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Ca 2+-Activated K + Channels and the Regulation of the Uteroplacental Circulation. Int J Mol Sci 2023; 24:ijms24021349. [PMID: 36674858 PMCID: PMC9867535 DOI: 10.3390/ijms24021349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca2+-activated K+ (KCa) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. KCa channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by KCa channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of KCa channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.
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De Silva TM, Sobey CG. Cerebral Vascular Biology in Health and Disease. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00001-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Ottolini M, Sonkusare SK. The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells. Compr Physiol 2021; 11:1831-1869. [PMID: 33792900 PMCID: PMC10388069 DOI: 10.1002/cphy.c200030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca2+ signals and Ca2+ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca2+ signal on arterial contractility depends on the type of Ca2+ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca2+ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca2+ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca2+ signals have already been confirmed, while further investigation is needed for other Ca2+ signals. This article focuses on endothelial and smooth muscle Ca2+ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca2+ entry pathways at the plasma membrane, Ca2+ release signals from the intracellular stores, the functional and physiological relevance of Ca2+ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca2+ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.
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Affiliation(s)
- Matteo Ottolini
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Swapnil K Sonkusare
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA.,Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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Koon CM, Wing-Shing Cheung D, Wong PH, Wat E, Ng SK, Cheung WH, Fu-Yuen Lam F, Chook P, Fung KP, Leung PC, Yan BP. Salviae miltiorrhizae radix and puerariae lobatae radix herbal formula improves circulation, vascularization and gait function in a peripheral arterial disease rat model. JOURNAL OF ETHNOPHARMACOLOGY 2021; 264:113235. [PMID: 32777518 DOI: 10.1016/j.jep.2020.113235] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/21/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE DG is a herbal formula, containing the root of Salvia miltiorrhiza Bunge (Danshen) and the root of Pueraria lobate (Willd.) Ohwi (Gegen), has a history of usage in China for cardiovascular protection and anti-atherosclerosis. AIM OF THE STUDY The present study aims to determine the beneficial effect of DG on the hind-limb ischemia rat model which mimics peripheral arterial disease (PAD) and its vasodilative effect on isolated femoral artery. MATERIALS AND METHODS The vasodilatory effects were assessed by contractile responses to DG in the isolated femoral artery and its underlying mechanisms were evaluated by the involvement of endothelium, potassium channel and calcium channel. For hind-limb ischemia study, treatment outcomes were assessed by evaluating hind-limb blood flow, functional limb recovery, muscle histology and angiogenesis. RESULTS Our results demonstrated positive dose-dependent vasodilatory response to DG via an endothelium-independent mechanism that involved inwardly rectifying K+ channels and Ca2+ channels. We also demonstrated significant improvement in blood perfusion and micro-vessel density in the ischemic limb and positive effects in functional limb recovery. CONCLUSION In conclusion, our study supported the potential use of DG as a novel treatment for symptomatic PAD.
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Affiliation(s)
- Chi-Man Koon
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Research on Bioactivities and Clinical Applications of Medicinal Plants, The Chinese University of Hong Kong, Hong Kong, China.
| | - David Wing-Shing Cheung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Pui-Han Wong
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Elaine Wat
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Research on Bioactivities and Clinical Applications of Medicinal Plants, The Chinese University of Hong Kong, Hong Kong, China.
| | - Sau-Kuen Ng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Wing-Hoi Cheung
- Department of Orthopaedics & Traumatology, The Chinese University of Hong Kong, Hong Kong, China.
| | - Francis Fu-Yuen Lam
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
| | - Ping Chook
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Research on Bioactivities and Clinical Applications of Medicinal Plants, The Chinese University of Hong Kong, Hong Kong, China.
| | - Kwok-Pui Fung
- State Key Laboratory of Research on Bioactivities and Clinical Applications of Medicinal Plants, The Chinese University of Hong Kong, Hong Kong, China; School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; CUHK-Zhejiang University Joint Laboratory on Natural Products and Toxicology Research, Hong Kong, China.
| | - Ping-Chung Leung
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Research on Bioactivities and Clinical Applications of Medicinal Plants, The Chinese University of Hong Kong, Hong Kong, China.
| | - Bryan P Yan
- Division of Cardiology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
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Paul S, Candelario-Jalil E. Emerging neuroprotective strategies for the treatment of ischemic stroke: An overview of clinical and preclinical studies. Exp Neurol 2020; 335:113518. [PMID: 33144066 DOI: 10.1016/j.expneurol.2020.113518] [Citation(s) in RCA: 291] [Impact Index Per Article: 72.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/20/2020] [Accepted: 10/23/2020] [Indexed: 12/12/2022]
Abstract
Stroke is the leading cause of disability and thesecond leading cause of death worldwide. With the global population aged 65 and over growing faster than all other age groups, the incidence of stroke is also increasing. In addition, there is a shift in the overall stroke burden towards younger age groups, particularly in low and middle-income countries. Stroke in most cases is caused due to an abrupt blockage of an artery (ischemic stroke), but in some instances stroke may be caused due to bleeding into brain tissue when a blood vessel ruptures (hemorrhagic stroke). Although treatment options for stroke are still limited, with the advancement in recanalization therapy using both pharmacological and mechanical thrombolysis some progress has been made in helping patients recover from ischemic stroke. However, there is still a substantial need for the development of therapeutic agents for neuroprotection in acute ischemic stroke to protect the brain from damage prior to and during recanalization, extend the therapeutic time window for intervention and further improve functional outcome. The current review has assessed the past challenges in developing neuroprotective strategies, evaluated the recent advances in clinical trials, discussed the recent initiative by the National Institute of Neurological Disorders and Stroke in USA for the search of novel neuroprotectants (Stroke Preclinical Assessment Network, SPAN) and identified emerging neuroprotectants being currently evaluated in preclinical studies. The underlying molecular mechanism of each of the neuroprotective strategies have also been summarized, which could assist in the development of future strategies for combinational therapy in stroke treatment.
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Affiliation(s)
- Surojit Paul
- Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.
| | - Eduardo Candelario-Jalil
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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Wright WS, Eshaq RS, Lee M, Kaur G, Harris NR. Retinal Physiology and Circulation: Effect of Diabetes. Compr Physiol 2020; 10:933-974. [PMID: 32941691 PMCID: PMC10088460 DOI: 10.1002/cphy.c190021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.
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Affiliation(s)
- William S Wright
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina, USA
| | - Randa S Eshaq
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Minsup Lee
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Gaganpreet Kaur
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
| | - Norman R Harris
- Department of Molecular and Cellular Physiology, Louisiana State University Health Shreveport, Shreveport, Louisiana, USA
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Aleksandrowicz M, Kozniewska E. Compromised regulation of the rat brain parenchymal arterioles in vasopressin-associated acute hyponatremia. Microcirculation 2020; 27:e12644. [PMID: 32603523 DOI: 10.1111/micc.12644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 05/21/2020] [Accepted: 06/18/2020] [Indexed: 12/12/2022]
Abstract
OBJECTIVE In this study, we examined the effect of acute hyponatremia associated with vasopressin (AVP) on the responses of the isolated rat's MCAs and PAs to acidosis, nitric oxide donor (SNAP) and to endothelium-dependent vasodilator ATP. METHODS The studies were performed on isolated, perfused and pressurized MCAs and PAs in control conditions and during AVP-associated hyponatremia. Hyponatremia was induced in vitro by lowering Na+ concentration from 144 to 121 mmol/L in intra- and extravascular fluid in the presence of AVP. RESULTS Parenchymal arterioles showed greater response to an increase in H+ and K+ ions concentration and to ATP in comparison with MCAs in control normonatremic conditions. Both PAs and MCAs constricted in response to acute hyponatremia associated with AVP. Interestingly, disordered regulation of vascular tone was observed in PAs but not in MCAs. The abnormalities in the regulation comprised a significant reduction of PA response to acidosis and the absence of the response to the administration of SNAP or ATP. CONCLUSIONS Arginine vasopressin-associated hyponatremia leads to constriction and dysregulation of PAs which may impair neurovascular coupling.
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Affiliation(s)
- Marta Aleksandrowicz
- Laboratory of Experimental and Clinical Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Ewa Kozniewska
- Laboratory of Experimental and Clinical Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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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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Acquarone E, Argyrousi EK, van den Berg M, Gulisano W, Fà M, Staniszewski A, Calcagno E, Zuccarello E, D’Adamio L, Deng SX, Puzzo D, Arancio O, Fiorito J. Synaptic and memory dysfunction induced by tau oligomers is rescued by up-regulation of the nitric oxide cascade. Mol Neurodegener 2019; 14:26. [PMID: 31248451 PMCID: PMC6598340 DOI: 10.1186/s13024-019-0326-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/05/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Soluble aggregates of oligomeric forms of tau protein (oTau) have been associated with impairment of synaptic plasticity and memory in Alzheimer's disease. However, the molecular mechanisms underlying the synaptic and memory dysfunction induced by elevation of oTau are still unknown. METHODS This work used a combination of biochemical, electrophysiological and behavioral techniques. Biochemical methods included analysis of phosphorylation of the cAMP-responsive element binding (CREB) protein, a transcriptional factor involved in memory, histone acetylation, and expression immediate early genes c-Fos and Arc. Electrophysiological methods included assessment of long-term potentiation (LTP), a type of synaptic plasticity thought to underlie memory formation. Behavioral studies investigated both short-term spatial memory and associative memory. These phenomena were examined following oTau elevation. RESULTS Levels of phospho-CREB, histone 3 acetylation at lysine 27, and immediate early genes c-Fos and Arc, were found to be reduced after oTau elevation during memory formation. These findings led us to explore whether up-regulation of various components of the nitric oxide (NO) signaling pathway impinging onto CREB is capable of rescuing oTau-induced impairment of plasticity, memory, and CREB phosphorylation. The increase of NO levels protected against oTau-induced impairment of LTP through activation of soluble guanylyl cyclase. Similarly, the elevation of cGMP levels and stimulation of the cGMP-dependent protein kinases (PKG) re-established normal LTP after exposure to oTau. Pharmacological inhibition of cGMP degradation through inhibition of phosphodiesterase 5 (PDE5), rescued oTau-induced LTP reduction. These findings could be extrapolated to memory because PKG activation and PDE5 inhibition rescued oTau-induced memory impairment. Finally, PDE5 inhibition re-established normal elevation of CREB phosphorylation and cGMP levels after memory induction in the presence of oTau. CONCLUSIONS Up-regulation of CREB activation through agents acting on the NO cascade might be beneficial against tau-induced synaptic and memory dysfunctions.
