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Lindquist BE. Spreading depolarizations pose critical energy challenges in acute brain injury. J Neurochem 2024; 168:868-887. [PMID: 37787065 PMCID: PMC10987398 DOI: 10.1111/jnc.15966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 08/08/2023] [Accepted: 09/10/2023] [Indexed: 10/04/2023]
Abstract
Spreading depolarization (SD) is an electrochemical wave of neuronal depolarization mediated by extracellular K+ and glutamate, interacting with voltage-gated and ligand-gated ion channels. SD is increasingly recognized as a major cause of injury progression in stroke and brain trauma, where the mechanisms of SD-induced neuronal injury are intimately linked to energetic status and metabolic impairment. Here, I review the established working model of SD initiation and propagation. Then, I summarize the historical and recent evidence for the metabolic impact of SD, transitioning from a descriptive to a mechanistic working model of metabolic signaling and its potential to promote neuronal survival and resilience. I quantify the energetic cost of restoring ionic gradients eroded during SD, and the extent to which ion pumping impacts high-energy phosphate pools and the energy charge of affected tissue. I link energy deficits to adaptive increases in the utilization of glucose and O2, and the resulting accumulation of lactic acid and CO2 downstream of catabolic metabolic activity. Finally, I discuss the neuromodulatory and vasoactive paracrine signaling mediated by adenosine and acidosis, highlighting these metabolites' potential to protect vulnerable tissue in the context of high-frequency SD clusters.
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Affiliation(s)
- Britta E Lindquist
- Department of Neurology, University of California, San Francisco, California, USA
- Gladstone Institute of Neurological Diseases, San Francisco, California, USA
- Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, California, USA
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2
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Ancatén-González C, Segura I, Alvarado-Sánchez R, Chávez AE, Latorre R. Ca 2+- and Voltage-Activated K + (BK) Channels in the Nervous System: One Gene, a Myriad of Physiological Functions. Int J Mol Sci 2023; 24:3407. [PMID: 36834817 PMCID: PMC9967218 DOI: 10.3390/ijms24043407] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 02/11/2023] Open
Abstract
BK channels are large conductance potassium channels characterized by four pore-forming α subunits, often co-assembled with auxiliary β and γ subunits to regulate Ca2+ sensitivity, voltage dependence and gating properties. BK channels are abundantly expressed throughout the brain and in different compartments within a single neuron, including axons, synaptic terminals, dendritic arbors, and spines. Their activation produces a massive efflux of K+ ions that hyperpolarizes the cellular membrane. Together with their ability to detect changes in intracellular Ca2+ concentration, BK channels control neuronal excitability and synaptic communication through diverse mechanisms. Moreover, increasing evidence indicates that dysfunction of BK channel-mediated effects on neuronal excitability and synaptic function has been implicated in several neurological disorders, including epilepsy, fragile X syndrome, mental retardation, and autism, as well as in motor and cognitive behavior. Here, we discuss current evidence highlighting the physiological importance of this ubiquitous channel in regulating brain function and its role in the pathophysiology of different neurological disorders.
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Affiliation(s)
- Carlos Ancatén-González
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Programa de Doctorado en Ciencias, Mención Neurociencia, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Ignacio Segura
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Rosangelina Alvarado-Sánchez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Doctorado en Ciencias Mención Biofísica y Biología Computacional, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Andrés E. Chávez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
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3
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Sodium Nitroprusside-Induced Activation of Vascular Smooth Muscle BK Channels Is Mediated by PKG Rather Than by a Direct Interaction with NO. Int J Mol Sci 2022; 23:ijms23052798. [PMID: 35269940 PMCID: PMC8911362 DOI: 10.3390/ijms23052798] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/21/2022] [Accepted: 02/28/2022] [Indexed: 11/27/2022] Open
Abstract
Nitric oxide (NO) is a powerful vasodilator in different vascular beds and NO-donors are widely used in clinical practice. Early data suggested that NO and NO-donors activate vascular smooth muscle high-conductance, calcium-activated potassium channels (BK channels). There exist two hypotheses explaining the effect of NO and NO-donors on BK channels—one stating that protein kinase G (PKG) mediates the effect of NO, and the other one stating that NO acts directly on the channel. Thus, the degree of contribution of PKG to the NO-induced activation of the BK channel is still not completely clear. This study tested the hypothesis that the sodium nitroprusside (SNP)-induced activation of vascular smooth muscle BK channels is fully mediated by PKG. This hypothesis was investigated using the patch-clamp technique and freshly isolated smooth muscle cells from rat tail artery. In whole-cell experiments, SNP considerably increased the outward current compared with the addition of the bath solution. SNP did not alter the current in the presence of iberiotoxin, the specific blocker of BK channels, during co-application with hydroxocobalamin, an NO-scavenger, and in the presence of Rp-8-Br-PET-cGMPS, the specific PKG-inhibitor. In inside-out patches, the activity of BK channels was increased by SNP, SNAP, and DEA-NO. However, these effects did not differ from the effect of the application of drug-free bath solution. Furthermore, a similar increase in single BK channel activity was induced by Rp-8-Br-PET-cGMPS, Rp-8-Br-PET-cGMPS together with SNP, hydroxocobalamin, and hydroxocobalamin together with SNP or DEA-NO. Finally, the activity of excised BK channels did not change in the absence of any application but was considerably increased by PKG compared with the addition of drug-free bath solution. These results suggest that NO released from NO-donors stimulates the BK current only through activation of PKG.
