Simultaneous measurement of intracellular pH and Ca2+ in insulin-secreting cells by spectral imaging microscopy.
AuthorsMartínez-Zaguilán R,Gurulé MW,Lynch RM
JournalThe American journal of physiology
PubMed ID8967445
An improved procedure for reconstitution of the uncoupling protein and in-depth analysis of H+/OH- transport.
AuthorsWinkler E,Klingenberg M
JournalEuropean journal of biochemistry
PubMed ID1378400
An improved procedure for reincorporation of isolated uncoupling protein (UCP) from brown adipose tissue into phospholipid vesicles is reported and H+ uptake in K(+)-driven exchange diffusion quantitatively analyzed. UCP is isolated and reconstituted with medium-length linear-chain alkyl polyoxyethylene. In the critical step of vesicle formation, the stepwise removal of the ... More
Defective acidification of intracellular organelles in cystic fibrosis.
AuthorsBarasch J, Kiss B, Prince A, Saiman L, Gruenert D, al-Awqati Q
JournalNature
PubMed ID1712081
'The phenotype of cystic fibrosis (CF) includes abnormalities in transepithelial transport of Cl- (refs 1-5), decreased sialylation and increased sulphation and fucosylation of glycoproteins, and lung colonization with Pseudomonas. It is not apparent how these abnormalities are interrelated, nor how they result from loss of function of the CF gene-encoded ... More
CFTR regulates phagosome acidification in macrophages and alters bactericidal activity.
AuthorsDi A, Brown ME, Deriy LV, Li C, Szeto FL, Chen Y, Huang P, Tong J, Naren AP, Bindokas V, Palfrey HC, Nelson DJ
JournalNat Cell Biol
PubMed ID16921366
'Acidification of phagosomes has been proposed to have a key role in the microbicidal function of phagocytes. Here, we show that in alveolar macrophages the cystic fibrosis transmembrane conductance regulator Cl- channel (CFTR) participates in phagosomal pH control and has bacterial killing capacity. Alveolar macrophages from Cftr-/- mice retained the ... More
Direct measurement of free Ca in organelles of gastric epithelial cells.
AuthorsHofer AM, Machen TE
JournalAm J Physiol
PubMed ID7943242
'When loaded as the acetoxymethyl ester (AM) derivative, the fluorescent probe mag-fura 2 accumulates in both the cytoplasm and the subcellular compartments. The relatively high dissociation constant of this dye for Ca (53 microM) permits the measurement of changes in the free concentration of this ion in a variety of ... More
Aggregation and organization of pardaxin in phospholipid membranes. A fluorescence energy transfer study.
AuthorsRapaport D, Shai Y
JournalJ Biol Chem
PubMed ID1551864
'Fluorescence resonance energy transfer has been used to study the aggregation and organization of pardaxin and its analogues within lipid membranes. Peptide molecules labeled with 5- (and 6-) carboxyfluorescein at their N-terminal amino acid served as donors in these energy transfer measurements, whereas peptides labeled with 5- (and 6-) carboxytetramethylrhodamine ... More
A prelysosomal compartment sequesters membrane-impermeant fluorescent dyes from the cytoplasmic matrix of J774 macrophages.
AuthorsSteinberg TH, Swanson JA, Silverstein SC
JournalJ Cell Biol
PubMed ID3417786
'After the membrane impermeant dye Lucifer Yellow is introduced into the cytoplasmic matrix of J774 cells, the dye is sequestered within cytoplasmic vacuoles and secreted into the extracellular medium. In the present work we studied the intracellular transport of Lucifer Yellow in J774 macrophages and the nature of the cytoplasmic ... More
Membrane potential modulates release of tumor necrosis factor in lipopolysaccharide-stimulated mouse macrophages.
AuthorsHaslberger A, Romanin C, Koerber R
JournalMol Biol Cell
PubMed ID1498365
'Lipopolysaccharide (LPS)-mediated synthesis of macrophage gene products such as tumor necrosis factor (TNF) is controlled by different signaling pathways. We investigated intracellular free Ca2+ (Ca2+ic) and the membrane potential as early cellular responses to LPS and their role in the synthesis and release of TNF. In peritoneal macrophages and in ... More
Determination of the intracellular free chloride concentration in rat brain synaptoneurosomes using a chloride-sensitive fluorescent indicator.
AuthorsEngblom AC, Akerman KE
JournalBiochim Biophys Acta
PubMed ID8274496
'The chloride-sensitive fluorescent indicator MQAE (N-(6-methoxyquinolyl) acetoacetyl ester) has been used for determination of the intracellular free chloride concentration in rat brain synaptoneurosomes. Loading of the synaptoneurosomes with MQAE occurs by transmembrane diffusion. Calibration of the intracellular MQAE was done by determining the correlation between fluorescence intensity and intrasynaptoneurosomal Cl- ... More
The relationship between valinomycin-induced alterations in membrane phospholipid fatty acid turnover, membrane potential, and cell volume in the human erythrocyte.
AuthorsDise CA, Goodman DB
JournalJ Biol Chem
PubMed ID3972807
'The relationship between alterations in transmembrane potential, cell volume, and phospholipid fatty acid turnover has been examined in human erythrocytes by treating the cells with the monovalent cation ionophore valinomycin. Valinomycin increases the cellular uptake of tetra[3H]phenylphosphonium ion by erythrocytes, indicating membrane hyperpolarization, and causes net loss of potassium chloride ... More
Mechanism of uptake of the fluorescent dye 2-(4-dimethylaminostyryl)-1-ethylpyridinium cation (DMP+) by phospholipid vesicles.
AuthorsSedgwick EG, Bragg PD
JournalBiochim Biophys Acta
PubMed ID8443217
'The fluorescent dye 2-(4-dimethylaminostyryl)-1-ethylpyridinium cation (DMP+) is taken up by liposomes of egg phosphatidylcholine in response to the imposition of a transmembrane potential. Entry of DMP+ into the bilayer driven by the transmembrane potential is accompanied by a change in the fluorescence emission maximum of the dye. This change reflects ... More
Acidification of the cytosol inhibits endocytosis from coated pits.
AuthorsSandvig K, Olsnes S, Petersen OW, van Deurs B
JournalJ Cell Biol
PubMed ID2887575
'Acidification of the cytosol of a number of different cell lines strongly reduced the endocytic uptake of transferrin and epidermal growth factor. The number of transferrin binding sites at the cell surface was increased in acidified cells. Electron microscopic studies showed that the number of coated pits at the cell ... More
Transmembrane potentials in cells: a diS-C3(3) assay for relative potentials as an indicator of real changes.