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Affiliation(s)
- Erica Acquarone
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- DiMi Department of Internal Medicine and Medical Specialties, University of Genoa, 16132 Genoa, Italy
| | - Elentina K. Argyrousi
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- Faculty of Psychology and Neuroscience, Maastricht University, 6229 Maastricht, Netherlands
| | - Manon van den Berg
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- Faculty of Psychology and Neuroscience, Maastricht University, 6229 Maastricht, Netherlands
| | - Walter Gulisano
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95125 Catania, Italy
| | - Mauro Fà
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
| | - Agnieszka Staniszewski
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
| | - Elisa Calcagno
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- Department of Experimental Medicine, Section of General Pathology, School of Medical and Pharmaceutical Sciences, University of Genoa, 16132 Genoa, Italy
| | - Elisa Zuccarello
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
| | - Luciano D’Adamio
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, Newark, NJ USA
| | - Shi-Xian Deng
- Department of Medicine, Columbia University, New York, NY 10032 USA
| | - Daniela Puzzo
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95125 Catania, Italy
- Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Ottavio Arancio
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- Department of Medicine, Columbia University, New York, NY 10032 USA
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032 USA
| | - Jole Fiorito
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, 630 West 168th Street, P&S 12-420D, New York, NY 10032 USA
- Department of Life Sciences, New York Institute of Technology, Northern Boulevard P.O. Box 8000, Theobald Science Center, room 425, Old Westbury, NY 11568 USA
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Alimoradi H, Greish K, Gamble AB, Giles GI. Controlled Delivery of Nitric Oxide for Cancer Therapy. Pharm Nanotechnol 2019; 7:279-303. [PMID: 31595847 PMCID: PMC6967185 DOI: 10.2174/2211738507666190429111306] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/21/2019] [Accepted: 04/16/2019] [Indexed: 04/13/2023]
Abstract
Nitric oxide (NO) is a short-lived, endogenously produced, signaling molecule which plays multiple roles in mammalian physiology. Underproduction of NO is associated with several pathological processes; hence a broad range of NO donors have emerged as potential therapeutics for cardiovascular and respiratory disorders, wound healing, the immune response to infection, and cancer. However, short half-lives, chemical reactivity, rapid systemic clearance, and cytotoxicity have hindered the clinical development of most low molecular weight NO donors. Hence, for controlled NO delivery, there has been extensive effort to design novel NO-releasing biomaterials for tumor targeting. This review covers the effects of NO in cancer biology, NO releasing moieties which can be used for NO delivery, and current advances in the design of NO releasing biomaterials focusing on their applications for tumor therapy.
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Affiliation(s)
| | - Khaled Greish
- Address correspondence to these authors at the Department of Molecular Medicine and Nanomedicine Unit, Princess
Al-Jawhara Centre for Molecular Medicine and Inherited Disorders, College of Medicine and Medical Sciences,
Arabian Gulf University, Manama, Kingdom of Bahrain; Tel: +973 17 237 393; E-mail: and Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand; Tel: +6434797322;, E-mail:
| | | | - Gregory I. Giles
- Address correspondence to these authors at the Department of Molecular Medicine and Nanomedicine Unit, Princess
Al-Jawhara Centre for Molecular Medicine and Inherited Disorders, College of Medicine and Medical Sciences,
Arabian Gulf University, Manama, Kingdom of Bahrain; Tel: +973 17 237 393; E-mail: and Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand; Tel: +6434797322;, E-mail:
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Heckman PRA, Blokland A, Bollen EPP, Prickaerts J. Phosphodiesterase inhibition and modulation of corticostriatal and hippocampal circuits: Clinical overview and translational considerations. Neurosci Biobehav Rev 2018; 87:233-254. [PMID: 29454746 DOI: 10.1016/j.neubiorev.2018.02.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 02/07/2018] [Accepted: 02/09/2018] [Indexed: 12/20/2022]
Abstract
The corticostriatal and hippocampal circuits contribute to the neurobiological underpinnings of several neuropsychiatric disorders, including Alzheimer's disease, Parkinson's disease and schizophrenia. Based on biological function, these circuits can be clustered into motor circuits, associative/cognitive circuits and limbic circuits. Together, dysfunctions in these circuits produce the wide range of symptoms observed in related neuropsychiatric disorders. Intracellular signaling in these circuits is largely mediated through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway with an additional role for the cyclic guanosine monophosphate (cGMP)/ protein kinase G (PKG) pathway, both of which can be regulated by phosphodiesterase inhibitors (PDE inhibitors). Through their effects on cAMP response element-binding protein (CREB) and Dopamine- and cAMP-Regulated PhosphoProtein MR 32 kDa (DARPP-32), cyclic nucleotide pathways are involved in synaptic transmission, neuron excitability, neuroplasticity and neuroprotection. In this clinical review, we provide an overview of the current clinical status, discuss the general mechanism of action of PDE inhibitors in relation to the corticostriatal and hippocampal circuits and consider several translational challenges.
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Affiliation(s)
- P R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands.
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - E P P Bollen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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Physiological and pathological processes of synaptic plasticity and memory in drug discovery: Do not forget the dose-response curve. Eur J Pharmacol 2017; 817:59-70. [DOI: 10.1016/j.ejphar.2017.05.058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/20/2017] [Accepted: 05/30/2017] [Indexed: 01/24/2023]
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13
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 212] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Heckman PRA, Blokland A, Prickaerts J. From Age-Related Cognitive Decline to Alzheimer's Disease: A Translational Overview of the Potential Role for Phosphodiesterases. ADVANCES IN NEUROBIOLOGY 2017; 17:135-168. [PMID: 28956332 DOI: 10.1007/978-3-319-58811-7_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Phosphodiesterase inhibitors (PDE-Is) are pharmacological compounds enhancing cAMP and/or cGMP signaling. Both these substrates affect neural communication by influencing presynaptic neurotransmitter release and postsynaptic intracellular pathways after neurotransmitter binding to its receptor. Both cAMP and cGMP play an important role in a variety of cellular functions including neuroplasticity and neuroprotection. This chapter provides a translational overview of the effects of different classes of PDE-Is on cognition enhancement in age-related cognitive decline and Alzheimer's disease (AD). The most effective PDE-Is in preclinical models of aging and AD appear to be PDE2-Is, PDE4-Is and PDE5-Is. Clinical studies are relatively sparse and so far PDE1-Is and PDE4-Is showed some promising results. In the future, the demonstration of clinical proof of concept and the generation of isoform selective PDE-Is are the hurdles to overcome in developing safe and efficacious novel PDE-Is for the treatment of age-related cognitive decline and cognitive dysfunction in AD.
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Affiliation(s)
- Pim R A Heckman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
| | - Arjan Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands
| | - Jos Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200, MD, Maastricht, The Netherlands.
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15
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Cseplo P, Vamos Z, Ivic I, Torok O, Toth A, Koller A. The Beta-1-Receptor Blocker Nebivolol Elicits Dilation of Cerebral Arteries by Reducing Smooth Muscle [Ca2+]i. PLoS One 2016; 11:e0164010. [PMID: 27716772 PMCID: PMC5055296 DOI: 10.1371/journal.pone.0164010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 09/19/2016] [Indexed: 01/22/2023] Open
Abstract
Rationale Nebivolol is known to have beta-1 blocker activity, but it was also suggested that it elicits relaxation of the peripheral arteries in part via release of nitric oxide (NO). However, the effect of nebivolol on the vasomotor tone of cerebral arteries is still unclear. Objective To assess the effects of nebivolol on the diameter of isolated rat basilar arteries (BA) in control, in the presence of inhibitors of vasomotor signaling pathways of know action and hemolysed blood. Methods and Results Vasomotor responses were measured by videomicroscopy and the intracellular Ca2+ by the Fura-2 AM ratiometric method. Under control conditions, nebivolol elicited a substantial dilation of the BA (from 216±22 to 394±20 μm; p<0.05) in a concentration-dependent manner (10−7 to 10−4 M). The dilatation was significantly reduced by endothelium denudation or by L-NAME (inhibitor of NO synthase) or by SQ22536 (adenylyl cyclase blocker). Dilatation of BA was also affected by beta-2 receptor blockade with butoxamine, but not by the guanylate cyclase blocker ODQ. Interestingly, beta-1 blockade by atenolol inhibited nebivolol-induced dilation. Also, the BKCa channel blocker iberiotoxin and KCa channel inhibitor TEA significantly reduced nebivolol-induced dilation. Nebivolol significantly reduced smooth muscle Ca2+ level, which correlated with the increases in diameters and moreover it reversed the hemolysed blood-induced constriction of BA. Conclusions Nebivolol seems to have an important dilator effect in cerebral arteries, which is mediated via several vasomotor mechanisms, converging on the reduction of smooth muscle Ca2+ levels. As such, nebivolol may be effective to improve cerebral circulation in various diseased conditions, such as hemorrhage.
