel antagonists such as nimodipine and flunarizine improve nigral graft survival. Agents that counteract oxidative stress and its consequences, such as superoxide dismutase overexpression, and lazaroids can significantly increase the survival of transplanted dopamine neurons. Also, the inhibition of apoptosis by a caspase inhibitor has marked positive effects. Finally, basic fibroblast growth factor and members of the transforming growth factor-beta superfamily, such as glial cell line-derived neurotrophic factor, significantly improve the outcome of nigral transplants. These recent advances provide hope for improved survival of transplanted neurons in patients with Parkinson's disease, reducing the need for human embryonic donor tissue and increasing the likelihood of a successful outcome.
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Affiliation(s)
- P Brundin
- Wallenberg Neuroscience Center, Department of Physiological Sciences, Lund University, Sweden.
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Kaminski Schierle GS, Hansson O, Brundin P. Flunarizine improves the survival of grafted dopaminergic neurons. Neuroscience 2000; 94:17-20. [PMID: 10613492 DOI: 10.1016/s0306-4522(99)00324-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Embryonic nigral grafts can survive, reinnervate the striatum and reverse functional deficits in both experimental and clinical Parkinsonism. A major drawback is that only around 10% of the implanted dopaminergic neurons survive. The underlying mechanisms leading to this 90% cell death are not fully understood, but oxidative stress and a substantial loss of neurotrophic support are likely to be involved. Hypoxia and mechanical trauma, which are unavoidable during tissue preparation, may be a trigger for cell death. Recent studies have provided evidence that the type of cell death occurring is, to a large extent, apoptotic. Flunarizine is an antagonist of L-, T- and N-type calcium channels, which permits calcium entry into cells via a voltage-dependent mechanism. Flunarizine has been shown to protect neurons against death induced by serum deprivation, nerve growth factor deprivation, oxidative stress, axotomy and ischemia. This study was designed to investigate whether flunarizine can protect grafted embryonic dopaminergic neurons from death when implanted in a rat model of Parkinson's disease. Addition of 1 microM flunarizine inhibited cell death in a suspension of cells derived from the rat's ventral mesencephalon and when such a treated suspension was injected into the neostriatum there was a 2.6-fold greater number of surviving dopaminergic neurons, a doubling of the graft volume and a doubling of the volume of the host neostriatum innervated by dopaminergic fibers from the graft, compared with suspensions not exposed to flunarizine. Furthermore, rats injected with cells that had been exposed to flunarizine displayed a greater recovery of function in the amphetamine-induced rotation test.
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Affiliation(s)
- G S Kaminski Schierle
- Wallenberg Neuroscience Center, Department of Physiological Sciences, Lund University, Sweden.
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Brundin P, Kaminski Schierle GS. Neuroprotective Strategies in Neural Grafting. NEUROMETHODS 2000. [DOI: 10.1007/978-1-59259-690-4_19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Kubista H, Hawkins T, Moss SE. Characterisation of calcium signalling in DT40 chicken B-cells. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1448:299-310. [PMID: 9920420 DOI: 10.1016/s0167-4889(98)00132-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The chicken DT40 pre-B-cell line is becoming a potent experimental tool in the elucidation of higher organism cellular functions due to its unique genetic tractability. While several publications have described the effects of disruption of a range of genes in DT40 cells on calcium signalling, there has been no general overview of Ca2+ responses in wild-type cells. Here, we present experimental data comparing and contrasting the calcium responses to a range of agonists, such as alphaIgM, H2O2 and thapsigargin, applied singly or consecutively in the presence or absence of extracellular calcium. Briefly, we show that calcium release is from thapsigargin-sensitive and also -insensitive stores. This release results in, or is concomitant with, calcium entry across the plasma membrane through store-operated, receptor-operated and possibly L-type like Ca2+ channels. The agonists activate these pathways differentially producing a wide range of different sized and shaped Ca2+ signals. Furthermore, we report that Ca2+ responses in DT40 cells are dependent on the growth conditions. The presence of 1% chicken serum in the growth medium increased amplitudes of calcium responses and enhanced the sustained phase of the alphaIgM response, while 10 microM beta-mercaptoethanol in the medium (not, however, present during calcium measurements) resulted in more transient H2O2 responses and larger amplitude alphaIgM responses while failing to affect thapsigargin responses. The possible causes of these effects and their importance in comparing data from different studies on DT40 cells is discussed.