AuthorsPlásek J, Dale RE, Sigler K, Laskay G
JournalBiochim Biophys Acta
PubMed ID7841182
'The mechanism by which the fluorescent cationic dye diS-C3(3) reports on cellular transmembrane potential has been investigated in murine haemopoietic cells. Due to the large molar absorbance of diS-C3(3) and its high quantum yield of fluorescence in cells, this dye can be used at very low labelling concentrations (5 x ... More
Effect of heat shock, [Ca2+]i, and cAMP on inositol trisphosphate in human epidermoid A-431 cells.
AuthorsKiang JG, McClain DE
JournalAm J Physiol
PubMed ID8392802
'The basal levels of inositol monophosphate, inositol bisphosphate, and inositol trisphosphate (InsP3) in A-431 cells incubated in Na(+)-Hanks'' solution were, respectively, 1.23 +/- 0.18, 0.17 +/- 0.03, and 0.69 +/- 0.07% of the total radioactivity in the cell. When cells were heated, InsP3 increased in a temperature-dependent manner related to ... More
Continuous measurement of mitochondrial pH gradients in isolated hepatocytes by difference ratio spectroscopy.
AuthorsThomas PJ, Gaspers LD, Pharr C, Thomas JA
JournalArch Biochem Biophys
PubMed ID1898020
'The pH gradient, delta pH, present across the inner mitochondrial membrane in isolated rat hepatocytes was continuously monitored with a novel spectroscopic technique that utilizes the weak acid fluorescein. Unlike most cytosolic pH indicators, such as 2'',7''-bis(carboxyethyl)-5,(6)-carboxyfluorescein (BCECF), fluorescein freely distributes between the cytosolic and mitochondrial compartments. As is typical ... More
Alpha interferon accelerates lateral diffusion of Daudi cell surface differentiation antigens: measurement by fluorescence redistribution after photobleaching.
AuthorsBalint E, Aszalos A, Grimley PM
JournalBiochem Biophys Res Commun
PubMed ID2462420
'Lateral diffusion coefficients (D) of two surface differentiation antigens (sIgM and Bp35) were determined on interferon-sensitive (-IFs) or resistant (-IFr) Daudi cells by fluorescence photobleaching, using monospecific FITC-anti-IgM or PE-anti-Leu 16 probes. For untreated Daudi -IFs, mean (D) were 5.8 and 5.3 (x10(-10) cm2/sec). These increased, to 11 and 7.9 ... More
An epithelial high-affinity amiloride-binding site, different from the Na+ channel.
AuthorsGoldstein O, Asher C, Barbry P, Cragoe E, Clauss W, Garty H
JournalJ Biol Chem
PubMed ID8385123
'Specific binding of the radioactive amiloride analogues [3H]phenamil and [3H]benzamil was studied in plasma membrane from chicken lower intestine. A single population of sites whose affinities and specificities towards pyrazinecarboxamides roughly resemble those of the epithelial Na+ channel, was identified. However, a matched comparison of pyrazinecarboxamide binding and Na+ transport ... More
Transport of organic anions through the erythrocyte membrane as K+-valinomycin complexes.
AuthorsMarinetti GV, Skarin A, Whitman P
JournalJ Membr Biol
PubMed ID660643
'K+, Rb+, or Cs+ complexes of valinomycin form ion pair complexes with picric acid and trinitrobenzenesulfonate (TNBS). The formation of a picrate-K+-valinomycin complex is supported by spectral evidence. These complexes have zero net charge and readily permeate the intact erythrocyte membrane. The K+-valinomycin complex has been used to convert the ... More
Effect of membrane potential on the cellular uptake of 2-N-methyl-ellipticinium by L1210 cells.
AuthorsCharcosset JY, Jacquemin-Sablon A, Le Pecq JB
JournalBiochem Pharmacol
PubMed ID6466349
'Some quaternary ammonium derivatives of ellipticine are active antitumor drugs on both experimental and human tumors. Because of their positive charge, the cellular uptake of these molecules is expected to be influenced by the electric membrane potential. Experimental variations of the potential were produced by changing the external potassium concentration ... More
The use of carotenoids and oxonol VI as probes for membrane potential in proteoliposomes.
Authorsvan Walraven HS, Krab K, Hagendoorn MJ, Kraayenhof R
JournalFEBS Lett
PubMed ID3157600
'Carotenoids present in lipids extracted from the cyanobacterium Synechococcus 6716 indicate trans-membrane potential in proteoliposomes reconstituted from these lipids and the ATPase complex isolated from the same organism. A carotenoid absorbance band shift to a longer wavelength is obtained with valinomycin-induced potassium ion diffusion potentials, irrespective of the polarity of ... More
'Adenylylcyclase (AC) from sea urchin sperm does not appear to be regulated by G proteins [Hildebrandt, J. D., Tash, J. S., Kirchick, H. J., Lipschunits, L., Secra, R. D., & Birmbaumer, L. (1985) Endocrinology 116, 1357-1366]. During sperm activation and the acrosome reaction, membrane potential changes and cAMP increases. Here ... More
SNARF-1 as an intracellular pH indicator in laser microspectrofluorometry: a critical assessment.
AuthorsSeksek O, Henry-Toulmé N, Sureau F, Bolard J
JournalAnal Biochem
PubMed ID2042742
'The use of SNARF-1-AM (seminaphtorhodafluor-1-acetoxymethylester) to measure the internal pH of a single living cell by laser microspectrofluorometry has been analyzed with a lymphocyte murine B cell line A20. After incubation of the cells at 37 degrees C in the presence of 10 microM SNARF-1-AM, the internal concentration of SNARF-1 ... More
Rat hepatocytes exhibit basolateral Na+/HCO3- cotransport.
AuthorsRenner EL, Lake JR, Scharschmidt BF, Zimmerli B, Meier PJ
JournalJ Clin Invest
PubMed ID2539394
'Primary cultures and plasma membrane vesicles were used to characterize Na+ and HCO3- transport by rat hepatocytes. Na+ uptake into hepatocytes was stimulated approximately 10-fold by 25 mM extracellular HCO3-.HCO3--stimulated Na+ uptake was saturable, abolished by 4-acetamido-4''-isothiocyano-2,2''-disulfonic acid stilbene (SITS), and unaffected by amiloride or Cl- removal. Neither propionate nor ... More
Molecular mechanisms of water and solute transport across archaebacterial lipid membranes.
AuthorsMathai JC, Sprott GD, Zeidel ML
JournalJ Biol Chem
PubMed ID11373291
'Archaebacteria thrive in environments characterized by anaeobiosis, saturated salt, and both high and low extremes of temperature and pH. The bulk of their membrane lipids are polar, characterized by the archaeal structural features typified by ether linkage of the glycerol backbone to isoprenoid chains of constant length, often fully saturated, ... More
Disease-causing mutations in the cystic fibrosis transmembrane conductance regulator determine the functional responses of alveolar macrophages.