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Affiliation(s)
- Peter Cseplo
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Central Anesthesiology and Intensive Therapy, Petz Aladar County Teaching Hospital, Gyor, Hungary
| | - Zoltan Vamos
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Pecs, Medical School, Pecs, Hungary
| | - Ivan Ivic
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anatomy, University of Pecs, Medical School, Pecs, Hungary
| | - Orsolya Torok
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary
| | - Attila Toth
- Institute of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Akos Koller
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Neurosurgery, University of Pecs, Medical School, Pecs, Hungary.,Department of Physiology, New York Medical College, Valhalla, New York, United States of America.,Institute of Natural Sciences, University of Physical Education, Budapest, Hungary
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16
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Effect of PGD 2 on middle meningeal artery and mRNA expression profile of L-PGD 2 synthase and DP receptors in trigeminovascular system and other pain processing structures in rat brain. Pharmacol Rep 2016; 69:50-56. [PMID: 27898338 DOI: 10.1016/j.pharep.2016.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 02/02/2023]
Abstract
BACKGROUND Prostaglandins (PGs), particularly prostaglandin D2 (PGD2), E2 (PGE2), and I2 (PGI2), are considered to play a role in migraine pain. In humans, infusion of PGD2 causes lesser headache as compared to infusion of PGE2 and PGI2. Follow-up studies in rats have shown that infusion of PGE2 and PGI2 dilate the middle meningeal artery (MMA), and mRNA for PGE2 and PGI2 receptors is present in rat trigeminovascular system (TVS) and in the brain structures associated with pain. In the present study, we have characterized the dilatory effect of PGD2 on rat MMA and studied the relative mRNA expression of PGD2 receptors and lipocalin-type of PGD2 synthase (L-PGDS). METHOD Rat closed-cranial window (CCW) model was used to study the effect of the DP1 receptor antagonist, MK-0524, on PGD2-induced vasodilation of middle meningeal artery. The qPCR technique was used for mRNA expression analysis. RESULTS PGD2 infusion evoked a dose-dependent dilation of the rat MMA. The calculated mean pED50 value was 5.23±0.10 and Emax was 103±18% (n=5). MK-0524 significantly (∼61%, p<0.05) blocked the PGD2-induced dilation of MMA. mRNA for the DP1, DP2 and L-PGDS were expressed differentially in all tested tissues. DP1 receptor mRNA was expressed maximally in trigeminal ganglion (TG) and in cervical dorsal root ganglion (DRG). CONCLUSIONS High expression of DP1 mRNA in the TG and DRG suggest that PGD2 might play a role in migraine pathophysiology. Activation of the DP1 receptor in MMA was mainly responsible for vasodilation induced by PGD2 infusion.
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17
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Hansen JM, Sitarz J, Birk S, Rahmann AM, Oturai PS, Fahrenkrug J, Olesen J, Ashina M. Vasoactive Intestinal Polypeptide Evokes Only a Minimal Headache in Healthy Volunteers. Cephalalgia 2016; 26:992-1003. [PMID: 16886936 DOI: 10.1111/j.1468-2982.2006.01149.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The role of the parasympathetic nervous system in the pathogenesis of migraine is disputed. The headache-eliciting effect of the parasympathetic neurotransmitter, vasoactive intestinal polypeptide (VIP), and its effect on cerebral arteries and brain haemodynamics has not been systematically studied in man. We hypothesized that infusion of VIP might induce headache in healthy subjects and cause changes in cerebral haemodynamics. VIP (8 pmol/kg per min) or placebo (0.9± saline) was infused for 25 min into 12 healthy young volunteers in a crossover, double-blind design. Headache was scored on a verbal rating scale from 0 to 10, regional cerebral blood flow (rCBF) was measured with single-photon emission computed tomography and 133Xe inhalation and mean flow velocity in the middle cerebral artery (VmeanMCA) was measured with transcranial Doppler ultrasonography. The headache was very mild with a maximum score of 2 and described as a pressing or throbbing sensation. Five participants developed headache during VIP and one during placebo. During the infusion, a significant drop in VmeanMCA was seen for VIP compared with placebo ( P < 0.001), but the effect quickly waned and no difference was found when comparing the time between 30 and 120 min. In addition, no significant difference in the diameter of the MCA could be found during the infusion. No significant differences in rCBF ( P = 0.10) were found between VIP and placebo. A marked dilation of the superficial temporal artery was seen ( P = 0.04) after VIP in the first 30 min but no difference was found when comparing the time between 30 and 120 min. We found no difference in mean arterial blood pressure between VIP and placebo days but the heart rate increased significantly on a VIP day compared with a placebo day (AUC0–30min, P < 0.001). Plasma VIP was significantly higher on a VIP day compared with placebo (AUC0–80min, P < 0.001). These results show that VIP causes a decrease in VmeanMCA without affecting rCBF. In spite of a marked vasodilator effect in the extracranial vessels and increased plasma VIP, healthy subjects developed only a very mild headache.
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Affiliation(s)
- J M Hansen
- Danish Headache Centre and Department of Neurology, Glostrup Hospital, University of Copenhagen, Denmark
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18
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19
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Bollen E, Akkerman S, Puzzo D, Gulisano W, Palmeri A, D'Hooge R, Balschun D, Steinbusch HWM, Blokland A, Prickaerts J. Object memory enhancement by combining sub-efficacious doses of specific phosphodiesterase inhibitors. Neuropharmacology 2015; 95:361-6. [PMID: 25896769 DOI: 10.1016/j.neuropharm.2015.04.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 02/13/2015] [Accepted: 04/03/2015] [Indexed: 01/17/2023]
Abstract
The second messengers cGMP and cAMP have a vital role in synaptic plasticity and memory processes. As such, phosphodiesterases inhibitors (PDE-Is), which prevent the breakdown of these cyclic nucleotides, represent a potential treatment strategy in memory decline. Recently it has been demonstrated that cGMP and cAMP signaling act in sequence during memory consolidation, with early cGMP signaling requiring subsequent cAMP signaling. Here, we sought to confirm this relationship, and to evaluate its therapeutic implications. Combining sub-efficacious doses of the cGMP-specific PDE type 5 inhibitor vardenafil (0.1 mg/kg) and cAMP-specific PDE type 4 inhibitor rolipram (0.01 mg/kg) during the early and late memory consolidation phase, respectively, led to improved memory performance in a 24 h interval object recognition task. Similarly, such a sub-efficacious combination treatment enhanced the transition of early-phase long-term potentiation (LTP) to late-phase LTP in hippocampal slices. In addition, both object memory and LTP were improved after administration of two sub-efficacious doses of the dual substrate PDE type 2 inhibitor BAY60 7550 (0.3 mg/kg) at the early and late consolidation phase, respectively. Taken together, combinations of sub-efficacious doses of cAMP- and cGMP-specific PDE-Is have an additive effect on long-term synaptic plasticity and memory formation and might prove a superior alternative to single PDE-I treatment.
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Affiliation(s)
- E Bollen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - S Akkerman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - D Puzzo
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - W Gulisano
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - A Palmeri
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - R D'Hooge
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - D Balschun
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - H W M Steinbusch
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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20
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Improved long-term memory via enhancing cGMP-PKG signaling requires cAMP-PKA signaling. Neuropsychopharmacology 2014; 39:2497-505. [PMID: 24813825 PMCID: PMC4207334 DOI: 10.1038/npp.2014.106] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 02/28/2014] [Accepted: 02/28/2014] [Indexed: 02/02/2023]
Abstract
Memory consolidation is defined by the stabilization of a memory trace after acquisition, and consists of numerous molecular cascades that mediate synaptic plasticity. Commonly, a distinction is made between an early and a late consolidation phase, in which early refers to the first hours in which labile synaptic changes occur, whereas late consolidation relates to stable and long-lasting synaptic changes induced by de novo protein synthesis. How these phases are linked at a molecular level is not yet clear. Here we studied the interaction of the cyclic nucleotide-mediated pathways during the different phases of memory consolidation in rodents. In addition, the same pathways were studied in a model of neuronal plasticity, long-term potentiation (LTP). We demonstrated that cGMP/protein kinase G (PKG) signaling mediates early memory consolidation as well as early-phase LTP, whereas cAMP/protein kinase A (PKA) signaling mediates late consolidation and late-phase-like LTP. In addition, we show for the first time that early-phase cGMP/PKG signaling requires late-phase cAMP/PKA-signaling in both LTP and long-term memory formation.
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21
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Pabbidi MR, Mazur O, Fan F, Farley JM, Gebremedhin D, Harder DR, Roman RJ. Enhanced large conductance K+ channel activity contributes to the impaired myogenic response in the cerebral vasculature of Fawn Hooded Hypertensive rats. Am J Physiol Heart Circ Physiol 2014; 306:H989-H1000. [PMID: 24464756 DOI: 10.1152/ajpheart.00636.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Recent studies have indicated that the myogenic response (MR) in cerebral arteries is impaired in Fawn Hooded Hypertensive (FHH) rats and that transfer of a 2.4 megabase pair region of chromosome 1 (RNO1) containing 15 genes from the Brown Norway rat into the FHH genetic background restores MR in a FHH.1(BN) congenic strain. However, the mechanisms involved remain to be determined. The present study examined the role of the large conductance calcium-activated potassium (BK) channel in impairing the MR in FHH rats. Whole-cell patch-clamp studies of cerebral vascular smooth muscle cells (VSMCs) revealed that iberiotoxin (IBTX; BK inhibitor)-sensitive outward potassium (K+) channel current densities are four- to fivefold greater in FHH than in FHH.1(BN) congenic strain. Inside-out patches indicated that the BK channel open probability (NPo) is 10-fold higher and IBTX reduced NPo to a greater extent in VSMCs isolated from FHH than in FHH.1(BN) rats. Voltage sensitivity of the BK channel is enhanced in FHH as compared with FHH.1(BN) rats. The frequency and amplitude of spontaneous transient outward currents are significantly greater in VSMCs isolated from FHH than in FHH.1(BN) rats. However, the expression of the BK-α and -β-subunit proteins in cerebral vessels as determined by Western blot is similar between the two groups. Middle cerebral arteries (MCAs) isolated from FHH rats exhibited an impaired MR, and administration of IBTX restored this response. These results indicate that there is a gene on RNO1 that impairs MR in the MCAs of FHH rats by enhancing BK channel activity.