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Boycott HE, Nguyen MN, Vrellaku B, Gehmlich K, Robinson P. Nitric Oxide and Mechano-Electrical Transduction in Cardiomyocytes. Front Physiol 2020; 11:606740. [PMID: 33384614 PMCID: PMC7770138 DOI: 10.3389/fphys.2020.606740] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/23/2020] [Indexed: 12/22/2022] Open
Abstract
The ability§ of the heart to adapt to changes in the mechanical environment is critical for normal cardiac physiology. The role of nitric oxide is increasingly recognized as a mediator of mechanical signaling. Produced in the heart by nitric oxide synthases, nitric oxide affects almost all mechano-transduction pathways within the cardiomyocyte, with roles mediating mechano-sensing, mechano-electric feedback (via modulation of ion channel activity), and calcium handling. As more precise experimental techniques for applying mechanical stresses to cells are developed, the role of these forces in cardiomyocyte function can be further understood. Furthermore, specific inhibitors of different nitric oxide synthase isoforms are now available to elucidate the role of these enzymes in mediating mechano-electrical signaling. Understanding of the links between nitric oxide production and mechano-electrical signaling is incomplete, particularly whether mechanically sensitive ion channels are regulated by nitric oxide, and how this affects the cardiac action potential. This is of particular relevance to conditions such as atrial fibrillation and heart failure, in which nitric oxide production is reduced. Dysfunction of the nitric oxide/mechano-electrical signaling pathways are likely to be a feature of cardiac pathology (e.g., atrial fibrillation, cardiomyopathy, and heart failure) and a better understanding of the importance of nitric oxide signaling and its links to mechanical regulation of heart function may advance our understanding of these conditions.
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Affiliation(s)
- Hannah E. Boycott
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
| | - My-Nhan Nguyen
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
| | - Besarte Vrellaku
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
| | - Katja Gehmlich
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Paul Robinson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
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5
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Al-Karagholi MAM, Ghanizada H, Nielsen CAW, Skandarioon C, Snellman J, Lopez Lopez C, Hansen JM, Ashina M. Opening of BKCa channels alters cerebral hemodynamic and causes headache in healthy volunteers. Cephalalgia 2020; 40:1145-1154. [DOI: 10.1177/0333102420940681] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Introduction Preclinical data implicate large conductance calcium-activated potassium (BKCa) channels in the pathogenesis of headache and migraine, but the exact role of these channels is still unknown. Here, we investigated whether opening of BKCa channels would cause headache and vascular effects in healthy volunteers. Methods In a randomized, double-blind, placebo-controlled, cross-over study, 21 healthy volunteers aged 18–39 years were randomly allocated to receive an intravenous infusion of 0.05 mg/min BKCa channel opener MaxiPost and placebo on two different days. The primary endpoints were the difference in incidence of headache and the difference in area under the curve (AUC) for headache intensity scores (0–12 hours) and for middle cerebral artery blood flow velocity (VMCA) (0–2 hours) between MaxiPost and placebo. The secondary endpoints were the differences in area under the curve for superficial temporal artery and radial artery diameter (0–2 hours) between MaxiPost and placebo. Results Twenty participants completed the study. Eighteen participants (90%) developed headache after MaxiPost compared with six (30%) after placebo ( p = 0.0005); the difference of incidence is 60% (95% confidence interval 36–84%). The area under the curve for headache intensity (AUC0–12 hours, p = 0.0003), for mean VMCA (AUC0–2 hours, p = 0.0001), for superficial temporal artery diameter (AUC0–2 hours, p = 0.003), and for radial artery diameter (AUC0–2 hours, p = 0.03) were significantly larger after MaxiPost compared to placebo. Conclusion MaxiPost caused headache and dilation in extra- and intracerebral arteries. Our findings suggest a possible role of BKCa channels in headache pathophysiology in humans. ClinicalTrials.gov, ID: NCT03887325.
