Caffeine inhibits inositol trisphosphate-mediated liberation of intracellular calcium in Xenopus oocytes.
AuthorsParker I, Ivorra I
JournalJ Physiol
PubMed ID1844813
'1. Voltage-clamp recording of Ca(2+)-activated chloride currents in Xenopus oocytes was used to study the effects of caffeine on the liberation of intracellular Ca2+ induced by photo-release of inositol 1,4,5-trisphosphate (InsP3) from caged InsP3. Bath application of caffeine, at concentrations between 0.1 and 10 mM, reduced or abolished the current ... More
Cyclic ADP-ribose and calcium-induced calcium release regulate neurotransmitter release at a cholinergic synapse of Aplysia.
'1. Presynaptic injection of cyclic ADP-ribose (cADPR), a modulator of the ryanodine receptor, increased the postsynaptic response evoked by a presynaptic spike at an identified cholinergic synapse in the buccal ganglion of Aplysia californica. 2. The statistical analysis of long duration postsynaptic responses evoked by square depolarizations of the voltage-clamped ... More
Calcium permeability of the neuronal nuclear envelope: evaluation using confocal volumes and intracellular perfusion.
AuthorsO'Malley DM
JournalJ Neurosci
PubMed ID7931542
'In many calcium-imaging studies, the nuclear envelope appears to maintain a gradient of free calcium between the nucleus and cytosol. This issue was examined by loading amphibian sympathetic neurons with the calcium indicator fluo 3 via whole-cell patch clamping. Confocal optical sectioning allowed acquisition of independent calibration curves for the ... More
Imaging of calcium transients in skeletal muscle fibers.
AuthorsVergara J, DiFranco M, Compagnon D, Suarez-Isla BA
JournalBiophys J
PubMed ID2015378
'Epifluorescence images of Ca2+ transients elicited by electrical stimulation of single skeletal muscle fibers were studied with fast imaging techniques that take advantage of the large fluorescence signals emitted at relatively long wavelengths by the dyes fluo-3 and rhod-2 in response to binding of Ca2+ ions, and of the suitable ... More
The membrane guanylyl cyclase, retinal guanylyl cyclase-1, is activated through its intracellular domain.
AuthorsLaura RP, Dizhoor AM, Hurley JB
JournalJ Biol Chem
PubMed ID8662612
'Retinal guanylyl cyclase-1 (RetGC-1) is a membrane guanylyl cyclase found in photoreceptor outer segments. It consists of an apparent extracellular domain (ECD) linked by a single transmembrane segment to an intracellular domain (ICD). Guanylyl cyclase activating protein-2 (GCAP-2) is a Ca2+-binding protein that activates RetGC-1 in a Ca2+-sensitive manner. To ... More
Metabolism of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate by the oocytes of Xenopus laevis.
AuthorsSims CE, Allbritton NL
JournalJ Biol Chem
PubMed ID9461597
'The pathway and kinetics of inositol 1,4,5-trisphosphate (IP3) metabolism were measured in Xenopus laevis oocytes and cytoplasmic extracts of oocytes. Degradation of microinjected IP3 in intact oocytes was similar to that in the extracts containing comparable concentrations of IP3 ([IP3]). The rate and route of metabolism of IP3 depended on ... More
Fluorescent indicators for cytosolic calcium based on rhodamine and fluorescein chromophores.
AuthorsMinta A, Kao JP, Tsien RY
JournalJ Biol Chem
PubMed ID2498308
'A new group of fluorescent indicators with visible excitation and emission wavelengths has been synthesized for measurements of cytosolic free Ca2+. The five compounds, "rhod-1," "rhod-2," "fluo-1," "fluo-2," and "fluo-3" (Figs. 2 and 3), combine the 8-coordinate tetracarboxylate chelating site of 1,2-bis(2-amino-phenoxyethane-N,N,N'',N''-tetraacetic acid with a xanthene chromophore to give a ... More
Modulation of mitochondrial Ca(2+) homeostasis by Bcl-2.
'We have investigated the role of mitochondrial Ca(2+) (Ca(m)) homeostasis in cell survival. Disruption of Ca(m) homeostasis via depletion of the mitochondrial Ca(2+) store was the earliest event that occurred during staurosporine-induced apoptosis in neuroblastoma cells (SH-SY5Y). The decrease of Ca(m) preceded activation of the caspase cascade and DNA fragmentation. ... More
Fluorescent calcium indicators: subcellular behavior and use in confocal imaging.
AuthorsO'Malley DM, Burbach BJ, Adams PR
JournalMethods Mol Biol
PubMed ID10231797
Kinetic properties of DM-nitrophen and calcium indicators: rapid transient response to flash photolysis.
