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Martiszus BJ, Tsintsadze T, Chang W, Smith SM. Enhanced excitability of cortical neurons in low-divalent solutions is primarily mediated by altered voltage-dependence of voltage-gated sodium channels. eLife 2021; 10:67914. [PMID: 33973519 PMCID: PMC8163501 DOI: 10.7554/elife.67914] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/10/2021] [Indexed: 11/17/2022] Open
Abstract
Increasing extracellular [Ca2+] ([Ca2+]o) strongly decreases intrinsic excitability in neurons but the mechanism is unclear. By one hypothesis, [Ca2+]o screens surface charge, reducing voltage-gated sodium channel (VGSC) activation and by another [Ca2+]o activates Calcium-sensing receptor (CaSR) closing the sodium-leak channel (NALCN). Here we report that neocortical neurons from CaSR-deficient (Casr-/-) mice had more negative resting potentials and did not fire spontaneously in reduced divalent-containing solution (T0.2) in contrast with wild-type (WT). However, after setting membrane potential to −70 mV, T0.2 application similarly depolarized and increased action potential firing in Casr-/- and WT neurons. Enhanced activation of VGSCs was the dominant contributor to the depolarization and increase in excitability by T0.2 and occurred due to hyperpolarizing shifts in VGSC window currents. CaSR deletion depolarized VGSC window currents but did not affect NALCN activation. Regulation of VGSC gating by external divalents is the key mechanism mediating divalent-dependent changes in neocortical neuron excitability.
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Affiliation(s)
- Briana J Martiszus
- Section of Pulmonary & Critical Care Medicine, VA Portland Health Care System, Portland, United States.,Department of Medicine, Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, Portland, United States
| | - Timur Tsintsadze
- Section of Pulmonary & Critical Care Medicine, VA Portland Health Care System, Portland, United States.,Department of Medicine, Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, Portland, United States
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center and University of California, San Francisco, San Francisco, United States
| | - Stephen M Smith
- Section of Pulmonary & Critical Care Medicine, VA Portland Health Care System, Portland, United States.,Department of Medicine, Division of Pulmonary & Critical Care Medicine, Oregon Health & Science University, Portland, United States
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2
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Hartings JA, Shuttleworth CW, Kirov SA, Ayata C, Hinzman JM, Foreman B, Andrew RD, Boutelle MG, Brennan KC, Carlson AP, Dahlem MA, Drenckhahn C, Dohmen C, Fabricius M, Farkas E, Feuerstein D, Graf R, Helbok R, Lauritzen M, Major S, Oliveira-Ferreira AI, Richter F, Rosenthal ES, Sakowitz OW, Sánchez-Porras R, Santos E, Schöll M, Strong AJ, Urbach A, Westover MB, Winkler MK, Witte OW, Woitzik J, Dreier JP. The continuum of spreading depolarizations in acute cortical lesion development: Examining Leão's legacy. J Cereb Blood Flow Metab 2017; 37:1571-1594. [PMID: 27328690 PMCID: PMC5435288 DOI: 10.1177/0271678x16654495] [Citation(s) in RCA: 271] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A modern understanding of how cerebral cortical lesions develop after acute brain injury is based on Aristides Leão's historic discoveries of spreading depression and asphyxial/anoxic depolarization. Treated as separate entities for decades, we now appreciate that these events define a continuum of spreading mass depolarizations, a concept that is central to understanding their pathologic effects. Within minutes of acute severe ischemia, the onset of persistent depolarization triggers the breakdown of ion homeostasis and development of cytotoxic edema. These persistent changes are diagnosed as diffusion restriction in magnetic resonance imaging and define the ischemic core. In delayed lesion growth, transient spreading depolarizations arise spontaneously in the ischemic penumbra and induce further persistent depolarization and excitotoxic damage, progressively expanding the ischemic core. The causal role of these waves in lesion development has been proven by real-time monitoring of electrophysiology, blood flow, and cytotoxic edema. The spreading depolarization continuum further applies to other models of acute cortical lesions, suggesting that it is a universal principle of cortical lesion development. These pathophysiologic concepts establish a working hypothesis for translation to human disease, where complex patterns of depolarizations are observed in acute brain injury and appear to mediate and signal ongoing secondary damage.
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Affiliation(s)
- Jed A Hartings
- 1 Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,2 Mayfield Clinic, Cincinnati, OH, USA
| | - C William Shuttleworth
- 3 Department of Neuroscience, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Sergei A Kirov
- 4 Department of Neurosurgery and Brain and Behavior Discovery Institute, Medical College of Georgia, Augusta, GA, USA
| | - Cenk Ayata
- 5 Neurovascular Research Unit, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jason M Hinzman
- 1 Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Brandon Foreman
- 6 Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - R David Andrew
- 7 Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Martyn G Boutelle
- 8 Department of Bioengineering, Imperial College London, London, United Kingdom
| | - K C Brennan
- 9 Department of Neurology, University of Utah, Salt Lake City, UT, USA.,10 Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, USA
| | - Andrew P Carlson
- 11 Department of Neurosurgery, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Markus A Dahlem
- 12 Department of Physics, Humboldt University of Berlin, Berlin, Germany
| | | | - Christian Dohmen
- 14 Department of Neurology, University of Cologne, Cologne, Germany
| | - Martin Fabricius
- 15 Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark
| | - Eszter Farkas
- 16 Department of Medical Physics and Informatics, Faculty of Medicine, and Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Delphine Feuerstein
- 17 Multimodal Imaging of Brain Metabolism, Max-Planck-Institute for Metabolism Research, Cologne, Germany
| | - Rudolf Graf
- 17 Multimodal Imaging of Brain Metabolism, Max-Planck-Institute for Metabolism Research, Cologne, Germany
| | - Raimund Helbok
- 18 Medical University of Innsbruck, Department of Neurology, Neurocritical Care Unit, Innsbruck, Austria
| | - Martin Lauritzen
- 15 Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark.,19 Department of Neuroscience and Pharmacology and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Sebastian Major
- 13 Department of Neurology, Charité University Medicine, Berlin, Germany.,20 Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany.,21 Department of Experimental Neurology, Charité University Medicine, Berlin, Germany
| | - Ana I Oliveira-Ferreira
- 20 Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany.,21 Department of Experimental Neurology, Charité University Medicine, Berlin, Germany
| | - Frank Richter
- 22 Institute of Physiology/Neurophysiology, Jena University Hospital, Jena, Germany
| | - Eric S Rosenthal
- 5 Neurovascular Research Unit, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Oliver W Sakowitz
- 23 Department of Neurosurgery, Klinikum Ludwigsburg, Ludwigsburg, Germany.,24 Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Renán Sánchez-Porras
- 24 Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Edgar Santos
- 24 Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Michael Schöll
- 24 Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Anthony J Strong
- 25 Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London
| | - Anja Urbach
- 26 Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
| | - M Brandon Westover