'Alveolar macrophages (AMs) play a major role in host defense against microbial infections in the lung. To perform this function, these cells must ingest and destroy pathogens, generally in phagosomes, as well as secrete a number of products that signal other immune cells to respond. Recently, we demonstrated that murine ... More
Photoactivated azido fatty acid irreversibly inhibits anion and proton transport through the mitochondrial uncoupling protein.
AuthorsJezek P, Hanus J, Semrad C, Garlid KD
JournalJ Biol Chem
PubMed ID8626410
'The protonophoretic function of uncoupling protein (UCP) is activated by fatty acids. According to the "docking site" hypothesis (Jezek, P., and Garlid, K. D., J. Biol. Chem. 265, 19303-19311, 1990), the fatty acid binding site is identical with the anion channel of UCP. Skulachev (Skulachev, V. P. (1991) FEBS Lett. ... More
Mitochondrial K+ as modulator of Ca(2+)-dependent cytotoxicity in hepatocytes. Novel application of the K(+)-sensitive dye PBFI (K(+)-binding benzofuran isophthalate) to assess free mitochondrial K+ concentrations.
AuthorsZoeteweij JP, van de Water B, de Bont HJ, Nagelkerke JF
JournalBiochem J
PubMed ID8172616
'In isolated rat hepatocytes a sustained high increase in intracellular free Ca2+ ([Ca2+]i), induced by extracellular ATP, is associated with mitochondrial dysfunction and cell death. The Ca(2+)-induced effects are Pi-dependent and less severe when the intracellular K+ content is low. In this study, the involvement of mitochondrial K+ processing in ... More
Mitochondrial mass and membrane potential in coelomocytes from the earthworm Eisenia foetida: studies with fluorescent probes in single intact cells.
AuthorsCossarizza A, Cooper EL, Quaglino D, Salvioli S, Kalachnikova G, Franceschi C
JournalBiochem Biophys Res Commun
PubMed ID7677758
'Earthworm coelomocytes exist in two forms, i.e., small (SC) and large (LC) cells, as demonstrated by velocity sedimentation, electron microscopy, and FCM. However, we know little concerning the functional activities of various, important organelles, such as mitochondria. In comparison with SC, LC from Eisenia foetida have a higher number of ... More
Absence of cardiolipin in the crd1 null mutant results in decreased mitochondrial membrane potential and reduced mitochondrial function.
AuthorsJiang F, Ryan MT, Schlame M, Zhao M, Gu Z, Klingenberg M, Pfanner N, Greenberg ML
JournalJ Biol Chem
PubMed ID10777514
'Cardiolipin (CL) is a unique phospholipid which is present throughout the eukaryotic kingdom and is localized in mitochondrial membranes. Saccharomyces cerevisiae cells containing a disruption of CRD1, the structural gene encoding CL synthase, have no CL in mitochondrial membranes. To elucidate the physiological role of CL, we compared mitochondrial functions ... More
pH sensitivity of the Na+:HCO3- cotransporter in basolateral membrane vesicles isolated from rabbit kidney cortex.
AuthorsSoleimani M, Hattabaugh YJ, Bizal GL
JournalJ Biol Chem
PubMed ID1526975
'HCO3- exit across the basolateral membrane of the kidney proximal tubule cell is mediated via an electrogenic Na+:HCO3- cotransporter. We have studied the effect of pH on the activity of this cotransport system in basolateral membrane vesicles isolated from rabbit renal cortex. At constant internal pH 6.0, increasing the external ... More
A noninvasive fluorimetric procedure for measurement of membrane potential. Quantification of the NADPH oxidase-induced depolarization in activated neutrophils.
AuthorsJankowski A, Grinstein S
JournalJ Biol Chem
PubMed ID10473559
'The electrogenic activity of the NADPH oxidase is associated with depolarization of the plasma membrane in activated neutrophils. The magnitude and consequences of this depolarization, however, remain unknown. Neutrophils are not amenable to electrophysiological determinations of membrane potential by current clamp. Instead, the occurrence of depolarization has been inferred from ... More
Bioenergetics of the staphylococcal multidrug export protein QacA. Identification of distinct binding sites for monovalent and divalent cations.
AuthorsMitchell BA, Paulsen IT, Brown MH, Skurray RA
JournalJ Biol Chem
PubMed ID9920900
'The multidrug efflux pump QacA from Staphylococcus aureus confers resistance to an extensive range of structurally dissimilar compounds. Fluorimetric analyses demonstrated that QacA confers resistance to the divalent cation 4'',6-diamidino-2-phenylindole, utilizing a proton motive force-dependent efflux mechanism previously demonstrated for QacA-mediated resistance to the monovalent cation ethidium. Both the ionophores ... More
The vacuolar H+-ATPase of clathrin-coated vesicles is reversibly inhibited by S-nitrosoglutathione.
AuthorsForgac M
JournalJ Biol Chem
PubMed ID9880499
'It has been previously demonstrated that the vacuolar H+-ATPase (V-ATPase) of clathrin-coated vesicles is reversibly inhibited by disulfide bond formation between conserved cysteine residues at the catalytic site on the A subunit (Feng, Y., and Forgac, M. (1994) J. Biol. Chem. 269, 13224-13230). Proton transport and ATPase activity of the ... More
Entry of poliovirus into cells is blocked by valinomycin and concanamycin A.
AuthorsIrurzun A, Carrasco L
JournalBiochemistry
PubMed ID11297425
'Poliovirus contains a virus particle devoid of a lipid envelope that does not require an intact pH to enter into susceptible cells. Thus, the blockade of pH gradient generated in endosomes is not sufficient to impede the translocation of poliovirus particles to the cytoplasm, suggesting that translocation takes place at ... More
Preparation of giant liposomes in physiological conditions and their characterization under an optical microscope.
AuthorsAkashi K, Miyata H, Itoh H, Kinosita K
JournalBiophys J
PubMed ID8968594
'Unilamellar liposomes with diameters of 25-100 microns were prepared in various physiological salt solutions, e.g., 100 mM KCl plus 1 mM CaCl2. Successful preparation of the giant liposomes at high ionic strengths required the inclusion of 10-20% of a charged lipid, such as phosphatidylglycerol, phosphatidylserine, phosphatidic acid, or cardiolipin, in ... More
Inhibition of endocytosis from coated pits by acidification of the cytosol.