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Affiliation(s)
- H Kubista
- Department of Physiology, University College London, UK
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29
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Carmeliet E, Mubagwa K. Antiarrhythmic drugs and cardiac ion channels: mechanisms of action. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1998; 70:1-72. [PMID: 9785957 DOI: 10.1016/s0079-6107(98)00002-9] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In this review a description and an analysis are given of the interaction of antiarrhythmic drugs with their molecular target, i.e. ion channels and receptors. Our approach is based on the concept of vulnerable parameter, i.e. the electrophysiological property which plays a crucial role in the genesis of arrhythmias. To prevent or stop the arrhythmia a drug should modify the vulnerable parameter by its action on channel or receptor targets. In the first part, general aspects of the interaction between drugs channel molecules are considered. Drug binding depends on the state of the channel: rested, activated pre-open, activated open, or inactivated state. The change in channel behaviour with state is presented in the framework of the modulated-receptor hypothesis. Not only inhibition but also stimulation can be the result of drug binding. In the second part a detailed and systematic description and an analysis are given of the interaction of drugs with specific channels (Na+, Ca2+, K+, "pacemaker") and non-channel receptors. Emphasis is given to the type of state-dependent block involved (rested, activated and inactivated state block) and the change in channel kinetics. These properties vary and determine the voltage- and frequency-dependence of the change in ionic current. Finally, the question is asked as to whether the available drugs by their action on channels and receptors modify the vulnerable parameter in the desired way to stop or prevent arrhythmias.
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Affiliation(s)
- E Carmeliet
- Centre for Experimental Surgery and Anaesthesiology, University of Leuven, Belgium.
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30
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Zapater P, Moreno J, Horga JF. Neuroprotection by the novel calcium antagonist PCA50938, nimodipine and flunarizine, in gerbil global brain ischemia. Brain Res 1997; 772:57-62. [PMID: 9406955 DOI: 10.1016/s0006-8993(97)00838-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Calcium is involved in the physiopathology of cerebral ischemia. Calcium antagonists might prevent the calcium overload and death of cells from ischemically compromised tissue. We compare the neuroprotective effect of various doses (0.2, 0.5 and 1 mg/kg) of two dihydropyridines, nimodipine and the novel 1,4-dihydropyridine derivative PCA50938, and flunarizine in the gerbil model of global ischemia. Improvements in morbidity were observed 2 h after the end of carotid occlusion (McGraw's scale) with 0.5 mg/kg of flunarizine, all doses of PCA50938 and 0.2 mg/kg nimodipine. Neuronal loss in the CA1 sector of the hippocampus was examined. The animals treated with 0.5 mg/kg flunarizine and those treated with 1 mg/kg PCA50938 showed a significant reduction in the percentage of damaged neurons in the hippocampal CA1 area, 72 h after transient ischemia. None of the animals treated with 0.5 mg/kg flunarizine had more than 80% of the evaluated neurons altered. We conclude that PCA50938 and flunarizine may act as neuroprotective drugs with different patterns of dose-response and neuroprotective-morbidity-mortality relationships, in the model of global cerebral ischemia in the gerbil. Flunarizine has a narrow therapeutic range.
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Affiliation(s)
- P Zapater
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Spain
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31
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Lakhe M, Furukawa Y, Yonezawa T, Nagashima Y, Hirose M, Chiba S. Negative chronotropic and inotropic effects of U-92032, a novel T-type Ca2+ channel blocker, on the isolated, blood-perfused dog atrium. JAPANESE JOURNAL OF PHARMACOLOGY 1996; 71:333-5. [PMID: 8886931 DOI: 10.1254/jjp.71.333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We investigated the effects of U-92032 ((7-((bis-4-fluorophenyl) methyl)-1-piperazinyl)-2-2(2-hydroxyethylamino)-4-(1-methylethyl)- 2,4, 6-cycloheptatrien-1-one), a novel T-type Ca2+ channel blocker, on sinus rate and atrial contractile force in the isolated, blood-perfused atrium of the dog. U-92032 (1 to 300 nmol) induced negative chronotropic and inotropic responses in a dose-dependent manner, and the percentage decrease in sinus rate was less than that in atrial contractile force. Atropine did not affect the negative responses to U-92032. These results suggest that U-92032, a T-type Ca2+ channel blocker, simultaneously decreases the sinus rate and atrial force as do L-type Ca2+ channel blockers in the isolated dog atrium.
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Affiliation(s)
- M Lakhe
- Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan
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32
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Tokuyama S, Ho IK. Inhibitory effects of diltiazem, an L-type Ca2+ channel blocker, on naloxone-increased glutamate levels in the locus coeruleus of opioid-dependent rats. Brain Res 1996; 722:212-6. [PMID: 8813371 DOI: 10.1016/0006-8993(96)00187-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To investigate the effects of diltiazem, an L-type Ca2+ channel blocker, on naloxone-precipitated withdrawal and elevations of glutamate levels in the locus coeruleus (LC) of opioid-dependent rats, animals were continuously infused with 26 nmol/microliter/h of morphine or butorphanol intracerebroventricularly (i.c.v.) via osmotic minipumps for 3 days. I.c.v. injection of naloxone (an opioid-receptor antagonist, 48 nmol/5 microliters) precipitated withdrawal signs and increased extracellular fluid levels of glutamate in the LC of morphine- or butorphanol-dependent rats measured by in vivo microdialysis. Meanwhile, concomitant infusion of opioids with diltiazem (10 or 100 nmol/microliter/h) inhibited the withdrawal signs and prevented the elevations of glutamate levels in the LC. These results suggest that an expeditious release of glutamate in the LC region regulated by L-type Ca2+ channels mediated system plays a role in the expression of withdrawal signs from opioids.
