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1.
J Mater Chem B ; 10(39): 8024-8032, 2022 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-36098268

RESUMO

Dopamine (DA) is an important neurotransmitter, which is essential for transmitting signals in neuronal communications. The deficiency of DA release from neurons is implicated in neurological disorders. There has been great interest in developing new optical probes for monitoring the release behavior of DA from neurons. H-aggregates of organic dyes represent an ordered supramolecular structure with delocalized excitons. In this paper, we use the self-assembly of 3,3'-diethylthiadicarbocyanine iodide (DiSC2(5)) in ammonia solution to develop crystalline H-aggregate nanoparticles, in which DiSC2(5) molecules show long-range π-π stacking. The crystalline H-aggregate nanoparticles are stable in cell culture medium and can serve as an efficient photo-induced electron transfer (PET) probe for the detection of DA with the concentration as low as 0.1 nM in cell culture medium. Furthermore, the crystalline H-aggregate nanoparticle-based PET probe is used to detect the release behavior of DA from the M17 human neuroblastoma cells. We find that the DA release from the cells is enhanced by nicotine stimulations. Our results highlight the potential of crystalline H-aggregate nanoparticle-based PET probes for diagnosing nervous system diseases and verifying therapies.


Assuntos
Ditiazanina , Nanopartículas , Neuroblastoma , Amônia , Corantes , Dopamina/farmacologia , Humanos , Iodetos , Neuroblastoma/diagnóstico por imagem , Neurotransmissores , Nicotina
2.
Chemistry ; 21(39): 13802-11, 2015 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-26263181

RESUMO

The interactions of a dicarbocyanine dye 3,3'-diethylthiadicarbocyanine, DiSC2(5), with DNA G-quadruplexes were studied by means of a combination of various spectroscopic techniques. Aggregation of excess dye as a result of its positive charge is promoted by the presence of the polyanionic quadruplex structure. Specific high-affinity binding to the parallel quadruplex of the MYC promoter sequence involves stacking of DiSC2(5) on the external G-tetrads; the 5'-terminal tetrad is the favored binding site. Significant energy transfer between DNA and the dye in the UV spectral region is observed upon DiSC2(5) binding. The transfer efficiency strongly depends on the DNA secondary structure as well as on the G-quadruplex topology. These photophysical features enable the selective detection of DNA quadruplexes through sensitized DiSC2(5) fluorescence in the visible region.


Assuntos
Carbocianinas/química , DNA/química , Ditiazanina/química , Corantes Fluorescentes/química , Ânions/química , Sítios de Ligação , DNA/metabolismo , Quadruplex G , Espectroscopia de Ressonância Magnética , Simulação de Dinâmica Molecular , Conformação de Ácido Nucleico , Processos Fotoquímicos
4.
Proc Natl Acad Sci U S A ; 110(29): 11751-6, 2013 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-23818631

RESUMO

Current therapy for glioblastoma multiforme is insufficient, with nearly universal recurrence. Available drug therapies are unsuccessful because they fail to penetrate through the region of the brain containing tumor cells and they fail to kill the cells most responsible for tumor development and therapy resistance, brain cancer stem cells (BCSCs). To address these challenges, we combined two major advances in technology: (i) brain-penetrating polymeric nanoparticles that can be loaded with drugs and are optimized for intracranial convection-enhanced delivery and (ii) repurposed compounds, previously used in Food and Drug Administration-approved products, which were identified through library screening to target BCSCs. Using fluorescence imaging and positron emission tomography, we demonstrate that brain-penetrating nanoparticles can be delivered to large intracranial volumes in both rats and pigs. We identified several agents (from Food and Drug Administration-approved products) that potently inhibit proliferation and self-renewal of BCSCs. When loaded into brain-penetrating nanoparticles and administered by convection-enhanced delivery, one of these agents, dithiazanine iodide, significantly increased survival in rats bearing BCSC-derived xenografts. This unique approach to controlled delivery in the brain should have a significant impact on treatment of glioblastoma multiforme and suggests previously undescribed routes for drug and gene delivery to treat other diseases of the central nervous system.


