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[PMID]:25761950
[Au] Autor:Hirai Y; Nishino E; Ohmori H
[Ad] Endereço:Department of Neurobiology and Physiology, Faculty of Medicine, Kyoto University, Kyoto, Kyoto, Japan; and Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Kyoto, Japan.
[Ti] Título:Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo.
[So] Source:J Neurophysiol;113(10):3930-42, 2015 Jun 01.
[Is] ISSN:1522-1598
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices.
[Mh] Termos MeSH primário: Mapeamento Encefálico
Encéfalo/citologia
Encéfalo/fisiologia
Fluorescência
Neurônios/fisiologia
[Mh] Termos MeSH secundário: 4-Aminopiridina/farmacologia
Estimulação Acústica
Potenciais de Ação/efeitos dos fármacos
Potenciais de Ação/fisiologia
Animais
Animais Recém-Nascidos
Vias Auditivas/fisiologia
Cálcio/metabolismo
Galinhas
Estimulação Elétrica
Antagonistas GABAérgicos/farmacologia
Técnicas In Vitro
Neurônios/efeitos dos fármacos
Fotometria
Bloqueadores dos Canais de Potássio/farmacologia
Piridazinas/farmacologia
Compostos de Tetraetilamônio/farmacologia
Transfecção
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (GABA Antagonists); 0 (Potassium Channel Blockers); 0 (Pyridazines); 0 (Tetraethylammonium Compounds); 99460MG420 (gabazine); BH3B64OKL9 (4-Aminopyridine); SY7Q814VUP (Calcium)
[Em] Mês de entrada:1603
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150313
[St] Status:MEDLINE
[do] DOI:10.1152/jn.00005.2015


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[PMID]:24675657
[Au] Autor:Ozkor MA; Rahman AM; Murrow JR; Kavtaradze N; Lin J; Manatunga A; Hayek S; Quyyumi AA
[Ad] Endereço:From the Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA (M.A.O., A.M.R., J.R.M., N.K., S.H., A.A.Q.); and Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA (J.L., A.M.).
[Ti] Título:Differences in vascular nitric oxide and endothelium-derived hyperpolarizing factor bioavailability in blacks and whites.
[So] Source:Arterioscler Thromb Vasc Biol;34(6):1320-7, 2014 Jun.
[Is] ISSN:1524-4636
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:OBJECTIVE: Abnormalities in nitric oxide (NO) bioavailability have been reported in blacks. Whether there are differences in endothelium-derived hyperpolarizing factor (EDHF) in addition to NO between blacks and whites and how these affect physiological vasodilation remain unknown. We hypothesized that the bioavailability of vascular NO and EDHF, at rest and with pharmacological and physiological vasodilation, varies between whites and blacks. APPROACH AND RESULTS: In 74 white and 86 black subjects without known cardiovascular disease risk factors, forearm blood flow was measured using plethysmography at rest and during inhibition of NO with N(G)-monomethyl-L-arginine and of K(+) Ca channels (EDHF) with tetraethylammonium. The reduction in resting forearm blood flow was greater with N(G)-monomethyl-L-arginine (P=0.019) and similar with tetraethylammonium in whites compared with blacks. Vasodilation with bradykinin, acetylcholine, and sodium nitroprusside was lower in blacks compared with whites (all P<0.0001). Inhibition with N(G)-monomethyl-L-arginine was greater in whites compared with blacks with bradykinin, acetylcholine, and exercise. Inhibition with tetraethylammonium was lower in blacks with bradykinin, but greater during exercise and with acetylcholine. CONCLUSIONS: The contribution to both resting and stimulus-mediated vasodilator tone of NO is greater in whites compared with blacks. EDHF partly compensates for the reduced NO release in exercise and acetylcholine-mediated vasodilation in blacks. Preserved EDHF but reduced NO bioavailability and sensitivity characterizes the vasculature in healthy blacks. CLINICAL TRIAL REGISTRATION URL: http://clinicaltrials.gov/. Unique identifier: NCT00166166.