AuthorsSandvig K, Olsnes S, Petersen OW, van Deurs B
JournalJ Cell Biochem
PubMed ID2893802
'Binding and endocytosis of the ligands transferrin, epidermal growth factor (EGF), and ricin were measured in a number of different cell lines after treatment of cells with compounds that react with SH-groups and under conditions where the cytosolic pH was lowered. N-ethylmalemide and diamide irreversibly inhibited endocytosis of all ligands ... More
Ca2+ transport by reconstituted synaptosomal ATPase is associated with H+ countertransport and net charge displacement.
AuthorsSalvador JM, Inesi G, Rigaud JL, Mata AM
JournalJ Biol Chem
PubMed ID9660785
'The synaptosomal plasma membrane Ca2+-ATPase (PMCA) purified from pig brain was reconstituted with liposomes prepared by reverse phase evaporation at a lipid to protein ratio of 150/1 (w/w). ATP-dependent Ca2+ uptake and H+ ejection by the reconstituted proteoliposomes were demonstrated by following light absorption and fluorescence changes undergone by arsenazo ... More
Confocal imaging of intracellular chloride in living brain slices: measurement of GABAA receptor activity.
AuthorsInglefield JR, Schwartz-Bloom RD
JournalJ Neurosci Methods
PubMed ID9288644
'We have developed a method using UV laser-scanning confocal microscopy and the fluorescent chloride ion indicator, 6-methoxy-N-ethylquinolinium chloride (MEQ), to image GABA-mediated changes in intracellular chloride (Cli-) in individual neurons of the rat acute brain slice. After bath-loading slices with the cell-permeant form (reduced) of MEQ, there was intense fluorescence ... More
Examination of sodium/glucose cotransport by using a visible glucose analogue.
AuthorsPeerce BE
JournalBiochemistry
PubMed ID2021610
'The glucose derivative, 2,2,6,6-tetramethylpiperidine-1-oxylglucose (TEMPO-glucose) was synthesized and examined for its ability to substitute for glucose as a substrate for the intestinal brush border membrane Na+/glucose cotransporter. TEMPO-glucose inhibited Na(+)-dependent phlorizin binding with an apparent KI of 18 microM and Na(+)-dependent glucose uptake with an apparent KI of 70 microM. ... More
Biochemical properties of vacuolar zinc transport systems of Saccharomyces cerevisiae.
AuthorsMacDiarmid CW, Milanick MA, Eide DJ
JournalJ Biol Chem
PubMed ID12161436
'The yeast vacuole plays an important role in zinc homeostasis by storing zinc for later use under deficient conditions, sequestering excess zinc for its detoxification, and buffering rapid changes in intracellular zinc levels. The mechanisms involved in vacuolar zinc sequestration are only poorly characterized. Here we describe the properties of ... More
Fusion peptides derived from the HIV type 1 glycoprotein 41 associate within phospholipid membranes and inhibit cell-cell Fusion. Structure-function study.
AuthorsKliger Y, Aharoni A, Rapaport D, Jones P, Blumenthal R, Shai Y
JournalJ Biol Chem
PubMed ID9153194
'The fusion domain of human immunodeficiency virus (HIV-1) envelope glycoprotein (gp120-gp41) is a conserved hydrophobic region located at the N terminus of the transmembrane glycoprotein (gp41). A V2E mutant has been shown to dominantly interfere with wild-type envelope-mediated syncytium formation and virus infectivity. To understand this phenomenon, a 33-residue peptide ... More
Optical imaging of hippocampal neurons with a chloride-sensitive dye: early effects of in vitro ischemia.
AuthorsInglefield JR, Schwartz-Bloom RD
JournalJ Neurochem
PubMed ID9603215
'We determined if changes in intraneuronal Cl- occur early after ischemia in the hippocampal slice. Slices from juvenile rats (14-19 days old) were loaded with the cell-permeant form of 6-methoxy-N-ethylquinolinium chloride (MEQ), a Cl(-)-sensitive fluorescent dye. Real-time changes in intracellular chloride concentration ([Cl-]i) were measured with UV laser scanning confocal ... More
Light-induced increase in free Mg2+ concentration in spinach chloroplasts: measurement of free Mg2+ by using a fluorescent probe and necessity of stromal alkalinization.
AuthorsIshijima S, Uchibori A, Takagi H, Maki R, Ohnishi M
JournalArch Biochem Biophys
PubMed ID12646275
'Free Mg(2+) in chloroplasts may contribute to the regulation of photosynthetic enzymes, but adequate methodology for the determination of free Mg(2+) concentration ([Mg(2+)]) in chloroplasts has been lacking. We measured internal chloroplast [Mg(2+)] by using a Mg-sensitive fluorescent indicator, mag-fura-2. In intact, dark-kept spinach chloroplasts, internal [Mg(2+)] was estimated to ... More
Membrane potential modulates photocycling rates of bacterial rhodopsins.
AuthorsManor D, Hasselbacher CA, Spudich JL
JournalBiochemistry
PubMed ID3191096
'Effects of membrane potential on photochemical reactions of three retinal-containing chromoproteins in Halobacterium halobium, sensory rhodopsin I (sR-I), bacteriorhodopsin, and halorhodopsin, are described. Each of the three exhibits a decreased rate of thermal decay of its principal intermediate when photoactivated in an artificially energized compared to a deenergized membrane. The ... More
Thallium mediates a rapid chloride/hydroxyl ion exchange through myelin lipid bilayers.
AuthorsDíaz RS, Monreal J
JournalMol Pharmacol
PubMed ID7808444
'We have investigated the effects of several heavy metal cations on the proton and chloride permeabilities of liposomes prepared with endogenous lipids from brain myelin, by monitoring the fluorescence emitted by acridine orange and N-(6-methoxyquinolyl)acetoethyl ester. In addition to Hg2+ and Cu+, nanomolar concentrations of Tl3+, but not Tl+, were ... More
Spatial organization of bacteriorhodopsin in model membranes. Light-induced mobility changes.
AuthorsKahya N, Wiersma DA, Poolman B, Hoekstra D
JournalJ Biol Chem
PubMed ID12167614
'Bacteriorhodopsin is a proton-transporting membrane protein in Halophilic archaea, and it is considered a prototype of membrane transporters and a model for G-protein-coupled receptors. Oligomerization of the protein has been reported, but it is unknown whether this feature is correlated with, for instance, light activation. Here, we have addressed this ... More
Fluorescence quenching of reconstituted NCD-4-labeled cytochrome c oxidase complex by DOXYL-stearic acids.