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Affiliation(s)
- Mallikarjuna R Pabbidi
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
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22
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Kunduri S, Dick G, Nayeem M, Mustafa S. Adenosine A 1 receptor signaling inhibits BK channels through a PKCα-dependent mechanism in mouse aortic smooth muscle. Physiol Rep 2013; 1. [PMID: 23977428 PMCID: PMC3747964 DOI: 10.1002/phy2.37] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adenosine receptors (AR; A1, A2A, A2B, and A3) contract and relax smooth muscle through different signaling mechanisms. Deciphering these complex responses remains difficult because relationships between AR subtypes and various end-effectors (e.g., enzymes and ion channels) remain to be identified. A1AR stimulation is associated with the production of 20–hydroxyeicosatetraenoic acid (20–HETE) and activation of protein kinase C (PKC). 20–HETE and PKC can inhibit large conductance Ca2+/voltage-sensitive K+ (BK) channels that regulate smooth muscle contraction. We tested the hypothesis that activation of A1AR inhibits BK channels via a PKC-dependent mechanism. Patch clamp recordings and Western blots were performed using aortae of wild type (WT) and A1AR knockout (A1KO) mice. There were no differences in whole-cell K+ current or α and β1 subunits expression between WT and A1KO. 20–HETE (100 nmol/L) inhibited BK current similarly in WT and A1KO mice. NECA (5′–N–ethylcarboxamidoadenosine; 10 μmol/L), a nonselective AR agonist, increased BK current in myocytes from both WT and A1KO mice, but the increase was greater in A1KO (52 ± 15 vs. 17 ± 3%; P < 0.05). This suggests that A1AR signaling negatively regulates BK channel activity. Accordingly, CCPA (2–chloro–N(6)-cyclopentyladenosine; 100 nmol/L), an A1AR-selective agonist, inhibited BK current in myocytes from WT but not A1KO mice (81 ± 4 vs. 100 ± 7% of control; P < 0.05). Gö6976 (100 nmol/L), a PKCα inhibitor, abolished the effect of CCPA to inhibit BK current (99 ± 3% of control). These data lead us to conclude that, in aortic smooth muscle, A1AR inhibits BK channel activity and that this occurs via a mechanism involving PKCα.
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Affiliation(s)
- Ss Kunduri
- Department of Physiology & Pharmacology, West Virginia University School of Medicine ; Center for Cardiovascular and Respiratory Sciences, West Virginia University School of Medicine
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23
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Dabertrand F, Nelson MT, Brayden JE. Ryanodine receptors, calcium signaling, and regulation of vascular tone in the cerebral parenchymal microcirculation. Microcirculation 2013; 20:307-16. [PMID: 23216877 PMCID: PMC3612564 DOI: 10.1111/micc.12027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 11/21/2012] [Indexed: 11/27/2022]
Abstract
The cerebral blood supply is delivered by a surface network of pial arteries and arterioles from which arise (parenchymal) arterioles that penetrate into the cortex and terminate in a rich capillary bed. The critical regulation of CBF, locally and globally, requires precise vasomotor regulation of the intracerebral microvasculature. This vascular region is anatomically unique as illustrated by the presence of astrocytic processes that envelope almost the entire basolateral surface of PAs. There are, moreover, notable functional differences between pial arteries and PAs. For example, in pial VSMCs, local calcium release events ("calcium sparks") through ryanodine receptor (RyR) channels in SR membrane activate large conductance, calcium-sensitive potassium channels to modulate vascular diameter. In contrast, VSMCs in PAs express functional RyR and BK channels, but under physiological conditions, these channels do not oppose pressure-induced vasoconstriction. Here, we summarize the roles of ryanodine receptors in the parenchymal microvasculature under physiologic and pathologic conditions, and discuss their importance in the control of CBF.
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Affiliation(s)
- Fabrice Dabertrand
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont, USA.
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24
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Hein TW, Xu W, Ren Y, Kuo L. Cellular signalling pathways mediating dilation of porcine pial arterioles to adenosine A₂A receptor activation. Cardiovasc Res 2013; 99:156-63. [PMID: 23539502 DOI: 10.1093/cvr/cvt072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Adenosine is a potent vasodilator contributing to cerebral blood flow regulation during metabolic stress. However, the distribution of adenosine receptor subtypes and underlying signalling mechanisms for dilation of pial arterioles remain unclear. The present study aimed at addressing these issues. METHODS AND RESULTS Isolated porcine pial arterioles were subjected to study of vasomotor function, localization of adenosine receptors, and production of nitric oxide (NO). Concentration-dependent vasodilation to adenosine was inhibited by A₂A receptor antagonist ZM241385 but not by A₁ receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. A₂A receptors were detected in endothelium and smooth muscle of pial arterioles via immunohistochemistry. Adenosine significantly increased arteriolar production of NO, and the induced dilation was insensitive to KATP channel blocker glibenclamide but was attenuated by endothelial denudation, NO synthase inhibitor L-NAME, or guanylyl cyclase inhibitor ODQ in a similar manner. Both inward rectifier potassium (Kir) channel inhibitor barium and cAMP signalling inhibitor Rp-8-Br-cAMPS attenuated adenosine-induced dilation. In the presence of L-NAME or the absence of endothelium, addition of Rp-8-Br-cAMPS but not barium further reduced adenosine-induced responses. Barium diminished endothelium-independent vasodilation to NO donor sodium nitroprusside. Comparable to the adenosine-induced response, vasodilation to A₂A receptor agonist CGS21680 was attenuated by endothelial removal, ZM241385, L-NAME, barium, or Rp-8-Br-cAMPS, but not by glibenclamide. CONCLUSION Adenosine evokes dilation of porcine pial arterioles via parallel activation of endothelial and smooth muscle A₂A receptors. Stimulation of endothelial NO production activates smooth muscle guanylyl cyclase for vasodilation by opening Kir channels. Adenosine also activates smooth muscle cAMP signalling leading to vasodilation.
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Affiliation(s)
- Travis W Hein
- Department of Surgery, Scott & White Healthcare, College of Medicine, Texas A&M Health Science Center, 702 Southwest HK Dodgen Loop, Temple, TX 76504, USA.
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25
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García-Osta A, Cuadrado-Tejedor M, García-Barroso C, Oyarzábal J, Franco R. Phosphodiesterases as therapeutic targets for Alzheimer's disease. ACS Chem Neurosci 2012; 3:832-44. [PMID: 23173065 DOI: 10.1021/cn3000907] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 10/01/2012] [Indexed: 01/10/2023] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia among the elderly. In AD patients, memory loss is accompanied by the formation of beta-amyloid plaques and the appearance of tau in a pathological form. Given the lack of effective treatments for AD, the development of new management strategies for these patients is critical. The continued failure to find effective therapies using molecules aimed at addressing the anti-beta amyloid pathology has led researchers to focus on other non-amyloid-based approaches to restore memory function. Promising non-amyloid related candidate targets include phosphosdiesterases (PDEs), and indeed, Rolipram, a specific PDE4 inhibitor, was the first compound found to effectively restore cognitive deficits in animal models of AD. More recently, PDE5 inhibitors have also been shown to effectively restore memory function. Accordingly, inhibitors of other members of the PDE family may also improve memory performance in AD and non-AD animal models. Hence, in this review, we will summarize the data supporting the use of PDE inhibitors as cognitive enhancers and we will discuss the possible mechanisms of action underlying these effects. We shall also adopt a medicinal chemistry perspective that leads us to propose the most promising PDE candidates on the basis of inhibitor selectivity, brain distribution, and mechanism of action.
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Affiliation(s)
- Ana García-Osta
- Molecular and Cell Neuropharmacology
Laboratory, Neurosciences Division, CIMA (Centro de investigación Médica Aplicada), Avda Pio
XII, Pamplona, Spain
| | - Mar Cuadrado-Tejedor
- Molecular and Cell Neuropharmacology
Laboratory, Neurosciences Division, CIMA (Centro de investigación Médica Aplicada), Avda Pio
XII, Pamplona, Spain
| | - Carolina García-Barroso
- Molecular and Cell Neuropharmacology
Laboratory, Neurosciences Division, CIMA (Centro de investigación Médica Aplicada), Avda Pio
XII, Pamplona, Spain
| | - Julen Oyarzábal
- Molecular and Cell Neuropharmacology
Laboratory, Neurosciences Division, CIMA (Centro de investigación Médica Aplicada), Avda Pio
XII, Pamplona, Spain
- Small
Molecule Discovery Platform, CIMA (Centro
de investigación Médica
Aplicada), Avda Pio XII, Pamplona, Spain
| | - Rafael Franco
- Molecular and Cell Neuropharmacology
Laboratory, Neurosciences Division, CIMA (Centro de investigación Médica Aplicada), Avda Pio
XII, Pamplona, Spain
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Howitt L, Grayson TH, Morris MJ, Sandow SL, Murphy TV. Dietary obesity increases NO and inhibits BKCa-mediated, endothelium-dependent dilation in rat cremaster muscle artery: association with caveolins and caveolae. Am J Physiol Heart Circ Physiol 2012; 302:H2464-76. [DOI: 10.1152/ajpheart.00965.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is a risk factor for hypertension and other vascular disease. The aim of this study was to examine the effect of diet-induced obesity on endothelium-dependent dilation of rat cremaster muscle arterioles. Male Sprague-Dawley rats (213 ± 1 g) were fed a cafeteria-style high-fat or control diet for 16–20 wk. Control rats weighed 558 ± 7 g compared with obese rats 762 ± 12 g ( n = 52–56; P < 0.05). Diet-induced obesity had no effect on acetylcholine (ACh)-induced dilation of isolated, pressurized (70 mmHg) arterioles, but sodium nitroprusside (SNP)-induced vasodilation was enhanced. ACh-induced dilation of arterioles from control rats was abolished by a combination of the KCa blockers apamin, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), and iberiotoxin (IBTX; all 0.1 μmol/l), with no apparent role for nitric oxide (NO). In arterioles from obese rats, however, IBTX had no effect on responses to ACh while the NO synthase (NOS)/guanylate cyclase inhibitors Nω-nitro-l-arginine methyl ester (l-NAME; 100 μmol/l)/1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μmol/l) partially inhibited ACh-induced dilation. Furthermore, NOS activity (but not endothelial NOS expression) was increased in arteries from obese rats. l-NAME/ODQ alone or removal of the endothelium constricted arterioles from obese but not control rats. Expression of caveolin-1 and -2 oligomers (but not monomers or caveolin-3) was increased in arterioles from obese rats. The number of caveolae was reduced in the endothelium of arteries, and caveolae density was increased at the ends of smooth muscle cells from obese rats. Diet-induced obesity abolished the contribution of large-conductance Ca2+-activated K+ channel to ACh-mediated endothelium-dependent dilation of rat cremaster muscle arterioles, while increasing NOS activity and inducing an NO-dependent component.