Assuntos
Antineoplásicos/uso terapêutico , Barreira Hematoencefálica/metabolismo , Ditiazanina/uso terapêutico , Sistemas de Liberação de Medicamentos/métodos , Glioblastoma/tratamento farmacológico , Nanopartículas/administração & dosagem , Animais , Antineoplásicos/administração & dosagem , Ditiazanina/administração & dosagem , Fluorescência , Estimativa de Kaplan-Meier , Tomografia por Emissão de Pósitrons , Ratos , Suínos
5.
J Phys Chem A ; 117(29): 5909-18, 2013 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-23176149

RESUMO

Certain cyanine dye molecules have been observed to self-assemble in DNA templates to form large chiral aggregates, which exhibit induced circular dichroism. The structure and circular dichroism (CD) of one such system, aggregates of a cationic DiSC2(5) cyanine dye, are investigated using the time-dependent Kohn-Sham density functional theory (TD-DFT) and exciton coupling model. A series of TD-DFT calculations on the aggregates with one, two, and four dye molecules clearly shows the onset of CD induced by the helically twisted structure compatible with the minor groove of DNA templates. More simplified exciton coupling model analysis successfully reproduces the major positive Cotton effect observed in the experiment as well as the TD-DFT calculations, but it is unable to capture minor features of the CD spectrum that are closely related to absolute configurations of constituent dyes in the complex. We assess the performance of various methods used for evaluation of the electronic coupling energies between interacting chromophores. Our results confirm that the interchromophore interactions in cyanine dye aggregates are primarily electrostatic in nature and indicate that the exciton coupling model is adequate for studying induced CD of self-assembled aggregates of cyanine dye molecules.


Assuntos
Corantes/química , DNA/química , Ditiazanina/química , Fenômenos Ópticos , Teoria Quântica , Simulação de Dinâmica Molecular , Conformação de Ácido Nucleico
6.
Biophys J ; 96(9): 3850-61, 2009 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-19413991

RESUMO

We investigated the coupling between glycolytic and mitochondrial membrane potential oscillations in Saccharomyces cerevisiae under semianaerobic conditions. Glycolysis was measured as NADH autofluorescence, and mitochondrial membrane potential was measured using the fluorescent dye 3,3'-diethyloxacarbocyanine iodide. The responses of glycolytic and membrane potential oscillations to a number of inhibitors of glycolysis, mitochondrial electron flow, and mitochondrial and plasma membrane H(+)-ATPase were investigated. Furthermore, the glycolytic flux was determined as the rate of production of ethanol in a number of different situations (changing pH or the presence and absence of inhibitors). Finally, the intracellular pH was determined and shown to oscillate. The results support earlier work suggesting that the coupling between glycolysis and mitochondrial membrane potential is mediated by the ADP/ATP antiporter and the mitochondrial F(0)F(1)-ATPase. The results further suggest that ATP hydrolysis, through the action of the mitochondrial F(0)F(1)-ATPase and plasma membrane H(+)-ATPase, are important in regulating these oscillations. We conclude that it is glycolysis that drives the oscillations in mitochondrial membrane potential.


Assuntos
Membrana Celular/fisiologia , Glicólise , Membranas Mitocondriais/fisiologia , ATPases Translocadoras de Prótons/metabolismo , Trifosfato de Adenosina/metabolismo , Dióxido de Carbono/metabolismo , Carbonil Cianeto p-Trifluormetoxifenil Hidrazona/farmacologia , Ditiazanina , Inibidores Enzimáticos/farmacologia , Etanol/metabolismo , Fluorescência , Concentração de Íons de Hidrogênio , Potencial da Membrana Mitocondrial/fisiologia , Potenciais da Membrana/fisiologia , NAD/metabolismo , Omeprazol/farmacologia , Consumo de Oxigênio , Periodicidade , ATPases Translocadoras de Prótons/antagonistas & inibidores , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo , Desacopladores/farmacologia
8.
J Biochem Biophys Methods ; 70(5): 735-41, 2007 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-17524491

RESUMO

The 3,3'-diethylthiacarbocyanine (DiSC(2)(5)) dye is able to aggregate on full matched PNA-DNA duplexes by changing its absorption properties, which are manifested by an instantaneous colour shift from blue to purple. However the spontaneous aggregation of the dye also on mismatched duplexes and even on free PNA strands makes the test quite aspecific. Here it is demonstrated that the addition of succinyl-beta-cyclodextrin (Succ-beta-CyD) to the solutions containing PNA-DNA duplexes and the dye strongly enhances the specificity of the colour shift, allowing for a fast, very specific and extremely sensitive visual recognition of mismatches in DNA strands by using PNA probes in combination with the DiSC(2)(5) dye. The phenomenon has been studied by CD and NMR spectroscopies. The method has been optimized and preliminarily applied for the recognition of an apoE gene mutation in human DNA samples.