AuthorsMusser SM, Larsen RW, Chan SI
JournalBiophys J
PubMed ID8312474
'It has been known for some time that dicyclohexylcarbodiimide (DCCD) inhibits the proton translocation function of the cytochrome c oxidase complex (CcO) and that there is one major site in subunit III which is modified upon reaction with DCCD (Glu-90 for the bovine enzyme). We have examined the reaction of ... More
Mechanism and specificity of lanthanide series cation transport by ionophores A23187, 4-BrA23187, and ionomycin.
AuthorsWang E, Taylor RW, Pfeiffer DR
JournalBiophys J
PubMed ID9726927
'A23187, 4-BrA23187, and ionomycin transport several lanthanide series trivalent cations at efficiencies similar to Ca2+, when compared at cation concentrations of approximately 10(-5) M, ionophore concentrations of approximately 10(-6) M, and a pH of 7.00. Selectivity sequences and the range of relative rates are as follows: A23187, Nd3+ > La3+ ... More
Acidification and ion permeabilities of highly purified rat liver endosomes.
AuthorsFuchs R, Mâle P, Mellman I
JournalJ Biol Chem
PubMed ID2914902
'While it is well established that acidic pH in endosomes plays a critical role in mediating the orderly traffic of receptors and ligands during endocytosis, little is known about the bioenergetics or regulation of endosome acidification. Using highly enriched fractions of rat liver endosomes prepared by free flow electrophoresis and ... More
Valinomycin-induced modulation of adriamycin resistance and cationic probe distribution in MCF-7 cell lines.
AuthorsCrifò C, Capuozzo E, Cucco C, Zupi G, Salerno C
JournalBiochem Int
PubMed ID1815496
'In vitro restoration of adriamycin sensitivity in a resistant human breast tumor cell line was obtained by continuous exposure to nanomolar nontoxic valinomycin concentrations. Seven-day treatment with nanomolar valinomycin concentrations caused a slight increase of the signal of the cationic fluorescent cyanine probe DiOC5(3) but did not appreciably affect adriamycin ... More
The mechanism of ion conduction by valinomycin: analysis of charge pulse responses.
AuthorsHladky SB, Leung JC, Fitzgerald WJ
JournalBiophys J
PubMed ID8580319
'Even though valinomycin has been employed and studied extensively for over 30 years, the attempts to explain its mechanism have not been entirely successful. The basic carrier model uses four rate constants that describe association of an ion and carrier, transfer of the complex across the membrane, dissociation of the ... More
Preservation of mitochondrial structure and function after Bid- or Bax-mediated cytochrome c release.
Authorsvon Ahsen O, Renken C, Perkins G, Kluck RM, Bossy-Wetzel E, Newmeyer DD
JournalJ Cell Biol
PubMed ID10973993
'Proapoptotic members of the Bcl-2 protein family, including Bid and Bax, can activate apoptosis by directly interacting with mitochondria to cause cytochrome c translocation from the intermembrane space into the cytoplasm, thereby triggering Apaf-1-mediated caspase activation. Under some circumstances, when caspase activation is blocked, cells can recover from cytochrome c ... More
The concentration-dependent membrane activity of cecropin A.
'Cecropin A is a naturally occurring, linear, cationic, 37-residue antimicrobial peptide. The precise mechanism by which it kills bacteria is not known, but its site of action is believed to be the cell membrane. To investigate the nature of its membrane activity, we examined the ability of cecropin A to ... More
ATP-dependent and DCCD-insensitive Cl- uptake by membrane vesicles from the rat brain plasma membrane fractions.
AuthorsShiroya T, Cragoe EJ, Inagaki C
JournalBiochem Biophys Res Commun
PubMed ID2719675
'ATP-dependent Cl- uptake by membrane vesicles from the rat brain plasma membrane fractions was not affected by the addition of 40 mM of K+, Na+ or HCO3- to the assay medium. Na+ and K+ did not alter the uptake even in the presence of a K+ ionophore, valinomycin (10 microM), ... More
Alkylsulfonates as probes of uncoupling protein transport mechanism. Ion pair transport demonstrates that direct H(+) translocation by UCP1 is not necessary for uncoupling.
AuthorsJaburek M, Varecha M, Jezek P, Garlid KD
JournalJ Biol Chem
PubMed ID11468281
'The mechanism of fatty acid-dependent uncoupling by mitochondrial uncoupling proteins (UCP) is still in debate. We have hypothesized that the anionic fatty acid head group is translocated by UCP, and the proton is transported electroneutrally in the bilayer by flip-flop of the protonated fatty acid. Alkylsulfonates are useful as probes ... More
Transport of the cationic fluorochrome rhodamine 123 in an insect's Malpighian tubule: indications of a reabsorptive function of the secondary cell type.
AuthorsMeulemans W, De Loof A
JournalJ Cell Sci
PubMed ID1629249
'The pathway of rhodamine 123 was examined after injection into Sarcophaga flies and after in vitro labeling of the Malpighian tubules. After in vitro labeling the primary cells only retained this potential-sensitive dye for a short period while all secondary cells accumulated the dye from the tubule lumen. In vivo ... More
Glucocorticoid stimulation of ileal Na+ absorptive cell brush border Na+/H+ exchange and association with an increase in message for NHE-3, an epithelial Na+/H+ exchanger isoform.
AuthorsYun CH, Gurubhagavatula S, Levine SA, Montgomery JL, Brant SR, Cohen ME, Cragoe EJ, Pouyssegur J, Tse CM, Donowitz M
JournalJ Biol Chem
PubMed ID8380155
'Methylprednisolone stimulates rabbit ileal neutral NaCl absorption; and aminoglutethimide, which decreases glucocorticoid levels, decreases NaCl absorption. Studies were carried out to determine the mechanism of these effects and to determine which members of the gene family of mammalian Na+/H+ exchangers were involved. Rabbits were treated subcutaneously with methylprednisolone (40 mg ... More
Proton-sodium stoichiometry of NhaA, an electrogenic antiporter from Escherichia coli.
AuthorsTaglicht D, Padan E, Schuldiner S
JournalJ Biol Chem
PubMed ID8383669
'The H+:Na+ exchange stoichiometry of NhaA, a sodium-proton antiporter coded by the nhaA gene of Escherichia coli, has been determined using purified NhaA protein reconstituted into sodium-loaded proteoliposomes. One approach involved measuring, in parallel experiments, the Na+ efflux and H+ influx from such proteoliposomes and calculating the stoichiometry from the ... More
Phospholipid subclass-specific alterations in the kinetics of ion transport across biologic membranes.