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Affiliation(s)
- Lauren Howitt
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
| | - T. Hilton Grayson
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Margaret J. Morris
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Shaun L. Sandow
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Timothy V. Murphy
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
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Howitt L, Sandow SL, Grayson TH, Ellis ZE, Morris MJ, Murphy TV. Differential effects of diet-induced obesity on BKCa {beta}1-subunit expression and function in rat skeletal muscle arterioles and small cerebral arteries. Am J Physiol Heart Circ Physiol 2011; 301:H29-40. [PMID: 21536854 DOI: 10.1152/ajpheart.00134.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanisms underlying obesity-related vascular dysfunction are unclear. This study examined the effect of diet-induced obesity on expression and function of large conductance Ca(2+)-activated potassium channel (BK(Ca)) in rat pressurized small resistance vessels with myogenic tone. Male Sprague-Dawley rats fed a cafeteria-style high fat diet (HFD; ∼30% energy from fat) for 16-20 wk were ∼30% heavier than controls fed standard chow (∼13% fat). Obesity did not alter BK(Ca) α-subunit function or α-subunit protein or mRNA expression in vessels isolated from the cremaster muscle or middle-cerebral circulations. In contrast, BK(Ca) β(1)-subunit protein expression and function were significantly reduced in cremaster muscle arterioles but increased in middle-cerebral arteries from obese animals. Immunohistochemistry showed α- and β(1)-subunits were present exclusively in the smooth muscle of both vessels. Cremaster muscle arterioles from obese animals showed significantly increased medial thickness, and media-to-lumen ratio and pressurized arterioles showed increased myogenic tone at 30 mmHg, but not at 50-120 mmHg. Myogenic tone was not affected by obesity in middle-cerebral arteries. The BK(Ca) antagonist iberiotoxin constricted both cremaster muscle and middle-cerebral arterioles from control rats; this effect of iberiotoxin was abolished in cremaster muscle arteries only from obese rats. Diet-induced obesity has contrasting effects on BK(Ca) function in different vascular beds, through differential effects on β(1)-subunit expression. However, these alterations in BK(Ca) function had little effect on overall myogenic tone, suggesting that the mechanisms controlling myogenic tone can be altered and compensate for altered BK(Ca) expression and function.
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Affiliation(s)
- Lauren Howitt
- Dept. of Physiology, School of Medical Sciences, Univ. of New South Wales, Sydney, NSW 2052 Australia.
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Li Y, Horiuchi T, Murata T, Hongo K. Mechanism of alkalosis-induced constriction of rat cerebral penetrating arterioles. Neurosci Res 2011; 70:98-103. [PMID: 21256899 DOI: 10.1016/j.neures.2011.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 12/22/2010] [Accepted: 01/11/2011] [Indexed: 10/18/2022]
Abstract
Cerebral arterioles are in close contact with the supplied tissue and are strong regulators of cerebrovascular tone. Transient ischemia can cause brain intracellular alkalosis producing vasoconstriction. However, the mechanisms of alkalosis-induced cerebral arteriolar constriction are poorly understood. Here, we determined the vascular responses to alkalosis under different conditions by monitoring the internal diameter of pressurized penetrating arterioles isolated from the rat cerebrum with an operating microscope. The roles of Na+/H+ exchanger (NHE), Na+/Ca²+ exchanger (NCX), Na+/K+-adenosine triphosphatase (NKA), and potassium (K+) channels during alkalosis were examined using specific inhibitors. Our results indicated that the extent of constriction of the penetrating arterioles was dependent on alkaline pH. Moreover, the alkalosis-induced vasoconstriction was significantly attenuated by inhibitors of NHE, NCX, and NKA, but not K+ channel inhibitors. Therefore, we concluded that NHE, NKA, and NCX are important regulators involved in alkalosis-induced vasoconstriction of rat cerebral penetrating arterioles.
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Affiliation(s)
- Yuhui Li
- Department of Neurosurgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
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29
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Vascular Biology and Atherosclerosis of Cerebral Arteries. Stroke 2011. [DOI: 10.1016/b978-1-4160-5478-8.10001-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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An Analysis of Changes in Cerebral Blood Flood Velocities in Depressive Pseudo-Dementia and Alzheimer Disease Patients. Neurologist 2010; 16:358-63. [DOI: 10.1097/nrl.0b013e3181a2eace] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Wienecke T, Olesen J, Ashina M. Discrepancy between strong cephalic arterial dilatation and mild headache caused by prostaglandin D2 (PGD2). Cephalalgia 2010; 31:65-76. [DOI: 10.1177/0333102410373156] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Introduction: Prostaglandins (PGs) are involved in nociception and mast cell degranulation. Prostaglandin D2 (PGD2) is a vasodilatator released during mast cell degranulation. The headache-eliciting effect of PGD2 has not been studied in man. Subjects and methods: Twelve healthy volunteers were randomly allocated to receive intravenous infusion of 384 ng/kg/min PGD2 over 25 min in a placebo-controlled, double-blind cross-over study. We recorded headache intensity and associated symptoms, velocity in the middle cerebral artery (VMCA) and diameter of the superficial temporal artery (STA) and radial artery (RA) using ultrasonography. Results: In the period 0–14 h, 11 subjects reported headache on PGD2 compared to one subject on placebo ( P = 0.002). During the in-hospital phase (0–120 min), the area under the headache curve was larger on PGD2 compared to placebo ( P < 0.05). Median peak headache, 1 (0–1), occurred 10 min after start of PGD2 infusion. There was no difference in incidence of headache in the post-hospital phase between PGD2 ( n = 3) and placebo ( n = 1). There was a decrease in VMCA ( P < 0.001), increase in STA ( P < 0.001) and RA ( P < 0.006) diameter during PGD2 infusion compared to placebo. Peak decrease in VMCA was 28.3% after 10 min and peak increase in STA was 55.7% after 20 min on the PGD2 day. Conclusions: The present study shows that PGD2 is a very strong vasodilator of MCA, STA and RA, but causes only mild headache.
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Zhang HF, Chen XQ, Hu GY, Wang YP. Magnesium lithospermate B dilates mesenteric arteries by activating BKCa currents and contracts arteries by inhibiting K(V) currents. Acta Pharmacol Sin 2010; 31:665-70. [PMID: 20453873 DOI: 10.1038/aps.2010.40] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIM To examine the involvement of K(+) channels and endothelium in the vascular effects of magnesium lithospermate B (MLB), a hydrophilic active component of Salviae miltiorrhiza Radix. METHODS Isolated rat mesenteric artery rings were employed to investigate the effects of MLB on KCl- or norepinephrine-induced contractions. Conventional whole-cell patch-clamp technique was used to study the effects of MLB on K(+) currents in single isolated mesenteric artery myocytes. RESULTS MLB produced a concentration-dependent relaxation in mesenteric artery rings precontracted by norepinephrine (1 micromol/L) with an EC(50) of 111.3 micromol/L. MLB-induced relaxation was reduced in denuded artery rings with an EC(50) of 224.4 micromol/L. MLB caused contractions in KCl-precontracted artery rings in the presence of N-nitro-L-arginine methyl ester (L-NAME) with a maximal value of 130.3%. The vasodilatory effect of MLB was inhibited by tetraethylammonium (TEA) in both intact and denuded artery rings. In single smooth muscle cells, MLB activated BK(Ca) currents (EC(50) 156.3 micromol/L) but inhibited K(V) currents (IC(50) 26.1 micromol/L) in a voltage- and concentration-dependent manner. CONCLUSION MLB dilated arteries by activating BK(Ca) channels in smooth muscle cells and increasing NO release from endothelium, but it also contracted arteries precontracted with KCl in the presence of L-NAME.