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Affiliation(s)
- S Tokuyama
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216, USA
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33
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Tokuyama S, Ho IK. Effects of diltiazem, a Ca2+ channel blocker, on naloxone-precipitated changes in dopamine and its metabolites in the brains of opioid-dependent rats. Psychopharmacology (Berl) 1996; 125:135-40. [PMID: 8783387 DOI: 10.1007/bf02249412] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effects of diltiazem, an L-type Ca2+ channel blocker, on naloxone (an opioid receptor antagonist)-precipitated withdrawal signs and changes in extracellular levels of dopamine (DA) and its metabolites in various brain regions of morphine (a mu-opioid receptor agonist) or butorphanol (a mu/delta/kappa mixed opioid receptor agonist) dependent rats were investigated using high performance liquid chromatography fitted with an electrochemical detector (HPLC-ED). Rats were rendered opioid-dependent by continuous intracerebroventricular (i.c.v.) infusion with morphine (26 nmol/microliters per h) or butorphanol (26 nmol/microliters per h) for 3 days. The expression of physical dependence produced by these opioids, as evaluated by naloxone (5 mg/kg. i.p.)-precipitated withdrawal signs, was reduced by concomitant infusion of diltiazem (10 and 100 nmol/microliters per h). Under the same condition, naloxone decreased the levels of: DA in the cortex, striatum, and midbrain; 3,4-dihydroxyphenylacetic acid (DOPAC) in the cortex, striatum, limbic areas, and midbrain: and homovanilic acid (HVA) in the striatum, limbic areas, and midbrain regions. In animals rendered dependent on butorphanol, the results obtained were similar to those of morphine-dependent rats except for the changes in DOPAC levels. Furthermore, concomitant infusion of diltiazem and opioids blocked the decreases in levels of DA, DOPAC, and HVA in a dose-dependent manner. These results suggest that the augmentation of intracellular Ca2+ mediated through L-type Ca2+ channels during continuous opioid infusion results in a decrease in extracellular levels of DA and its metabolites in some specific regions, which are intimately involved in the expression of withdrawal syndrome precipitated by naloxone.
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Affiliation(s)
- S Tokuyama
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216-4505, USA
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34
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Dzhura IO, Naidenov VG, Lyubanova OP, Kostyuk PG, Shuba YM. Characterization of hypothalamic low-voltage-activated Ca channels based on their functional expression in Xenopus oocytes. Neuroscience 1996; 70:729-38. [PMID: 9045084 DOI: 10.1016/s0306-4522(96)83010-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ca-channel currents expressed in Xenopus oocytes by means of messenger RNA extracted from rat thalamohypothalamic complex were studied using the double microelectrode technique. Currents were recorded in Cl(-)-free extracellular solutions with 40 mM Ba2+ as a charge carrier. In response to depolarizations from a very negative holding potential (Vh = -120 mV), inward Ba2+ current activated at around -80 mV, peaked at -30 to -20 mV and reversed at +50 mV indicating that it may be transferred through the low voltage-activated calcium channels. The time-dependent inactivation of the current during prolonged depolarization to -20 mV was quite slow and followed a single exponential decay with a time-constant of 1550 ms and a maintained component constituting 30% of the maximal amplitude. The current could not be completely inactivated at any holding potential. As expected for low voltage-activated current, steady-state inactivation curve shifted towards negative potentials. It could be described by the Boltzmann equation with half inactivation potential -78 mV, slope factor 15 mV and maintained level 0.3. Expressed Ba2+ current could be blocked by flunarizine with Kd = 0.42 microM, nifedipine, Kd = 10 microM, and amiloride at 500 microM concentration. Among inorganic Ca-channel blockers the most potent was La3+ (Kd = 0.48 microM) while Cd2+ and Ni2+ were not very discriminative and almost 1000-fold less effective than La3+ (Kd = 0.52 mM and Kd = 0.62 mM, respectively). Our data show that messenger RNA purified from thalamohypothalamic complex induces expression in the oocytes of almost exclusively low voltage-activated calcium channels with voltage-dependent and pharmacological properties very similar to those observed for T-type calcium current in native hypothalamic neurons, though kinetic properties of the expressed and natural currents are somewhat different.