- 5 Neurovascular Research Unit, Department of Radiology, and Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Maren Kl Winkler
- 20 Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany
| | - Otto W Witte
- 26 Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany.,27 Brain Imaging Center, Jena University Hospital, Jena, Germany
| | - Johannes Woitzik
- 20 Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany.,28 Department of Neurosurgery, Charité University Medicine, Berlin, Germany
| | - Jens P Dreier
- 13 Department of Neurology, Charité University Medicine, Berlin, Germany.,20 Center for Stroke Research Berlin, Charité University Medicine, Berlin, Germany.,21 Department of Experimental Neurology, Charité University Medicine, Berlin, Germany
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3
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Cerebral Blood Flow Threshold Is Higher for Membrane Repolarization Than for Depolarization and Is Lowered by Intraischemic Hypothermia in Rats*. Crit Care Med 2015; 43:e350-5. [DOI: 10.1097/ccm.0000000000001095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4
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Salas D, Puebla C, Lampe PD, Lavandero S, Sáez JC. Role of Akt and Ca2+ on cell permeabilization via connexin43 hemichannels induced by metabolic inhibition. Biochim Biophys Acta Mol Basis Dis 2015; 1852:1268-77. [PMID: 25779082 DOI: 10.1016/j.bbadis.2015.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/25/2015] [Accepted: 03/06/2015] [Indexed: 10/23/2022]
Abstract
Connexin hemichannels are regulated under physiological and pathological conditions. Metabolic inhibition, a model of ischemia, promotes surface hemichannel activation associated, in part, with increased surface hemichannel levels, but little is known about its underlying mechanism. Here, we investigated the role of Akt on the connexin43 hemichannel's response induced by metabolic inhibition. In HeLa cells stably transfected with rat connexin43 fused to EGFP (HeLa43 cells), metabolic inhibition induced a transient Akt activation necessary to increase the amount of surface connexin43. The increase in levels of surface connexin43 was also found to depend on an intracellular Ca2+ signal increase that was partially mediated by Akt activation. However, the metabolic inhibition-induced Akt activation was not significantly affected by intracellular Ca2+ chelation. The Akt-dependent increase in connexin43 hemichannel activity in HeLa43 cells also occurred after oxygen-glucose deprivation, another ischemia-like condition, and in cultured cortical astrocytes (endogenous connexin43 expression system) under metabolic inhibition. Since opening of hemichannels has been shown to accelerate cell death, inhibition of Akt-dependent phosphorylation of connexin43 hemichannels could reduce cell death induced by ischemia/reperfusion.
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Affiliation(s)
- Daniela Salas
- Advanced Center for Chronic Diseases (ACCDIS) & Centro Estudios Moleculares de la Célula (CMEC), Facultad Ciencias Químicas y Farmacéuticas & Facultad Medicina, Universidad de Chile, Santiago, Chile; Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Carlos Puebla
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paul D Lampe
- Translational Research Program, Human Biology and Public Health Sciences Divisions, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDIS) & Centro Estudios Moleculares de la Célula (CMEC), Facultad Ciencias Químicas y Farmacéuticas & Facultad Medicina, Universidad de Chile, Santiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Valparaíso, Chile.
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5
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Yu K, Wu Y, Hu Y, Zhang Q, Xie H, Liu G, Chen Y, Guo Z, Jia J. Prior exposure to enriched environment reduces nitric oxide synthase after transient MCAO in rats. Neurotoxicology 2013; 39:146-52. [DOI: 10.1016/j.neuro.2013.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 09/08/2013] [Accepted: 09/08/2013] [Indexed: 01/27/2023]
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6
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Bas DF, Topcuoglu MA, Gursoy-Ozdemir Y, Saatci I, Bodur E, Dalkara T. Plasma 3-nitrotyrosine estimates the reperfusion-induced cerebrovascular stress, whereas matrix metalloproteinases mainly reflect plasma activity: a study in patients treated with thrombolysis or endovascular recanalization. J Neurochem 2012; 123 Suppl 2:138-47. [DOI: 10.1111/j.1471-4159.2012.07952.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Demet Funda Bas
- Department of Neurology; Hacettepe University; Ankara; Turkey
| | | | | | - Isil Saatci
- Department of Radiology; Hacettepe University; Ankara; Turkey
| | - Ebru Bodur
- Department of Biochemistry; Hacettepe University; Ankara; Turkey
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7
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Influence of ShuJinHuoXue tablets on ischemia reperfusion injury of animals' skeletal muscle. Molecules 2012; 17:8494-505. [PMID: 22801363 DOI: 10.3390/molecules17078494] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/27/2012] [Accepted: 07/06/2012] [Indexed: 11/17/2022] Open
Abstract
Ischemia-reperfusion (IR) can lead to serious tissue oxidative injury in animals. ShuJinHuoXue tablet (SJHXT) is a Chinese Traditional Medicine which can relax the muscles and stimulate the blood circulation and has been used as a clinical medicine. In the present study, we investigated the effects of SJHXT pretreatment on oxidative injury using an animal model of acute limb IR. Results showed that SJHXT pre-treatment (200, 300 and 400 mg/kg/day) markedly reduced serum endothelin-1 (ET-1), thromboxane B2 (TXB₂) levels and thromboxane B2/6-keto- prostaglandin F1α (TXB₂/6-Keto-PGF(1α)), wet weight/dried weight (W/D) ratio, myeloperoxidase (MPO), creatine kinase (CK), lactate dehydrogenase (LDH) activities, and increased serum nitric oxide (NO), 6-Keto-PGF(1α) levels and NO/ET-1 ratio in the IR+SJHXT groups. In addition, the SJHXT pre-treatment (200, 300 and 400 mg/kg/day) markedly reduced skeletal muscle Ca²⁺, malondialdehyde (MDA) levels, increased Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities. Our results suggest that SJHXT pre-treatment may improve skeletal muscle blood vessel microcirculation, decrease skeletal muscle oxidative injury and enhance antioxidant enzymes activities in IR animals.
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8
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Nakamura H, Strong AJ, Dohmen C, Sakowitz OW, Vollmar S, Sué M, Kracht L, Hashemi P, Bhatia R, Yoshimine T, Dreier JP, Dunn AK, Graf R. Spreading depolarizations cycle around and enlarge focal ischaemic brain lesions. ACTA ACUST UNITED AC 2010; 133:1994-2006. [PMID: 20504874 PMCID: PMC2892938 DOI: 10.1093/brain/awq117] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
How does infarction in victims of stroke and other types of acute brain injury expand to its definitive size in subsequent days? Spontaneous depolarizations that repeatedly spread across the cerebral cortex, sometimes at remarkably regular intervals, occur in patients with all types of injury. Here, we show experimentally with in vivo real-time imaging that similar, spontaneous depolarizations cycle repeatedly around ischaemic lesions in the cerebral cortex, and enlarge the lesion in step with each cycle. This behaviour results in regular periodicity of depolarization when monitored at a single point in the lesion periphery. We present evidence from clinical monitoring to suggest that depolarizations may cycle in the ischaemic human brain, perhaps explaining progressive growth of infarction. Despite their apparent detrimental role in infarct growth, we argue that cycling of depolarizations around lesions might also initiate upregulation of the neurobiological responses involved in repair and remodelling.