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Affiliation(s)
- WILLIAM F. JACKSON
- Department of Biological Sciences, College of Arts and Sciences, Western Michigan University, Kalamazoo, MI, USA
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Rutten K, Van Donkelaar EL, Ferrington L, Blokland A, Bollen E, Steinbusch HW, Kelly PA, Prickaerts JH. Phosphodiesterase inhibitors enhance object memory independent of cerebral blood flow and glucose utilization in rats. Neuropsychopharmacology 2009; 34:1914-25. [PMID: 19262466 DOI: 10.1038/npp.2009.24] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phosphodiesterase (PDE) inhibitors prevent the breakdown of the second messengers, cyclic AMP (cAMP) and cyclic GMP (cGMP), and are currently studied as possible targets for cognitive enhancement. Earlier studies indicated beneficial effects of PDE inhibitors in object recognition. In this study we tested the effects of three PDE inhibitors on spatial memory as assessed in a place and object recognition task. Furthermore, as both cAMP and cGMP are known vasodilators, the effects of PDE inhibition on cognitive functions could be explained by enhancement of cerebrovascular function. We examined this possibility by measuring the effects of PDE5 and PDE4 inhibitor treatment on local cerebral blood flow and glucose utilization in rats using [14C]-iodoantipyrine and [14C]-2-deoxyglucose quantitative autoradiography, respectively. In the spatial location task, PDE5 inhibition (cGMP) with vardenafil enhanced only early phase consolidation, PDE4 inhibition (cAMP) with rolipram enhanced only late phase consolidation, and PDE2 inhibition (cAMP and cGMP) with Bay 60-7550 enhanced both consolidation processes. Furthermore, PDE5 inhibition had no cerebrovascular effects in hippocampal or rhinal areas. PDE4 inhibition increased rhinal, but not hippocampal blood flow, whereas it decreased glucose utilization in both areas. In general, PDE5 inhibition decreased the ratio between blood flow and glucose utilization, indicative of general oligaemia; whereas PDE4 inhibition increased this ratio, indicative of general hyperemia. Both oligaemic and hyperemic conditions are detrimental for brain function and do not explain memory enhancement. These results underscore the specific effects of cAMP and cGMP on memory consolidation (object and spatial memory) and provide evidence that the underlying mechanisms of PDE inhibition on cognition are independent of cerebrovascular effects.
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Affiliation(s)
- Kris Rutten
- Department of Neuroscience, Faculty of Health, Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
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Selective phosphodiesterase inhibitors: a promising target for cognition enhancement. Psychopharmacology (Berl) 2009; 202:419-43. [PMID: 18709359 PMCID: PMC2704616 DOI: 10.1007/s00213-008-1273-x] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 07/23/2008] [Indexed: 12/15/2022]
Abstract
RATIONALE One of the major complaints most people face during aging is an impairment in cognitive functioning. This has a negative impact on the quality of daily life and is even more prominent in patients suffering from neurodegenerative and psychiatric disorders including Alzheimer's disease, schizophrenia, and depression. So far, the majority of cognition enhancers are generally targeting one particular neurotransmitter system. However, recently phosphodiesterases (PDEs) have gained increased attention as a potential new target for cognition enhancement. Inhibition of PDEs increases the intracellular availability of the second messengers cGMP and/or cAMP. OBJECTIVE The aim of this review was to provide an overview of the effects of phosphodiesterase inhibitors (PDE-Is) on cognition, the possible underlying mechanisms, and the relationship to current theories about memory formation. MATERIALS AND METHODS Studies of the effects of inhibitors of different PDE families (2, 4, 5, 9, and 10) on cognition were reviewed. In addition, studies related to PDE-Is and blood flow, emotional arousal, and long-term potentiation (LTP) were described. RESULTS PDE-Is have a positive effect on several aspects of cognition, including information processing, attention, memory, and executive functioning. At present, these data are likely to be explained in terms of an LTP-related mechanism of action. CONCLUSION PDE-Is are a promising target for cognition enhancement; the most suitable candidates appear to be PDE2-Is or PDE9-Is. The future for PDE-Is as cognition enhancers lies in the development of isoform-specific PDE-Is that have limited aversive side effects.
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36
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Molecular studies of BKCa channels in intracranial arteries: presence and localization. Cell Tissue Res 2008; 334:359-69. [DOI: 10.1007/s00441-008-0701-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 09/16/2008] [Indexed: 01/17/2023]
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Blanco VM, Stern JE, Filosa JA. Tone-dependent vascular responses to astrocyte-derived signals. Am J Physiol Heart Circ Physiol 2008; 294:H2855-63. [PMID: 18456724 DOI: 10.1152/ajpheart.91451.2007] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A growing number of studies support an important contribution of astrocytes to neurovascular coupling, i.e., the phenomenon by which variations in neuronal activity trigger localized changes in blood flow that serve to match the metabolic demands of neurons. However, since both constriction and dilations have been observed in brain parenchymal arterioles upon astrocyte stimulation, the specific influences of these cells on the vasculature remain unclear. Using acute brain slices, we present evidence showing that the specific degree of constriction of rat cortical arterioles (vascular tone) is a key determinant of the magnitude and polarity of the diameter changes elicited by signals associated with neurovascular coupling. Thus elevation of extracellular K+ concentration, stimulation of metabotropic glutamate receptors (mGluR), or 11,12-epoxyeicosatrienoic acid application all elicited vascular responses that were affected by the particular resting arteriolar tone. Interestingly, the data suggest that the extent and/or polarity of the vascular responses are influenced by a delimited set point centered between 30 and 40% tone. In addition, we report that distinct, tone-dependent effects on arteriolar diameter occur upon stimulation of mGluR during inhibition of enzymes of the arachidonic acid pathway [i.e., phospholipase A2, cytochrome P-450 (CYP) omega-hydroxylase, CYP epoxygenase, and cycloxygenase-1]. Our findings may reconcile previous evidence in which direct astrocytic stimulation elicited either vasoconstrictions or vasodilations and also suggest the novel concept that, in addition to participating in functional hyperemia, astrocyte-derived signals play a role in adjusting vascular tone to a range where dilator responses are optimal.
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Affiliation(s)
- Víctor M Blanco
- Department of Psychiatry, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA
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MINAMITANI H, OHTA H, NAKADATE H, ODAWARA M, SEKIZUKA E, OSHIO C. Evaluation of effects of ibudilast on adhesion of platelets and leukocytes to photochemically-stimulated endothelial cells. ACTA ACUST UNITED AC 2008. [DOI: 10.2491/jjsth.19.129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Wu BN, Chen CF, Hong YR, Howng SL, Lin YL, Chen IJ. Activation of BKCa channels via cyclic AMP- and cyclic GMP-dependent protein kinases by eugenosedin-A in rat basilar artery myocytes. Br J Pharmacol 2007; 152:374-85. [PMID: 17700725 PMCID: PMC2042951 DOI: 10.1038/sj.bjp.0707406] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE The study investigated whether eugenosedin-A, a 5-hydroxytryptamine and alpha/beta adrenoceptor antagonist, enhanced delayed-rectifier potassium (K(DR))- or large-conductance Ca(2+)-activated potassium (BK(Ca))-channel activity in basilar artery myocytes through cyclic AMP/GMP-dependent and -independent protein kinases. EXPERIMENTAL APPROACH Cerebral smooth muscle cells (SMCs) were enzymatically dissociated from rat basilar arteries. Conventional whole cell, perforated and inside-out patch-clamp electrophysiology was used to monitor K(+)- and Ca(2+)-channel activities. KEY RESULTS Eugenosedin-A (1 microM) did not affect the K(DR) current but dramatically augmented BK(Ca) channel activity in a concentration-dependent manner. Increased BK(Ca) current was abolished by charybdotoxin (ChTX, 0.1 microM) or iberiotoxin (IbTX, 0.1 microM), but not affected by a small-conductance K(Ca) blocker (apamin, 100 microM). BK(Ca) current activation by eugenosedin-A was significantly inhibited by an adenylate cyclase inhibitor (SQ 22536, 10 microM), a soluble guanylate cyclase inhibitor (ODQ, 10 microM), competitive antagonists of cAMP and cGMP (Rp-cAMP, 100 microM and Rp-cGMP, 100 microM), and cAMP- and cGMP-dependent protein kinase inhibitors (KT5720, 0.3 microM and KT5823, 0.3 microM). Eugenosedin-A reversed the inhibition of BK(Ca) current induced by the protein kinase C activator, phorbol myristyl acetate (PMA, 0.1 microM). Eugenosedin-A also prevented BK(Ca) current inhibition induced by adding PMA, KT5720 and KT5823. Moreover, eugenosedin-A reduced the amplitude of voltage-dependent L-type Ca(2+) current (I(Ca,L)), but without modifying the voltage-dependence of the current. CONCLUSIONS AND IMPLICATIONS Eugenosedin-A enhanced BK(Ca) currents by stimulating the activity of cyclic nucleotide-dependent protein kinases. Physiologically, this activation would result in the closure of voltage-dependent calcium channels and thereby relax cerebral SMCs.
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Affiliation(s)
- B-N Wu
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
| | - C-F Chen
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
| | - Y-R Hong
- Graduate Institute of Biochemistry, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
| | - S-L Howng
- Department of Neurosurgery, Kaohsiung Medical University Hospital Kaohsiung, Taiwan
| | - Y-L Lin
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
| | - I-J Chen
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
- Author for correspondence:
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Abstract
The excitability of smooth muscle cells is regulated, in part, by stretch-activated ion channels in the plasma membrane. The response to stretch of a particular muscle or organ is tuned to specific functional needs by the types of ion channels expressed. Mechanosensitive ionic conductances that yield either inward or outward currents have been observed in and characterized in studies of smooth muscles. In vascular muscles, the dominant response to stretch is muscle contraction (the myogenic response). This chapter proposes several mechanisms for the myogenic response; one of these hypotheses involves stretch-dependent activation of nonselective cation channels. The inward current resulting from an activation of these channels causes plasma membrane depolarization, activation of voltage-gated Ca(2+) channels, Ca(2+) entry, and excitation-contraction coupling. Thus, increasing the vascular pressure and distension of blood vessels cause responsive vasoconstriction. Other conductances are also proposed as participants in the myogenic response, and progress characterizing the inward current channels responsive to stretch is summarized. Outward currents responding to muscle stretch are also present in smooth muscles. For example, expression of stretch-sensitive two-pore domain K(+) (K2P) channels has been reported in visceral smooth muscles. These organs resist contraction on filling and provide a reservoir function. Stretch-dependent outward current channels are hypothesized to help stabilize membrane potential until it becomes desirable to empty the stored contents. Mechanosensitive conductances participate in the integrated responses of smooth muscle tissues. The chapter summarizes the class of channels found in smooth muscles.