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Affiliation(s)
- I O Dzhura
- A. A. Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kiev
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35
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Tytgat J, Vereecke J, Carmeliet E. Mechanism of L- and T-type Ca2+ channel blockade by flunarizine in ventricular myocytes of the guinea-pig. Eur J Pharmacol 1996; 296:189-97. [PMID: 8838456 DOI: 10.1016/0014-2999(95)00691-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Flunarizine is a substance known to block voltage-dependent Ca2+ channels in smooth muscle and neuronal cells. Reports on the effect on voltage-dependent cardiac Ca2+ channels are however sparse. Therefore, the mechanism of action of flunarizine on two types of voltage-dependent cardiac Ca2+ channels, the L- and T-type, in single ventricular myocytes of the guinea-pig was investigated using the whole-cell voltage clamp technique. Both channel types can be blocked by flunarizine in a time-, frequency-, voltage-, Ca(2+)-, and proton-dependent way. While the overall mechanism of action on cardiac myocytes is similar to the one reported for other cell types, we found that cardiomyocytes are less susceptible to block (Kd 3.3-11 mM). We also describe a complete analysis of the different components of block, together with evidence for open channel state block and drug-induced changes in channel gating. These findings provide new insights into the mechanism of action of flunarizine on voltage-dependent Ca2+ channels.
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Affiliation(s)
- J Tytgat
- Laboratory of Physiology, University of Leuven, Belgium
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36
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Tokuyama S, Feng Y, Wakabayashi H, Ho IK. Ca2+ channel blocker, diltiazem, prevents physical dependence and the enhancement of protein kinase C activity by opioid infusion in rats. Eur J Pharmacol 1995; 279:93-8. [PMID: 7556388 DOI: 10.1016/0014-2999(95)00140-g] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The influence of an L-type Ca2+ channel blocker, diltiazem [(2S-cis)-3-(acetyloxy)-5-[2-(dimethylamino)-ethyl]-2,3-dihydro-2- (4- methoxyphenyl)-1,5-benzothiazepin-4(5H)-one], on the behavioral signs of naloxone (opioid receptor antagonist)-precipitated withdrawal syndrome and the enhancement of protein kinase C activity in the pons/medulla regions of rats rendered dependent on morphine (mu-opioid receptor agonist) or butorphanol (mu/delta/kappa mixed opioid receptor agonist) was investigated. The expression of physical dependence produced by continuous intracerebroventricular (i.c.v.) infusion of morphine (26 nmol/microliters per h) or butorphanol (26 nmol/microliters per h) for 3 days, as evaluated by naloxone (5 mg/kg, i.p.)-precipitated withdrawal signs, was dose dependently attenuated by concomitant infusion of diltiazem (10 and 100 nmol/microliters per h). Furthermore, diltiazem (100 nmol/microliters per h) completely inhibited the enhancement of cytosolic protein kinase C activity in the pons/medulla regions in rats rendered dependent by continuous infusion with morphine or butorphanol. These results suggest that the augmentation of intracellular Ca2+ concentration mediated through L-type Ca2+ channels during continuous opioid infusion leads to the enhancement of cytosolic protein kinase C activity in the pons/medulla region which is intimately involved in the development and/or expression of physical dependence on opioids.
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Affiliation(s)
- S Tokuyama
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216, USA
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37
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Verduyn SC, Vos MA, Gorgels AP, van der Zande J, Leunissen JD, Wellens HJ. The effect of flunarizine and ryanodine on acquired torsades de pointes arrhythmias in the intact canine heart. J Cardiovasc Electrophysiol 1995; 6:189-200. [PMID: 7620644 DOI: 10.1111/j.1540-8167.1995.tb00770.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Ryanodine, a specific blocker of the Ca2+ release channel of the sarcoplasmic reticulum, and flunarizine, a [Ca2+]i overload blocker, possess antiarrhythmic effects against delayed afterdepolarizations (DADs) and DAD-dependent arrhythmias. In vitro controversy exists about their effect on early after-depolarizations (EADs): no effect was reported on cesium-induced EADs, while ryanodine did prevent EADs induced by isoproterenol. To study the possible role of intracellular Ca2+ overload in acquired EAD-dependent torsades de pointes (TdP) arrhythmias, we tested the effects of flunarizine and ryanodine in our animal model of TdP. METHODS AND RESULTS Anaesthetized dogs with chronic AV block received d-sotalol or almokalant followed by pacing. A subset of dogs with reproducible TdP (> or = 3 times) were selected to receive flunarizine (2 mg/kg per 2 min) or ryanodine (10 micrograms/kg per 10 min). After d-sotalol, TdP was induced at a mean cycle length of the idioventricular rhythm (CL-IVR) of 2070 +/- 635 msec and a QT(U) interval of 535 +/- 65 msec. Induction of TdP was prevented by flunarizine in all experiments (8/8): electrophysiologically this was associated with a decrease in CL-IVR, QT(U), and QTc interval (390 +/- 100 to 320 +/- 45, P < 0.05). Ryanodine prevented TdP induction in 4 of 5 experiments and decreased the CL-IVR, QT(U), and the QTc interval from 385 +/- 75 to 320 +/- 20 msec (P < 0.05). Both drugs also suppressed the almokalant-induced EADs and related ectopic activity. This antiarrhythmic action corresponded with the inability to reinduce TdP by pacing. CONCLUSIONS Blockade of the Ca2+ release channel of the sarcoplasmic reticulum by ryanodine or the reduction of [Ca2+]i overload by flunarizine prevents induction of EAD-dependent acquired TdP arrhythmias, suggesting a role for [Ca2+]i overload in acquired TdP.