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Affiliation(s)
- Hajime Nakamura
- Max Planck Institute for Neurological Research, Gleueler Str. 50, 50931 Cologne, Germany
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9
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Hertz L. Bioenergetics of cerebral ischemia: a cellular perspective. Neuropharmacology 2008; 55:289-309. [PMID: 18639906 DOI: 10.1016/j.neuropharm.2008.05.023] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 12/27/2022]
Abstract
In cerebral ischemia survival of neurons, astrocytes, oligodendrocytes and endothelial cells is threatened during energy deprivation and/or following re-supply of oxygen and glucose. After a brief summary of characteristics of different cells types, emphasizing the dependence of all on oxidative metabolism, the bioenergetics of focal and global ischemia is discussed, distinguishing between events during energy deprivation and subsequent recovery attempt after re-circulation. Gray and white matter ischemia are described separately, and distinctions are made between mature and immature brains. Next comes a description of bioenergetics in individual cell types in culture during oxygen/glucose deprivation or exposure to metabolic inhibitors and following re-establishment of normal aerated conditions. Due to their expression of NMDA and non-NMDA receptors neurons and oligodendrocytes are exquisitely sensitive to excitotoxicity by glutamate, which reaches high extracellular concentrations in ischemic brain for several reasons, including failing astrocytic uptake. Excitotoxicity kills brain cells by energetic exhaustion (due to Na(+) extrusion after channel-mediated entry) combined with mitochondrial Ca(2+)-mediated injury and formation of reactive oxygen species. Many (but not all) astrocytes survive energy deprivation for extended periods, but after return to aerated conditions they are vulnerable to mitochondrial damage by cytoplasmic/mitochondrial Ca(2+) overload and to NAD(+) deficiency. Ca(2+) overload is established by reversal of Na(+)/Ca(2+) exchangers following Na(+) accumulation during Na(+)-K(+)-Cl(-) cotransporter stimulation or pH regulation, compensating for excessive acid production. NAD(+) deficiency inhibits glycolysis and eventually oxidative metabolism, secondary to poly(ADP-ribose)polymerase (PARP) activity following DNA damage. Hyperglycemia can be beneficial for neurons but increases astrocytic death due to enhanced acidosis.
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Affiliation(s)
- Leif Hertz
- College of Basic Medical Sciences, China Medical University, Shenyang, PR China.
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10
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Zhao H, Steinberg GK, Sapolsky RM. General versus specific actions of mild-moderate hypothermia in attenuating cerebral ischemic damage. J Cereb Blood Flow Metab 2007; 27:1879-94. [PMID: 17684517 DOI: 10.1038/sj.jcbfm.9600540] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Mild or moderate hypothermia is generally thought to block all changes in signaling events that are detrimental to ischemic brain, including ATP depletion, glutamate release, Ca(2+) mobilization, anoxic depolarization, free radical generation, inflammation, blood-brain barrier permeability, necrotic, and apoptotic pathways. However, the effects and mechanisms of hypothermia are, in fact, variable. We emphasize that, even in the laboratory, hypothermic protection is limited. In certain models of permanent focal ischemia, hypothermia may not protect at all. In cases where hypothermia reduces infarct, some studies have overemphasized its ability to maintain cerebral blood flow and ATP levels, and to prevent anoxic depolarization, glutamate release during ischemia. Instead, hypothermia may protect against ischemia by regulating cascades that occur after reperfusion, including blood-brain barrier permeability and the changes in gene and protein expressions associated with necrotic and apoptotic pathways. Hypothermia not only blocks multiple damaging cascades after stroke, but also selectively upregulates some protective genes. However, most of these mechanisms are addressed in models with intraischemic hypothermia; much less information is available in models with postischemic hypothermia. Moreover, although it has been confirmed that mild hypothermia is clinically feasible for acute focal stroke treatment, no definite beneficial effect has been reported yet. This lack of clinical protection may result from suboptimal criteria for patient entrance into clinical trials. To facilitate clinical translation, future efforts in the laboratory should focus more on the protective mechanisms of postischemic hypothermia, as well as on the effects of sex, age and rewarming during reperfusion on hypothermic protection.
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Affiliation(s)
- Heng Zhao
- Department of Neurosurgery, Stanford University, Stanford, California 94305-5327, USA.
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11
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Retamal MA, Schalper KA, Shoji KF, Orellana JA, Bennett MVL, Sáez JC. Possible involvement of different connexin43 domains in plasma membrane permeabilization induced by ischemia-reperfusion. J Membr Biol 2007; 218:49-63. [PMID: 17705051 DOI: 10.1007/s00232-007-9043-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Accepted: 06/15/2007] [Indexed: 01/04/2023]
Abstract
In vitro and in vivo studies support the involvement of connexin 43-based cell-cell channels and hemichannels in cell death propagation induced by ischemia-reperfusion. In this context, open connexin hemichannels in the plasma membrane have been proposed to act as accelerators of cell death. Progress on the mechanisms underlying the cell permeabilization induced by ischemia-reperfusion reveals the involvement of several factors leading to an augmented open probability and increased number of hemichannels on the cell surface. While open probability can be increased by a reduction in extracellular concentration of divalent cations and changes in covalent modifications of connexin 43 (oxidation and phosphorylation), increase in number of hemichannels requires an elevation of the intracellular free Ca(2+) concentration. Reversal of connexin 43 redox changes and membrane permeabilization can be induced by intracellular, but not extracellular, reducing agents, suggesting a cytoplasmic localization of the redox sensor(s). In agreement, hemichannels formed by connexin 45, which lacks cytoplasmic cysteines, or by connexin 43 with its C-terminal domain truncated to remove its cysteines are insensitive to reducing agents. Although further studies are required for a precise localization of the redox sensor of connexin 43 hemichannels, modulation of the redox potential is proposed as a target for the design of pharmacological tools to reduce cell death induced by ischemia-reperfusion in connexin 43-expressing cells.
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Affiliation(s)
- Mauricio A Retamal
- Departamento de Ciencias Fisiológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
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12
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Jiang MH, Hada J. Early and sharp nitric oxide production and anoxic depolarization in the rat hippocampus during transient forebrain ischemia. Eur J Pharmacol 2007; 567:83-8. [PMID: 17451676 DOI: 10.1016/j.ejphar.2007.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 03/09/2007] [Accepted: 03/13/2007] [Indexed: 11/17/2022]
Abstract
This study was designed to characterize nitric oxide (NO) production and anoxic depolarization in the rat hippocampus during transient forebrain ischemia using two NO synthase (NOS) inhibitors, L-N(5)-(1-iminoethyl)ornithine (L-NIO), a relatively selective endothelial NOS (eNOS) inhibitor, and 7-nitroindazole, a relatively selective neuronal NOS (nNOS) inhibitor, and an NO scavenger, [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] (carboxy-PTIO). We measured the mean arterial blood pressure, hippocampal blood flow, NO concentration and direct current potential before, during and after transient forebrain ischemia, which was induced by 4-vessel occlusion for 10 min. Saline, L-NIO (20 mg/kg), 7-nitroindazole (25 mg/kg), L-NIO (20 mg/kg)+7-nitroindazole (25 mg/kg) or carboxy-PTIO (1 mg/kg) was administered intraperitoneally 20 min before the onset of ischemia. We observed early and sharp NO production in the hippocampus during ischemia in the saline group. This NO increase during ischemia was significantly reduced by L-NIO (20 mg/kg)+7-nitroindazole (25 mg/kg) or carboxy-PTIO (1 mg/kg), but not L-NIO (20 mg/kg) or 7-nitroindazole (25 mg/kg). On the other hand, NO production after ischemia was significantly reduced by 7-nitroindazole (25 mg/kg), L-NIO (20 mg/kg)+7-nitroindazole (25 mg/kg) or carboxy-PTIO (1 mg/kg), but not L-NIO (20 mg/kg). The peak latency of NO production during ischemia always preceded the onset latency of anoxic depolarization in both the saline group and the carboxy-PTIO group. In the carboxy-PTIO group, the onset latency of anoxic depolarization was significantly longer than that in the saline group. Moreover, carboxy-PTIO significantly reduced the anoxic depolarization amplitude, compared with that of the saline group. These results suggest that both NOS-dependent and-independent NO formation contributes to early and sharp NO production during ischemia, and that this NO increase is, at least in part, related to the triggering of anoxic depolarization.