AuthorsEscobar AL, Velez P, Kim AM, Cifuentes F, Fill M, Vergara JL
JournalPflugers Arch
PubMed ID9242727
'We describe a high temporal resolution confocal spot microfluorimetry setup which makes possible the detection of fluorescence transients elicited by Ca2+ indicators in response to large (50-200 microM), short duration (< 100 ns), free [Ca2+] transients generated by laser flash photolysis of DM-nitrophen (DM-n; caged Ca2+). The equilibrium and kinetic ... More
Ryanodine receptor adaptation: control mechanism of Ca(2+)-induced Ca2+ release in heart.
AuthorsGyörke S, Fill M
JournalScience
PubMed ID8387229
'Adaptation of single cardiac ryanodine receptor (RyR) channels was demonstrated by application of the caged calcium ion (Ca2+) methodology. In contrast to conventional desensitization found in surface membrane ligand-gated channels, single cardiac RyR channels adapted to maintained Ca2+ stimuli, preserving their ability to respond to a second (larger) Ca2+ stimulus. ... More
Modulation of Ca2+ transients by photorelease of caged nucleotides in frog skeletal muscle fibers.
AuthorsSanchez JA, Vergara J
JournalAm J Physiol
PubMed ID8203494
'Action potentials and intracellular Ca2+ transients were monitored in current-clamped segments of frog skeletal muscle fibers using the triple vaseline-gap technique. Calcium signals were measured with the fluorescent indicator rhod 2. Action potentials produced a transient increase in intracellular Ca2+ that was estimated, by deconvolution of the fluorescence signals, to ... More
Measurement of free Zn2+ ion concentration with the fluorescent probe mag-fura-2 (furaptra).
AuthorsSimons TJ
JournalJ Biochem Biophys Methods
PubMed ID8409208
'The fluorescent probe mag-fura-2, previously used to measure [Mg2+], can also be used to measure [Zn2+]. The peak in the excitation spectrum occurs at 323 nm for Zn2+, compared with 335 nm for Ca2+ and Mg2+. This allows simultaneous measurements of [Zn2+] and either [Ca2+] or [Mg2+], by using 3 ... More
Cyclic AMP-dependent phosphorylation of the inositol-1,4,5-trisphosphate receptor inhibits Ca2+ release from platelet membranes.
AuthorsQuinton TM, Dean WL
JournalBiochem Biophys Res Commun
PubMed ID1315537
Purified internal platelet membranes were treated with the catalytic subunit of protein kinase A to determine its effect on inositol-1,4,5-trisphosphate (IP3)-mediated Ca2+ release. Release kinetics were monitored using rhod-2, a Ca(2+)-specific fluorophore. Protein kinase A maximally inhibited the rate of IP3-mediated Ca2+ release by approximately 30% at saturating IP3 (10 ... More
Range of messenger action of calcium ion and inositol 1,4,5-trisphosphate.
AuthorsAllbritton NL, Meyer T, Stryer L
JournalScience
PubMed ID1465619
The range of messenger action of a point source of Ca2+ or inositol 1,4,5-trisphosphate (IP3) was determined from measurements of their diffusion coefficients in a cytosolic extract from Xenopus laevis oocytes. The diffusion coefficient (D) of [3H]IP3 injected into an extract was 283 microns 2/s. D for Ca2+ increased from ... More
Localized all-or-none calcium liberation by inositol trisphosphate.
AuthorsParker I, Ivorra I
JournalScience
PubMed ID2237441
Laser confocal microscopy was used to monitor calcium ion (Ca2+) liberation from highly localized (micrometer) regions of intact Xenopus oocytes in response to photo-released inositol 1,4,5-trisphosphate (InsP3). Local Ca2+ release varied in an all-or-none manner with increasing amount of InsP3, in contrast to signals recorded from larger areas, which grew ... More
Measurement of intracellular calcium.
AuthorsTakahashi A, Camacho P, Lechleiter JD, Herman B
JournalPhysiol Rev
PubMed ID10508230
To a certain extent, all cellular, physiological, and pathological phenomena that occur in cells are accompanied by ionic changes. The development of techniques allowing the measurement of such ion activities has contributed substantially to our understanding of normal and abnormal cellular function. Digital video microscopy, confocal laser scanning microscopy, and ... More
Kinetics of Ca2+ release and contraction induced by photolysis of caged D-myo-inositol 1,4,5-trisphosphate in smooth muscle. The effects of heparin, procaine, and adenine nucleotides.
AuthorsSomlyo AV, Horiuti K, Trentham DR, Kitazawa T, Somlyo AP
JournalJ Biol Chem
PubMed ID1429583
The kinetics of Ca2+ release and contraction induced by photolytic release of inositol 1,4,5-trisphosphate (InsP3) were determined in permeabilized smooth muscle. The rate of Ca2+ release was half-maximal at 1 microM InsP3. The concentration-dependent delay of Ca2+ release at saturating InsP3 concentration was approximately 10 ms and within the uncertainty ... More
Three-dimensional structure of guanylyl cyclase activating protein-2, a calcium-sensitive modulator of photoreceptor guanylyl cyclases.