[Mh] Termos MeSH primário: Fatores Biológicos/fisiologia
Óxido Nítrico/fisiologia
Vasodilatação/fisiologia
[Mh] Termos MeSH secundário: Acetilcolina/farmacologia
Adulto
Afroamericanos
Disponibilidade Biológica
Bradicinina/farmacologia
Grupo com Ancestrais do Continente Europeu
Exercício
Feminino
Antebraço/irrigação sanguínea
Seres Humanos
Masculino
Meia-Idade
Nitroprussiato/farmacologia
Canais de Potássio Cálcio-Ativados/fisiologia
Compostos de Tetraetilamônio/farmacologia
Resistência Vascular/efeitos dos fármacos
Vasodilatação/efeitos dos fármacos
ômega-N-Metilarginina/farmacologia
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Biological Factors); 0 (Potassium Channels, Calcium-Activated); 0 (Tetraethylammonium Compounds); 0 (endothelium-dependent hyperpolarization factor); 169D1260KM (Nitroprusside); 27JT06E6GR (omega-N-Methylarginine); 31C4KY9ESH (Nitric Oxide); N9YNS0M02X (Acetylcholine); S8TIM42R2W (Bradykinin)
[Em] Mês de entrada:1407
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:140329
[Cl] Clinical Trial:ClinicalTrial
[St] Status:MEDLINE
[do] DOI:10.1161/ATVBAHA.113.303136


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[PMID]:24596399
[Au] Autor:Wu CT; Qi XY; Huang H; Naud P; Dawson K; Yeh YH; Harada M; Kuo CT; Nattel S
[Ad] Endereço:Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China.
[Ti] Título:Disease and region-related cardiac fibroblast potassium current variations and potential functional significance.
[So] Source:Cardiovasc Res;102(3):487-96, 2014 Jun 01.
[Is] ISSN:1755-3245
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:AIMS: Fibroblasts, which play an important role in cardiac function/dysfunction, including arrhythmogenesis, have voltage-dependent (Kv) currents of unknown importance. Here, we assessed the differential expression of Kv currents between atrial and ventricular fibroblasts from control dogs and dogs with an atrial arrhythmogenic substrate caused by congestive heart failure (CHF). METHODS AND RESULTS: Left atrial (LA) and ventricular (LV) fibroblasts were freshly isolated from control and CHF dogs (2-week ventricular tachypacing, 240 bpm). Kv currents were measured with whole-cell voltage-clamp, mRNA by quantitative polymerase chain reaction (qPCR) and fibroblast proliferation by (3)H-thymidine incorporation. Robust voltage-dependent tetraethylammonium (TEA)-sensitive K(+) currents (IC50 ∼1 mM) were recorded. The morphologies and TEA responses of LA and LV fibroblast Kv currents were similar. LV fibroblast Kv-current densities were significantly greater than LA, and Kv-current densities were significantly less in CHF than control. The mRNA expression of Kv-channel subunits Kv1.5 and Kv4.3 was less in LA vs. LV fibroblasts and was down-regulated in CHF, consistent with K(+)-current recordings. Ca(2+)-dependent K(+)-channel subunit (KCa1.1) mRNA and currents were less expressed in LV vs. LA fibroblasts. Inhibiting LA fibroblast K(+) current with 1 mmol/L of TEA or KCa1.1 current with paxilline increased proliferation. CONCLUSIONS: Fibroblast Kv-current expression is smaller in CHF vs. control, as well as LA vs. LV. KCa1.1 current is greater in LA vs. LV. Suppressing Kv current with TEA enhances fibroblast proliferation, suggesting that Kv current might act to check fibroblast proliferation and that reduced Kv current in CHF may contribute to fibrosis. Fibroblast Kv-current remodelling may play a role in the atrial fibrillation (AF) substrate; modulating fibroblast K(+) channels may present a novel strategy to prevent fibrosis and AF.