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Affiliation(s)
- Min Hai Jiang
- Department of Neurology, Hangzhou First People's Hospital, 261, Huansha Road, Hangzhou, Zhejiang, 310006, China
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13
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Shin HK, Dunn AK, Jones PB, Boas DA, Moskowitz MA, Ayata C. Vasoconstrictive neurovascular coupling during focal ischemic depolarizations. J Cereb Blood Flow Metab 2006; 26:1018-30. [PMID: 16340958 DOI: 10.1038/sj.jcbfm.9600252] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ischemic depolarizing events, such as repetitive spontaneous periinfarct spreading depolarizations (PIDs), expand the infarct size after experimental middle cerebral artery (MCA) occlusion. This worsening may result from increased metabolic demand, exacerbating the mismatch between cerebral blood flow (CBF) and metabolism. Here, we present data showing that anoxic depolarization (AD) and PIDs caused vasoconstriction and abruptly reduced CBF in the ischemic cortex in a distal MCA occlusion model in mice. This reduction in CBF during AD increased the area of cortex with 20% or less residual CBF by 140%. With each subsequent PID, this area expanded by an additional 19%. Drugs that are known to inhibit cortical spreading depression (CSD), such as N-methyl-D-aspartate receptor antagonists MK-801 and 7-chlorokynurenic acid, and sigma-1 receptor agonists dextromethorphan and carbetapentane, did not reduce the frequency of PIDs, but did diminish the severity of episodic hypoperfusions, and prevented the expansion of severely hypoperfused cortex, thus improving CBF during 90 mins of acute focal ischemia. In contrast, AMPA receptor antagonist NBQX, which does not inhibit CSD, did not impact the deterioration in CBF. When measured 24 h after distal MCA occlusion, infarct size was reduced by MK-801, but not by NBQX. Our results suggest that AD and PIDs expand the CBF deficit, and by so doing negatively impact lesion development in ischemic mouse brain. Mitigating the vasoconstrictive neurovascular coupling during intense ischemic depolarizations may provide a novel hemodynamic mechanism of neuroprotection by inhibitors of CSD.
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Affiliation(s)
- Hwa Kyoung Shin
- Stroke and Neurovascular Regulation Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA
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14
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Umegaki M, Sanada Y, Waerzeggers Y, Rosner G, Yoshimine T, Heiss WD, Graf R. Peri-infarct depolarizations reveal penumbra-like conditions in striatum. J Neurosci 2005; 25:1387-94. [PMID: 15703392 PMCID: PMC6726005 DOI: 10.1523/jneurosci.4182-04.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 12/21/2004] [Accepted: 12/21/2004] [Indexed: 11/21/2022] Open
Abstract
Spreading depression-like peri-infarct depolarizations not only characterize but also worsen penumbra conditions in cortical border zones of experimental focal ischemia. We intended to investigate the relevance of ischemic depolarization in subcortical regions of ischemic territories. Calomel electrodes measured DC potentials simultaneously in the lateral and medial portions of the caudate nucleus (CN) of 11 anesthetized cats after permanent occlusion of the middle cerebral artery. Additionally, platinum electrodes measured cerebral blood flow (CBF) in the CN, and laser Doppler probes CBF in the cortex. Depolarizations (negative DC shifts >10 mV) were obtained in 10 of 11 cats. Further differentiation revealed that short-lasting spreading depression-like depolarizations (SDs; 5 of 10 cats: 5.24 +/- 1.22 min total duration; 23.3 +/- 4.2 mV amplitude) were predominantly found in medial and longer depolarizations (LDs; 4 of 10 cats: 64.7 +/- 47.5 min; 25.0 +/- 11.3 mV) in the lateral CN. Terminal depolarizations (TDs; 6 of 10 cats; without repolarization) occurred immediately after occlusion or at later stages, being then accompanied by elevations of intracranial pressure presumably inducing secondary CBF reduction. CBF tended to be lower in regions with TDs (33.3 +/- 29.9% of control) and LDs (37.3 +/- 22.8%) than in regions with SDs (51.5 +/- 48.0%). We conclude that in focal ischemia, transient peri-infarct depolarizations emerge not only in cortical but also in striatal gray matter, thereby demonstrating the existence of subcortical zones of ischemic penumbra. The generation of these ischemic depolarizations is a multifocal process possibly linked to brain swelling and intracranial pressure rise in the later course of focal ischemia, and therefore a relevant correlate of progressively worsening conditions.
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Affiliation(s)
- Masao Umegaki
- Max-Planck Institute for Neurological Research, D-50931 Köln, Germany
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15
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Abstract
Hypothermia to mitigate ischemic brain tissue damage has a history of about six decades. Both in clinical and experimental studies of hypothermia, two principal arbitrary patterns of core temperature lowering have been defined: mild (32-35 degrees C) and moderate hypothermia (30-33 degrees C). The neuroprotective effectiveness of postischemic hypothermia is typically viewed with skepticism because of conflicting experimental data. The questions to be resolved include the: (i) postischemic delay; (ii) depth; and (iii) duration of hypothermia. However, more recent experimental data have revealed that a protected reduction in brain temperature can provide sustained behavioral and histological neuroprotection, especially when thermoregulatory responses are suppressed by sedation or anesthesia. Conversely, brief or very mild hypothermia may only delay neuronal damage. Accordingly, protracted hypothermia of 32-34 degrees C may be beneficial following acute cerebral ischemia. But the pathophysiological mechanism of this protection remains yet unclear. Although reduction of metabolism could explain protection by deep hypothermia, it does not explain the robust protection connected with mild hypothermia. A thorough understanding of the experimental data of postischemic hypothermia would lead to a more selective and effective clinical therapy. For this reason, we here summarize recent experimental data on the application of hypothermia in cerebral ischemia, discuss problems to be solved in the experimental field, and try to draw parallels to therapeutic potentials and limitations.