Assuntos
Colorimetria/métodos , DNA/química , Ácidos Nucleicos Peptídicos/química , Apolipoproteínas E/genética , Pareamento Incorreto de Bases , Sequência de Bases , Corantes , DNA/genética , Primers do DNA/genética , Ditiazanina , Corantes Fluorescentes , Humanos , Técnicas In Vitro , Substâncias Macromoleculares/química , Dados de Sequência Molecular , Mutação Puntual , Polimorfismo de Nucleotídeo Único , Solventes , Espectrofotometria , beta-Ciclodextrinas/química
9.
Parasitology ; 131(Pt 3): 383-92, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16178360

RESUMO

Strongyloides ratti is a parasitic nematode of rats. The host immune response against S. ratti affects the development of its free-living generation, favouring the development of free-living adult males and females at the expense of directly developing, infective 3rd-stage larvae. However, how the host immune response brings about these developmental effects is not clear. To begin to investigate this, we have determined the effect of non-immune stresses on the development of S. ratti. These non-immune stresses were subcurative doses of the anthelmintic drugs Ivermectin, Dithiazanine iodide and Thiabendazole, and infection of a non-natural host, the mouse. These treatments produced the opposite developmental outcome to that of the host immune response. Thus, in infections treated with subcurative doses of Ivermectin, Dithiazanine iodide and in infections of a non-natural host, the sex ratio of developing larvae became more female-biased and the proportion of female larvae that developed into free-living adult females decreased. This suggests that the mechanism by which the host immune response and these non-immune stresses affect S. ratti development differs.


Assuntos
Strongyloides ratti/efeitos dos fármacos , Strongyloides ratti/fisiologia , Animais , Antinematódeos/farmacologia , Ditiazanina/farmacologia , Feminino , Ivermectina/farmacologia , Masculino , Camundongos , Ratos , Strongyloides ratti/crescimento & desenvolvimento , Estrongiloidíase/tratamento farmacológico , Tiabendazol/farmacologia
10.
J Membr Biol ; 196(1): 51-9, 2003 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-14724756

RESUMO

A potential-sensitive fluorescent probe, 3,3'-dipropylthiadicarbocyanine iodide, was used to analyze, at pH 7.5 and 10.5, the effects of Bacillus thuringiensis toxins on the membrane potential generated by the efflux of K(+) ions from brush border membrane vesicles purified from the midgut of the tobacco hornworm, Manduca sexta. Fluorescence levels were strongly influenced by the pH and ionic strength of the media. Therefore, characterization of the effects of the toxins was conducted at constant pH and ionic strength. Under these conditions, the toxins had little effect on the fluorescence levels measured in the presence or absence of ionic gradients, indicating that the ionic selectivity of their pores is similar to that of the intact membrane. Valinomycin greatly increased the potential generated by the diffusion of K(+) ions although membrane permeability to the other ions used to maintain the ionic strength constant also influenced fluorescence levels. In the presence of valinomycin, active toxins (Cry1Aa, Cry1Ab, Cry1Ac, Cry1C and Cry1E) efficiently depolarized the membrane at pH 7.5 and 10.5.


Assuntos
Bacillus thuringiensis/química , Toxinas Bacterianas/toxicidade , Ditiazanina , Mucosa Intestinal/metabolismo , Intestinos/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Espectrometria de Fluorescência/métodos , Testes de Toxicidade/métodos , Animais , Permeabilidade da Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/fisiologia , Eletroquímica/instrumentação , Eletroquímica/métodos , Corantes Fluorescentes , Concentração de Íons de Hidrogênio , Insetos/química , Insetos/efeitos dos fármacos , Intestinos/química , Intestinos/citologia , Intestinos/ultraestrutura , Manduca/química , Manduca/efeitos dos fármacos , Manduca/fisiologia , Manduca/ultraestrutura , Microvilosidades/química , Microvilosidades/efeitos dos fármacos , Microvilosidades/fisiologia , Potássio/metabolismo , Espectrometria de Fluorescência/instrumentação , Testes de Toxicidade/instrumentação , Valinomicina/química , Valinomicina/farmacologia
11.
Nucleic Acids Res ; 30(2): E3, 2002 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-11788729

RESUMO

As the relationship between human genes and various malfunctions and diseases becomes revealed at an ever-increasing pace, the need arises for the development of rapid genetic screening methods for diagnostic purposes. Genetic diseases show great diversity. Some are caused by a few characteristic localised mutations, while others arise from a large number of variations. Hence, it is unlikely that a single, general diagnostic method that applies to all cases will ever exist. Instead, a combination of methods is frequently applied. Here we propose the use of a dramatic colour change that a cyanine dye, 3,3'-diethylthiadicarbocyanine, displays upon binding to DNA-PNA duplexes. This method could become an inexpensive, fast and simple genetic screening test by visual inspection, with no need for complicated equipment. Our results demonstrate that this diagnostic method may be sufficiently sensitive to discriminate between even a fully complementary and a single mutation DNA sequence.