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Affiliation(s)
- Mohammad Al-Mahdi Al-Karagholi
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Hashmat Ghanizada
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Cherie Amalie Waldorff Nielsen
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Camilla Skandarioon
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | | | | | - Jakob Møller Hansen
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
- Danish Headache Knowledge Center, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Messoud Ashina
- Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
- Danish Headache Knowledge Center, Rigshospitalet Glostrup, Glostrup, Denmark
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6
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Al-Karagholi MAM, Gram C, Nielsen CAW, Ashina M. Targeting BK Ca Channels in Migraine: Rationale and Perspectives. CNS Drugs 2020; 34:325-335. [PMID: 32060729 DOI: 10.1007/s40263-020-00706-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Large (big)-conductance calcium-activated potassium (BKCa) channels are expressed in migraine-related structures such as the cranial arteries, trigeminal ganglion and trigeminal spinal nucleus, and they play a substantial role in vascular tonus and neuronal excitability. Using synthetic BKCa channels openers was associated with headache as a frequent adverse effect in healthy volunteers. Additionally, BKCa channels are downstream molecules in migraine signalling pathways that are activated by several compounds known to provoke migraine, including calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP) and glyceryl trinitrate (GTN). Also, there is a high affinity and a close coupling between BKCa channels and ATP-sensitive potassium (KATP) channels, the role of which has recently been established in migraine pathophysiology. These observations raise the question as to whether direct BKCa channel activation can provoke migraine in migraine patients, and whether the BKCa channel could be a potential novel anti-migraine target. Hence, randomized and placebo-controlled clinical studies on BKCa channel openers or blockers in migraine patients are needed.
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Affiliation(s)
- Mohammad Al-Mahdi Al-Karagholi
- Danish Headache Center, Department of Neurology, University of Copenhagen, Valdemar Hansen Vej 5, 2600, Glostrup, Denmark
| | - Christian Gram
- Danish Headache Center, Department of Neurology, University of Copenhagen, Valdemar Hansen Vej 5, 2600, Glostrup, Denmark
| | - Cherie Amalie Waldorff Nielsen
- Danish Headache Center, Department of Neurology, University of Copenhagen, Valdemar Hansen Vej 5, 2600, Glostrup, Denmark
| | - Messoud Ashina
- Danish Headache Center, Department of Neurology, University of Copenhagen, Valdemar Hansen Vej 5, 2600, Glostrup, Denmark. .,Glostrup Research Park, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark.
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7
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Manoury B, Idres S, Leblais V, Fischmeister R. Ion channels as effectors of cyclic nucleotide pathways: Functional relevance for arterial tone regulation. Pharmacol Ther 2020; 209:107499. [PMID: 32068004 DOI: 10.1016/j.pharmthera.2020.107499] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 02/05/2020] [Indexed: 02/07/2023]
Abstract
Numerous mediators and drugs regulate blood flow or arterial pressure by acting on vascular tone, involving cyclic nucleotide intracellular pathways. These signals lead to regulation of several cellular effectors, including ion channels that tune cell membrane potential, Ca2+ influx and vascular tone. The characterization of these vasocontrictive or vasodilating mechanisms has grown in complexity due to i) the variety of ion channels that are expressed in both vascular endothelial and smooth muscle cells, ii) the heterogeneity of responses among the various vascular beds, and iii) the number of molecular mechanisms involved in cyclic nucleotide signalling in health and disease. This review synthesizes key data from literature that highlight ion channels as physiologically relevant effectors of cyclic nucleotide pathways in the vasculature, including the characterization of the molecular mechanisms involved. In smooth muscle cells, cation influx or chloride efflux through ion channels are associated with vasoconstriction, whereas K+ efflux repolarizes the cell membrane potential and mediates vasodilatation. Both categories of ion currents are under the influence of cAMP and cGMP pathways. Evidence that some ion channels are influenced by CN signalling in endothelial cells will also be presented. Emphasis will also be put on recent data touching a variety of determinants such as phosphodiesterases, EPAC and kinase anchoring, that complicate or even challenge former paradigms.