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Affiliation(s)
- B Schaller
- Max-Planck-Institute for Neurological Research, Cologne, Germany
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16
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Millar JC. Real-time direct measurement of nitric oxide in bovine perfused eye trabecular meshwork using a clark-type electrode. J Ocul Pharmacol Ther 2003; 19:299-313. [PMID: 12964955 DOI: 10.1089/108076803322279363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
NO was detected in bovine trabecular meshwork (TM). Bovine eyes were perfused (posterior ciliary artery). In some eyes (operated eyes) a NO electrode was inserted adjacent to the TM (scleral flap). Vascular perfusion/intraocular pressures (VPP/IOP) were recorded. In operated eyes, epinephrine (1 nM-100 microM) increased NO (maximally 979.9 +/- 117.6 nM, mean +/- SDM). Timolol (1 mM) shifted the epinephrine-NO concentration-response curve rightward (2.94 log units) without significantly changing the maximal response (903.0 +/- 67.7 nM, mean +/- SDM). The non-selective NO synthase (NOS) inhibitor L-NMMA (100 microM) virtually abolished the NO response to epinephrine. L-NMMA alone (1 microM-100 microM) significantly reduced tonic NO generation (maximally 109.5 +/- 24.9 nM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. In unoperated eyes, epinephrine (1 nM-100 microM) reduced IOP (maximally 2.56 +/- 0.64 mmHg, mean +/- SDM). Epinephrine (100 microM) mildly increased VPP (4.6 +/- 1.3 mmHg, mean +/- SDM). Baseline aqueous humor formation rate (11.5 +/- 3.2 microl/min, mean +/- SDM) was unaffected. Effluent perfusate (effusate) total NO(2)(-) was determined by enzymatically reducing all NO(3)(-) to NO(2)(-), then assessing resultant NO(2)(-) (Griess assay). Epinephrine (1 nM-1 microM) increased effusate NO(2)(-) (maximally 15.8 +/- 4.9 microM, mean +/- SDM). Timolol (1 mM) reduced, and L-NMMA (100 microM) virtually abolished effusate NO(2)(-) response to epinephrine. L-NMMA alone (1 microM-100 microM) reduced tonic effusate NO(2)(-) (maximally from 5.8 +/- 1.6 microM to 1.1 +/- 0.9 microM, mean +/- SDM), whereas timolol alone (1 microM-1 mM) had no effect. NO is generated tonically in bovine TM and increases in response to epinephrine.
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Affiliation(s)
- J C Millar
- Department of Biology & Health Science, Faculty of Science, Technology & Design, University of Luton, Park Square Campus, Luton, England.
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17
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Leung MCP, Lo SCL, Siu FKW, So KF. Treatment of experimentally induced transient cerebral ischemia with low energy laser inhibits nitric oxide synthase activity and up-regulates the expression of transforming growth factor-beta 1. Lasers Surg Med 2003; 31:283-8. [PMID: 12355575 DOI: 10.1002/lsm.10096] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND OBJECTIVES Nitric oxide (NO) has been shown to be neurotoxic while transforming growth factor-beta 1 (TGF-beta1) is neuroprotective in the stroke model. The present study investigates the effects of low energy laser on nitric oxide synthase (NOS) and TGF-beta1 activities after cerebral ischemia and reperfusion injury. STUDY DESIGN/MATERIALS AND METHODS Cerebral ischemia was induced for 1 hour in male adult Sprague-Dawley (S.D.) rats with unilateral occlusion of middle cerebral artery (MCAO). Low energy laser irradiation was then applied to the cerebrum at different durations (1, 5, or 10 minutes). The activity of NOS and the expression of TGF-beta1 were evaluated in groups with different durations of laser irradiation. RESULTS After ischemia, the activity of NOS was gradually increased from day 3, became significantly higher from day 4 to 6 (P < 0.001), but returned to the normal level after day 7. The activity and expression of the three isoforms of NOS were significantly suppressed (P < 0.001) to different extents after laser irradiation. In addition, laser irradiation was shown to trigger the expression of TGF-beta1 (P < 0.001). CONCLUSIONS Low energy laser could suppress the activity of NOS and up-regulate the expression of TGF-beta1 after stroke in rats.
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Affiliation(s)
- Mason C P Leung
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, The University of Hong Kong, Hong Kong. rsmcpleung.edu.hk
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18
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Coert BA, Anderson RE, Meyer FB. Effects of the nitric oxide donor 3-morpholinosydnonimine (SIN-1) in focal cerebral ischemia dependent on intracellular brain pH. J Neurosurg 2002; 97:914-21. [PMID: 12405381 DOI: 10.3171/jns.2002.97.4.0914] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT A nitric oxide (NO) donor that has been successfully used in the treatment of myocardial infarction, 3-morpholinosydnonimine (SIN-1), may be a potential neuroprotective agent. Production of NO in brain microsomes is dependent on the pH. The purpose of this study was to determine the efficacy of SIN-1 and its dependence on pH in vivo during periods of focal cerebral ischemia. METHODS At 0.1 or 1 mg/kg, SIN-1 was administered to 54 Wistar rats 30 minutes before a 2-hour period of focal cerebral ischemia under moderate hypo-, normo-, and hyperglycemic conditions. Measurements of brain intracellular pH (pHi); regional cortical blood flow, and the redox state of nicotinamide adenine dinucleotide were obtained in three additional animals to confirm the effects of the serum glucose manipulations. The animals were killed at 72 hours after the ischemic period to obtain infarction volumes. Administration of SIN-1 significantly reduced infarction in normoglycemic animals and, to a lesser extent, in hyperglycemic animals, indicating that SIN-1 was less effective under hyperglycemic conditions. At either dose SIN-1 had no significant effect on infarction volume in moderately hypoglycemic animals because moderate hypoglycemia in itself significantly (p < 0.005) reduced infarction volume. CONCLUSIONS The NO donor SIN-1 may be a useful intraoperative cerebral protective agent. Furthermore, it is hypothesized that a mechanism that could explain the published discrepancies regarding the effects of NO donors in vivo may be affected by differences in ischemic brain acidosis.
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Affiliation(s)
- Bernard A Coert
- Thoralf M. Sundt, Jr., Neurosurgery Research Laboratory, Mayo Clinic, and Mayo Graduate School of Medicine, Rochester, Minnesota 55905, USA
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Uetsuka S, Fujisawa H, Yasuda H, Shima H, Suzuki M. Severe cerebral blood flow reduction inhibits nitric oxide synthesis. J Neurotrauma 2002; 19:1105-16. [PMID: 12482122 DOI: 10.1089/089771502760342009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The purpose of this study was to investigate the relationship between cerebral blood flow (CBF) and nitric oxide (NO) synthesis using a rat model of transient forebrain ischemia of varying severity. Forebrain ischemia was induced for 30 min by occlusion of the bilateral common carotid arteries without hemorrhagic hypotension. The production of NO end-products (nitrite and nitrate) was measured by in vivo microdialysis, and CBF by the hydrogen clearance technique. Ischemia induced NO synthesis, although the increase in the quantity of NO end-products was not remarkable during the ischemic period but became prominent after reperfusion. Such increases were abolished by Nomega-nitro-L-arginine methyl ester (L-NAME), although 7-nitroindazole (7-NI) appeared to have only slight effects. The production of NO end-products during ischemia increased when the CBF during ischemia was less than 60 mL/100 g/min. In animals in which the CBF during ischemia was higher than 22.7 mL/100 g/min, the production of NO end-products increased gradually after the induction of ischemia and reached a peak during the reperfusion period, whereas in other animals in which the CBF during ischemia fell below 22.7 mL/100 g/min, the NO end-products decreased during ischemia and increased transiently after reperfusion. These results suggest that the increase in NO end-products is NO synthase (NOS)-dependent and that most of the increase is derived from endothelial NOS. It is also suggested that NO synthesis during ischemia is closely related to CBF, and that severe CBF reduction may inhibit NO synthesis.