[Mh] Termos MeSH primário: Fibroblastos/fisiologia
Miocárdio/metabolismo
Canais de Potássio de Abertura Dependente da Tensão da Membrana/fisiologia
[Mh] Termos MeSH secundário: Animais
Fibrilação Atrial/etiologia
Cães
Fibrose
Insuficiência Cardíaca/complicações
Insuficiência Cardíaca/metabolismo
Masculino
Miocárdio/patologia
Compostos de Tetraetilamônio/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Potassium Channels, Voltage-Gated); 0 (Tetraethylammonium Compounds)
[Em] Mês de entrada:1503
[Cu] Atualização por classe:161019
[Lr] Data última revisão:
161019
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:140306
[St] Status:MEDLINE
[do] DOI:10.1093/cvr/cvu055


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[PMID]:24412196
[Au] Autor:Cao J; Tan H; Mi W; Zuo Z
[Ad] Endereço:Department of Anesthesiology, University of Virginia, Charlottesville, VA 22903, USA; Department of Anesthesiology and Operation Center, Chinese PLA General Hospital, Beijing 100853, China.
[Ti] Título:Glutamate transporter type 3 regulates mouse hippocampal GluR1 trafficking.
[So] Source:Biochim Biophys Acta;1840(6):1640-5, 2014 Jun.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: Rapid trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) to the plasma membrane is considered a fundamental biological process for learning and memory. GluR1 is an AMPAR subunit. We have shown that mice with knockout of excitatory amino acid transporter type 3 (EAAT3), a neuronal glutamate transporter, have impaired learning and memory. The mechanisms for this impairment are not known and may be via regulation of AMPAR trafficking. METHODS: Freshly prepared 300µm coronal hippocampal slices from wild-type or EAAT3 knockout mice were incubated with or without 25mM tetraethylammonium for 10min. The trafficking of GluR1, an AMPAR subunit, to the plasma membrane and its phosphorylation were measured. RESULTS: Tetraethylammonium increased the trafficking of GluR1 and EAAT3 to the plasma membrane in the wild-type mouse hippocampal slices but did not cause GluR1 trafficking in the EAAT3 knockout mice. Tetraethylammonium also increased the phosphorylation of GluR1 at S845, a protein kinase A (PKA) site, in the wild-type mice but not in the EAAT3 knockout mice. The PKA antagonist KT5720 attenuated tetraethylammonium-induced GluR1 phosphorylation and trafficking in the wild-type mice. The PKA agonist 6-BNz-cAMP caused GluR1 trafficking to the plasma membrane in the EAAT3 knockout mice. In addition, EAAT3 was co-immunoprecipitated with PKA. CONCLUSIONS: These results suggest that EAAT3 is upstream of PKA in a pathway to regulate GluR1 trafficking. GENERAL SIGNIFICANCE: Our results provide initial evidence for the involvement of EAAT3 in the biochemical cascade of learning and memory.
[Mh] Termos MeSH primário: Transportador 3 de Aminoácido Excitatório/fisiologia
Hipocampo/metabolismo
Receptores de AMPA/metabolismo
[Mh] Termos MeSH secundário: Animais
Proteínas Quinases Dependentes de AMP Cíclico/fisiologia
Masculino
Camundongos
Transporte Proteico
Compostos de Tetraetilamônio/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Excitatory Amino Acid Transporter 3); 0 (Receptors, AMPA); 0 (Slc1a1 protein, mouse); 0 (Tetraethylammonium Compounds); 0 (glutamate receptor ionotropic, AMPA 1); EC 2.7.11.11 (Cyclic AMP-Dependent Protein Kinases)
[Em] Mês de entrada:1407
[Cu] Atualização por classe:161126
[Lr] Data última revisão:
161126
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:140114
[St] Status:MEDLINE


  5 / 3226 MEDLINE  
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[PMID]:23142267
[Au] Autor:Zanotto C; Abib RT; Batassini C; Tortorelli LS; Biasibetti R; Rodrigues L; Nardin P; Hansen F; Gottfried C; Leite MC; Gonçalves CA
[Ad] Endereço:Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, Porto Alegre, RS, Brazil.
[Ti] Título:Non-specific inhibitors of aquaporin-4 stimulate S100B secretion in acute hippocampal slices of rats.
[So] Source:Brain Res;1491:14-22, 2013 Jan 23.