Assuntos
Colorimetria/métodos , DNA/metabolismo , Ditiazanina/metabolismo , Testes Genéticos/métodos , Ácidos Nucleicos Peptídicos/metabolismo , Sequência de Bases , Cor , DNA/química , DNA/genética , Análise Mutacional de DNA/métodos , Ditiazanina/química , Corantes Fluorescentes/metabolismo , Humanos , Metanol , Mutação/genética , Desnaturação de Ácido Nucleico , Hibridização de Ácido Nucleico , Ácidos Nucleicos Peptídicos/química , Ácidos Nucleicos Peptídicos/genética , Sensibilidade e Especificidade , Espectrofotometria , Temperatura , Fatores de Tempo
12.
Yeast ; 12(13): 1301-13, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8923735

RESUMO

The existence of a K+/H+ transport system in plasma membrane vesicles from Saccharomyces cerevisiae is demonstrated using fluorimetric monitoring of proton fluxes across vesicles (ACMA fluorescence quenching). Plasma membrane vesicles used for this study were obtained by a purification/reconstitution protocol based on differential and discontinuous sucrose gradient centrifugations followed by an octylglucoside dilution/gel filtration procedure. This method produces a high percentage of tightly-sealed inside-out plasma membrane vesicles. In these vesicles, the K+/H+ transport system, which is able to catalyse both K+ influx and efflux, is mainly driven by the K+ transmembrane gradient and can function even if the plasma membrane H(+)-ATPase is not active. Using the anionic oxonol VI and the cationic DISC2(5) probes, it was shown that a membrane potential is not created during K+ fluxes. Such a dye response argues for the presence of a K+/H+ exchange system in S. cerevisiae plasma membrane and established the non-electrogenic character of the transport. The maximal rate of exchange is obtained at pH 6.8. This reversible transport system presents a high selectivity for K+ among other monovalent cations and a higher affinity for the K+ influx into the vesicles (exit from cells). The possible role of this K+/H+ exchange system in regulation of internal potassium concentration in S. cerevisiae is discussed.


Assuntos
Membrana Celular/enzimologia , Vesículas Revestidas/enzimologia , ATPase Trocadora de Hidrogênio-Potássio/isolamento & purificação , ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Saccharomyces cerevisiae/enzimologia , Transporte Biológico Ativo , Permeabilidade da Membrana Celular , Centrifugação com Gradiente de Concentração , Cromatografia em Gel , Ditiazanina/farmacologia , Complexo IV da Cadeia de Transporte de Elétrons/análise , Concentração de Íons de Hidrogênio , Isoxazóis/farmacologia , Manose/análise , Manosidases/análise , Potenciais da Membrana , Potássio/farmacocinética , Prótons , Espectrometria de Fluorescência , alfa-Manosidase
13.
Biomed Chromatogr ; 10(4): 189-90, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8831965

RESUMO

The highly sensitive detection of four near-infrared (near-IR) fluorescent dyes, methylene blue, pyridine 1, oxazine 1 and 3,3'-diethylthiadicarbocyanine iodide (DTDCI) by high-performance liquid chromatography (HPLC) with post-column peroxyoxalate chemiluminescence (PO-CL) detection utilizing bis(4-nitro-2-(3, 6,9-trioxadecyloxycarbonyl)phenyl) oxalate (TDPO) and hydrogen peroxide was examined. The detection limits for methylene blue, pyridine 1, oxazine 1 and DTDCI were 120, 27, 31, 0.19 fmol on-column at a signal-to-noise ratio of 2, respectively. The sensitivity for DTDCI was 250 times that obtained by HPLC with the conventional fluorescent detection.


