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McCarthy CI, Mustafá ER, Cornejo MP, Yaneff A, Rodríguez SS, Perello M, Raingo J. Chlorpromazine, an Inverse Agonist of D1R-Like, Differentially Targets Voltage-Gated Calcium Channel (Ca V) Subtypes in mPFC Neurons. Mol Neurobiol 2023; 60:2644-2660. [PMID: 36694048 DOI: 10.1007/s12035-023-03221-1] [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: 07/15/2022] [Accepted: 01/04/2023] [Indexed: 01/26/2023]
Abstract
The dopamine receptor type 1 (D1R) and the dopamine receptor type 5 (D5R), which are often grouped as D1R-like due to their sequence and signaling similarities, exhibit high levels of constitutive activity. The molecular basis for this agonist-independent activation has been well characterized through biochemical and mutagenesis in vitro studies. In this regard, it was reported that many antipsychotic drugs act as inverse agonists of D1R-like constitutive activity. On the other hand, D1R is highly expressed in the medial prefrontal cortex (mPFC), a brain area with important functions such as working memory. Here, we studied the impact of D1R-like constitutive activity and chlorpromazine (CPZ), an antipsychotic drug and D1R-like inverse agonist, on various neuronal CaV conductances, and we explored its effect on calcium-dependent neuronal functions in the mouse medial mPFC. Using ex vivo brain slices containing the mPFC and transfected HEK293T cells, we found that CPZ reduces CaV2.2 currents by occluding D1R-like constitutive activity, in agreement with a mechanism previously reported by our lab, whereas CPZ directly inhibits CaV1 currents in a D1R-like activity independent manner. In contrast, CPZ and D1R constitutive activity did not affect CaV2.1, CaV2.3, or CaV3 currents. Finally, we found that CPZ reduces excitatory postsynaptic responses in mPFC neurons. Our results contribute to understanding CPZ molecular targets in neurons and describe a novel physiological consequence of CPZ non-canonical action as a D1R-like inverse agonist in the mouse brain.
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Affiliation(s)
- Clara Inés McCarthy
- Electrophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina
| | - Emilio Román Mustafá
- Electrophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina
| | - María Paula Cornejo
- Neurophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina
| | - Agustín Yaneff
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Silvia Susana Rodríguez
- Electrophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Neurophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina
- Department of Surgical Sciences, Functional Pharmacology and Neuroscience, University of Uppsala, Uppsala, Sweden
| | - Jesica Raingo
- Electrophysiology Laboratory of the Multidisciplinary Institute of Cell Biology (Argentine Research Council CONICET, Scientific Research Commission of the Buenos Aires Province and National University of La Plata), La Plata, Buenos Aires, Argentina.
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Su CL, Cheng CC, Yen PH, Huang JX, Ting YJ, Chiang PH. Wireless neuromodulation in vitro and in vivo by intrinsic TRPC-mediated magnetomechanical stimulation. Commun Biol 2022; 5:1166. [PMID: 36323817 PMCID: PMC9630493 DOI: 10.1038/s42003-022-04124-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
Various magnetic deep brain stimulation (DBS) methods have been developing rapidly in the last decade for minimizing the invasiveness of DBS. However, current magnetic DBS methods, such as magnetothermal and magnetomechanical stimulation, require overexpressing exogeneous ion channels in the central nervous system (CNS). It is unclear whether magnetomechanical stimulation can modulate non-transgenic CNS neurons or not. Here, we reveal that the torque of magnetic nanodiscs with weak and slow alternative magnetic field (50 mT at 10 Hz) could activate neurons through the intrinsic transient receptor potential canonical channels (TRPC), which are mechanosensitive ion channels widely expressed in the brain. The immunostaining with c-fos shows the increasement of neuronal activity by wireless DBS with magnetomechanical approach in vivo. Overall, this research demonstrates a magnetic nanodiscs-based magnetomechanical approach that can be used for wireless neuronal stimulation in vitro and untethered DBS in vivo without implants or genetic manipulation.
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Affiliation(s)
- Chih-Lun Su
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C
| | - Chao-Chun Cheng
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C
| | - Ping-Hsiang Yen
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C
| | - Jun-Xuan Huang
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C
| | - Yen-Jing Ting
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C
| | - Po-Han Chiang
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan, R.O.C..
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Enhanced BDNF Actions Following Acute Hypoxia Facilitate HIF-1α-Dependent Upregulation of Cav3-T-Type Ca 2+ Channels in Rat Cardiomyocytes. MEMBRANES 2021; 11:membranes11070470. [PMID: 34202148 PMCID: PMC8307968 DOI: 10.3390/membranes11070470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 06/16/2021] [Accepted: 06/23/2021] [Indexed: 01/19/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) has recently been recognized as a cardiovascular regulator particularly in the diseased condition, including coronary artery disease, heart failure, cardiomyopathy, and hypertension. Here, we investigate the role of BDNF on the T-type Ca2+ channel, Cav3.1 and Cav3.2, in rat neonatal cardiomyocytes exposed to normoxia (21% O2) and acute hypoxia (1% O2) in vitro for up to 3 h. The exposure of cardiomyocytes to hypoxia (1 h, 3 h) caused a significant upregulation of the mRNAs for hypoxia-inducible factor 1α (Hif1α), Cav3.1, Cav3.2 and Bdnf, but not tropomyosin-related kinase receptor B (TrkB). The upregulation of Cav3.1 and Cav3.2 caused by hypoxia was completely halted by small interfering RNA (siRNA) targeting Hif1a (Hif1a-siRNA) or Bdnf (Bdnf-siRNA). Immunocytochemical staining data revealed a distinct upregulation of Cav3.1- and Cav3.2-proteins caused by hypoxia in cardiomyocytes, which was markedly suppressed by Bdnf-siRNA. These results unveiled a novel regulatory action of BDNF on the T-type Ca2+ channels expression through the HIF-1α-dependent pathway in cardiomyocytes.