AuthorsChen X, Gross RW
JournalBiochemistry
PubMed ID7947788
'Although the predominance of plasmalogens in electrically-active membranes (e.g., sarcolemma) is well-known, identification of the molecular mechanisms through which the vinyl ether linkage facilitates electrophysiologic function has remained elusive. Herein we demonstrate that the kinetics of both carrier-mediated (i.e., valinomycin) and passive ion transport are substantially different in membranes comprised ... More
Reconstitution of the leucine transport system of Lactococcus lactis into liposomes composed of membrane-spanning lipids from Sulfolobus acidocaldarius.
'The effect of bipolar tetraether lipids, extracted from the thermophilic archaebacterium Sulfolobus acidocaldarius, on the branched-chain amino acid transport system of the mesophilic bacterium Lactococcus lactis was investigated. Liposomes were prepared from mixtures of monolayer lipids and the bilayer lipid phosphatidylcholine (PC), analyzed on their miscibility, and fused with membrane ... More
Fibre optic sensor for the detection of potassium using fluorescence energy transfer.
AuthorsRoe JN, Szoka FC, Verkman AS
JournalAnalyst
PubMed ID2363517
'A fluorescence fibre optic sensor has been developed for measurement of the potassium concentration in aqueous solution based on the change in optical absorbance of the hydrophobic indicator 7-decyl-2-methyl-4-(3'',5''-dichlorophen-4''-one)indonaphth-1-o l (MEDPIN). The sensor was constructed by dipping the distal end of a single optical fibre in a poly(vinyl chloride) (PVC) ... More
Kinetic analysis of rhodamines efflux mediated by the multidrug resistance protein (MRP1).
AuthorsSaengkhae C, Loetchutinat C, Garnier-Suillerot A
JournalBiophys J
PubMed ID12944313
'Characterization of rhodamine 123 as functional assay for MDR has been primarily focused on P-glycoprotein-mediated MDR. Several studies have suggested that Rh123 is also a substrate for MRP1. However, no quantitative studies of the MRP1-mediated efflux of rhodamines have, up to now, been performed. Measurement of the kinetic characteristics of ... More
Differential movement of ions in artificial phospholipid vesicles.
AuthorsSedgwick EG, Bragg PD
JournalFEBS Lett
PubMed ID1699806
'Pyranine was incorporated into sonicated unilamellar vesicles of soybean phosphatidylcholine to monitor changes in the internal pH of the vesicles. Dilution of soybean phosphatidylcholine vesicles loaded with 0.3 M KCl, KNO3 or K2SO4 into salt-free buffer resulted in rapid exchange of K+ and protons. A pseudoequilibrium distribution of ions was ... More
Mechanisms of amiloride stimulation of Mg2+ uptake in immortalized mouse distal convoluted tubule cells.
AuthorsDai LJ, Raymond L, Friedman PA, Quamme GA
JournalAm J Physiol
PubMed ID9124403
'The distal convoluted tubule reabsorbs approximately 10% of the filtered magnesium, which is approximately 70% of that delivered to it from the loop of Henle. The cellular mechanisms of magnesium transport in the distal convoluted tubule are not known. Amiloride has been reported to promote magnesium conservation. Studies were performed ... More
Antibiotic-mediated transport of alkali ions across lipid barriers.
AuthorsPressman BC, Harris EJ, Jagger WS, Johnson JH
JournalProc Natl Acad Sci U S A
PubMed ID4230180
Rapid measurement of toxicity using electrochromic dyes and frog embryos.
AuthorsStringer BK, Blankemeyer JT
JournalBull Environ Contam Toxicol
PubMed ID7691282
Analysis of mitochondria during cell death.
AuthorsCossarizza A, Salvioli S
JournalMethods Cell Biol
PubMed ID11060854
Probing mitochondrial probes.
AuthorsIsola R, Falchi AM, Diana A, Diaz G
JournalCytometry
PubMed ID11002271
Flow cytometric detection of fluorescent redistributional dyes for measurement of cell transmembrane potential.
AuthorsTanner MK, Wellhausen SR
JournalMethods Mol Biol
PubMed ID9664484
Control of coated-pit function by cytoplasmic pH.
AuthorsSandvig K, Olsnes S, Petersen OW, Van Deurs B
JournalMethods Cell Biol
PubMed ID2575206
Cell membrane potential analysis.
AuthorsShapiro HM
JournalMethods Cell Biol
PubMed ID7532258
Effect of local anaesthetics on mitochondrial membrane potential in living cells.
AuthorsGrouselle M, Tueux O, Dabadie P, Georgescaud D, Mazat JP
JournalBiochem J
PubMed ID2222418
Using the laser dye rhodamine 123, we demonstrated that local anaesthetics can reach mitochondria in cell culture and reversibly decrease, or even collapse, their transmembrane potential. This effect is highly dependent on the lipid-solubility of the local anaesthetic and can be facilitated by the presence of a lipophilic anion. ... More
Bicarbonate stimulation of Na+ transport in liver basolateral plasma membrane vesicles requires the presence of a transmembrane pH gradient.
AuthorsFelipe A, Moule SK, McGivan JD
JournalBiochim Biophys Acta
PubMed ID2171655
The effect of bicarbonate on the uptake of 22Na+ into liver basolateral plasma membrane vesicles was studied under conditions where the pH of the medium was controlled by the use of high buffer concentrations. Bicarbonate stimulated the rate of Na+ uptake only in the presence of a pH gradient (acid ... More
Calcium efflux through cardiac calcium channels reconstituted into liposomes--flux measurement with fura-2.
AuthorsKameyama A, Nakayama T
JournalBiochem Biophys Res Commun
PubMed ID2457364
Cardiac Ca2+ channels were solubilized and reconstituted into liposomes, and Ca2+ efflux from the proteoliposomes was measured with the fluorescent dye fura-2. The Ca2+ efflux, induced by K+ depolarization, was sensitive to Ca2+ channel modulators such as nifedipine, D-600 and Bay K 8644, and was dependent on the membrane potential. ... More
Activators of protein kinase C and phenylephrine depolarize the astrocyte membrane by reducing the K+ permeability.
AuthorsAkerman KE, Enkvist MO, Holopainen I
JournalNeurosci Lett
PubMed ID3200485
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. ... More
A structure-activity study of fatty acid interaction with mitochondrial uncoupling protein.
AuthorsJezek P, Modrianský M, Garlid KD
JournalFEBS Lett
PubMed ID9187360
Fatty acid (FA) uniport via mitochondrial uncoupling protein (UcP) was detected fluorometrically with PBFI, potassium-binding benzofuran phthalate and SPQ, 6-methoxy-N-(3-sulfopropyl)-quinolinium, indicating K+ and H+, respectively. The FA structural patterns required for FA flip-flop, UcP-mediated FA uniport, activation of UcP-mediated H+ transport in proteoliposomes, and inhibition of UcP-mediated Cl- uniport by ... More
Synergistic incorporation of daunorubicin in erythrocytes in the presence of polyene antibiotics. Role of the membrane potential.