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Affiliation(s)
- Boris Manoury
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France.
| | - Sarah Idres
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
| | - Véronique Leblais
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
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8
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Shvedova M, Litvak MM, Roberts JD, Fukumura D, Suzuki T, Şencan İ, Li G, Reventun P, Buys ES, Kim HH, Sakadžić S, Ayata C, Huang PL, Feil R, Atochin DN. cGMP-dependent protein kinase I in vascular smooth muscle cells improves ischemic stroke outcome in mice. J Cereb Blood Flow Metab 2019; 39:2379-2391. [PMID: 31423931 PMCID: PMC6893979 DOI: 10.1177/0271678x19870583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 07/18/2019] [Indexed: 11/15/2022]
Abstract
Recent works highlight the therapeutic potential of targeting cyclic guanosine monophosphate (cGMP)-dependent pathways in the context of brain ischemia/reperfusion injury (IRI). Although cGMP-dependent protein kinase I (cGKI) has emerged as a key mediator of the protective effects of nitric oxide (NO) and cGMP, the mechanisms by which cGKI attenuates IRI remain poorly understood. We used a novel, conditional cGKI knockout mouse model to study its role in cerebral IRI. We assessed neurological deficit, infarct volume, and cerebral perfusion in tamoxifen-inducible vascular smooth muscle cell-specific cGKI knockout mice and control animals. Stroke experiments revealed greater cerebral infarct volume in smooth muscle cell specific cGKI knockout mice (males: 96 ± 16 mm3; females: 93 ± 12 mm3, mean±SD) than in all control groups: wild type (males: 66 ± 19; females: 64 ± 14), cGKI control (males: 65 ± 18; females: 62 ± 14), cGKI control with tamoxifen (males: 70 ± 8; females: 68 ± 10). Our results identify, for the first time, a protective role of cGKI in vascular smooth muscle cells during ischemic stroke injury. Moreover, this protective effect of cGKI was found to be independent of gender and was mediated via improved reperfusion. These results suggest that cGKI in vascular smooth muscle cells should be targeted by therapies designed to protect brain tissue against ischemic stroke.
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Affiliation(s)
- Maria Shvedova
- Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Maxim M Litvak
- Tomsk Polytechnic University, RASA Center, Tomsk, Russian Federation
| | - Jesse D Roberts
- Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Dai Fukumura
- Department of Radiation Oncology, Edwin L. Steele Laboratories, Massachusetts General Hospital, Boston, MA, USA
| | - Tomoaki Suzuki
- Department of Radiology, Neurovascular Research Laboratory, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - İkbal Şencan
- Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Ge Li
- Department of Radiology, Neurovascular Research Laboratory, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Paula Reventun
- Department of Biology Systems, School of Medicine, University of Alcalá, Madrid, Spain
| | - Emmanuel S Buys
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Hyung-Hwan Kim
- Department of Radiology, Neurovascular Research Laboratory, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Cenk Ayata
- Department of Radiology, Neurovascular Research Laboratory, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Paul L Huang
- Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
| | - Robert Feil
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Dmitriy N Atochin
- Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA, USA
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Apelin Reduces Nitric Oxide-Induced Relaxation of Cerebral Arteries by Inhibiting Activation of Large-Conductance, Calcium-Activated K Channels. J Cardiovasc Pharmacol 2019; 71:223-232. [PMID: 29620606 DOI: 10.1097/fjc.0000000000000563] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Activation of the apelin/APJ receptor signaling system causes endothelium-dependent and nitric oxide (NO)-dependent relaxation in several peripheral arteries. The effects of apelin in cerebral arteries are unknown; however, apelin inhibits voltage-dependent increases in large-conductance, calcium-activated K channel (BKCa) currents in cerebral artery smooth muscle cells. Because NO-induced relaxation of cerebral arteries is mediated, in part, by activation of BKCa channels, the goals of this study were to determine the net effect of apelin in cerebral arteries, as well as test the hypothesis that the actions of apelin in cerebral arteries are secondary to stimulation of APJ receptors. Immunoblot and quantitative reverse transcription polymerase chain reaction analyses detected APJ receptors in cerebral arteries of male Sprague-Dawley rats, and immunofluorescence studies using confocal microscopy confirmed APJ receptor localization in smooth muscle cells. In myograph studies, apelin itself had no direct vasomotor effect but inhibited relaxations to the NO-donor, diethylamine NONOate, and to the endothelium-dependent vasodilator, bradykinin. These effects of apelin were mimicked by the selective BKCa-channel blocker, iberiotoxin, and suppressed by the APJ receptor antagonist, F13A. Apelin also inhibited relaxations evoked by the BKCa-channel openers, NS1619 and BMS 191011, but had no effect on relaxation to levcromakalim, a selective KATP-channel opener. Apelin had no effect on diethylamine NONOate-induced or bradykinin-induced increases in cyclic guanosine monophosphate levels. Patch clamp recordings demonstrated that apelin and iberiotoxin each suppressed the increase in BKCa currents induced by DEA and NS1619 in freshly isolated cerebral artery smooth muscle cells. The results demonstrate that apelin inhibits NO-induced relaxation of cerebral arteries through a mechanism involving activation of APJ receptors and inhibition of BKCa channels in cerebral arterial smooth muscle cells.