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To KHT, Gui P, Li M, Zawieja SD, Castorena-Gonzalez JA, Davis MJ. T-type, but not L-type, voltage-gated calcium channels are dispensable for lymphatic pacemaking and spontaneous contractions. Sci Rep 2020; 10:70. [PMID: 31919478 PMCID: PMC6952455 DOI: 10.1038/s41598-019-56953-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 12/10/2019] [Indexed: 12/28/2022] Open
Abstract
The spontaneous contractions of collecting lymphatic vessels provide an essential propulsive force to return lymph centrally. These contractions are driven by an intrinsic electrical pacemaker, working through an unknown underlying ionic mechanism that becomes compromised in some forms of lymphedema. In previous studies, T-type voltage-gated Ca2+ channels (VGCCs) were implicated in this pacemaking mechanism, based on the effects of the reputedly selective T-type VGCC inhibitors mibefradil and Ni2+. Our goal was to test this idea in a more definitive way using genetic knock out mice. First, we demonstrated through both PCR and immunostaining that mouse lymphatic muscle cells expressed Cav3.1 and Cav3.2 and produced functional T-type VGCC currents when patch clamped. We then employed genetic deletion strategies to selectively test the roles of each T-type VGCC isoform in the regulation of lymphatic pacemaking. Surprisingly, global deletion of either, or both, isoform(s) was without significant effect on either the frequency, amplitude, or fractional pump flow of lymphatic collectors from two different regions of the mouse, studied ex vivo. Further, both WT and Cav3.1-/-; 3.2-/- double knock-out lymphatic vessels responded similarly to mibefradil and Ni2+, which substantially reduced contraction amplitudes and slightly increased frequencies at almost all pressures in both strains: a pattern consistent with inhibition of L-type rather than T-type VGCCs. Neither T-type VGCC isoform was required for ACh-induced inhibition of contraction, a mechanism by which those channels in smooth muscle are thought to be targets of endothelium-derived nitric oxide. Sharp intracellular electrode measurements in lymphatic smooth muscle revealed only subtle, but not significant, differences in the resting membrane potential and action potential characteristics between vessels from wild-type and Cav3.1-/-; 3.2-/- double knock-out mice. In contrast, smooth-muscle specific deletion of the L-type VGCC, Cav1.2, completely abolished all lymphatic spontaneous contractions. Collectively our results suggest that, although T-type VGCCs are expressed in mouse lymphatic smooth muscle, they do not play a significant role in modulating the frequency of the ionic pacemaker or the amplitude of spontaneous contractions. We conclude that the effects of mibefradil and Ni2+ in other lymphatic preparations are largely or completely explained by off-target effects on L-type VGCCs, which are essential for controlling both the frequency and strength of spontaneous contractions.
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MESH Headings
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/chemistry
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/deficiency
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Lymphatic Vessels/physiology
- Male
- Membrane Potentials/drug effects
- Mibefradil/pharmacology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/metabolism
- Nickel/pharmacology
- Pacemaker, Artificial
- Rats
- Rats, Wistar
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Affiliation(s)
- Kim H T To
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Jorge A Castorena-Gonzalez
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA.
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5
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NS8593 inhibits Ca 2+ permeant channels reversing mouse airway smooth muscle contraction. Life Sci 2019; 238:116953. [PMID: 31626793 DOI: 10.1016/j.lfs.2019.116953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/09/2019] [Accepted: 10/09/2019] [Indexed: 01/24/2023]
Abstract
AIMS This study focused on investigating whether NS8593 reverses airway smooth muscle (ASM) contraction and the underlying mechanism. MAIN METHODS ASM contraction in mouse tracheal rings and lung slices was measured. Currents mediated by voltage dependent Ca2+ channels (VDCCs) and ACH-activated channels were measured using the whole-cell patch-clamp technique in single tracheal smooth muscle cells (TSMCs). Intracellular Ca2+ level and cell length were measured using an LSM 700 laser confocal microscope and a Zen 2010 software. Mouse respiratory system resistance (Rrs) was assessed using a FlexiVent FX system. KEY FINDINGS High K+ (80 mM K+) and ACH induced ASM contraction in mouse tracheal rings and lung slices, which was partially relaxed by nifedipine (blocker of L-type VDCCs, LVDCCs), YM-58483 (blocker of store-operated Ca2+ entry (SOCE), transient receptor potential C3 (TRPC3) and TRPC5 channels), respectively. However, the contraction was completely reversed by NS8593, whereas, slightly relaxed by formoterol. ACH activated inward currents, which displayed linear and reversed around 0 mV, indicating the currents were mediated by non-selective cation channels (NSCCs). Moreover, these currents were blocked by YM-58483. In addition, such currents were abolished by NS8593, implicating that NS8593 inhibits the same channels. Besides, NS8593 inhibited increases of intracellular Ca2+ and the associated cell shortening. Finally, NS8593 inhibited ACH-induced increases of mouse respirator system resistance (Rrs). SIGNIFICANCE Our results indicate that NS8593 inhibits LVDCCs and NSCCs, resulting in decreases of intracellular Ca2+ and then leading to ASM relaxation. These data suggest that NS8593 might be a new bronchodilator.
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Singh D, Parihar AK, Patel S, Srivastava S, Diwan P, Singh MR. Scleroderma: An insight into causes, pathogenesis and treatment strategies. ACTA ACUST UNITED AC 2019; 26:103-114. [PMID: 31130325 DOI: 10.1016/j.pathophys.2019.05.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/02/2019] [Accepted: 05/13/2019] [Indexed: 12/11/2022]
Abstract
Scleroderma is an autoimmune disorder, characterized by morphological changes in skin followed by visceral organs. The pathogenesis of scleroderma involves immune imbalance and generation of auto antibodies. The major causes of scleroderma include multitude of factors such as immune imbalance, oxidative stress, genetics and environment factors. A constant effort has been made to treat scleroderma through different approaches and necessitates life time administration of drugs for maintenance of a good quality life. It has been reported more in women compared to men. Traditional treatment strategies are restricted by limited therapeutic capability due to associated side effects. Advancement in development of novel drug delivery approaches has opened a newer avenue for efficient therapy. Current review is an effort to reflect scleroderma in provisions of its pathogenesis, causative factors, and therapeutic approaches, with concern to mode of action, pharmacokinetics, marketed products, and side effects of drugs.
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Affiliation(s)
- Deependra Singh
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India; National Centre for Natural Resources, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India
| | - Arun Ks Parihar
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India; Drugs Testing Laboratory Avam Anusandhan Kendra, Raipur (C.G), 492001, India
| | - Satish Patel
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India
| | - Shikha Srivastava
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India; Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University, Greater Noida, U.P, India
| | - Prakriti Diwan
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India
| | - Manju R Singh
- University Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India; National Centre for Natural Resources, Pt. Ravishankar Shukla University, Raipur, C.G, 492010, India.
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7
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Visa A, Shaikh S, Alza L, Herreros J, Cantí C. The Hard-To-Close Window of T-Type Calcium Channels. Trends Mol Med 2019; 25:571-584. [PMID: 31031178 DOI: 10.1016/j.molmed.2019.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 01/03/2023]
Abstract
T-Type calcium channels (TTCCs) are key regulators of membrane excitability, which is the reason why TTCC pharmacology is subject to intensive research in the neurological and cardiovascular fields. TTCCs also play a role in cancer physiology, and pharmacological blockers such as tetralols and dihydroquinazolines (DHQs) reduce the viability of cancer cells in vitro and slow tumor growth in murine xenografts. However, the available compounds are better suited to blocking TTCCs in excitable membranes rather than TTCCs contributing window currents at steady potentials. Consistently, tetralols and dihydroquinazolines exhibit cytostatic/cytotoxic activities at higher concentrations than those required for TTCC blockade, which may involve off-target effects. Gene silencing experiments highlight the targetability of TTCCs, but further pharmacological research is required for TTCC blockade to become a chemotherapeutic option.