AuthorsAmes JB, Dizhoor AM, Ikura M, Palczewski K, Stryer L
JournalJ Biol Chem
PubMed ID10383444
Guanylyl cyclase activating protein-2 (GCAP-2) is a Ca2+-sensitive regulator of phototransduction in retinal photoreceptor cells. GCAP-2 activates retinal guanylyl cyclases at low Ca2+ concentration (<100 nM) and inhibits them at high Ca2+ (>500 nM). The light-induced lowering of the Ca2+ level from approximately 500 nM in the dark to approximately ... More
Calcium oscillations in freshly dispersed and cultured interstitial cells from canine colon.
AuthorsPublicover NG, Horowitz NN, Sanders KM
JournalAm J Physiol
PubMed ID1550205
Spontaneous oscillations in intracellular Ca2+ concentration ([Ca2+]i) and membrane potential were used to monitor rhythmicity in freshly dispersed and cultured interstitial cells (IC) from the canine colon. The frequency of oscillations and responses to a number of channel blockers, agonists, ionic substitutions, and temperature were similar in freshly dispersed and ... More
Calcium measurements in perfused mouse heart: quantitating fluorescence and absorbance of Rhod-2 by application of photon migration theory.
AuthorsDu C, MacGowan GA, Farkas DL, Koretsky AP
JournalBiophys J
PubMed ID11159425
Both theoretical and experimental results are presented for the quantitative detection of calcium transients in the perfused mouse heart loaded with the calcium-sensitive fluorescent dye Rhod-2. Analytical models are proposed to calculate both the reflected absorbance and fluorescence spectra detected from the mouse heart. These models allow correlation of the ... More
Rapid Ca2+ extrusion via the Na+/Ca2+ exchanger of the human platelet.
AuthorsValant PA, Adjei PN, Haynes DH
JournalJ Membr Biol
PubMed ID1469706
This communication reports the kinetics of the Na+/Ca2+ exchanger and of the plasma membrane (PM) Ca2+ pump of the intact human platelet. The kinetic properties of these two systems were deduced by studying the rate of Ca2+ extrusion and its Na+ dependence for concentrations of cytoplasmic free Ca2+ ([Ca2+]cyt) in ... More
Inositol tetrakisphosphate liberates stored Ca2+ in Xenopus oocytes and facilitates responses to inositol trisphosphate.
AuthorsParker I, Ivorra I
JournalJ Physiol
PubMed ID1841939
1. The actions of the putative second messenger inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) were studied by injecting it into voltage-clamped oocytes while recording Ca(2+)-dependent chloride membrane currents and, in some experiments, fluorescence signals from Ca2+ indicators. 2. Ins(1,3,4,5)P4 evoked a rise in intracellular Ca2+ and associated chloride current in oocytes bathed in ... More
Imaging of Ca2+ transients induced in Paramecium cells by a polyamine secretagogue.
AuthorsKlauke N, Plattner H
JournalJ Cell Sci
PubMed ID9152023
In Paramecium tetraurelia cells analysis of transient changes in Ca2+ concentration, [Ca2+]i, during aminoethyldextran (AED) stimulated synchronous (<1 second) trichocyst exocytosis has been hampered by various technical problems which we now have overcome. While Fura Red was found appropriate for quantitative double wavelength recordings, Fluo-3 allowed to follow, semi-quantitatively but ... More
Fast calcium removal during single twitches in amphibian skeletal muscle fibres.
AuthorsCaputo C, Bolaños P, Escobar AL
JournalJ Muscle Res Cell Motil
PubMed ID10555074
Fluorescence signals from the calcium sensitive dyes Fluo-3 or Rhod-2 were obtained simultaneously with isometric tension in single fibres isolated from the anterior tibialis muscle of Leptodactylus insularis (20-22 degrees C). Fluo-3 fluorescence signals were transformed into [Ca2+]i transients as previously described. Most of the decay phase of single twitch ... More
Low temperature molecular adaptation of the skeletal muscle sarco(endo)plasmic reticulum Ca2+-ATPase 1 (SERCA 1) in the wood frog (Rana sylvatica).
AuthorsDode L, Van Baelen K, Wuytack F, Dean WL
JournalJ Biol Chem
PubMed ID11044449
We have compared the primary sequence and enzymatic properties of the sarcoplasmic reticulum Ca(2+)-ATPases from a cold-tolerant frog Rana sylvatica with those of a closely related cold-intolerant frog, Rana clamitans. Sarcoplasmic reticulum isolated from leg muscles of both species contains a major protein ( approximately 100 kDa) that reacts with ... More