Assuntos
Cromatografia Líquida de Alta Pressão , Corantes Fluorescentes/análise , Ditiazanina/análise , Ditiazanina/química , Corantes Fluorescentes/química , Raios Infravermelhos , Medições Luminescentes , Azul de Metileno/análogos & derivados , Azul de Metileno/análise , Azul de Metileno/química , Oxalatos/química , Compostos de Piridínio/análise , Compostos de Piridínio/química , Sensibilidade e Especificidade
14.
Ann Clin Lab Sci ; 24(2): 164-72, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7515607

RESUMO

The change in transmembrane potential of rat adipocytes was measured using the fluorescent probe 3,3'-diethylthiadicarbocyanine iodide, diS-C2-(5). The method was calibrated by altering the potassium ion concentration while keeping the sum of potassium and sodium ions at a constant concentration of 153 mM (Bailey et al: Bioelectrochem. Bioenergetics 21:333-42, 1989). Two insulin-mimetic agents, phospholipase C from Clostridium perfringens and concanavalin A, induced a dose dependent hyperpolarization of rat epididymal adipocytes, like insulin. Removal of endogenous adenosine with adenosine deaminase or adenosine receptor blockade with isobutylmethylxanthine following the initiation of insulin-induced hyperpolarization resulted in depolarization. These same agents induced hyperpolarization of -6 to -8 mV when added without insulin. The replacement of adenosine with its analogue, N6-phenylisopropyladenosine, plus insulin depolarized the cells toward the transmembrane potential established by insulin, -2.0 mV. These studies suggest that adenosine receptor occupancy is required to maintain insulin-induced hyperpolarization.


Assuntos
Adenosina/farmacologia , Tecido Adiposo/fisiologia , Membrana Celular/fisiologia , Concanavalina A/farmacologia , Fosfolipases Tipo C/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , Adenosina Desaminase/farmacologia , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/ultraestrutura , Animais , Membrana Celular/efeitos dos fármacos , Ditiazanina , Corantes Fluorescentes , Insulina/farmacologia , Masculino , Potenciais da Membrana , Fenilisopropiladenosina/farmacologia , Antagonistas de Receptores Purinérgicos P1 , Ratos , Ratos Sprague-Dawley
15.
J Neurochem ; 58(4): 1321-9, 1992 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1548466

RESUMO

The cationic potentiometric fluorescent probe 3,3'-diethylthiadicarbocyanine iodide [DiS-C2(5)] was used in synaptosomes to assess the relative contributions of plasma and mitochondrial membrane potentials (psi p and psi m, respectively) to overall fluorescence. Addition of synaptosomes to media containing 0.5 microM dye caused a decrease in fluorescence intensity due to dye accumulation, which equilibrated usually within 5 min. Depolarization of mitochondria by combined treatment with cyanide and oligomycin increased fluorescence by 42%, indicating significant prior accumulation of dye into intrasynaptosomal mitochondria. psi p was calculated to be -54 mV and was not altered significantly by prior depolarization of psi m with cyanide and oligomycin (hereafter referred to as "poisoned" synaptosomes). Similarly, the linear relationship between dye fluorescence and psi p was not altered by depolarization of psi m. Valinomycin, a K+ ionophore, caused a psi p-dependent increase in fluorescence in control (nonpoisoned) synaptosomes, but did not alter fluorescence of poisoned synaptosomes except when the extracellular concentration of K+ ([K+]e) was 2 mM, in which case valinomycin hyperpolarized psi p by about 5 mV. The pore-forming antibiotic gramicidin depolarized both psi p and psi m maximally. Under these conditions, Triton X-100 further increased fluorescence by 40%, indicating significant dye binding to synaptosomal components. In poisoned synaptosomes depolarized by 75 mM K+, gramicidin caused a decrease in fluorescence intensity (hyperpolarization of psi p). The organic solvent dimethyl sulfoxide, used as a vehicle for the hydrophobic ionophores, had voltage-dependent effects on psi p and psi m.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Mitocôndrias/fisiologia , Sinaptossomos/fisiologia , Animais , Cátions/metabolismo , Membrana Celular/fisiologia , Dimetil Sulfóxido/farmacologia , Ditiazanina , Potenciais da Membrana , Concentração Osmolar , Potássio/farmacologia , Sinaptossomos/metabolismo , Valinomicina/farmacologia
16.
Biochim Biophys Acta ; 1067(1): 38-42, 1991 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-1868102

RESUMO

The aim of the present study was to reconstitute and purify an epithelial potassium channel from rabbit kidney. Renal brush border membrane vesicles (BBMV) were found to contain a potassium conductance which was inhibited by amiloride, 5-(N-methyl-N-isobutyl)amiloride (MIA) and by barium. Membrane vesicle proteins were solubilized and reconstituted in proteoliposomes. Channel activity was assayed using Acridine orange and the voltage sensitive dye, 3,3'-diethylthiadicarbocyanine iodide (DiSC2(5)). Both methods yielded similar results which indicated the presence of an amiloride-sensitive, cation channel in the proteoliposomes. This channel was more permeable to K than to Na and its activity was increased in reconstituted proteoliposomes as compared to native brush border membranes. We conclude that rabbit BBMV possess an amiloride sensitive cation channel. Channel activity was successfully reconstituted in proteoliposomes and the protein was partially purified during reconstitution.