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Affiliation(s)
- Anna Visa
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Soni Shaikh
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Lía Alza
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Judit Herreros
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Carles Cantí
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain.
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Liu TT, Feng L, Liu HF, Shu Y, Xiao B. Altered axon initial segment in hippocampal newborn neurons, associated with recurrence of temporal lobe epilepsy in rats. Mol Med Rep 2017; 16:3169-3178. [PMID: 28713955 PMCID: PMC5547972 DOI: 10.3892/mmr.2017.7017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 07/06/2017] [Indexed: 01/23/2023] Open
Abstract
Hippocampal neurogenesis in temporal lobe epilepsy (TLE) may result in alteration of the excitability of neurons, which contributes to spontaneous recurrent seizures. Axon initial segment (AIS) structural and functional plasticity is important in the control of neuronal excitability. It remains to be elucidated whether the plasticity of AIS occurs in hippocampal newly-generated neurons that are involved in recurrent seizures following pilocarpine-induced status epilepticus (SE). The present study first established a pilocarpine-induced TLE rat model to assess the features of newborn neurons and AIS plasticity alterations using double immunofluorescence staining of Ankyrin G and doublecortin (DCX). AIS plasticity alterations include length and distance from soma in the hippocampal newly-generated neurons post-SE. The results of the present study demonstrated that pilocarpine-induced epileptic rats exhibited aberrant hippocampal neurogenesis and longer DCX-labeled cell dendrites in the dentate gyrus. Pilocarpine-induced epileptic rats demonstrated shortened lengths of AIS and an increased distance from the soma in hippocampal newborn neurons. Mibefradil, a T/L-type calcium blocker, reversed the alterations in length and position of AIS in hippocampal newborn neurons post-SE, accompanied by decreased long-term seizure activity without increased aberrant neurogenesis. These findings indicate that the plasticity of AIS in hippocampal neurogenesis may have profound consequences in epilepsy, at least in animals.
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Affiliation(s)
- Tian-Tian Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Li Feng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Heng-Fang Liu
- Department of Neurology, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yi Shu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
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9
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Affiliation(s)
- J-L Balligand
- From the Université Catholique de Louvain, Brussels, Belgium.
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10
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A concerted action of L- and T-type Ca2+ channels regulates locus coeruleus pacemaking. Mol Cell Neurosci 2015; 68:293-302. [DOI: 10.1016/j.mcn.2015.08.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 08/18/2015] [Accepted: 08/21/2015] [Indexed: 11/18/2022] Open
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Hannon E, Chand AN, Evans MD, Wong CCY, Grubb MS, Mill J. A role for Ca V1 and calcineurin signaling in depolarization-induced changes in neuronal DNA methylation. ACTA ACUST UNITED AC 2015; 3:1-6. [PMID: 26702400 PMCID: PMC4659419 DOI: 10.1016/j.nepig.2015.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/22/2015] [Accepted: 06/23/2015] [Indexed: 01/08/2023]
Abstract
Direct manipulations of neuronal activity have been shown to induce changes in DNA methylation (DNAm), although little is known about the cellular signaling pathways involved. Using reduced representation bisulfite sequencing, we identify DNAm changes associated with moderate chronic depolarization in dissociated rat hippocampal cultures. Consistent with previous findings, these changes occurred primarily in the vicinity of loci implicated in neuronal function, being enriched in intergenic regions and underrepresented in CpG-rich promoter regulatory regions. We subsequently used 2 pharmacological interventions (nifedipine and FK-506) to test whether the identified changes depended on 2 interrelated signaling pathways known to mediate multiple forms of neuronal plasticity. Both pharmacological manipulations had notable effects on the extent and magnitude of depolarization-induced DNAm changes indicating that a high proportion of activity-induced changes are likely to be mediated by calcium entry through L-type CaV1 channels and/or downstream signaling via the calcium-dependent phosphatase calcineurin.
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Affiliation(s)
- Eilis Hannon
- University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Annisa N Chand
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Mark D Evans
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Chloe C Y Wong
- MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London UK
| | - Matthew S Grubb
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
| | - Jonathan Mill
- University of Exeter Medical School, University of Exeter, Exeter, UK ; MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London UK
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A distinct subtype of dopaminergic interneuron displays inverted structural plasticity at the axon initial segment. J Neurosci 2015; 35:1573-90. [PMID: 25632134 DOI: 10.1523/jneurosci.3515-14.2015] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The axon initial segment (AIS) is a specialized structure near the start of the axon that is a site of neuronal plasticity. Changes in activity levels in vitro and in vivo can produce structural AIS changes in excitatory cells that have been linked to alterations in excitability, but these effects have never been described in inhibitory interneurons. In the mammalian olfactory bulb (OB), dopaminergic interneurons are particularly plastic, undergoing constitutive turnover throughout life and regulating tyrosine hydroxylase expression in an activity-dependent manner. Here we used dissociated cultures of rat and mouse OB to show that a subset of bulbar dopaminergic neurons possess an AIS and that these AIS-positive cells are morphologically and functionally distinct from their AIS-negative counterparts. Under baseline conditions, OB dopaminergic AISs were short and located distally along the axon but, in response to chronic 24 h depolarization, lengthened and relocated proximally toward the soma. These activity-dependent changes were in the opposite direction to both those we saw in non-GABAergic OB neurons and those reported previously for excitatory cell types. Inverted AIS plasticity in OB dopaminergic cells was bidirectional, involved all major components of the structure, was dependent on the activity of L-type CaV1 calcium channels but not on the activity of the calcium-activated phosphatase calcineurin, and was opposed by the actions of cyclin-dependent kinase 5. Such distinct forms of AIS plasticity in inhibitory interneurons and excitatory projection neurons may allow considerable flexibility when neuronal networks must adapt to perturbations in their ongoing activity.
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Abstract
The lateral habenula (LHb) is a small epithalamic structure that projects via the fasciculus retroflexus to the midbrain. The LHb is known to modulate midbrain dopamine (DA) neurons, including inhibition of ventral tegmental area (VTA) neurons via glutamatergic excitation of the GABAergic rostromedial tegmental nucleus (RMTg). A variety of lines of evidence show activity in LHb and the LHb-RMTg pathway is correlated with, and is sufficient to support, punishment learning. However, it is not immediately clear whether LHb is necessary for punishment. Here we used a within-subjects punishment task to assess the role of LHb in the acquisition and expression of punishment as well as in aversive choice. Rats that pressed two individually presented levers for pellet rewards rapidly suppressed responding to one lever if it also caused footshock deliveries (punished lever) but continued pressing a second lever that did not cause footshock (unpunished lever). Infusions of an AMPA receptor antagonist (NBQX) into LHb had no effect on the acquisition or expression of this punishment, or on aversive choice, but did increase locomotion. Infusion of the sodium channel blocker bupivacaine likewise had no effect on expression of punishment. However, infusion of the calcium channel blocker mibefradil did affect expression of punishment by significantly decreasing the latency with which rats responded on the punished lever and significantly increasing unpunished lever-pressing. Taken together, these findings indicate that the LHb plays a limited role in punishment, influencing only latency to respond. This role is linked to calcium channel permeability and not AMPA receptor or sodium channel permeability.