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10
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Zhang J, Wang Y, Chen L, Wier WG, Blaustein MP. Na +/Ca 2+ exchanger overexpression in smooth muscle augments cytosolic Ca 2+ in femoral arteries of living mice. Am J Physiol Heart Circ Physiol 2019; 316:H298-H310. [PMID: 30461304 PMCID: PMC6397384 DOI: 10.1152/ajpheart.00185.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 11/05/2018] [Accepted: 11/15/2018] [Indexed: 11/22/2022]
Abstract
Plasma membrane Na+/Ca2+ exchanger-1 (NCX1) helps regulate the cytosolic Ca2+ concentration ([Ca2+]CYT) in arterial myocytes. NCX1 mediates both Ca2+ entry and exit and tends to promote net Ca2+ entry in partially constricted arteries. Mean blood pressure (telemetry) is elevated by ≈10 mmHg in transgenic (TG) mice that overexpress NCX1 specifically in smooth muscle. We tested the hypothesis that NCX1 overexpression mediates Ca2+ gain and elevated [Ca2+]CYT in exposed femoral arteries that also express the Ca2+ biosensor exogenous myosin light chain kinase. [Ca2+]CYT and the NCX1-dependent (SEA0400-sensitive) component, ≈15% of total basal constriction in controls, were increased in TG arteries, but constrictions to phenylephrine and ANG II were comparable in TG and control arteries. Normalized phenylephrine dose-response curves and constriction to 30 and 300 ng/kg iv ANG II were virtually identical in control and TG arteries. ANG II-evoked constrictions, superimposed on elevated basal tone, accounted for the larger blood pressure responses to ANG II in TG arteries. TG and control mouse arteries fit the same pCa-constriction relationship over a wide range of pCa (≈125-500 nM). Vasodilation to acetylcholine, normalized to passive diameter, was also comparable in TG and control arteries, implying normal endothelial function. TG artery Na+ nitroprusside (nitric oxide donor)-induced dilations were, however, shifted to lower Na+ nitroprusside concentrations, indicating that TG myocyte vasodilator mechanisms were augmented. Maximum arterial dilation was comparable in TG and control mice, although passive diameter was ≈6-7% smaller in TG mice. The changes in TG arteries were apparently largely functional rather than structural, despite the congenital hypertension. NEW & NOTEWORTHY Smooth muscle Na+/Ca2+ exchanger-1 transgene overexpression (TG mice) increases femoral artery basal cytosolic Ca2+ concentration ([Ca2+]CYT) and tone in vivo and raises blood pressure. Arterial constriction to phenylephrine and angiotensin II are normal but superimposed on the augmented basal [Ca2+]CYT and tone (constriction) in TG mouse arteries. Similar effects in resistance arteries would explain the elevated blood pressure. Acetylcholine-induced vasodilation is unimpaired, implying a normal endothelium, but TG arteries are hypersensitive to sodium nitroprusside.