[Is] ISSN:1872-6240
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Aquaporin-4 (AQP-4) is the principal brain water channel and is predominantly expressed in astrocytes suggesting its dynamic involvement in water homeostasis in brain tissue. Due to the co-localization of AQP-4 and inward rectifier K(+) channels Kir 4.1, a functional coupling between these proteins has been proposed. AQP-4 has a putative role in the physiopathology of brain disorders including epilepsy and trauma. S100B is a calcium-binding protein expressed and secreted by astrocytes, and commonly used as a parameter of astroglial activation. Here, we investigate a possible link between AQP-4 activity (and Kir 4.1) and S100B secretion in hippocampal slices of rats of different ages using non-specific inhibitors of AQP-4 (AZA, acetazolamide and TEA, tetraethylammonium) and Kir 4.1 (barium chloride). We found that blockade of AQP-4 with TEA and AZA produced an increase in S100B secretion in young rats, compatible with an astroglial activation observed in many conditions of brain injury. On the other hand, BaCl(2) induced Kir 4.1 inhibition caused a decrease in S100B secretion. Both channels, AQP-4 and Kir 4.1, exhibited a similar ontogenetic profile, in spite of the functional uncoupling, in relation to S100B secretion. Moreover, we found a significant increase in the S100B secretion basal levels with the increasing of animal age and the incubation with high levels of potassium resulted in a decrease of S100B secretion in 30 and 90-day old rats. These data, together with previous observations from gap junctions and glutamate transport of astrocytes, contribute to characterize the operational system involving astroglial activation, particularly on S100B secretion, in brain disorders.
[Mh] Termos MeSH primário: Aquaporina 4/antagonistas & inibidores
Hipocampo/metabolismo
Fatores de Crescimento Neural/metabolismo
Proteínas S100/metabolismo
[Mh] Termos MeSH secundário: Acetazolamida/farmacologia
Animais
Compostos de Bário/farmacologia
Western Blotting
Cloretos/farmacologia
Ensaio de Imunoadsorção Enzimática
Técnicas In Vitro
Potássio/farmacologia
Canais de Potássio/efeitos dos fármacos
Canais de Potássio Corretores do Fluxo de Internalização/metabolismo
Ratos
Ratos Wistar
Subunidade beta da Proteína Ligante de Cálcio S100
Compostos de Tetraetilamônio/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Aquaporin 4); 0 (Barium Compounds); 0 (Chlorides); 0 (Kcnj10 (channel)); 0 (Nerve Growth Factors); 0 (Potassium Channels); 0 (Potassium Channels, Inwardly Rectifying); 0 (S100 Calcium Binding Protein beta Subunit); 0 (S100 Proteins); 0 (S100b protein, rat); 0 (Tetraethylammonium Compounds); 0VK51DA1T2 (barium chloride); O3FX965V0I (Acetazolamide); RWP5GA015D (Potassium)
[Em] Mês de entrada:1305
[Cu] Atualização por classe:141120
[Lr] Data última revisão:
141120
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:121113
[St] Status:MEDLINE


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[PMID]:22342118
[Au] Autor:Eliav U; Shekar SC; Ling W; Navon G; Jerschow A
[Ad] Endereço:School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
[Ti] Título:Magnetic alignment and quadrupolar/paramagnetic cross-correlation in complexes of Na with LnDOTP5-.
[So] Source:J Magn Reson;216:114-20, 2012 Mar.
[Is] ISSN:1096-0856
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The observation of a double-quantum filtered signal of quadrupolar nuclei (e.g. (23)Na) in solution has been traditionally interpreted as a sign for anisotropic reorientational motion. Ling and Jerschow (2007) have found that a (23)Na double-quantum signal is observed also in solutions of TmDOTPNa(5). Interference effects between the quadrupolar and the paramagnetic interactions have been reported to lead to the appearance of double-quantum coherences even in the absence of a residual quadrupolar interaction. In addition, such processes lead to differential linebroadening effects between the satellite transitions, akin to effects that are well known for dipolar-CSA cross-correlation. Here, we report experiments on sodium in the presence of LnDOTP compounds, where it is shown that these cross-correlation effects correlate well with the pseudo-contact shift. In addition, anisotropic g-values of the lanthanide compounds in question, can also lead to alignment within the magnetic field, and consequently to the appearance of line splitting and double-quantum coherences. The two competing effects are demonstrated and it is concluded that both cross-correlated relaxation and alignment in the magnetic field must be at work in the systems described here.
