JournalAdvances in experimental medicine and biology
PubMed ID8109389
The effect of Ca2+ on the time course of force generation in frog skinned muscle fibres has been investigated using laser flash photolysis of the caged-calcium, either nitr-5 or DM-Nitrophen. Gradations in the rate and extent of contraction could be achieved by changing the energy of the laser pulse, which ... More
Ion selectivities of the Ca(2+) sensors for exocytosis in rat phaeochromocytoma cells.
AuthorsKishimoto T, Liu TT, Ninomiya Y, Takagi H, Yoshioka T, Ellis-Davies GC, Miyashita Y, Kasai H
JournalJ Physiol
PubMed ID11410622
'1. The ion selectivities of the Ca(2+) sensors for the two components of exocytosis in rat phaeochromocytoma (PC12) cells were examined by measurement of membrane capacitance and amperometry. The cytosolic concentrations of metal ions were increased by photolysis of caged-Ca(2+) compounds and measured with low-affinity indicators benzothiazole coumarin (BTC) or ... More
Ca2+ and voltage inactivate Ca2+ channels in guinea-pig ventricular myocytes through independent mechanisms.
AuthorsHadley RW, Lederer WJ
JournalJ Physiol
PubMed ID1668348
'1. L-type Ca2+ currents and Ca2+ channel gating currents were studied in isolated guinea-pig ventricular heart cells using the whole-cell patch-clamp technique, in order to investigate the mechanism of Ca(2+)-dependent inactivation. The effect of altering the intracellular Ca2+ concentration ([Ca2+]i) on these currents was studied through photorelease of intracellular Ca2+ ... More
Ca(2+)-dependent block and potentiation of L-type calcium current in guinea-pig ventricular myocytes.
AuthorsBates SE, Gurney AM
JournalJ Physiol
PubMed ID8410697
'1. The caged calcium compound nitr-5 has been used to investigate the response of the L-type calcium current (ICa) of guinea-pig ventricular cells to a rapid increase in the free intracellular calcium concentration ([Ca2+]i). 2. When 2 mM nitr-5 or 3 mM DM-nitrophen was loaded into cells via a patch ... More
Rapid activation of the cardiac ryanodine receptor by submillisecond calcium stimuli.
AuthorsZahradníková A, Zahradník I, Györke I, Györke S
JournalJ Gen Physiol
PubMed ID10578015
'The local control concept of excitation-contraction coupling in the heart postulates that the activity of the sarcoplasmic reticulum ryanodine receptor channels (RyR) is controlled by Ca(2+) entry through adjoining sarcolemmal single dihydropyridine receptor channels (DHPRs). One unverified premise of this hypothesis is that the RyR must be fast enough to ... More
Frequency decoding of fast calcium oscillations by calpain.
AuthorsTompa P, Töth-Boconádi R, Friedrich P
JournalCell Calcium
PubMed ID11162853
'We report the development of a novel procedure for generating fast, high-frequency Ca2+ oscillations in vitro and the frequency-dependent activation of m-calpain, the Ca2+-activated intracellular cysteine protease. The procedure is based upon liberating Ca2+ from a cage, DM-Nitrophen, by repetitive UV laser pulses and its concomitant binding by a ''slow'' ... More
Modal gating transitions in cardiac ryanodine receptors during increases of Ca2+ concentration produced by photolysis of caged Ca2+.
AuthorsZahradníková A, Dura M, Györke S
JournalPflugers Arch
PubMed ID10398857
'Channel adaptation is a basic property of the sarcoplasmic reticulum Ca2+-release channels/ryanodine receptors (RyRs). It allows channel activity to decay during sustained increases in the concentration of activating Ca2+. Despite the potential physiological importance of this self-confining process, its molecular mechanism is not well understood. To define the mechanism of ... More
Photolabile chelators for the rapid photorelease of divalent cations.