Assuntos
Amilorida/farmacologia , Túbulos Renais Proximais/química , Proteínas de Membrana/análise , Canais de Potássio/química , Laranja de Acridina , Animais , Membrana Basal/química , Membrana Celular/química , Ditiazanina , Masculino , Canais de Potássio/efeitos dos fármacos , Proteolipídeos/análise , Coelhos
17.
Brain Res ; 496(1-2): 187-96, 1989 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-2572293

RESUMO

The effects of glutamate, kainate and aspartate on the membrane potential of striatal synaptoneurosome, synaptosome and membrane sac preparations were studied by using a potential sensitive cyanine dye DiS-C2-(5). Excitatory amino acids glutamate and aspartate had a depolarizing effect on synaptoneurosomes. 7.9 microM glutamate and 2.8 microM aspartate produced a half-maximal response. Depolarizations induced by glutamate and aspartate were dependent on the concentration of extracellular sodium ions, a maximal response occurred at around 40 mM of external Na+. Kainate induced a dual effect on synaptoneurosomes. In a standard Na+-based medium a hyperpolarization, likely due to inhibition of a presynaptic sodium-dependent glutamate uptake, predominated over a postsynaptic kainate receptor-mediated depolarization that was observed when electrogenic glutamate uptake was inhibited. This interpretation was supported by results obtained with synaptosome and membrane sac preparations. In a standard Na+-based medium kainate had a hyperpolarizing effect on synaptosomes while in the membrane sac preparation kainate induced a depolarization.


Assuntos
Ácido Aspártico/farmacologia , Corpo Estriado/fisiologia , Glutamatos/farmacologia , Ácido Caínico/farmacologia , Sinaptossomos/fisiologia , Animais , Ditiazanina , Corantes Fluorescentes , Ácido Glutâmico , Cobaias , Potenciais da Membrana/efeitos dos fármacos , Sinaptossomos/efeitos dos fármacos
18.
Biochim Biophys Acta ; 979(3): 371-4, 1989 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-2923890

RESUMO

In isolated basolateral and canalicular rat liver plasma membrane vesicles the membrane potential (measured with DiS-C2 (5] varied with transmembrane concentration gradients of Na+, K+ and Cl- revealing the following ion permeabilities: basolateral vesicles: PNa/PK: 0.76, PCl/PK: 0.45 and canalicular vesicles: PNa/PK: 0.69, PCl/PK: 0.56. The data indicate a permselectivity of PK greater than PNa greater than PCl for both membranes.


Assuntos
Permeabilidade da Membrana Celular , Cloretos/metabolismo , Fígado/fisiologia , Potássio/metabolismo , Sódio/metabolismo , Animais , Membrana Celular/fisiologia , Corantes , Ditiazanina , Potenciais da Membrana , Ratos , Espectrometria de Fluorescência
19.
Neurosci Lett ; 92(3): 265-9, 1988 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-3200485

RESUMO

The membrane potential of astrocytes has been measured by monitoring the absorbance of a cyanine dye DiS-C2-(5). Ba2+, the phorbol ester 12-tetradecanoylphorbol myristateacetate (TPA) and the diglyceride, dioctanoylglycerol (DiC8) depolarize the membrane. Valinomycin which makes the membrane potential dependent on the K+ electrochemical potential evokes a hyperpolarization when added subsequently. The alpha-adrenergic receptor agonist phenylephrine was blocked by Ba2+, TPA, DiC8 and valinomycin. The results suggest that a protein kinase C-mediated reduction in the K+ permeability is responsible for the depolarizing effect of TPA, DiC8 and phenylephrine.


Assuntos
Astrócitos/fisiologia , Fenilefrina/fisiologia , Potássio/fisiologia , Proteína Quinase C/fisiologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Células Cultivadas , Diglicerídeos/farmacologia , Ditiazanina , Fenilefrina/metabolismo , Potássio/metabolismo , Proteína Quinase C/metabolismo , Ratos , Acetato de Tetradecanoilforbol/farmacologia
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