[Mh] Termos MeSH primário: Lantânio/química
Oxazóis/química
Pirimidinonas/química
Sódio/química
[Mh] Termos MeSH secundário: Algoritmos
Anisotropia
Campos Eletromagnéticos
Espectroscopia de Ressonância de Spin Eletrônica
Concentração de Íons de Hidrogênio
Espectroscopia de Ressonância Magnética
Soluções
Temperatura Ambiente
Compostos de Tetraetilamônio/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
0 (Oxazoles); 0 (Pyrimidinones); 0 (Solutions); 0 (Tetraethylammonium Compounds); 123495-11-4 (2,3-dihydro-5H-oxazolo(3,2-a)thieno(3,2-d)pyrimidin-5-one); 6I3K30563S (Lanthanum); 9NEZ333N27 (Sodium)
[Em] Mês de entrada:1207
[Cu] Atualização por classe:131121
[Lr] Data última revisão:
131121
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:120221
[St] Status:MEDLINE
[do] DOI:10.1016/j.jmr.2012.01.012


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[PMID]:22145309
[Au] Autor:Evstigneev DA; Glukhova NV; Kuznetsova IV
[Ti] Título:[The role of fast and slow potassium currents in electrical activity of amphibian myelinated nerve fibres].
[So] Source:Usp Fiziol Nauk;42(4):20-38, 2011 Oct-Dec.
[Is] ISSN:0301-1798
[Cp] País de publicação:Russia (Federation)
[La] Idioma:rus
[Ab] Resumo:The paper reviews the information about the role of fast and slow potassium currents in electrical activity of amphibian myelinated nerve fibres. It demonstrates the importance of discovering of fast and slow potassium currents and their following pharmacological separation (by potassium channels blockers 4-aminopyridine and tetraethylammonium) in investigation of mechanisms of biological potentials generation. The information about the existence of fast and slow potassium channels in the nerve membrane and about the properties of 4-aminopyridine and tetraethylammonium action served as a base for determination the nature of biological potentials and discovering the mechanism of potential-dependent action of 4-aminopyridine that for tens of years suffered from the lack of adequate explanation.
[Mh] Termos MeSH primário: Potenciais de Ação/fisiologia
Anfíbios/fisiologia
Bloqueadores dos Canais de Potássio/farmacologia
Canais de Potássio/fisiologia
Potássio/metabolismo
Potenciais Sinápticos/fisiologia
[Mh] Termos MeSH secundário: 4-Aminopiridina/farmacologia
Potenciais de Ação/efeitos dos fármacos
Animais
Decapodiformes/fisiologia
Fenômenos Eletrofisiológicos
Microeletrodos
Fibras Nervosas Mielinizadas/efeitos dos fármacos
Fibras Nervosas Mielinizadas/fisiologia
Canais de Potássio/classificação
Canais de Potássio/efeitos dos fármacos
Potenciais Sinápticos/efeitos dos fármacos
Compostos de Tetraetilamônio/farmacologia
[Pt] Tipo de publicação:ENGLISH ABSTRACT; JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Potassium Channel Blockers); 0 (Potassium Channels); 0 (Tetraethylammonium Compounds); BH3B64OKL9 (4-Aminopyridine); RWP5GA015D (Potassium)
[Em] Mês de entrada:1112
[Cu] Atualização por classe:131121
[Lr] Data última revisão:
131121
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:111208
[St] Status:MEDLINE


  8 / 3226 MEDLINE  
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[PMID]:21346204
[Au] Autor:Winlove CI; Roberts A
[Ad] Endereço:Neurobiology, School of Biological Sciences, Woodland Road, Bristol BS8 2UG, United Kingdom. c.i.p.winlove@bristol.ac.uk
[Ti] Título:Pharmacology of currents underlying the different firing patterns of spinal sensory neurons and interneurons identified in vivo using multivariate analysis.
[So] Source:J Neurophysiol;105(5):2487-500, 2011 May.