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14
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Nox1 upregulates the function of vascular T-type calcium channels following chronic nitric oxide deficit. Pflugers Arch 2014; 467:727-35. [PMID: 24923576 DOI: 10.1007/s00424-014-1548-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 05/29/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023]
Abstract
Cardiovascular disease is characterised by reduced nitric oxide bioavailability resulting from oxidative stress. Our previous studies have shown that nitric oxide deficit per se increases the contribution of T-type calcium channels to vascular tone through increased superoxide from NADPH oxidase (Nox). The aim of the present study was therefore to identify the Nox isoform responsible for modulating T-type channel function, as T-type channels are implicated in several pathophysiological conditions involving oxidative stress. We evaluated T-channel function in skeletal muscle arterioles in vivo, using a novel T-channel blocker, TTA-A2 (3 μmol/L), which demonstrated no cross reactivity with L-type channels. Wild-type and Nox2 knockout (Nox2ko) mice were treated with the nitric oxide synthase inhibitor L-NAME (40 mg/kg/day) for 2 weeks. L-NAME treatment significantly increased systolic blood pressure and the contribution of T-type calcium channels to arteriolar tone in wild-type mice, and this was not prevented by Nox2 deletion. In Nox2ko mice, pharmacological inhibition of Nox1 (10 μmol/L ML171), Nox4 (10 μmol/L VAS2870) and Nox4-derived hydrogen peroxide (500 U/mL catalase) significantly reduced the effect of chronic nitric oxide inhibition on T-type channel function. In contrast, in wild-type mice, ML171 and VAS2870, but not catalase, reduced the contribution of T-type channels to vascular tone, suggesting a role for Nox1 and non-selective actions of VAS2870. We conclude that Nox1, but not Nox2 or Nox4, is responsible for the upregulation of T-type calcium channels elicited by chronic nitric oxide deficit. These data point to an important role for this isoform in increasing T-type channel function during oxidative stress.
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15
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Park MH, Son YK, Hong DH, Choi IW, Kim DJ, Lee H, Bang H, Na SH, Li H, Jo SH, Park WS. The Ca2+ channel inhibitor efonidipine decreases voltage-dependent K+ channel activity in rabbit coronary arterial smooth muscle cells. Vascul Pharmacol 2013; 59:90-5. [DOI: 10.1016/j.vph.2013.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/12/2013] [Accepted: 07/12/2013] [Indexed: 12/22/2022]
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16
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Calcineurin signaling mediates activity-dependent relocation of the axon initial segment. J Neurosci 2013; 33:6950-63. [PMID: 23595753 DOI: 10.1523/jneurosci.0277-13.2013] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The axon initial segment (AIS) is a specialized neuronal subcompartment located at the beginning of the axon that is crucially involved in both the generation of action potentials and the regulation of neuronal polarity. We recently showed that prolonged neuronal depolarization produces a distal shift of the entire AIS structure away from the cell body, a change associated with a decrease in neuronal excitability. Here, we used dissociated rat hippocampal cultures, with a major focus on the dentate granule cell (DGC) population, to explore the signaling pathways underlying activity-dependent relocation of the AIS. First, a pharmacological screen of voltage-gated calcium channels (VGCCs) showed that AIS relocation is triggered by activation of L-type Cav1 VGCCs with negligible contribution from any other VGCC subtypes. Additional pharmacological analysis revealed that downstream signaling events are mediated by the calcium-sensitive phosphatase calcineurin; inhibition of calcineurin with either FK506 or cyclosporin A totally abolished both depolarization- and optogenetically-induced activity-dependent AIS relocation. Furthermore, calcineurin activation is sufficient for AIS plasticity, because expression of a constitutively active form of the phosphatase resulted in relocation of the AIS of DGCs without a depolarizing stimulus. Finally, we assessed the role of calcineurin in other forms of depolarization-induced plasticity. Neither membrane resistance changes nor spine density changes were affected by FK506 treatment, suggesting that calcineurin acts via a separate pathway to modulate AIS plasticity. Together, these results emphasize calcineurin as a vital player in the regulation of intrinsic plasticity as governed by the AIS.
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17
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Harraz OF, Welsh DG. Protein kinase A regulation of T-type Ca2+ channels in rat cerebral arterial smooth muscle. J Cell Sci 2013; 126:2944-54. [PMID: 23613468 DOI: 10.1242/jcs.128363] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent investigations have identified that T-type Ca(2+) channels (CaV3.x) are expressed in rat cerebral arterial smooth muscle. In the study reported here, we isolated the T-type conductance, differentiated the current into the CaV3.1/CaV3.2 subtypes and determined whether they are subject to protein kinase regulation. Using patch clamp electrophysiology, whole-cell Ba(2+) current was monitored and initially subdivided into nifedipine-sensitive and -insensitive components. The latter conductance was abolished by T-type Ca(2+) channel blockers and was faster with leftward shifted activation/inactivation properties, reminiscent of a T-type channel. Approximately 60% of this T-type conductance was blocked by 50 µM Ni(2+), a concentration that selectively interferes with CaV3.2 channels. Subsequent work revealed that the whole-cell T-type conductance was subject to protein kinase A (PKA) modulation. Specifically, positive PKA modulators (db-cAMP, forskolin, isoproterenol) suppressed T-type currents and evoked a hyperpolarized shift in steady-state inactivation. Blocking PKA (with KT5720) masked this suppression without altering the basal T-type conductance. A similar effect was observed with stHt31, a peptide inhibitor of A-kinase anchoring proteins. A final set of experiments revealed that PKA-induced suppression targeted the CaV3.2 subtype. In summary, this study revealed that a T-type Ca(2+) channel conductance can be isolated in arterial smooth muscle, and differentiated into CaV3.1 and CaV3.2 components. It also showed that vasodilatory signaling cascades inhibit this conductance by targeting CaV3.2. Such targeting would impact Ca(2+) dynamics and consequent tone regulation in the cerebral circulation.