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Marvar PJ, Falck JR, Boegehold MA. High dietary salt reduces the contribution of 20-HETE to arteriolar oxygen responsiveness in skeletal muscle. Am J Physiol Heart Circ Physiol 2007; 292:H1507-15. [PMID: 17114243 DOI: 10.1152/ajpheart.00754.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The coupling of tissue blood flow to cellular metabolic demand involves oxygen-dependent adjustments in arteriolar tone, and arteriolar responses to oxygen can be mediated, in part, by changes in local production of 20-HETE. In this study, we examined the long-term effect of dietary salt on arteriolar oxygen responsiveness in the exteriorized, superfused rat spinotrapezius muscle and the role of 20-HETE in this responsiveness. Rats were fed either a normal-salt (NS, 0.45%) or high-salt (HS, 4%) diet for 4–5 wk. There was no difference in steady-state tissue Po2 between NS and HS rats, and elevation of superfusate oxygen content from 0% to 10% caused tissue Po2 to increase by the same amount in both groups. However, the resulting reductions in arteriolar diameter and blood flow were less in HS rats than NS rats. Inhibition of 20-HETE formation with N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) or 17-octadecynoic acid (17-ODYA) attenuated oxygen-induced constriction in NS rats but not HS rats. Exogenous 20-HETE elicited arteriolar constriction that was greatly reduced by the large-conductance Ca2+-activated potassium (KCa) channel inhibitors tetraethylammonium chloride (TEA) and iberiotoxin (IbTx) in NS rats and a smaller constriction that was less sensitive to TEA or IbTx in HS rats. Arteriolar responses to exogenous angiotensin II were similar in both groups but more sensitive to inhibition with DDMS in NS rats. Norepinephrine-induced arteriolar constriction was similar and insensitive to DDMS in both groups. We conclude that 20-HETE contributes to oxygen-induced constriction of skeletal muscle arterioles via inhibition of KCa channels and that a high-salt diet impairs arteriolar responses to increased oxygen availability due to a reduction in vascular smooth muscle responsiveness to 20-HETE.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Arterioles/drug effects
- Arterioles/physiology
- Hydroxyeicosatetraenoic Acids/metabolism
- Indomethacin/pharmacology
- Male
- Models, Animal
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Norepinephrine/pharmacology
- Oxygen/blood
- Rats
- Rats, Sprague-Dawley
- Sodium, Dietary/pharmacology
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- Paul J Marvar
- Dept of Physiology and Pharmacology, West Virginia Univ School of Medicine, Robert C Byrd Health Science Center, Morgantown, WV 26506-9229, USA
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Magnusson L, Sorensen CM, Braunstein TH, Holstein-Rathlou NH, Salomonsson M. Renovascular BKCachannels are not activated in vivo under resting conditions and during agonist stimulation. Am J Physiol Regul Integr Comp Physiol 2007; 292:R345-53. [PMID: 16973937 DOI: 10.1152/ajpregu.00337.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the role of large-conductance Ca2+-activated K+(BKCa) channels for the basal renal vascular tone in vivo. Furthermore, the possible buffering by BKCaof the vasoconstriction elicited by angiotensin II (ANG II) or norepinephrine (NE) was investigated. The possible activation of renal vascular BKCachannels by cAMP was investigated by infusing forskolin. Renal blood flow (RBF) was measured in vivo using electromagnetic flowmetry or ultrasonic Doppler. Renal preinfusion of tetraethylammonium (TEA; 3.0 μmol/min) caused a small reduction of baseline RBF, but iberiotoxin (IBT; 0.3 nmol/min) did not have any effect. Renal injection of ANG II (1–4 ng) or NE (10–40 ng) produced a transient decrease in RBF. These responses were not affected by preinfusion of TEA or IBT. Renal infusion of the BKCaopener NS-1619 (90.0 nmol/min) did not affect basal RBF or the response to NE, but it attenuated the response to ANG II. Coadministration of NS-1619 with TEA or IBT abolished this effect. Forskolin caused renal vasodilation that was not inhibited by IBT. The presence of BKCachannels in the preglomerular vessels was confirmed by immunohistochemistry. Despite their presence, there is no indication for a major role for BKCachannels in the control of basal renal tone in vivo. Furthermore, BKCachannels do not have a buffering effect on the rat renal vascular responses to ANG II and NE. The fact that NS-1619 attenuates the ANG II response indicates that the renal vascular BKCachannels can be activated under certain conditions.
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Affiliation(s)
- Linda Magnusson
- Division of Renal and Cardiovascular Research, Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
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Wu BN, Tu HF, Welsh DG, Chen IJ. KMUP-1 activates BKCa channels in basilar artery myocytes via cyclic nucleotide-dependent protein kinases. Br J Pharmacol 2006; 146:862-71. [PMID: 16151435 PMCID: PMC1751209 DOI: 10.1038/sj.bjp.0706387] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
This study investigated whether KMUP-1, a synthetic xanthine-based derivative, augments the delayed-rectifier potassium (K(DR))- or large-conductance Ca2+-activated potassium (BKCa) channel activity in rat basilar arteries through protein kinase-dependent and -independent mechanisms. Cerebral smooth muscle cells were enzymatically dissociated from rat basilar arteries. Conventional whole cell, perforated and inside-out patch-clamp electrophysiology was used to monitor K+- and Ca2+ channel activities. KMUP-1 (1 microM) had no effect on the K(DR) current but dramatically enhanced BKCa channel activity. This increased BKCa current activity was abolished by charybdotoxin (100 nM) and iberiotoxin (100 nM). Like KMUP-1, the membrane-permeable analogs of cGMP (8-Br-cGMP) and cAMP (8-Br-cAMP) enhanced the BKCa current. BKCa current activation by KMUP-1 was markedly inhibited by a soluble guanylate cyclase inhibitor (ODQ 10 microM), an adenylate cyclase inhibitor (SQ 22536 10 microM), competitive antagonists of cGMP and cAMP (Rp-cGMP, 100 microM and Rp-cAMP, 100 microM), and cGMP- and cAMP-dependent protein kinase inhibitors (KT5823, 300 nM and KT5720, 300 nM). Voltage-dependent L-type Ca2+ current was significantly suppressed by KMUP-1 (1 microM), and nearly abolished by a calcium channel blocker (nifedipine, 1 microM). In conclusion, KMUP-1 stimulates BKCa currents by enhancing the activity of cGMP-dependent protein kinase, and in part this is due to increasing cAMP-dependent protein kinase. Physiologically, this activation would result in the closure of voltage-dependent calcium channels and the relaxation of cerebral arteries.
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Affiliation(s)
- Bin-Nan Wu
- Department and Graduate Institute of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
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Asil T, Uzuner N. Differentiation of vascular dementia and Alzheimer disease: a functional transcranial Doppler ultrasonographic study. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2005; 24:1065-70. [PMID: 16040820 DOI: 10.7863/jum.2005.24.8.1065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
OBJECTIVE In brain perfusion studies, perfusion defects have been reported mainly in the temporal and parietal regions in patients with Alzheimer disease (AD), but it is known that the occipital cortex is partially preserved from metabolic defects in patients with AD, at least in the early stage of the disease. We therefore evaluated the reactivity of the posterior cerebral arteries during visual stimulation with transcranial Doppler ultrasonography (TDU). METHODS Fifteen patients with AD (mean age, 70 years), 12 patients with vascular dementia (VD) (mean age, 61.5 years), and 9 healthy control subjects (mean age, 58 years) were enrolled in the study. The reactivity of both posterior cerebral arteries during visual stimulation was measured with TDU. Reactivity was calculated by the differences in mean relative blood flow velocity (rBFv) between stimulation (vs) and rest (vr) divided by the resting value [rBFv = 100 x (vs - vr)/vr]. RESULTS Significant increases of vascular reactivity were obtained during visual stimulation for each group (P < .001). There was no significant right or left side difference for vascular reactivity within the groups except in VD; therefore, values of the right and left sides were pooled for patients with AD and control subjects. Reactivity to visual stimulation was similar for the patients with AD (mean +/- SD, 38% +/- 2.2%) and control subjects (35% +/- 1.8%), but reactivity was found significantly decreased in both sides of patients with VD (25.7% +/- 2.1% for the left side and 24% +/- 2.6% for the right side) compared with the healthy control subjects and the patients with AD (P < .001). CONCLUSIONS These results indicate that the occipital cortex is partially preserved in patients with AD and that functional TDU may be a valuable tool for differentiating VD and AD.
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Affiliation(s)
- Talip Asil
- Department of Neurology, Faculty of Medicine, University of Trakya, Edirne, Turkey.