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Affiliation(s)
- Shinpei Uetsuka
- Department of Neurosurgery, Clinical Neuroscience, Yamaguchi University School of Medicine, Ube, Japan
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20
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Shin CY, Choi JW, Ryu JR, Ko KH, Choi JJ, Kim HS, Kim HS, Lee JC, Lee SJ, Kim HC, Kim WK. Glucose deprivation decreases nitric oxide production via NADPH depletion in immunostimulated rat primary astrocytes. Glia 2002; 37:268-74. [PMID: 11857685 DOI: 10.1002/glia.10032] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously reported that the production of nitric oxide (NO) in immunostimulated astrocytes was markedly decreased under glucose-deprived conditions. The present study was undertaken to find the contributing factor(s) for the decreased NO production in glucose-deprived immunostimulated astrocytes. NO production in rat primary astrocytes was stimulated for 24-48 h by cotreatment with lipopolysaccharides (1 microg/ml) and interferon-gamma (100 U/ml). Decreased NO production in immunostimulated astrocytes by glucose deprivation was mimicked by the glycolytic inhibitor 2-deoxyglucose and reversed by addition of pyruvate and lactate. Glucose deprivation did not alter the expression of inducible nitric oxide synthase (iNOS) in immunostimulated astrocytes. Addition of beta-NADPH, but not tetrahydrobiopterine, both of which are essential cofactors for NOS function, completely restored the NO production that was decreased in glucose-deprived immunostimulated astrocytes. Glucose deprivation and immunostimulation synergistically reduced intracellular NADPH level in astrocytes. The results indicate that glucose deprivation decreases NO production in immunostimulated astrocytes by depleting intracellular NADPH, a cofactor of iNOS.
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Affiliation(s)
- Chan Young Shin
- Department of Pharmacology, College of Pharmacy, Seoul National University, Seoul, South Korea
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Pinard E, Nallet H, MacKenzie ET, Seylaz J, Roussel S. Penumbral microcirculatory changes associated with peri-infarct depolarizations in the rat. Stroke 2002; 33:606-12. [PMID: 11823677 DOI: 10.1161/hs0202.102738] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE This study was designed to investigate the influence of peri-infarct depolarization elicited by occlusion of the middle cerebral artery on the dynamics of the microcirculation. METHODS The microcirculation in the frontoparietal cortex of 9 rats was visualized in real time through a closed cranial window with the use of laser-scanning confocal fluorescence microscopy combined with intravenous fluorescein isothiocyanate (FITC)-dextran and FITC-labeled erythrocytes. The direct current potential/electrocorticogram was continuously monitored. Intraluminal focal ischemia was induced for 2 hours in 6 rats anesthetized with halothane and mechanically ventilated. Reperfusion was monitored for 1 hour. Three rats underwent sham operation. Brains were removed 24 hours after occlusion and processed for histology. RESULTS In control conditions, the velocity of fluorescent erythrocytes through capillaries was 0.51+/-0.19 mm/s (mean+/-SD), and the diameter of the arterioles studied was 33+/-12 microm. Under ischemia, erythrocyte velocity through capillaries was significantly decreased to 0.33+/-0.14 mm/s, while arteriole diameter did not change significantly. During spontaneous peri-infarct depolarizations, arteriole diameter was significantly increased (119+/-23% of baseline), while capillary erythrocyte velocity was further decreased by 14+/-34%. The direction of arteriolar blood flow episodically and transiently reversed during approximately half of the peri-infarct depolarizations. The decrease in capillary erythrocyte velocity was more pronounced (23+/-37%) in these cases. After reperfusion, the microcirculatory variables rapidly returned to baseline. All rats in the ischemic group had infarcts 24 hours after occlusion. CONCLUSIONS Peri-infarct depolarization has an adverse influence on penumbral microcirculation, reducing capillary perfusion by erythrocytes, despite dilatation of arterioles. These findings suggest that a steal phenomenon contributes to the deleterious effect of these depolarizations.
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Affiliation(s)
- Elisabeth Pinard
- Laboratoire de Recherches Cérébrovasculaires, CNRS UPR 646, Université Paris 7, IFR 6, Paris, France.
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Sakaki T, Graf R, Nozaki H, Rosner G, Heiss WD. Possible control of intermittent cerebral ischemia by monitoring of direct-current potentials. J Neurosurg 2001; 95:495-9. [PMID: 11565873 DOI: 10.3171/jns.2001.95.3.0495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Neurosurgically induced temporary occlusion of intracranial arteries carries the risk of cerebral ischemic damage. Because negative shifts in the cortical direct-current (DC) potential indicate tissue depolarization and, thus, critical ischemic stress, the authors hypothesized that recordings of these potentials could help to determine the optimal duration and frequency of induced intermittent focal ischemia to prevent brain injury. The investigators related the results of DC recordings both to simultaneously recorded decreases in extracellular Ca++ concentration ([Ca++]o), which reflect Ca++ entry into cells, and to histological outcome. METHODS In cats anesthetized with halothane the effects of intermittent brief (10 minutes long, six times [6 x 10-min group]) and prolonged (20 minutes long, three times [3 x 20-min group]) episodes of middle cerebral artery occlusions were compared with those of a single continuous episode (1 x 60-min group). Laser Doppler flow probes and ion-selective microelectrodes were used to measure cerebral blood flow, DC potentials, and [Ca++]o in cortical tissues of ectosylvian gyri. Negative shifts in DC potential were evaluated in the three groups during the entire 60-minute-long period of ischemia and were smallest in the 6 x 10-min group, larger in the 3 x 20-min group, and largest in the 1 x 60-min group. Accordingly, infarct volumes were smallest in the 6 x 10-min group, intermediate in the 3 x 20-min group, and largest in the 1 x 60-min group. Decreases in ischemic [Ca++]o were significantly greater in the 1 x 60-min group than in the two groups in which there were repetitive occlusions, and recovery of [Ca++]o after reperfusion normalized only in the 1 x 60-min group. CONCLUSIONS The DC potential may provide a reliable measure to optimize intermittent ischemia and to achieve minimal ischemic brain injury during temporary neurosurgical occlusion of cerebral arteries.