AuthorsHenry N, Bolard J
JournalBiochim Biophys Acta
PubMed ID3942720
The synergistic incorporation into red blood cells of the antitumor compound daunorubicin, in the presence of the polyene antibiotics amphotericin B and vacidin A, depended on the composition of the external medium. Synergism was observed only for concentrations of polyene antibiotics that induce cation permeability. The same synergistic effect was ... More
Changes in intramitochondrial cardiolipin distribution in apoptosis-resistant HCW-2 cells, derived from the human promyelocytic leukemia HL-60.
AuthorsGarcia Fernandez M, Troiano L, Moretti L, Pedrazzi J, Salvioli S, Castilla-Cortazar I, Cossarizza A
JournalFEBS Lett
PubMed ID10930584
Using a cytofluorimetric approach, we studied intramitochondrial cardiolipin (CL) distribution in HCW-2 cells, an apoptosis-resistant clone of human HL-60 cells. In HL-60, about 50% of total CL is distributed in the outer leaflet of mitochondrial inner membrane, while in HCW-2 a significantly higher amount of CL (about 65%) is in ... More
Mitochondrial transport of cations: channels, exchangers, and permeability transition.
AuthorsBernardi P
JournalPhysiol Rev
PubMed ID10508231
This review provides a selective history of how studies of mitochondrial cation transport (K+, Na+, Ca2+) developed in relation to the major themes of research in bioenergetics. It then covers in some detail specific transport pathways for these cations, and it introduces and discusses open problems about their nature and ... More
Effects of valinomycin on calcium mobilization in vascular smooth muscle cells induced by angiotensin II.
AuthorsKoh E, Morimoto S, Takamoto S, Morita R, Kim S, Hironaka T, Nabata T, Onishi T, Ogihara T
JournalBiochem Biophys Res Commun
PubMed ID2526631
The effect of the specific potassium (K+) ionophore valinomycin on increase in intracellular calcium concentration [( Ca2+]i) was studied in vascular smooth muscle cells (VSMC). Valinomycin at more than 10(-9) M dose-dependently suppressed phasic increase in [Ca2+]i in VSMC induced by angiotensin II (AII) in both control and Ca2+-free solution, ... More
Transmembrane voltage regulates binding of annexin V and lactadherin to cells with exposed phosphatidylserine.
AuthorsSmith C, Gibson DF, Tait JF,
JournalBMC Biochem
PubMed ID19222854
BACKGROUND: Cells expose phosphatidylserine during apoptosis. The voltage across the plasma membrane also decreases or disappears during apoptosis, but the physiological significance of this is unknown. RESULTS: Here we show that transmembrane potential regulates membrane binding of two unrelated proteins that recognize exposed phosphatidylserine on apoptotic cells. In Jurkat T ... More
ZP3-dependent activation of sperm cation channels regulates acrosomal secretion during mammalian fertilization.
AuthorsArnoult C, Zeng Y, Florman HM
JournalJ Cell Biol
PubMed ID8707844
The sperm acrosome reaction is a Ca(2+)-dependent secretory event required for fertilization. Adhesion to the egg's zona pellucida promotes Ca2+ influx through voltage-sensitive channels, thereby initiating secretion. We used potentiometric fluorescent probes to determine the role of sperm membrane potential in regulating Ca2+ entry. ZP3, the glycoprotein agonist of the ... More
Protein kinase A regulates chloride conductance in endocytic vesicles from proximal tubule.
AuthorsBae HR, Verkman AS
JournalNature
PubMed ID1701220
Regulation of ion transport by phosphorylation and G proteins occurs in several epithelial and non-epithelial cell plasma membranes1-5. It is not known whether transporters on intracellular membranes are target sites for second messengers. Here we present direct evidence that a chloride conductance in endocytic vesicles from rabbit proximal tubule is ... More
Effect of gangliosides on membrane permeability studied by enzymic and fluorescence-spectroscopy techniques.
AuthorsSarti P, Antonini G, Malatesta F, Vallone B, Brunori M, Masserini M, Palestini P, Tettamanti G
JournalBiochem J
PubMed ID2159281
The effect of gangliosides on membrane permeability was investigated by studying the kinetic properties of cytochrome c oxidase, the activity of which, when the enzyme is reconstituted in phospholipid vesicles, is dependent on membrane permeability to H+ and K+. The experiments indicate that three different gangliosides (GM1, DD1a, GT1b) incorporated ... More
Monitoring of relative mitochondrial membrane potential in living cells by fluorescence microscopy.
AuthorsJohnson LV, Walsh ML, Bockus BJ, Chen LB
JournalJ Cell Biol
PubMed ID6783667
Permeant cationic fluorescent probes are shown to be selectively accumulated by the mitochondria of living cells. Mitochondria-specific interaction of such molecules is apparently dependent on the high trans-membrane potential (inside negative) maintained by functional mitochondria. Dissipation of the mitochondrial trans-membrane and potential by ionophores or inhibitors of electron transport eliminates ... More
Effect of membrane potential on furosemide-inhibitable sodium influxes in human red blood cells.
AuthorsKracke GR, Dunham PB
JournalJ Membr Biol
PubMed ID3669066
Furosemide-inhibitable Na influx (a measure of Na/K/Cl cotransport) was determined as a function of membrane potential in human red blood cells. The membrane potential was varied from -42 to +118 mV using valinomycin and gradients of K. The furosemide-inhibitable, unidirectional Na influx was independent of membrane potential over the entire ... More
The plasma membrane potential of human neutrophils. Role of ion channels and the sodium/potassium pump.
AuthorsMajander A, Wikström M
JournalBiochim Biophys Acta
PubMed ID2539191
Calcium-depleted human neutrophils are depolarised when suspended in calcium-free media containing sodium ions, and are repolarised by extracellular replenishment of Ca2+. The depolarisation is due to a high inward sodium current, which is blocked by calcium and by several other divalent cations, but not by barium. Addition of calcium results ... More
A stopped-flow kinetic study of the interaction of potential-sensitive oxonol dyes with lipid vesicles.
AuthorsClarke RJ, Apell HJ
JournalBiophys Chem
PubMed ID2611347
The interaction of the dyes oxonol V and oxonol VI with unilamellar dioleoylphosphatidylcholine vesicles was investigated using a fluorescence stopped-flow technique. On mixing with the vesicles, both dyes exhibit an increase in their fluorescence, which occurs in two phases. According to the dependence of the reciprocal relaxation time on vesicle ... More
Dual-wavelength ratiometric fluorescence measurements of membrane potential.