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Affiliation(s)
- S C Verduyn
- Department of Cardiology, Cardiovascular Research Institute Maastricht, University of Limburg, The Netherlands
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38
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Saxena AK, Saxena M. Developments in anticonvulsants. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1995; 44:185-291. [PMID: 7644666 DOI: 10.1007/978-3-0348-7161-7_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- A K Saxena
- Division of Medicinal Chemistry, Central Drug Research Institute, Lucknow, India
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Eichler ME, Dubinsky JM, Tong J, Rich KM. The ability of diphenylpiperazines to prevent neuronal death in dorsal root ganglion neurons in vitro after nerve growth factor deprivation and in vivo after axotomy. J Neurochem 1994; 62:2148-57. [PMID: 8189223 DOI: 10.1046/j.1471-4159.1994.62062148.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mechanism of neuroprotection by the calcium channel antagonist flunarizine against neuronal death is unknown. We investigated the ability of other calcium channel antagonists (cinnarizine, nimodipine, nicardipine, diltiazem, and verapamil), calmodulin antagonists, and calpain inhibitors to prevent neuronal death in rat dorsal root ganglion neurons in vitro after nerve growth factor (NGF) deprivation and the ability of cinnarizine and diltiazem to protect in vivo after axotomy. In vitro, only neurons treated with cinnarizine or flunarizine were protected from death after withdrawal. In vivo, cinnarizine, but not diltiazem, protected dorsal root ganglion neurons in rats after unilateral sciatic nerve crush. Intracellular calcium concentration ([Ca2+]i) was evaluated with fura 2 after NGF deprivation in vitro. Neurons "committed to die" 24 h after NGF deprivation displayed a decline in [Ca2+]i before visible morphological deterioration consistent with cell death. The influx of extracellular calcium was not necessary to produce neuronal death. Neurons deprived of NGF gradually lost the ability to respond to elevated external potassium with an increase in [Ca2+]i during the first 24 h after trophic factor deprivation. After 24 h, neurons deprived of NGF could not be rescued by readministration of NGF. Neurons protected from cell death with diphenylpiperazines maintained their response to high external potassium, suggesting continued membrane integrity. We speculate that diphenylpiperazines may protect sensory neurons via an unknown mechanism that stabilizes cell membranes.
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Affiliation(s)
- M E Eichler
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri 78284-7756
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40
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Antzelevitch C, Sicouri S. Clinical relevance of cardiac arrhythmias generated by afterdepolarizations. Role of M cells in the generation of U waves, triggered activity and torsade de pointes. J Am Coll Cardiol 1994; 23:259-77. [PMID: 8277090 DOI: 10.1016/0735-1097(94)90529-0] [Citation(s) in RCA: 356] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recent findings point to an important heterogeneity in the electrical behavior of cells spanning the ventricular wall as well as important differences in the response of the various cell types to cardioactive drugs and pathophysiologic states. These observations have permitted a fine tuning and, in some cases, a reevaluation of basic concepts of arrhythmia mechanisms. This brief review examines the implications of some of these new findings within the scope of what is already known about early and delayed afterdepolarizations and triggered activity and discusses the possible relevance of these mechanisms to clinical arrhythmias.