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Affiliation(s)
- T Sakaki
- Max-Planck-Institut für neurologische Forschung, Cologne, Germany
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Ohta K, Graf R, Rosner G, Heiss WD. Calcium ion transients in peri-infarct depolarizations may deteriorate ion homeostasis and expand infarction in focal cerebral ischemia in cats. Stroke 2001; 32:535-43. [PMID: 11157194 DOI: 10.1161/01.str.32.2.535] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Harmful effects of peri-infarct depolarizations (PIDs) may depend on recurrent Ca(2+) influx. Thus far, few studies have documented the relevance of PIDs in gyrencephalic animals, and the progressive nature of this process has not been investigated over extended periods. We therefore studied in prolonged focal ischemia in cats spatial and temporal profiles of extracellular calcium ([Ca(2+)](o)) shifts in relation to direct current (DC) potential, nitric oxide (NO) concentration and regional cerebral blood flow alterations, and final pathological outcome. METHODS In halothane-anesthetized cats receiving either vehicle (n=12) or MK-801 treatment (5 mg/kg IV; n=10), the left middle cerebral artery was permanently occluded. Laser-Doppler probes, ion-selective microelectrodes, and NO electrodes measured simultaneously regional cerebral blood flow, DC potential, electrocorticogram, [Ca(2+)](o), and NO concentrations in ectosylvian and suprasylvian gyri of the left cerebral cortex. RESULTS Persistent depolarization immediately after middle cerebral artery occlusion occurred in 10 ectosylvian and 4 suprasylvian gyri of vehicle-treated animals and in 9 ectosylvian and 3 suprasylvian gyri of MK-801-treated animals. PIDs associated with transient decreases of [Ca(2+)](o) were detected in suprasylvian gyri of only 4 vehicle-treated animals, of which 3 developed recurrent PIDs. Electrocorticogram was suppressed during PIDs, and electrocorticogram recovery worsened in a stepwise manner with consecutive depolarizations. PID duration increased slightly with ongoing ischemia and evolved to persistent depolarization at a final stage. NO transients were not detected during PID, and regional cerebral blood flow transients were not pronounced. Infarction was larger with initial persistent depolarization than with PID and was smallest in MK-801-treated animals. CONCLUSIONS PID is not a common finding in peri-infarct zones in cats, and it is suppressed by the N:-methyl-D-aspartate antagonist MK-801. However, if repeated PIDs are generated, they result in a stepwise, progressive breakdown of neuronal function and ion homeostasis, probably contributing to the growth of infarction in focal cerebral ischemia. Recurrent Ca(2+) influx is a mechanism that presumably contributes to this process.
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Affiliation(s)
- K Ohta
- Max-Planck-Institut für neurologische Forschung, Cologne, Germany
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Gürsoy-Ozdemir Y, Bolay H, Saribaş O, Dalkara T. Role of endothelial nitric oxide generation and peroxynitrite formation in reperfusion injury after focal cerebral ischemia. Stroke 2000; 31:1974-80; discussion 1981. [PMID: 10926966 DOI: 10.1161/01.str.31.8.1974] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Reperfusion injury is one of the factors that unfavorably affects stroke outcome and shortens the window of opportunity for thrombolysis. Surges of nitric oxide (NO) and superoxide generation on reperfusion have been demonstrated. Concomitant generation of these radicals can lead to formation of the strong oxidant peroxynitrite during reperfusion. METHODS We have examined the role of NO generation and peroxynitrite formation on reperfusion injury in a mouse model of middle cerebral artery occlusion (2 hours) and reperfusion (22 hours). The infarct volume was assessed by 2,3,5-triphenyl tetrazolium chloride staining; blood-brain barrier permeability was evaluated by Evans blue extravasation. Nitrotyrosine formation and matrix metalloproteinase-9 expression were detected by immunohistochemistry. RESULTS Infarct volume was significantly decreased (47%) in animals treated with the nonselective nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine (L-NA) at reperfusion. The specific inhibitor of neuronal NOS, 7-nitroindazole (7-NI), given at reperfusion, showed no protection, although preischemic treatment with 7-NI decreased infarct volume by 40%. Interestingly, prereperfusion administration of both NOS inhibitors decreased tyrosine nitration (a marker of peroxynitrite toxicity) in the ischemic area. L-NA treatment also significantly reduced vascular damage, as indicated by decreased Evans blue extravasation and matrix metalloproteinase-9 expression. CONCLUSIONS These data support the hypothesis that in addition to the detrimental action of NO formed by neuronal NOS during ischemia, NO generation at reperfusion plays a significant role in reperfusion injury, possibly through peroxynitrite formation. Contrary to L-NA, failure of 7-NI to protect against reperfusion injury suggests that the source of NO is the cerebrovascular compartment.
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Affiliation(s)
- Y Gürsoy-Ozdemir
- Department of Neurology, Faculty of Medicine, and Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
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Anderson RE, Meyer FB. Is intracellular brain pH a dependent factor in NOS inhibition during focal cerebral ischemia? Brain Res 2000; 856:220-6. [PMID: 10677629 DOI: 10.1016/s0006-8993(99)02435-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The interaction between nitric oxide (NO.) and focal cerebral ischemia is multifaceted. Experiments have shown that inhibition of nitric oxide synthase (NOS) either ameliorates or exacerbates focal cerebral ischemia. Recent in vitro experiments have shown that NOS activity is pH-dependent. Previous work from this laboratory has demonstrated that N(G)-nitro-L-arginine-methyl-ester (L-NAME) mitigated cerebral ischemia independent from regional cerebral blood flow (rCBF) changes during moderate focal cerebral ischemia. This study examined the effects of L-NAME inhibition on brain pH(i), rCBF, and NADH redox state during 3 h of severe focal cerebral ischemia. Fifteen fasted rabbits under 1.5% halothane were equally divided into three groups: ischemic controls and two drug groups receiving either 1.0 or 10 mg/kg L-NAME intravenously 30 min prior to ischemia. In the ischemic controls, brain pH(i) declined from 6.95+/-0.04 to 6.60+/-0.05, rCBF declined from 48+/-7 to 10+/-3 ml/100 g/min, and NADH fluorescence increased by 149+/-15% 3 h after onset of ischemia (p<0.01 for all three parameters). L-NAME at either dose did not significantly alter these values. Infarct volume was not significantly different between both the L-NAME treated groups and the ischemic control group. This data suggests that during severe focal cerebral ischemia, NO. mechanisms of injury have a less important punitive role. One possible explanation is that the severity of acidosis secondary to anaerobic metabolism during severe focal cerebral ischemia attenuates NOS activity.
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Affiliation(s)
- R E Anderson
- Thoralf M. Sundt Jr., M.D. Neurosurgical Research Laboratory, Mayo Clinic and Mayo Graduate School of Medicine, Rochester, MN, USA.