AuthorsMontana V, Farkas DL, Loew LM
JournalBiochemistry
PubMed ID2765500
This work shows that the voltage across membranes in two very different preparations, lipid vesicles in suspension and individual HeLa cells under a microscope, is linearly related to the ratio of fluorescence excited from the two wings of the absorption spectrum of a voltage-sensitive dye. The dye di-4-ANEPPS [1-(3-sulfonatopropyl)-4-[beta-[2-(di-n-butylamino)-6-naphthyl] vin ... More
Reversal of multidrug resistance by valinomycin is overcome by CCCP.
AuthorsGoda K, Krasznai Z, Gaspar R, Lankelma J, Westerhoff HV, Damjanovich S, Szabó G
JournalBiochem Biophys Res Commun
PubMed ID8604982
Reversal of P-glycoprotein-mediated multidrug resistance by valinomycin is overcome by the proton ionophore, CCCP. This effect, a complete suppression of the 5- to 10-fold valinomycin-induced reversal ("re-reversal"), exhibits a sharp extracellular potassium concentration ([K+(0)]) dependence. It is observed at [K+(0)] > 2-4 mM and not at [K+(0)] greater than or ... More
Intracellular turnover of fluorescein diacetate. Influence of membrane ionic gradients on fluorescein efflux.
AuthorsProsperi E
JournalHistochem J
PubMed ID2387757
The influence of the membrane ionic gradient on the efflux of Fluorescein after intracellular turnover of Fluorescein diacetate was studied in HeLa cells. The kinetics of Fluorescein efflux was monitored by determining with flow cytometry the decrease in fluorescence intensity of single cells. Alterations of the Na+ and K+ gradients ... More
Ionophore-induced apoptosis: role of DNA fragmentation and calcium fluxes.
AuthorsOjcius DM, Zychlinsky A, Zheng LM, Young JD
JournalExp Cell Res
PubMed ID1915662
Two ionophores specific for K+, valinomycin and beauvericin, induce a type of cell death very similar to apoptosis due to tumor necrosis factor (TNF alpha). Both ionophores cause cytolysis accompanied by internucleosomal DNA fragmentation of the dying cell into units of 200 base pairs. Morphologically, the cell death appears to ... More
Dependency of delta pH-relaxation across vesicular membranes on the buffering power of bulk solutions and lipids.
AuthorsGrzesiek S, Dencher NA
JournalBiophys J
PubMed ID3017468
The dependency of delta pH-relaxation kinetics across the membrane of sonicated small phospholipid vesicles on the concentration of internally entrapped buffer has been investigated by means of the pH-indicator dye pyranine. A very high contribution of lipid headgroups to the internal buffering power of the liposomes is observed, amounting to ... More
Assessment of membrane potential changes using the carbocyanine dye, diS-C3-(5): synchronous excitation spectroscopy studies.
AuthorsPlásek J, Hrouda V
JournalEur Biophys J
PubMed ID2029874
The fluorescence of the voltage sensitive dye, diS-C3-(5), has been analyzed by means of synchronous excitation spectroscopy. Using this rather rare fluorescence technique we have been able to distinguish between the slightly shifted spectra of diS-C3-(5) fluorescence from cells and from the supernatant. It has been found that diS-C3-(5) fluorescence ... More
Impermeant potential-sensitive oxonol dyes: I. Evidence for an "on-off" mechanism.
AuthorsGeorge EB, Nyirjesy P, Basson M, Ernst LA, Pratap PR, Freedman JC, Waggoner AS
JournalJ Membr Biol
PubMed ID3184175
This series of papers addresses the mechanism by which certain impermeant oxonol dyes respond to membrane-potential changes, denoted delta Em. Hemispherical oxidized cholesterol bilayer membranes provided a controlled model membrane system for determining the dependence of the light absorption signal from the dye on parameters such as the wavelength and ... More
Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential.
AuthorsCorda D, Pasternak C, Shinitzky M
JournalJ Membr Biol
PubMed ID7062341
Diffusion potential of potassium ions was found in unilamellar vesicles of phosphatidyl choline. The vesicles, which included potassium sulfate buffered with potassium phosphate were diluted into an analogous salt solution made of sodium sulfate and sodium phosphate. The diffusion potential was created by the addition of the potassium-ionophore, valinomycin. The ... More
Caspase-8-mediated BID cleavage and release of mitochondrial cytochrome c during Nomega-hydroxy-L-arginine-induced apoptosis in MDA-MB-468 cells. Antagonistic effects of L-ornithine.
AuthorsSingh R, Pervin S, Chaudhuri G
JournalJ Biol Chem
PubMed ID12145284
We have previously reported that N(omega)-hydroxy-l-arginine (NOHA), a stable intermediate product formed during the conversion of l-arginine to nitric oxide, induced apoptosis in MDA-MB-468 cells, and this action was antagonized in the presence of l-ornithine. We also reported that apoptosis induced by NOHA in this cell line could not be ... More
Electrophysiological study with oxonol VI of passive NO3- transport by isolated plant root plasma membrane.
AuthorsPouliquin P, Grouzis J, Gibrat R
JournalBiophys J
PubMed ID9876148
In contrast to animal cells, plant cells contain approximately 5-50 mM nitrate in cytosol and vacuole. The lack of specific spectroscopic probes, or suitable isotopes, impedes in vitro studies of NO3- transport. Reconstitution of root cell plasma membrane (PM) proteins in mixed soybean lipid:egg phosphatidylcholine allowed for the generation of ... More
Determination of the membrane potential of cultured mammalian Schwann cells and its sensitivity to potassium using a thiocarbocyanine fluorescent dye.
AuthorsHargittai PT, Youmans SJ, Lieberman EM
JournalGlia
PubMed ID1835962
The membrane potential of cultured rat sciatic nerve Schwann cells was determined with conventional microelectrode and voltage-sensitive fluorescent dye, Di-S-C3(5), optical techniques. The value for membrane potential obtained with microelectrodes was -42.1 +/- 4.7 mV (n = 8). Using optically determined fluorescent intensity changes caused by changes in external potassium ... More
Determination of the viability of Trichomonas vaginalis using flow cytometry.
AuthorsHumphreys MJ, Allman R, Lloyd D
JournalCytometry
PubMed ID8026224
In clinical laboratories, viability of Trichomonas vaginalis is determined by using light microscopy (differential count of motile to nonmotile organisms). Alternative methods are proposed that utilise flow cytometry. Under an epifluorescence microscope, live organisms fluorescence intensely green with fluorescein diacetate (FDA), whereas dead cells fluoresce orange with propidium iodide (PI). ... More