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Affiliation(s)
- C Antzelevitch
- Masonic Medical Research Laboratory, Utica, New York 13504
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41
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Barrios M, Robles I, Baeyens JM. Role of L-type calcium channels on yohimbine-precipitated clonidine withdrawal in vivo and in vitro. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1993; 348:601-7. [PMID: 7510854 DOI: 10.1007/bf00167236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This study was designed to elucidate the possible participation of L-type calcium channels in the expression of clonidine-withdrawal precipitated by yohimbine in clonidine-dependent animals. Mice implanted for 5 days with osmotic minipumps containing the alpha 2-adrenoceptor agonist clonidine showed symptoms of a withdrawal syndrome (jerks, headshakes, defecations and weight loss) when yohimbine, an alpha 2-adrenoceptor antagonist, was injected. Similarly, isolated rat ilea incubated with clonidine in vitro showed a withdrawal contracture when yohimbine was added to the organ bath. The effects of L-type calcium channel blockers (verapamil and diltiazem) and the stimulant Bay K 8644 on these two different types of withdrawal responses were evaluated. A dose-dependent decrease in yohimbine-precipitated clonidine withdrawal in vivo was observed when verapamil (10-40 mg/kg, s.c. and 120 micrograms/mouse, i.c.v.) or diltiazem (5-20 mg/kg, s.c. and 160 micrograms/mouse, i.c.v.) were administered to mice dependent on clonidine. No effect was found after Bay K 8644 (0.5-5 mg/kg, s.c. and 1-5 micrograms/mouse) was injected under these conditions. In vitro, both verapamil (0.1-5 microM) and D-cis-diltiazem (1-50 microM) concentration-dependently reduced the height of the yohimbine-precipitated withdrawal contracture in rat ileum incubated with clonidine. Furthermore, the effect of diltiazem was stereospecific, as D-cis-diltiazem 10 microM markedly inhibited clonidine withdrawal, whereas the same concentration of L-cis-diltiazem had no effect. In contrast, the calcium channel stimulant Bay K 8644 (0.1-1 microM) increased the height of the ileum withdrawal contracture.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Barrios
- Department of Pharmacology, Medical School, University of Granada, Spain
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42
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Cohan SL, Redmond DJ, Chen M, Wilson D, Cyr P. Flunarizine blocks elevation of free cytosolic calcium in synaptosomes following sustained depolarization. J Cereb Blood Flow Metab 1993; 13:947-54. [PMID: 8408319 DOI: 10.1038/jcbfm.1993.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Gerbil cerebral cortical synaptosomes loaded with the fluorescent calcium probe FURA-2 were used to study depolarization-induced presynaptic cytosolic free calcium concentration, as an in vitro model of cerebral ischemia. The depolarization-induced increase in intrasynaptosomal cytosolic free calcium concentration is not sodium-dependent or sodium channel-dependent and may be due to an influx of extrasynaptosomal calcium resulting from a cadmium- and omega-conotoxin-sensitive, nickel-, nifedipine-, and nimodipine-insensitive voltage-regulated channel. The depolarization-induced increase in intrasynaptosomal free cytosolic calcium concentration is also inhibited by flunarizine, a calcium antagonist that has protective effects in animal models of cerebral anoxia and ischemia. Our results suggest that presynaptic calcium uptake following depolarization may be mediated in part by an N-type channel. Flunarizine may block presynaptic calcium accumulation, in part, by blocking this N-type channel; this blockade may be just one of several mechanisms by which flunarizine exerts protective effects following cerebral ischemia.
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Affiliation(s)
- S L Cohan
- Department of Neurology, Georgetown University School of Medicine, Washington, D.C. 20007
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Zhorov BS. Comparison of lowest energy conformations of dimethylcurine and methoxyverapamil: evidence of ternary association of calcium channel, Ca2+, and calcium entry blockers. J Membr Biol 1993; 135:119-27. [PMID: 8411133 DOI: 10.1007/bf00231437] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Verapamil and dimethylcurine are Ca2+ entry blockers of essentially different chemical structures which presumably bind to the same arylalkylamine receptor of the L-type Ca channel. A systematic conformational analysis of methoxyverapamil (D-600) and dimethylcurine has been carried out using a molecular mechanics method. The lowest minimum-energy conformations of D-600 are predisposed to chelate Ca2+ by four oxygen atoms of the stacked methoxyphenyl moieties. Comparison of the lowest energy conformations of D-600-Ca2+ and dimethylcurine revealed a similar spatial disposition of cationic groups and methoxyphenyl moieties in the two compounds. A three-dimensional model of arylalkylamine receptor was suggested which incorporates two nucleophilic areas of the Ca channel. Dimethylcurine binds to these areas by its quaternary amine functions, whereas D-600 does so by amine function and via coordinated Ca2+. The results support the hypotheses on ternary complex formation between the ligands of Ca channel, their receptors, and Ca2+.
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Affiliation(s)
- B S Zhorov
- Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada
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44
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Cousin MA, Nicholls DG, Pocock JM. Flunarizine inhibits both calcium-dependent and -independent release of glutamate from synaptosomes and cultured neurones. Brain Res 1993; 606:227-36. [PMID: 8098253 DOI: 10.1016/0006-8993(93)90989-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Flunarizine, an established Ca2+ channel antagonist, blocks both exocytotic glutamate release from mammalian cultured cerebellar granule cells and isolated presynaptic nerve endings (synaptosomes) prepared from two distinct areas of the mammalian brain. This blockade of release displays the same flunarizine concentration dependency in synaptosomes in the presence or absence of Ca2+, with total inhibition at a concentration of 10 microM. In cultured neurones, a selective effect on the L-channel-coupled component of the KCl-evoked rise in intracellular Ca2+, [Ca2+]c, can be demonstrated between flunarizine concentrations of 100 nM and 10 microM, while at concentrations above 10 microM, the remaining residual and transient components are affected. In synaptosomes, flunarizine blocks the KCl-evoked elevation in [Ca2+]c in a concentration-dependent manner. Additionally, 10 microM flunarizine directly antagonises ouabain-induced tetrodotoxin (TTX)-sensitive Na+ influx, glutamate, aspartate and GABA release from synaptosomes, whilst inhibiting veratridine-induced Ca(2+)-independent TTX-sensitive Na+ influx and glutamate release at 15 microM and 10 microM in cells and synaptosomes, respectively. In both cultured neurones and synaptosomes, the ability of flunarizine to block both neurotransmitter and cytoplasmic glutamate release is due to a direct antagonism of both voltage dependent Ca2+ channels and tetrodotoxin-sensitive Na+ channels.