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Faraci FM, Lynch C, Lamping KG. Responses of cerebral arterioles to ADP: eNOS-dependent and eNOS-independent mechanisms. Am J Physiol Heart Circ Physiol 2005; 287:H2871-6. [PMID: 15548728 DOI: 10.1152/ajpheart.00392.2004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ADP mediates platelet-induced relaxation of blood vessels and may function as an important intercellular signaling molecule in the brain. We used pharmacological and genetic approaches to examine mechanisms that mediate responses of cerebral arterioles to ADP, including the role of endothelial nitric oxide synthase (eNOS). We examined responses of cerebral arterioles (control diameter approximately 30 microm) in anesthetized wild-type (WT, eNOS+/+) and eNOS-deficient (eNOS-/-) mice using a cranial window. In WT mice, local application of ADP produced vasodilation that was not altered by indomethacin but was reduced by approximately 50% by NG-nitro-L-arginine (L-NNA) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (inhibitors of NOS and soluble guanylate cyclase, respectively). In eNOS-/- mice, responses to ADP were largely preserved, and a significant component of the response was resistant to L-NNA (a finding similar to that in WT mice treated with L-NNA). In the absence of L-NNA, responses to ADP were markedly reduced by charybdotoxin plus apamin [inhibitors of Ca2+-dependent K+ channels and responses mediated by endothelium-derived hyperpolarizing factor (EDHF)] in both WT and eNOS-/- mice. Thus pharmacological and genetic evidence suggests that a significant portion of the response to ADP in cerebral microvessels is mediated by a mechanism independent of eNOS. The eNOS-independent mechanism is functional in the absence of inhibited eNOS and most likely is mediated by an EDHF.
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Affiliation(s)
- Frank M Faraci
- Dept. of Internal Medicine, E318-2 GH, Univ. of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
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Abstract
Vascular smooth muscle (VSM) cells, endothelial cells (EC), and pericytes that form the walls of vessels in the microcirculation express a diverse array of ion channels that play an important role in the function of these cells and the microcirculation in both health and disease. This brief review focuses on the K+ channels expressed in smooth muscle and endothelial cells in arterioles. Microvascular VSM cells express at least four different classes of K+ channels, including inward-rectifier K+ channels (Kin), ATP-sensitive K+ channels (KATP), voltage-gated K+ channels (Kv), and large conductance Ca2+-activated K+ channels (BKCa). VSM KIR participate in dilation induced by elevated extracellular K+ and may also be activated by C-type natriuretic peptide, a putative endothelium-derived hyperpolarizing factor (EDHF). Vasodilators acting through cAMP or cGMP signaling pathways in VSM may open KATP, Kv, and BKCa, causing membrane hyperpolarization and vasodilation. VSMBKc. may also be activated by epoxides of arachidonic acid (EETs) identified as EDHF in some systems. Conversely, vasoconstrictors may close KATP, Kv, and BKCa through protein kinase C, Rho-kinase, or c-Src pathways and contribute to VSM depolarization and vasoconstriction. At the same time Kv and BKCa act in a negative feedback manner to limit depolarization and prevent vasospasm. Microvascular EC express at least 5 classes of K+ channels, including small (sKCa) and intermediate(IKCa) conductance Ca2+-activated K+ channels, Kin, KATP, and Kv. Both sK and IK are opened by endothelium-dependent vasodilators that increase EC intracellular Ca2+ to cause membrane hyper-polarization that may be conducted through myoendothelial gap junctions to hyperpolarize and relax arteriolar VSM. KIR may serve to amplify sKCa- and IKCa-induced hyperpolarization and allow active transmission of hyperpolarization along EC through gap junctions. EC KIR channels may also be opened by elevated extracellular K+ and participate in K+-induced vasodilation. EC KATP channels may be activated by vasodilators as in VSM. Kv channels may provide a negative feedback mechanism to limit depolarization in some endothelial cells.
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Affiliation(s)
- William F Jackson
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008-5410, USA.
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Peng X, Zhang C, Alkayed NJ, Harder DR, Koehler RC. Dependency of cortical functional hyperemia to forepaw stimulation on epoxygenase and nitric oxide synthase activities in rats. J Cereb Blood Flow Metab 2004; 24:509-17. [PMID: 15129182 DOI: 10.1097/00004647-200405000-00004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Individual inhibition of nitric oxide (NO) synthase and cytochrome P450 (CYP) epoxygenase activity attenuates cortical functional hyperemia evoked by whisker stimulation. The objectives of the present study were to determine (1) if administration of epoxygenase inhibitors attenuates cortical functional hyperemia by using a different modality of sensory activation (i.e., electrical stimulation of the rat forepaw), (2) if epoxygenase inhibition has an additive effect with NO synthase inhibition on the flow response, and (3) the cellular localization of the epoxygenase CYP2C11 in cerebral cortex. In six groups of anesthetized rats, the cortical surface was superfused for 90 minutes with (1) vehicle; (2) 1-mmol/L Nomega-nitro-L-arginine (L-NNA), to inhibit NO synthase activity; (3) 20-micromol/L N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH), a substrate inhibitor of P450 epoxygenase; (4) MS-PPOH plus L-NNA; (5) 20-micromol/L miconazole, a reversible inhibitor at the heme site of P450 epoxygenase; and (6) miconazole plus L-NNA. The percent increases in laser-Doppler perfusion over primary sensory cortex during 20-second forepaw stimulation were reduced by 44% to 64% in all drug-treated groups. The addition of L-NNA to MS-PPOH produced no additional reduction (64%) compared with MS-PPOH alone (64%) or L-NNA alone (60%). The addition of L-NNA to miconazole also produced no additional reduction in the flow response. In situ hybridization of CYP2C11 mRNA showed localization in astrocytes, including those adjacent to blood vessels. Thus, activity of both epoxygenase, presumably localized in astrocytes, and NO synthase is required for generating a complete cortical hyperemic response evoked by electrical forepaw stimulation. The lack of additional blood flow attenuation with the combination of the NO synthase and the distinct epoxygenase inhibitors suggests that the signaling pathways do not act in a simple parallel fashion and that other mediators may be involved in coupling cortical blood flow to neuronal activation.
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Affiliation(s)
- Xinqi Peng
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Vascular Biology and Atherosclerosis of Cerebral Arteries. Stroke 2004. [DOI: 10.1016/b0-44-306600-0/50044-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Wellman GC, Nelson MT. Signaling between SR and plasmalemma in smooth muscle: sparks and the activation of Ca2+-sensitive ion channels. Cell Calcium 2003; 34:211-29. [PMID: 12887969 DOI: 10.1016/s0143-4160(03)00124-6] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Intracellular calcium ions are involved in the regulation of nearly every aspect of cell function. In smooth muscle, Ca2+ can be delivered to Ca2+-sensitive effector molecules either by influx through plasma membrane ion channels or by intracellular Ca2+ release events. Ca2+ sparks are transient local increases in intracellular Ca2+ that arise from the opening of ryanodine-sensitive Ca2+ release channels (ryanodine receptors) located in the sarcoplasmic reticulum. In arterial myocytes, Ca2+ sparks occur near the plasma membrane and act to deliver high (microM) local Ca2+ to plasmalemmal Ca2+-sensitive ion channels, without directly altering global cytosolic Ca2+ concentrations. The two major ion channel targets of Ca2+ sparks are Ca2+-activated chloride (Cl(Ca)) channels and large-conductance Ca2+-activated potassium (BK) channels. The activation of BK channels by Ca2+ sparks play an important role in the regulation of arterial diameter and appear to be involved in the action of a variety of vasodilators. The coupling of Ca2+ sparks to BK channels can be influenced by a number of factors including membrane potential and modulatory beta subunits of BK channels. Cl(Ca) channels, while not present in all smooth muscle, can also be activated by Ca2+ sparks in some types of smooth muscle. Ca2+ sparks can also influence the activity of Ca2+-dependent transcription factors and expression of immediate early response genes such as c-fos. In summary, Ca2+ sparks are local Ca2+ signaling events that in smooth muscle can act on plasma membrane ion channels to influence excitation-contraction coupling as well as gene expression.
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Affiliation(s)
- George C Wellman
- Department of Pharmacology, The University of Vermont College of Medicine, Given Building, Room B-321, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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Peng X, Carhuapoma JR, Bhardwaj A, Alkayed NJ, Falck JR, Harder DR, Traystman RJ, Koehler RC. Suppression of cortical functional hyperemia to vibrissal stimulation in the rat by epoxygenase inhibitors. Am J Physiol Heart Circ Physiol 2002; 283:H2029-37. [PMID: 12384482 DOI: 10.1152/ajpheart.01130.2000] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Application of glutamate to glial cell cultures stimulates the formation and release of epoxyeicosatrienoic acids (EETs) from arachidonic acid by cytochome P-450 epoxygenases. Epoxygenase inhibitors reduce the cerebral vasodilator response to glutamate and N-methyl-D-aspartate. We tested the hypothesis that epoxygenase inhibitors reduce the somatosensory cortical blood flow response to whisker activation. In chloralose-anesthetized rats, percent changes in cortical perfusion over whisker barrel cortex were measured by laser-Doppler flowmetry during whisker stimulation. Two pharmacologically distinct inhibitors were superfused subdurally: 1) N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH), an epoxygenase substrate inhibitor; and 2) miconazole, a reversible cytochrome P-450 inhibitor acting on the heme moiety. Superfusion with 5 micromol/l MS-PPOH decreased the hyperemic response to whisker stimulation by 28% (from 25 +/- 9 to 18 +/- 7%, means +/- SD, n = 8). With 20 micromol/l MS-PPOH superfusion, the response was decreased by 69% (from 28 +/- 9% to 9 +/- 4%, n = 8). Superfusion with 20 micromol/l miconazole decreased the flow response by 67% (from 31 +/- 6% to 10 +/- 3%, n = 8). Subsequent superfusion with vehicle restored the response to 26 +/- 11%. Indomethacin did not prevent MS-PPOH inhibition of the flow response, suggesting that EET-related vasodilation was not dependent solely on cyclooxygenase metabolism of 5,6-EET. Neither MS-PPOH nor miconazole changed baseline flow, reduced the blood flow response to an adenosine A(2) agonist, or decreased somatosensory evoked potentials. The marked reduction of the cortical flow response to whisker stimulation with two different types of epoxygenase inhibitors indicates that EETs play an important role in the physiological coupling of blood flow to neural activation.
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Affiliation(s)
- Xinqi Peng
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University School of Medicine, 600 North Wolfe Street/Blalock 1404-E, Baltimore, MD 21287, USA
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