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Affiliation(s)
- Osama F Harraz
- Hotchkiss Brain and Libin Cardiovascular Research Institutes and Department of Physiology and Pharmacology, University of Calgary, AB, T2N 4N1, Canada
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18
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The influence of cold temperature on cellular excitability of hippocampal networks. PLoS One 2012; 7:e52475. [PMID: 23300680 PMCID: PMC3534091 DOI: 10.1371/journal.pone.0052475] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 11/14/2012] [Indexed: 11/19/2022] Open
Abstract
The hippocampus plays an important role in short term memory, learning and spatial navigation. A characteristic feature of the hippocampal region is its expression of different electrical population rhythms and activities during different brain states. Physiological fluctuations in brain temperature affect the activity patterns in hippocampus, but the underlying cellular mechanisms are poorly understood. In this work, we investigated the thermal modulation of hippocampal activity at the cellular network level. Primary cell cultures of mouse E17 hippocampus displayed robust network activation upon light cooling of the extracellular solution from baseline physiological temperatures. The activity generated was dependent on action potential firing and excitatory glutamatergic synaptic transmission. Involvement of thermosensitive channels from the transient receptor potential (TRP) family in network activation by temperature changes was ruled out, whereas pharmacological and immunochemical experiments strongly pointed towards the involvement of temperature-sensitive two-pore-domain potassium channels (K2P), TREK/TRAAK family. In hippocampal slices we could show an increase in evoked and spontaneous synaptic activity produced by mild cooling in the physiological range that was prevented by chloroform, a K2P channel opener. We propose that cold-induced closure of background TREK/TRAAK family channels increases the excitability of some hippocampal neurons, acting as a temperature-sensitive gate of network activation. Our findings in the hippocampus open the possibility that small temperature variations in the brain in vivo, associated with metabolism or blood flow oscillations, act as a switch mechanism of neuronal activity and determination of firing patterns through regulation of thermosensitive background potassium channel activity.
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Abd El-Rahman RR, Harraz OF, Brett SE, Anfinogenova Y, Mufti RE, Goldman D, Welsh DG. Identification of L- and T-type Ca2+ channels in rat cerebral arteries: role in myogenic tone development. Am J Physiol Heart Circ Physiol 2012; 304:H58-71. [PMID: 23103495 DOI: 10.1152/ajpheart.00476.2012] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
L-type Ca(2+) channels are broadly expressed in arterial smooth muscle cells, and their voltage-dependent properties are important in tone development. Recent studies have noted that these Ca(2+) channels are not singularly expressed in vascular tissue and that other subtypes are likely present. In this study, we ascertained which voltage-gated Ca(2+) channels are expressed in rat cerebral arterial smooth muscle and determined their contribution to the myogenic response. mRNA analysis revealed that the α(1)-subunit of L-type (Ca(v)1.2) and T-type (Ca(v)3.1 and Ca(v)3.2) Ca(2+) channels are present in isolated smooth muscle cells. Western blot analysis subsequently confirmed protein expression in whole arteries. With the use of patch clamp electrophysiology, nifedipine-sensitive and -insensitive Ba(2+) currents were isolated and each were shown to retain electrical characteristics consistent with L- and T-type Ca(2+) channels. The nifedipine-insensitive Ba(2+) current was blocked by mibefradil, kurtoxin, and efonidpine, T-type Ca(2+) channel inhibitors. Pressure myography revealed that L-type Ca(2+) channel inhibition reduced tone at 20 and 80 mmHg, with the greatest effect at high pressure when the vessel is depolarized. In comparison, the effect of T-type Ca(2+) channel blockade on myogenic tone was more limited, with their greatest effect at low pressure where vessels are hyperpolarized. Blood flow modeling revealed that the vasomotor responses induced by T-type Ca(2+) blockade could alter arterial flow by ∼20-50%. Overall, our findings indicate that L- and T-type Ca(2+) channels are expressed in cerebral arterial smooth muscle and can be electrically isolated from one another. Both conductances contribute to myogenic tone, although their overall contribution is unequal.
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Affiliation(s)
- Rasha R Abd El-Rahman
- Hotchkiss Brain and Libin Cardiovascular Research Institute and Department of Physiology and Pharmacology, University of Calgary, Alberta, Canada
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20
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Le Quang K, Naud P, Qi XY, Duval F, Shi YF, Gillis MA, Comtois P, Tardif JC, Li D, Levesque PC, Dobrev D, Charpentier F, Nattel S. Role of T-type calcium channel subunits in post-myocardial infarction remodelling probed with genetically engineered mice. Cardiovasc Res 2011; 91:420-8. [DOI: 10.1093/cvr/cvr082] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Impact of renal function on cardiovascular events in elderly hypertensive patients treated with efonidipine. Hypertens Res 2010; 33:1211-20. [PMID: 20844543 DOI: 10.1038/hr.2010.162] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This study evaluated the impact of renal function on cardiovascular outcomes in elderly hypertensive patients enrolled in the Japanese Trial to Assess Optimal Systolic Blood Pressure in Elderly Hypertensive patients. The patients were randomly assigned to either a strict-treatment group (target systolic blood pressure (BP) <140 mm Hg, n=2212) or a mild-treatment group (target systolic BP, 140 to <160 mm Hg, n=2206), each with efonidipine (a T/L-type Ca channel blocker)-based regimens. Cardiovascular events (stroke, cardiovascular disease and renal disease) were evaluated during the 2-year follow-up period following the prospective randomized open-blinded end-point method. Estimated glomerular filtration rate (eGFR) was elevated throughout the trial period in both the strict-treatment (59.4-62 ml min⁻¹ per 1.73 m²) and the mild-treatment group (58.8-61.4 ml min⁻¹ per 1.73 m²). This tendency was also observed in diabetic patients and patients aged ≥75 years, with baseline eGFR<60 ml min⁻¹ per 1.73 m². Baseline eGFR (<60 vs. ≥60 ml min⁻¹ per 1.73 m²) had no definite relationship with the incidence of cardiovascular events, nor did the level of BP control. Proteinuria at the time of entry into the study, however, was significantly correlated with cardiovascular event rates (7.1%), an association that was more apparent in patients with eGFR<60 ml min⁻¹ per 1.73 m² (8.2%). Furthermore, the event rate was more elevated in patients with greater declines in eGFR and was amplified when the baseline eGFR was <60 ml min⁻¹ per 1.73 m². In conclusion, the rates of decline of renal function and proteinuria constitute critical risk factors for cardiovascular events in elderly hypertensive patients, trends that are enhanced when baseline eGFR is diminished. Furthermore, the fact that efonidipine-based regimens ameliorate renal function in elderly hypertensive patients with chronic kidney disease may offer novel information on the mechanisms of cardiovascular protection.