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Affiliation(s)
- M A Cousin
- Department of Biochemistry, University of Dundee, Scotland, UK
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45
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Battaini F, Trabucchi M, Chikvaidze V, Govoni S. Effect of Aging on Brain Voltage-Dependent Calcium Channels. ACTA ACUST UNITED AC 1993. [DOI: 10.1007/978-94-011-1725-8_32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2023]
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46
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Kenny BA, Fraser S, Spedding M. Identification of a novel calcium antagonist binding site in rat brain by SR 33557. Br J Pharmacol 1993; 108:93-9. [PMID: 7679034 PMCID: PMC1907724 DOI: 10.1111/j.1476-5381.1993.tb13445.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
1. In K(+)-depolarized taenia preparations from guinea-pig caecum SR 33557 was a potent antagonist of Ca(2+)-induced contractions and antagonized the effect of the calcium channel activator Bay K 8644. 2. SR 33557 displayed high affinity (pKi 9.54 +/- 0.04, nH 1.01) for the [3H]-(+/-)-PN 200-110 binding site in rat cerebral cortex membranes. In the presence of 5 mM Ca2+ this affinity was reduced (pKi 8.82 +/- 0.01, nH 1.05) whilst the affinity of nitrendipine was unaffected by this concentration of Ca2+. 3. Saturation binding experiments in rat cerebral cortex carried out in the absence and presence of SR 33557 (0.1-1.0 nM) indicated an apparently competitive interaction at the dihydropyridine site, in that SR 33557 reduced the KD of [3H]-(+/-)-PN 200-110 binding without any effect on Bmax. In kinetic experiments, the rate of dissociation of [3H]-(+/-)-PN 200-110 from rat cerebral cortex was unchanged in the presence of SR 33557 (5 nM). 4. D-cis-diltiazem fully reversed the inhibition [3H]-nitrendipine binding to rat cerebral cortex produced by SR 33557 indicating the site of action of SR 33557 to be distinct from the dihydropyridine (DHP) binding site. 5. Saturation analysis indicated that [3H]-SR 33557 (0.01-0.8 nM) labelled a single class of binding sites in rat cerebral cortex membranes with high affinity (KD 0.12 +/- 0.01, Bmax 222 +/- 20 fmol mg-1 protein), although kinetic data indicated the existence of negative cooperativity between the binding sites. 6.In competition studies, a variety of different calcium antagonists displayed similar affinity for [3H]-SR 33557 and [3H]-(+/-)-PN 200-110 sites. The [3H]-SR 33557 site was sensitive to the inhibitory effect of divalent cations. The affinity of Cd2+ was 0.026 +/- 0.015 mM and the rank order of affinity was Cd2+ >Ca2+ >Mn2+ >Mg2+ >Na+.7. We propose that SR 33557 labels a distinct site in rat cerebral cortex. The coupling between the SR 33557 and DHP site appears to be very close, resulting in apparently competitive interactions in some experimental protocols but can be revealed as negatively allosteric in other circumstances.