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Uchikado H, Tanaka E, Yamamoto S, Isagai T, Shigemori M, Higashi H. Na+/Ca2+ exchanger activity induces a slow DC potential after in vitro ischemia in rat hippocampal CA1 region. Neurosci Res 2000; 36:129-40. [PMID: 10711810 DOI: 10.1016/s0168-0102(99)00119-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In rat hippocampal CA1 neurons recorded intracellularly from tissue slices, a rapid depolarization occurred approximately 5 min after application of ischemia-simulating medium. In extracellular recordings obtained from CA1 region, a rapid negative-going DC potential (rapid DC potential) was recorded, corresponding to a rapid depolarization. When oxygen and glucose were reintroduced after generating the rapid depolarization, the membrane further depolarized and the potential became 0 mV after 5 min. Contrary, the DC potential began to repolarize slowly and subsequently a slow negative-going DC potential (slow DC potential) occurred within 1 min. A prolonged application of ischemia-simulating medium suppressed the slow DC potential. Addition of a high concentration of ouabain in normoxic medium reproduced a rapid but not a slow DC potential. The slow DC potential was reduced in low Na+- or Co2+-containing medium, but was not affected in low Cl-, high K+ or K+-free medium, suggesting that the slow DC potential is Na+-and Ca2+-dependent. Ni2+ (Ca2+ channel blocker as well as the Na+/Ca2+ exchanger blocker) and benzamil hydrochloride (Na+/Ca2+ exchanger blocker) reduced the slow DC potential dose-dependently. These results suggest that the slow DC potential is mediated by forward mode operation of Na+/Ca2+ exchangers in non-neuronal cells, and that reactivation of Na+, K+-ATPase is necessary to the Na+/Ca2 +exchanger activity.
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Affiliation(s)
- H Uchikado
- Department of Physiology, Kurume University School of Medicine, Fukuoka, Japan
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Fujisawa H, Koizumi H, Ito H, Yamashita K, Maekawa T. Effects of mild hypothermia on the cortical release of excitatory amino acids and nitric oxide synthesis following hypoxia. J Neurotrauma 1999; 16:1083-93. [PMID: 10595824 DOI: 10.1089/neu.1999.16.1083] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Studies concerning neurotransmitter release following cerebral hypoxia are scarce, and the effects of mild hypothermia on hypoxia-induced neurotransmitter release are unknown. The purpose of this study was to investigate changes in excitatory amino acid (EAA) concentrations and nitric oxide (NO) synthesis following cerebral hypoxia in rats, and the effects of mild hypothermia on both. Cerebral hypoxia (PaO2, 30-40 mm Hg) was induced in each rat for 60 min. Cerebral blood flow (CBF) was measured by laser-Doppler flowmetry, and the extracellular concentrations of EAAs and NO end-products (nitrite and nitrate) were measured by in vivo microdialysis in normothermic (37 degrees C) and hypothermic (32 degrees C) rats. In both groups, CBF showed modest increases during hypoxia and returned to baseline during reoxygenation. The EAA levels of the normothermic rats increased markedly after hypoxia induction and returned to baseline levels during reoxygenation. Hypothermia abolished these increases completely. The NO end-product levels under normothermic conditions declined slightly during hypoxia, and then increased transiently during reoxygenation. Hypothermia appeared to attenuate the NO end-product level and to delay the peak. When the relationship between glutamate and the NO end-products was examined on an individual-animal basis, glutamate release did not parallel NO synthesis. The results indicate that hypothermic neuroprotection during cerebral hypoxia may be attributable to the amelioration of damage by reduction of presynaptic EAA release. Although it is unclear from the present results alone whether endothelial NO synthase, neuronal NO synthase or both caused the elevation of the NO end-products during reoxygenation, it is possible that the attenuation and delay of the peak of the NO end-product level plays a role in protection from NO-induced neuronal damage.
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Affiliation(s)
- H Fujisawa
- Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Japan.
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Nallet H, MacKenzie ET, Roussel S. The nature of penumbral depolarizations following focal cerebral ischemia in the rat. Brain Res 1999; 842:148-58. [PMID: 10526105 DOI: 10.1016/s0006-8993(99)01859-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
It has been previously suggested that the transient ischemic depolarizations (IDs), thought involved in the gradual expansion of ischemic injury in the first hours following middle cerebral artery occlusion (MCAo), are akin to spreading depression (SD). However, previous studies indicate that the characteristics of these events are heterogeneous (unlike those of SDs). We therefore sought to determine whether different types of IDs exist or not. Using four cortical microelectrodes, we compared the spatial and the temporal characteristics of IDs that occur following intraluminal MCAo in halothane-anesthetized rats to those of electrically induced SDs. An average 4.6+/-3.2 series of events, sequentially affecting the four electrodes, were recorded in 5 h following the induction of ischemia. The distribution of ID duration disclosed two types: short IDs (<7 min, 53% of all events) and long IDs (>7 min; 9% of all events). Most long IDs occurred within the first 30 min and as the initial electrophysiological event. Later on and often restricted to a single or reduced number of recording sites, intermittent IDs were of reduced amplitude or even replaced entirely by suppressed electrocorticographic activity (38% of all events). While the amplitude, duration and spreading characteristics were similar between short IDs and SDs provoked in the cortex of non-ischemic rats, those of long IDs were markedly different. Our results indicate that two types of IDs exist and confirm that most IDs (short ones) are similar in nature to SDs. Long IDs may represent a penumbral anoxic depolarization (AD), reversed by an improvement of perfusion, in the early stages of ischemia. Furthermore, we show that intermittent blockade of depolarization waves occurs and that its incidence increases with time. This blockade may reflect adaptive mechanisms which take place to prevent further depolarizations, the nature of which remains to be determined. The present description of electrophysiological abnormalities might have implications for anti-depolarization therapy in focal cerebral ischemia and to interpret the results of non-invasive techniques which enable the imaging of depolarized areas following stroke.
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Affiliation(s)
- H Nallet
- University of Caen, CNRS-UMR 6551, CYCERON, Boulevard Henri Becquerel, BP 5229, 14074, Caen, France.
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Kumura E, Graf R, Dohmen C, Rosner G, Heiss WD. Breakdown of calcium homeostasis in relation to tissue depolarization: comparison between gray and white matter ischemia. J Cereb Blood Flow Metab 1999; 19:788-93. [PMID: 10413034 DOI: 10.1097/00004647-199907000-00009] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In vitro studies suggest that ischemic injury of cerebral white matter is mediated by nonsynaptic cellular mechanisms, such as Ca2+ entry into axons through reversal of the Na+ -Ca2+ exchanger. The authors investigated extracellular Ca2+ concentration in relation to tissue depolarization (direct current potential) in vivo using ion-selective electrodes in cortical gray and subcortical white matter of alpha-chloralose-anesthetized cats during 120 minutes of global cerebral ischemia. On induction of ischemia, regional CBF, as measured by hydrogen clearance, ceased. The direct current potential decreased rapidly within minutes in gray matter and with little time delay in white matter. Extracellular Ca2+ concentration decreased just as quickly in gray matter. In white matter, in contrast, extracellular Ca2+ increased in the first 20 to 30 minutes, and a delayed and much slower decline, compared with gray matter, was observed thereafter, reaching a minimal level only about 60 minutes after occlusion. Our results suggest that smaller and delayed transmembrane shifts of Ca2+ are correlates of delayed ischemic membrane dysfunction in central white matter tracts, which may be explained by a lack of synaptic mechanisms.
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Affiliation(s)
- E Kumura
- Max-Planck-Institut für neurologische Forschung Köln, Germany
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