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22
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Grubb MS, Burrone J. Activity-dependent relocation of the axon initial segment fine-tunes neuronal excitability. Nature 2010; 465:1070-4. [PMID: 20543823 PMCID: PMC3196626 DOI: 10.1038/nature09160] [Citation(s) in RCA: 443] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 05/10/2010] [Indexed: 12/27/2022]
Abstract
In neurons, the axon initial segment (AIS) is a specialized region near the start of the axon that is the site of action potential initiation. The precise location of the AIS varies across and within different neuronal types, and has been linked to cells' information-processing capabilities; however, the factors determining AIS position in individual neurons remain unknown. Here we show that changes in electrical activity can alter the location of the AIS. In dissociated hippocampal cultures, chronic depolarization with high extracellular potassium moves multiple components of the AIS, including voltage-gated sodium channels, up to 17 mum away from the soma of excitatory neurons. This movement reverses when neurons are returned to non-depolarized conditions, and depends on the activation of T- and/or L-type voltage-gated calcium channels. The AIS also moved distally when we combined long-term LED (light-emitting diode) photostimulation with sparse neuronal expression of the light-activated cation channel channelrhodopsin-2; here, burst patterning of activity was successful where regular stimulation at the same frequency failed. Furthermore, changes in AIS position correlate with alterations in current thresholds for action potential spiking. Our results show that neurons can regulate the position of an entire subcellular structure according to their ongoing levels and patterns of electrical activity. This novel form of activity-dependent plasticity may fine-tune neuronal excitability during development.
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Affiliation(s)
- Matthew S Grubb
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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23
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Kuo IY, Ellis A, Seymour VAL, Sandow SL, Hill CE. Dihydropyridine-insensitive calcium currents contribute to function of small cerebral arteries. J Cereb Blood Flow Metab 2010; 30:1226-39. [PMID: 20125181 PMCID: PMC2949209 DOI: 10.1038/jcbfm.2010.11] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although dihydropyridines are widely used for the treatment of vasospasm, their effectiveness is questionable, suggesting that other voltage-dependent calcium channels (VDCCs) contribute to control of cerebrovascular tone. This study therefore investigated the role of dihydropyridine-insensitive VDCCs in cerebrovascular function. Using quantitative PCR and immunohistochemistry, we found mRNA and protein for L-type (Ca(V)1.2) and T-type (Ca(V)3.1 and Ca(V)3.2) channels in adult rat basilar and middle cerebral arteries and their branches. Immunoelectron microscopy revealed both L- and T-type channels in smooth muscle cell (SMC) membranes. Using patch clamp electrophysiology, we found that a high-voltage-activated calcium current, showing T-type channel kinetics and insensitivity to nifedipine and nimodipine, comprised approximately 20% of current in SMCs of the main arteries and approximately 45% of current in SMCs from branches. Both components were abolished by the T-type antagonists mibefradil, NNC 55-0396, and efonidipine. Although nifedipine completely blocked vasoconstriction in pressurized basilar arteries, a nifedipine-insensitive constriction was found in branches and this increased in magnitude as vessel size decreased. We conclude that a heterogeneous population of VDCCs contributes to cerebrovascular function, with dihydropyridine-insensitive channels having a larger role in smaller vessels. Sensitivity of these currents to nonselective T-type channel antagonists suggests that these drugs may provide a more effective treatment for therapy-refractory cerebrovascular constriction.
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Affiliation(s)
- Ivana Y Kuo
- John Curtin School of Medical Research, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, Australian Capital Territory, Australia
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24
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José O, Hernández-Hernández O, Chirinos M, González-González ME, Larrea F, Almanza A, Felix R, Darszon A, Treviño CL. Recombinant human ZP3-induced sperm acrosome reaction: evidence for the involvement of T- and L-type voltage-gated calcium channels. Biochem Biophys Res Commun 2010; 395:530-4. [PMID: 20394732 DOI: 10.1016/j.bbrc.2010.04.059] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 04/09/2010] [Indexed: 11/17/2022]
Abstract
For successful fertilization mammalian spermatozoa must undergo the acrosome reaction (AR), an exocytotic event that allows this cell to penetrate the outer layer of the oocyte, the zona pellucida (ZP). Four glycoproteins (ZP1-ZP4) compose the human ZP, being ZP3 the physiological inductor of the AR. This process requires changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) involving not fully understood mechanisms. Even in mouse sperm, the pharmacologically documented participation of voltage-gated Ca(2+) (Ca(V)) channels and store-operated channels (SOCs) in the ZP-induced AR is being debated. The situation in human sperm is even less clear due to the limited availability of human ZP. Here, we used recombinant human ZP3 (rhZP3) produced in baculovirus-infected Sf9 cells to investigate the involvement of Ca(V) channels in the human sperm AR. Our findings showed that Ni(2+) and mibefradil at concentrations that block T-type or Ca(V)3 channels, and nimodipine and diltiazem that block L-type or Ca(V)1 channels, significantly inhibited the rhZP3-initiated AR. On the other hand, the AR was insensitive to concentrations of omega-Agatoxin IVA, omega-Conotoxin GVIA and SNX-482 that block P/Q, N and R-type channels, respectively (Ca(V)2 channels). Our overall findings suggest that Ca(V)1 and Ca(V)3 channels participate in human sperm AR. Consistent with this, we detected in human sperm transcripts for the Ca(V)1 auxiliary subunits, alpha(2)delta, beta(1), beta(2) and beta(4), but not the neuronal specific isoforms beta(3) and gamma(2).
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Affiliation(s)
- Omar José
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
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25
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Senatore A, Spafford JD. Transient and big are key features of an invertebrate T-type channel (LCav3) from the central nervous system of Lymnaea stagnalis. J Biol Chem 2010; 285:7447-58. [PMID: 20056611 DOI: 10.1074/jbc.m109.090753] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here we describe features of the first non-mammalian T-type calcium channel (LCa(v)3) expressed in vitro. This molluscan channel possesses combined biophysical properties that are reminiscent of all mammalian T-type channels. It exhibits T-type features such as "transient" kinetics, but the "tiny" label, usually associated with Ba(2+) conductance, is hard to reconcile with the "bigness" of this channel in many respects. LCa(v)3 is 25% larger than any voltage-gated ion channel expressed to date. It codes for a massive, 322-kDa protein that conducts large macroscopic currents in vitro. LCa(v)3 is also the most abundant Ca(2+) channel transcript in the snail nervous system. A window current at typical resting potentials appears to be at least as large as that reported for mammalian channels. This distant gene provides a unique perspective to analyze the structural, functional, drug binding, and evolutionary aspects of T-type channels.