AuthorsKaplan JH, Ellis-Davies GC
JournalProc Natl Acad Sci U S A
PubMed ID3137570
'The properties of a recently synthesized photolabile chelator for divalent cations are described, the affinity of which for Ca2+ changes by some 5 orders of magnitude on illumination. The compound 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N'',N''-tetrakis[(oxycarbonyl)me thyl]-1,2-ethanediamine (DM-nitrophen) binds Ca2+ (Kd approximately 5.0 x 10(-9) M) and Mg2+ (Kd approximately 2.5 x 10(-6) M) with ... More
Astrocyte-mediated control of cerebral blood flow.
AuthorsTakano T, Tian GF, Peng W, Lou N, Libionka W, Han X, Nedergaard M
JournalNat Neurosci
PubMed ID16388306
'Local increase in blood flow during neural activity forms the basis for functional brain imaging, but its mechanism remains poorly defined. Here we show that cortical astrocytes in vivo possess a powerful mechanism for rapid vasodilation. We imaged the activity of astrocytes labeled with the calcium (Ca(2+))-sensitive indicator rhod-2 in ... More
Ca2+ cooperativity in neurosecretion measured using photolabile Ca2+ chelators.
AuthorsLandò L, Zucker RS
JournalJ Neurophysiol
PubMed ID7983538
'1. The photolabile Ca2+ chelator DM-nitrophen was injected into crayfish motor neuron terminals and photolyzed with light flashes of different intensity to determine the cooperativity of Ca2+ action in releasing neurotransmitter. 2. Each flash elicited a phasic postsynaptic response resembling an excitatory junctional potential, apparently due to a presynaptic "spike" ... More
The effects of changing intracellular Ca2+ buffering on the excitability of cultured dorsal root ganglion neurones.
AuthorsAyar A, Storer C, Tatham EL, Scott RH
JournalNeurosci Lett
PubMed ID10507696
'The whole cell patch clamp technique was used to study the effects of changes in [Ca2+]i on the excitability of cultured dorsal root ganglion (DRG) neurones. Increases in [Ca2+]i caused membrane depolarization, altered the characteristics of evoked action potentials and activated potassium, chloride and non-selective cation conductances. Mobilization of Ca2+ ... More
Differential Ca2+ and Sr2+ regulation of intracellular divalent cations release in ventricular myocytes.
AuthorsZoghbi ME, Copello JA, Villalba-Galea CA, Vélez P, Diaz Sylvester PL, Bolaños P, Marcano A, Fill M, Escobar AL
JournalCell Calcium
PubMed ID15193860
'The regulation of the Ca2+ -induced Ca2+ release (CICR) from intracellular stores is a critical step in the cardiac cycle. The inherent positive feedback of CICR should make it a self-regenerating process. It is accepted that CICR must be governed by some negative control, but its nature is still debated. ... More
Role of myosin heavy chain composition in kinetics of force development and relaxation in rat myocardium.
AuthorsFitzsimons DP, Patel JR, Moss RL
JournalJ Physiol
PubMed ID9782168
'1. The effects of ventricular myosin heavy chain (MHC) composition on the kinetics of activation and relaxation were examined in both chemically skinned and intact myocardial preparations from adult rats. Thyroid deficiency was induced to alter ventricular MHC isoform expression from approximately 80% alpha-MHC/20% beta-MHC in euthyroid rats to 100% ... More
Simultaneous capacitance and amperometric measurements of exocytosis: a comparison.
AuthorsOberhauser AF, Robinson IM, Fernandez JM
JournalBiophys J
PubMed ID8842250
'We measured the exocytotic response induced by flash photolysis of caged compounds in isolated mast cells and chromaffin cells. Vesicle fusion was measured by monitoring the cell membrane capacitance. The release of vesicular contents was followed by amperometry. In response to a GTP gamma S stimulus we found that the ... More
Activation of Na-Ca exchange current by photolysis of "caged calcium".
AuthorsNiggli E, Lederer WJ
JournalBiophys J
PubMed ID8218911
'Intracellular photorelease of Ca2+ from "caged calcium" (DM-nitrophen) was used to investigate the Ca(2+)-activated currents in ventricular myocytes isolated from guinea pig hearts. The patch-clamp technique was applied in the whole-cell configuration to measure membrane current and to dialyze the cytosol with a pipette solution containing the caged compound. In ... More
Kinetics of tension development in skinned cardiac myocytes measured by photorelease of Ca2+.