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Affiliation(s)
- Jin Zhang
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Youhua Wang
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Physical Education, Shaanxi Normal University , Xi'an, Shaanxi , China
| | - Ling Chen
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine , Baltimore, Maryland
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine , Baltimore, Maryland
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11
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Lubomirov LT, Papadopoulos S, Filipova D, Baransi S, Todorović D, Lake P, Metzler D, Hilsdorf S, Schubert R, Schroeter MM, Pfitzer G. The involvement of phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and MYPT1 isoform expression in NO/cGMP mediated differential vasoregulation of cerebral arteries compared to systemic arteries. Acta Physiol (Oxf) 2018; 224:e13079. [PMID: 29694711 DOI: 10.1111/apha.13079] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/30/2018] [Accepted: 04/17/2018] [Indexed: 12/23/2022]
Abstract
AIM Constitutive release of NO blunts intrinsic and stimulated contractile activity in cerebral arteries (CA). Here, we explored whether phosphorylation and expression levels of the PKG-sensitive, leucine zipper positive (LZ+ ) splice variants of the regulatory subunit of myosin phosphatase (MYPT1) are involved and whether its expression is associated with higher cGMP sensitivity. METHODS Vascular contractility was investigated by wire myography. Phosphorylation of MYPT1 was determined by Western blotting. RESULTS Constitutive phosphorylation of MYPT1-T696 and T853 was lower and that of S695 and S668 was higher in cerebral arteries from the circulus arteriosus (CA-w) than in femoral arteries (FA), while total MYPT1 expression was not different. In CA-w but not in FA, L-NAME lowered phosphorylation of S695/S668 and increased phosphorylation of T696/T853 and of MLC20 -S19, plus basal tone. The increase in basal tone was attenuated in CA-w and basilar arteries (BA) from heterozygous MYPT1-T696A/+ mice. Compared to FA, expression of the LZ+ -isoform was ~2-fold higher in CA-w coincident with a higher sensitivity to DEA-NONOate, cinaciguat and Y27632 in BA and 8-Br-cGMP (1 μmol/L) in pre-constricted (pCa 6.1) α-toxin permeabilized CAs. In contrast, 6-Bnz-cAMP (10 μmol/L) relaxed BA and FA similarly by ~80%. CONCLUSION Our results indicate that (i) regulation of the intrinsic contractile activity in CA involves phosphorylation of MYPT1 at T696 and S695/S668, (ii) the higher NO/cGMP/PKG sensitivity of CAs can be ascribed to the higher expression level of the LZ+ -MYPT1 isoform and (iii) relaxation by cAMP/PKA pathway is less dependent on the expression level of the LZ+ splice variants of MYPT1.
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Affiliation(s)
- L. T. Lubomirov
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - S. Papadopoulos
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - D. Filipova
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - S. Baransi
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - D. Todorović
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - P. Lake
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - D. Metzler
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - S. Hilsdorf
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - R. Schubert
- Research Division Cardiovascular Physiology; Centre for Biomedicine and Medical Technology Mannheim (CBTM); Ruprecht-Karls-University Heidelberg; Heidelberg Germany
| | - M. M. Schroeter
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
| | - G. Pfitzer
- Institute of Vegetative Physiology; University of Cologne; Cologne Germany
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SKA-31, an activator of endothelial Ca 2+-activated K + channels evokes robust vasodilation in rat mesenteric arteries. Eur J Pharmacol 2018; 831:60-67. [PMID: 29753043 DOI: 10.1016/j.ejphar.2018.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 12/17/2022]
Abstract
It is now well recognized that endothelial KCa2.3 and KCa3.1 channel activities contribute to dilation of resistance arteries via endothelium-mediated hyperpolarization and vascular smooth muscle relaxation. In this study, we have investigated the functional effect of the KCa channel activator SKA-31 in third order rat mesenteric arteries using arterial pressure myography. Isolated arteries were cannulated, pressurized intraluminally to 70 mmHg at 36 °C and then constricted with 1 μM phenylephrine. Acute bath exposure to SKA-31 evoked a robust and reversible inhibition of developed tone (IC50 = 0.22 μM). The vasodilatory effects of SKA-31 and acetylcholine were blunted in the presence of KCa2.3 and KCa3.1 channel antagonists, and were largely prevented following endothelial denudation. Western blot and q-PCR analyses of isolated mesenteric arteries revealed KCa2.3 and KCa3.1 channel expression at the protein and mRNA levels, respectively. Penitrem-A, an inhibitor of KCa1.1 channels, decreased vasodilatory responses to acetylcholine, sodium nitroprusside and NS-1619, but had little effect on SKA-31. Similarly, bath exposure to the eNOS inhibitor L-NAME did not alter SKA-31 and acetylcholine-mediated vasodilation. Collectively, these data highlight the major cellular mechanisms by which the endothelial KCa channel activator SKA-31 inhibits agonist-evoked vasoconstriction in rat small mesenteric arteries.
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