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Affiliation(s)
- Adriano Senatore
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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26
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Romanov RA, Yatzenko YE, Kabanova NV, Bystrova MF, Kolesnikov SS. Voltage-gated Ca2+ channels in type III taste cells. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2009. [DOI: 10.1134/s1990747809030039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Belardetti F, Tringham E, Eduljee C, Jiang X, Dong H, Hendricson A, Shimizu Y, Janke DL, Parker D, Mezeyova J, Khawaja A, Pajouhesh H, Fraser RA, Arneric SP, Snutch TP. A Fluorescence-Based High-Throughput Screening Assay for the Identification of T-Type Calcium Channel Blockers. Assay Drug Dev Technol 2009; 7:266-80. [DOI: 10.1089/adt.2009.191] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Francesco Belardetti
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: Panora Pharmaceuticals Inc., Vancouver, British Columbia, Canada
| | | | - Cyrus Eduljee
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Xinpo Jiang
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Haiheng Dong
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: WuXi Pharmatech, Shanghai, China
| | - Adam Hendricson
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: Bristol-Myers Squibb, Wallingford, Connecticut
| | - Yoko Shimizu
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: Centre for Drug Research and Development, University of British Columbia, Vancouver, British Columbia, Canada
| | - Diana L. Janke
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: WorkSafeBC, Burnaby, British Columbia, Canada
| | - David Parker
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Janette Mezeyova
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Afsheen Khawaja
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Hassan Pajouhesh
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada
| | - Robert A. Fraser
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: Centre for Drug Research and Development, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephen P. Arneric
- Neuromed Pharmaceuticals Ltd., Vancouver, British Columbia, Canada. Present address: Eli Lilly & Company, Indianapolis, Indiana
| | - Terrance P. Snutch
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
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28
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Ohashi N, Mitamura H, Ogawa S. Development of newer calcium channel antagonists: therapeutic potential of efonidipine in preventing electrical remodelling during atrial fibrillation. Drugs 2009; 69:21-30. [PMID: 19192934 DOI: 10.2165/00003495-200969010-00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Calcium channel antagonists are most frequently prescribed for the treatment of hypertension and the majority specifically inhibit the L-type Ca2+ channel. In order to prevent reflex sympathetic over activity caused by L-type calcium channel antagonists (calcium channel blockers [CCBs]), increasing attention has focused on the blockade of the T-type Ca2+ channel. The T-type Ca2+ channel is found in the kidney and can also appear in the ventricle of the heart when in failure. Therefore, the T-type Ca2+ channel is a possible new target for the treatment of nephropathy and heart failure. In clinical trials, the efficacy and safety of T-type CCBs in hypertension and chronic renal disease have been reported. It is well known that the T-type Ca2+ channel is present in the adult atrium and plays a role in the cardiac pacemaker, but recent experimental studies suggest that this current also promotes electrical remodelling of the atrium. Using efonidipine, a dual L- and T-type CCB, it has been demonstrated that atrial electrical remodelling can be diminished in dogs. Furthermore, the T-type Ca2+ channel has recently been found in the pulmonary veins, contributing to the pulmonary vein pacemaker activity and triggered activity. A variety of drugs having T-type CCB effects have been shown to be effective in the management of atrial fibrillation, suggesting that this channel may be a novel therapeutic target.
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Affiliation(s)
- Narutaka Ohashi
- Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
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29
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Jensen LJ, Holstein-Rathlou NH. Is there a role for T-type Ca2+ channels in regulation of vasomotor tone in mesenteric arterioles? Can J Physiol Pharmacol 2009; 87:8-20. [PMID: 19142211 DOI: 10.1139/y08-101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The largest peripheral blood pressure drop occurs in terminal arterioles (<40 microm lumen diameter). L-type voltage-dependent Ca2+ channels (VDCCs) are considered the primary pathway for Ca2+ influx during physiologic activation of vascular smooth muscle cells (VSMC). Recent evidence suggests that T-type VDCCs are expressed in renal afferent and efferent arterioles, mesenteric arterioles, and skeletal muscle arterioles. T-type channels are small-conductance, low voltage-activated, fast-inactivating channels. Thus, their role in supplying Ca2+ for contraction of VSMC has been disputed. However, T-type channels display non-inactivating window currents, which may play a role in sustained Ca2+ entry. Here, we review the possible role of T-type channels in vasomotor tone regulation in rat mesenteric terminal arterioles. The CaV3.1 channel was immunolocalized in VSMC, whereas the CaV3.2 channel was predominantly expressed in endothelial cells. Voltage-dependent Ca2+ entry was inhibited by the new specific T-type blockers R(-)-efonidipine and NNC 55-0396. The effect of NNC 55-0396 persisted in depolarized arterioles, suggesting an unusually high activation threshold of mesenteric T-type channels. T-type channels were not necessary for conduction of vasoconstriction, but appear to be important for local electromechanical coupling in VSMC. The first direct demonstration of endothelial T-type channels warrants new investigations of their role in vascular biology.
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Affiliation(s)
- Lars Jørn Jensen
- Division of Renal and Vascular Research, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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30
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Ball CJ, Wilson DP, Turner SP, Saint DA, Beltrame JF. Heterogeneity of L- and T-Channels in the Vasculature. Hypertension 2009; 53:654-60. [DOI: 10.1161/hypertensionaha.108.125831] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Christine J. Ball
- From the Cardiology Research Laboratory, Queen Elizabeth Hospital (C.J.B., D.P.W., S.P.T., J.F.B.), and Department of Physiology, School of Molecular and Biomedical Science (D.P.W., D.A.S., J.F.B.), University of Adelaide, Adelaide, Australia
| | - David P. Wilson
- From the Cardiology Research Laboratory, Queen Elizabeth Hospital (C.J.B., D.P.W., S.P.T., J.F.B.), and Department of Physiology, School of Molecular and Biomedical Science (D.P.W., D.A.S., J.F.B.), University of Adelaide, Adelaide, Australia
| | - Stuart P. Turner
- From the Cardiology Research Laboratory, Queen Elizabeth Hospital (C.J.B., D.P.W., S.P.T., J.F.B.), and Department of Physiology, School of Molecular and Biomedical Science (D.P.W., D.A.S., J.F.B.), University of Adelaide, Adelaide, Australia
| | - David A. Saint
- From the Cardiology Research Laboratory, Queen Elizabeth Hospital (C.J.B., D.P.W., S.P.T., J.F.B.), and Department of Physiology, School of Molecular and Biomedical Science (D.P.W., D.A.S., J.F.B.), University of Adelaide, Adelaide, Australia
| | - John F. Beltrame
- From the Cardiology Research Laboratory, Queen Elizabeth Hospital (C.J.B., D.P.W., S.P.T., J.F.B.), and Department of Physiology, School of Molecular and Biomedical Science (D.P.W., D.A.S., J.F.B.), University of Adelaide, Adelaide, Australia
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31
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Koh KK, Oh PC, Quon MJ. Does reversal of oxidative stress and inflammation provide vascular protection? Cardiovasc Res 2008; 81:649-59. [PMID: 19098298 DOI: 10.1093/cvr/cvn354] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Chronic inflammation is a pathogenic feature of atherosclerosis and cardiovascular disease mediated by substances including angiotensin II, proinflammatory cytokines, and free fatty acids. This promotes generation of reactive oxygen species in vascular endothelial cells and smooth muscle cells, which mediate injury through several mechanisms. Reciprocal relationships between endothelial dysfunction and insulin resistance as well as cross-talk between hyperlipidaemia and the renin-angiotensin-aldosterone system (RAAS) at multiple levels contribute importantly to a variety of risk factors. Therefore, combination therapy that simultaneously addresses multiple mechanisms for the pathogenesis of atherosclerosis is an attractive emerging concept for slowing progression of atherosclerosis. Combined therapy with statins, peroxisome proliferator-activated receptors, and RAAS blockade demonstrates additive beneficial effects on endothelial dysfunction and insulin resistance when compared with monotherapies in patients with cardiovascular risk factors due to both distinct and interrelated mechanisms. These additive beneficial effects of combined therapies are consistent with laboratory and recent clinical studies. Thus, combination therapy may be an important paradigm for treating and slowing progression of atherosclerosis, coronary heart disease, and co-morbid metabolic disorders characterized by endothelial dysfunction and insulin resistance.