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Affiliation(s)
- B A Kenny
- Department of Pharmacology, Syntex Research Centre, Riccarton, Edinburgh
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De la Fuente MT, Guantes JM, Del Valle M, Garcia AG. Mechanism of blockade by flunarizine of bovine adrenal catecholamine release. Eur J Pharmacol 1992; 229:189-96. [PMID: 1490523 DOI: 10.1016/0014-2999(92)90554-h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
How flunarizine, a class IV Ca2+ antagonist, affects the secretion of catecholamines in response to nicotinic receptor activation (10-s pulses with 100 microM dimethylphenylpiperazinium, DMPP) or direct depolarization of chromaffin cells (10-s pulses with 100 mM K+ and 2.5 mM Ca2+, 100 K+/2.5 Ca2+) was studied in bovine adrenal glands perfused with an oxygenated Krebs-Tris solution at 37 degrees C at a rate of 20 ml/min. Experimental protocols aimed to test voltage and time dependence of the flunarizine blocking effects on secretion are described. The DMPP pulses released an average of 217 micrograms catecholamines and the K+ pulses, an average of 117 micrograms. These responses were blocked by flunarizine concentration dependently; IC50s were 3.7 microM for DMPP and 1.1 microM for K+. Under polarizing conditions (60-s perfusion with a solution containing 5.9 mM K+ and nominally zero Ca2+), a 10-s pulse with 100 K+/2.5 Ca2+ released 117 +/- 26 micrograms of catecholamines (n = 12). Under depolarizing conditions (60-s perfusion with 118 K+/0 Ca2+ prior to the Ca2+ pulse), the pulse with 118 K+/2.5 Ca2+ released 307 +/- 36 micrograms of catecholamines (n = 14). Flunarizine blocked these secretory responses equally and concentration dependently with an IC50 of 3.4 microM under polarizing conditions and of 3.8 microM under depolarizing conditions. Thus, blockade by flunarizine of secretion was apparently not voltage-dependent. The blockade was, however, clearly dependent on the time of exposure of the adrenal medullary tissue to flunarizine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M T De la Fuente
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Spain
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Pacini DJ, Boachie-Ansah G, Kane KA. Modification by hypoxia, hyperkalaemia and acidosis of the cardiac electrophysiological effects of a range of antiarrhythmic drugs. Br J Pharmacol 1992; 107:665-70. [PMID: 1472965 PMCID: PMC1907770 DOI: 10.1111/j.1476-5381.1992.tb14504.x] [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: 12/27/2022] Open
Abstract
1. The electrophysiological effects of a series of drugs with Class I antiarrhythmic activity were examined in sheep Purkinje fibres, superfused in vitro with either a normal or hypoxic, hyperkalaemic and acidotic physiological salt solution (PSS). 2. In normal sheep Purkinje fibres, lignocaine, disopyramide, nicainoprol and propranolol all significantly reduced action potential height and the maximum rate of depolarization of phase zero (MRD) and abbreviated the action potential, without modifying resting membrane potential (RMP). 3. Verapamil at the highest concentration studied, 8 microM, significantly reduced MRD with an associated slight membrane depolarization and abbreviated action potential duration measured at 50% repolarization (APD50). 4. Superfusion of sheep Purkinje fibres with a hypoxic, hyperkalaemic and acidotic PSS resulted in marked reductions in resting membrane potential, upstroke and duration of the action potential. 5. In the presence of modified PSS, lignocaine, propranolol and verapamil all reduced MRD to a greater extent than in normal PSS. The effects of nicainoprol on MRD were not affected whereas those of disopyramide were significantly attenuated. 6. Under simulated ischaemic conditions, lignocaine, propranolol and nicainoprol did not produce a concentration-dependent reduction in action potential duration whereas disopyramide and verapamil, respectively, prolonged and abbreviated both APD50 and APD90. 7. The Na+ channel blocking actions of the different subtypes of Class I antiarrhythmic agents studied, as well as their effects on action potential duration, were modified differently by simulated ischaemia.
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Affiliation(s)
- D J Pacini
- Department of Physiology and Pharmacology, University of Strathclyde, Glasgow
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PARK JEANNYK, DANILO PETER, ROSEN MICHAELR. Effects of Flunarizine on Impulse Initiation in Canine Purkinje Fibers. J Cardiovasc Electrophysiol 1992. [DOI: 10.1111/j.1540-8167.1992.tb00976.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Cohan SL, Redmond D, Chen M. Effect of flunarizine on electroencephalogram recovery and brain temperature in gerbils after brain ischemia. Stroke 1992; 23:229-33. [PMID: 1561653 DOI: 10.1161/01.str.23.2.229] [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: 12/27/2022]
Abstract
BACKGROUND AND PURPOSE This study was designed to determine whether flunarizine enhances the rate of brain recovery as measured by electroencephalography after cerebral ischemia and whether these effects are attributable to changes in brain temperature. METHODS Male gerbils (n = 81) were treated with either 10 mg/kg flunarizine or its vehicle, beta-cyclodextrin, intraperitoneally, 60 minutes before bilateral carotid occlusion of either 4 or 6 minutes' duration. The electroencephalogram was continuously recorded in the preischemic, ischemic, and postischemic stages of the experiment and rated for the time necessary for the return of 4-6, 7-10, and 11-15 Hz activity. In a second set of experiments, intracerebral temperature was monitored for 60 minutes before ischemia, during 10 minutes of carotid occlusion, and for 60 minutes after ischemia. RESULTS Flunarizine pretreatment resulted in significantly more rapid return of electroencephalographic activity in each of the three frequency categories monitored when compared with those animals pretreated with vehicle alone (p less than 0.001). Flunarizine had no effect on brain temperature before, during, or up to 60 minutes after termination of ischemia. CONCLUSIONS Flunarizine, which has been of efficacy in reducing neuronal death, mortality, and functional impairment when administered after ischemic insults, may have prophylactic value in accelerating brain recovery from ischemia, but does not have this effect as a result of altered brain temperature.
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Affiliation(s)
- S L Cohan
- Department of Neurology, Georgetown University School of Medicine, Washington, DC
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