[Is] ISSN:1522-1598
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The operation of neuronal networks depends on the firing patterns of the network's neurons. When sustained current is injected, some neurons in the central nervous system fire a single action potential and others fire repetitively. For example, in Xenopus laevis tadpoles, primary-sensory Rohon-Beard (RB) neurons fired a single action potential in response to 300-ms rheobase current injections, whereas dorsolateral (DL) interneurons fired repetitively at 10-20 Hz. To investigate the basis for these differences in vivo, we examined drug-induced changes in the firing patterns of Xenopus spinal neurons using whole cell current-clamp recordings. Neuron types were initially separated through cluster analysis, and we compared results produced using different clustering algorithms. We used these results to develop a predictive function to classify subsequently recorded neurons. The potassium channel blocker tetraethylammonium (TEA) converted single-firing RB neurons to low-frequency repetitive firing but reduced the firing frequency of repetitive-firing DL interneurons. Firing frequency in DL interneurons was also reduced by the potassium channel blockers 4-aminopyridine (4-AP), catechol, and margatoxin; 4-AP had the greatest effect. The calcium channel blockers amiloride and nimodipine had few effects on firing in either neuron type but reduced action potential duration in DL interneurons. Muscarine, which blocks M-currents, did not affect RB neurons but reduced firing frequency in DL interneurons. These results suggest that potassium currents may control neuron firing patterns: a TEA-sensitive current prevents repetitive firing in RB neurons, whereas a 4-AP-sensitive current underlies repetitive firing in DL interneurons. The cluster and discriminant analysis described could help to classify neurons in other systems.
[Mh] Termos MeSH primário: Potenciais de Ação/fisiologia
Interneurônios/fisiologia
Bloqueadores dos Canais de Potássio/farmacologia
Canais de Potássio/fisiologia
Células Receptoras Sensoriais/fisiologia
[Mh] Termos MeSH secundário: Potenciais de Ação/efeitos dos fármacos
Animais
Interneurônios/efeitos dos fármacos
Análise Multivariada
Células Receptoras Sensoriais/efeitos dos fármacos
Compostos de Tetraetilamônio/farmacologia
Xenopus laevis
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Potassium Channel Blockers); 0 (Potassium Channels); 0 (Tetraethylammonium Compounds)
[Em] Mês de entrada:1204
[Cu] Atualização por classe:170922
[Lr] Data última revisão:
170922
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:110225
[St] Status:MEDLINE
[do] DOI:10.1152/jn.00779.2010


  9 / 3226 MEDLINE  
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[PMID]:22128447
[Au] Autor:Castillo-Hernandez Mdel C; Meraz-Cruz N; Guevara-Balcazar G; Lopez-Canales J; Lopez-Canales O; Galindo N; Castillo-Henkel C
[Ad] Endereço:Seccion de Estudios de Posgrado e Investigación de la Escuela Superior de Medicina, I.P.N, México. drcarloscastillo@hotmail.com
[Ti] Título:Age-related differences in the beta-adrenergic vasodilator response in rat aortic rings.
[So] Source:Proc West Pharmacol Soc;53:29-32, 2010.
[Is] ISSN:0083-8969
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Mechanisms underlying age-dependent changes in vasodilator responses to beta-adrenergic drugs are poorly understood. The aim of the current study was to compare responses to isoproterenol (a non-selective beta-adrenergic receptor agonist) in phenylephrine or KCl precontracted aortic rings from 3 week and 3 month old male Wistar rats. Both the mechanism and the subtype of beta-adrenergic receptor underlying the response to isoproterenol in the both age groups were examined. Endothelial removal, pre-contraction with KCl (40 mM), pre-treatment with tetraethylammonium or with N(omega)-Nitro-L-arginine methyl ester inhibited the vasodilator response to isoproterenol only in aortic rings from older rats. The inhibition was total when TEA and L-NAME were administered together. In both age groups the response to isoproterenol was unaffected by the beta1-adrenergic antagonist CGP20712A, but was significantly inhibited by ICI 118551 (a beta2-adrenergic-antagonist) and to a greater extent by SR 59230A (a non-selective beta 3-adrenergic antagonist), the inhibition being more evident in the older rats. Unlike younger rats, in older animals the response to isoproterenol was partially dependent on endothelial nitric oxide and on K+ channels. In both age groups, beta2- and beta3-, but not beta1-adrenergic receptors were involved. The degree of relative participation of beta2 and beta3 adrenergic receptors may change with age and explain the differences in response to isoproterenol.