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Affiliation(s)
- Kwang Kon Koh
- Vascular Medicine and Atherosclerosis Unit, Division of Cardiology, Gachon University, Gil Medical Center, 1198 Kuwol-dong, Namdong-gu, Incheon 405-760, South Korea.
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32
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Nie L, Zhu J, Gratton MA, Liao A, Mu KJ, Nonner W, Richardson GP, Yamoah EN. Molecular identity and functional properties of a novel T-type Ca2+ channel cloned from the sensory epithelia of the mouse inner ear. J Neurophysiol 2008; 100:2287-99. [PMID: 18753322 DOI: 10.1152/jn.90707.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular identity of non-Cav1.3 channels in auditory and vestibular hair cells has remained obscure, yet the evidence in support of their roles to promote diverse Ca2+-dependent functions is indisputable. Recently, a transient Cav3.1 current that serves as a functional signature for the development and regeneration of hair cells has been identified in the chicken basilar papilla. The Cav3.1 current promotes spontaneous activity of the developing hair cell, which may be essential for synapse formation. Here, we have isolated and sequenced the full-length complementary DNA of a distinct isoform of Cav3.1 in the mouse inner ear. The channel is derived from alternative splicing of exon14, exon25A, exon34, and exon35. Functional expression of the channel in Xenopus oocytes yielded Ca2+ currents, which have a permeation phenotype consistent with T-type channels. However, unlike most multiion channels, the T-type channel does not exhibit the anomalous mole fraction effect, possibly reflecting comparable permeation properties of divalent cations. The Cav3.1 channel was expressed in sensory and nonsensory epithelia of the inner ear. Moreover, there are profound changes in the expression levels during development. The differential expression of the channel during development and the pharmacology of the inner ear Cav3.1 channel may have contributed to the difficulties associated with identification of the non-Cav1.3 currents.
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Affiliation(s)
- Liping Nie
- Center for Neuroscience, Program in Communication Science, University of California, Davis, 1544 Newton Ct., Davis, CA 95618, USA
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Tanaka H, Komikado C, Namekata I, Nakamura H, Suzuki M, Tsuneoka Y, Shigenobu K, Takahara A. Species difference in the contribution of T-type calcium current to cardiac pacemaking as revealed by r(-)-efonidipine. J Pharmacol Sci 2008; 107:99-102. [PMID: 18460822 DOI: 10.1254/jphs.sc0070405] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The contribution of the T-type Ca2+ current to cardiac pacemaking was examined in isolated right atrial tissue from the mouse, guinea pig, and rabbit using a specific blocker, R(-)-efonidipine. At 10(-6) M, R(-)-efonidipine produced negative chronotropy, which was prominent in the mouse and small but significant in the guinea pig. No effect was observed in the rabbit. Microelectrode recordings revealed that R(-)-efonidipine significantly prolongs the pacemaker (phase 4) depolarization of the sinoatrial-node action potential in the mouse and guinea pig. These results provide the first pharmacological evidence that the contribution of T-type Ca2+ current to cardiac pacemaking differs among experimental animal species.
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Affiliation(s)
- Hikaru Tanaka
- Department of Pharmacology, Toho University Faculty of Pharmaceutical Sciences, Japan
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34
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Broughton BRS, Walker BR, Resta TC. Chronic hypoxia induces Rho kinase-dependent myogenic tone in small pulmonary arteries. Am J Physiol Lung Cell Mol Physiol 2008; 294:L797-806. [PMID: 18263668 DOI: 10.1152/ajplung.00253.2007] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Myogenic tone in the pulmonary vasculature of normoxic adult animals is minimal or nonexistent. Whereas chronic hypoxia (CH) increases basal tone in pulmonary arteries, it is unclear if a portion of this elevated tone is due to development of myogenicity. Since basal arterial RhoA activity and Rho kinase (ROK) expression are augmented by CH, we hypothesized that CH elicits myogenic reactivity in pulmonary arteries through ROK-dependent vascular smooth muscle (VSM) Ca(2+) sensitization. To test this hypothesis, we assessed the contribution of ROK to basal tone and pressure-induced vasoconstriction in endothelium-disrupted pulmonary arteries [50-300 microm inner diameter (ID)] from control and CH [4 wk at 0.5 atmosphere (atm)] rats. Arteries were loaded with fura-2 AM to continuously monitor VSM intracellular Ca(2+) concentration ([Ca(2+)](i)). Basal VSM [Ca(2+)](i) was not different between groups. The ROK inhibitor, HA-1077 (100 nM to 30 microM), caused a concentration-dependent reduction of basal tone in CH arteries but had no effect in control vessels. In contrast, PKC inhibition with GF109203X (1 microM) did not alter basal tone. Furthermore, significant vasoconstriction in response to stepwise increases in intraluminal pressure (5-45 mmHg) was observed at 12, 15, 25, and 35 mmHg in arteries (50-200 microm ID) from CH rats. This myogenic reactivity was abolished by HA-1077 (10 microM) but not by GF109203X. VSM [Ca(2+)](i) was unaltered by HA-1077, GF109203X, or increases in pressure in either group. Myogenicity was not observed in larger vessels (200-300 microm ID). We conclude that CH induces myogenic tone in small pulmonary arteries through ROK-dependent myofilament Ca(2+) sensitization.
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Affiliation(s)
- Brad R S Broughton
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131-0001, USA
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35
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Koh KK, Quon MJ, Lee SJ, Han SH, Ahn JY, Kim JA, Chung WJ, Lee Y, Shin EK. Efonidipine simultaneously improves blood pressure, endothelial function, and metabolic parameters in nondiabetic patients with hypertension. Diabetes Care 2007; 30:1605-7. [PMID: 17351278 DOI: 10.2337/dc06-2267] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Kwang Kon Koh
- Department of Cardiology, Gil Heart Center, Gachon Medical School, Incheon, Korea.
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