[Mh] Termos MeSH primário: Aorta/efeitos dos fármacos
Receptores Adrenérgicos beta/fisiologia
Vasodilatação/efeitos dos fármacos
[Mh] Termos MeSH secundário: Fatores Etários
Animais
Aorta/fisiologia
Técnicas In Vitro
Isoproterenol/farmacologia
Masculino
NG-Nitroarginina Metil Éster/farmacologia
Cloreto de Potássio/farmacologia
Ratos
Ratos Wistar
Compostos de Tetraetilamônio/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Receptors, Adrenergic, beta); 0 (Tetraethylammonium Compounds); 660YQ98I10 (Potassium Chloride); L628TT009W (Isoproterenol); V55S2QJN2X (NG-Nitroarginine Methyl Ester)
[Em] Mês de entrada:1112
[Cu] Atualização por classe:141120
[Lr] Data última revisão:
141120
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:111201
[St] Status:MEDLINE


  10 / 3226 MEDLINE  
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Texto completo
[PMID]:20850441
[Au] Autor:Yu Y; Ali DW; Chang JP
[Ad] Endereço:Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
[Ti] Título:Characterization of ionic currents and electrophysiological properties of goldfish somatotropes in primary culture.
[So] Source:Gen Comp Endocrinol;169(3):231-43, 2010 Dec 01.
[Is] ISSN:1095-6840
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Growth hormone release in goldfish is partly dependent on voltage-sensitive Ca(2+) channels but somatotrope electrophysiological events affecting such channel activities have not been elucidated in this system. The electrophysiological properties of goldfish somatotropes in primary culture were studied using the whole-cell and amphotericin B-perforated patch-clamp techniques. Intracellular Ca(2+) concentration ([Ca(2+)]i) of identified somatotropes was measured using Fura-2/AM dye. Goldfish somatotropes had an average resting membrane potential of -78.4 ± 4.6 mV and membrane input resistance of 6.2 ± 0.2 GΩ. Voltage steps from a holding potential of -90 mV elicited a non-inactivating outward current and transient inward currents at potentials more positive than 0 and -30 mV, respectively. Isolated current recordings indicate the presence of 4-aminopyridine- and tetraethylammonium (TEA)-sensitive K(+), tetrodotoxin (TTX)-sensitive Na(+), and nifedipine (L-type)- and ω-conotoxin GVIA (N-type)-sensitive Ca(2+) channels. Goldfish somatotropes rarely fire action potentials (APs) spontaneously, but single APs can be induced at the start of a depolarizing current step; this single AP was abolished by TTX and significantly reduced by nifedipine and ω-conotoxin GVIA. TEA increased AP duration and triggered repetitive AP firing resulting in an increase in [Ca(2+)]i, whereas TTX, nifedipine and ω-conotoxin GVIA inhibited TEA-induced [Ca(2+)]i pulses. These results indicate that in goldfish somatotropes, TEA-sensitive K(+) channels regulate excitability while TTX-sensitive Na(+) channels together with N- and L-type Ca channels mediates the depolarization phase of APs. Opening of voltage-sensitive Ca(2+) channels during AP firing leads to increases in [Ca(2+)]i.
[Mh] Termos MeSH primário: Carpa Dourada/fisiologia
Somatotrofos/fisiologia
[Mh] Termos MeSH secundário: 4-Aminopiridina/farmacologia
Potenciais de Ação/efeitos dos fármacos
Animais
Bário/fisiologia
Canais de Cálcio/fisiologia
Células Cultivadas
Potenciais da Membrana/fisiologia
Nifedipino
Técnicas de Patch-Clamp
Canais de Potássio/fisiologia
Canais de Sódio/fisiologia
Compostos de Tetraetilamônio/farmacologia
ômega-Conotoxina GVIA/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Calcium Channels); 0 (Potassium Channels); 0 (Sodium Channels); 0 (Tetraethylammonium Compounds); 24GP945V5T (Barium); 92078-76-7 (omega-Conotoxin GVIA); BH3B64OKL9 (4-Aminopyridine); I9ZF7L6G2L (Nifedipine)
[Em] Mês de entrada:1102
[Cu] Atualização por classe:131121
[Lr] Data última revisão:
131121
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:100921
[St] Status:MEDLINE
[do] DOI:10.1016/j.ygcen.2010.09.008



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