AuthorsAraujo A, Walker JW
JournalAm J Physiol
PubMed ID7977795
'The rate of activation of tension development by free Ca2+ was examined in skinned rat ventricular myocytes. Pulse photolysis of the photosensitive Ca2+ chelator, Nitr-7, was used to rapidly elevate Ca2+ in the vicinity of the myofilaments. Tension increased exponentially with a first-order rate constant (kCa) that depended on the ... More
Kinetic properties of DM-nitrophen binding to calcium and magnesium.
AuthorsFaas GC, Karacs K, Vergara JL, Mody I
JournalBiophys J
PubMed ID15778435
'Caged-Ca(2+) compounds such as nitrophenyl-EGTA (NP-EGTA) and DM-nitrophen (DMn) are extremely useful in biological research, but their use in live cells is hampered by cytoplasmic [Mg(2+)]. We determined the properties of Ca(2+) release from NP-EGTA and DMn by using Oregon green BAPTA-5N to measure changes in [Ca(2+)] after ultraviolet flash ... More
FMRFamide modulation of secretory machinery underlying presynaptic inhibition of synaptic transmission requires a pertussis toxin-sensitive G-protein.
AuthorsHaydon PG, Man-Son-Hing H, Doyle RT, Zoran M
JournalJ Neurosci
PubMed ID1683900
'The neuropeptide FMRFamide modulates synaptic transmission between identified neurons of the pond snail Helisoma trivolvis. FMRFamide causes a presynaptic inhibition of transmitter release by actions on ion channels and secretory machinery (Man-Son-Hing et al., 1989). The actions of FMRFamide on secretory machinery were studied using giant synapses that form between ... More
Laser photolysis of caged compounds at 405 nm: photochemical advantages, localisation, phototoxicity and methods for calibration.
AuthorsTrigo FF, Corrie JE, Ogden D,
JournalJ Neurosci Methods
PubMed ID19427524
'Rapid, localised photolytic release of neurotransmitters from caged precursors at synaptic regions in the extracellular space is greatly hampered at irradiation wavelengths in the near-UV, close to the wavelength of maximum absorption of the caged precursor, because of inner-filtering by strong absorption of light in the cage solution between the ... More
Ca2+-dependent exocytotic pathways in Chinese hamster ovary fibroblasts revealed by a caged-Ca2+ compound.
AuthorsNinomiya Y, Kishimoto T, Miyashita Y, Kasai H
JournalJ Biol Chem
PubMed ID8663485
'Ca2+-dependent exocytosis and endocytosis of Chinese hamster ovary (CHO) fibroblasts were investigated using capacitance measurement and rapid photolysis of a caged-Ca2+ compound, dimethoxynitrophenamine tetrasodium salt. CHO cells exhibited large and fast increases in membrane capacitance (1.9 +/- 1 picofarads, or 13 +/- 7% of total membrane area, mean +/- S.D., ... More
Serotonergic effects of dotarizine in coronary artery and in oocytes expressing 5-HT2 receptors.
AuthorsMontiel C, Herrero CJ, García-Palomero E, Renart J, García AG, Lomax RB
JournalEur J Pharmacol
PubMed ID9286620
'In strips of pig coronary arteries incubated in oxygenated Krebs-bicarbonate solution at 37 degrees C, dotarizine blocked the phasic contractions evoked by 5-HT (0.5 microM) or K+ depolarization (35 mM K+) with an IC50 of 0.22 and 3.7 microM, respectively. Flunarizine inhibited both types of contractions with IC50 values of ... More
In vivo two-photon laser-scanning microscopy of Ca2+ dynamics in visual motion-sensitive neurons.
AuthorsKalb J, Nielsen T, Fricke M, Egelhaaf M, Kurtz R
JournalBiochem Biophys Res Commun
PubMed ID15020223
'We applied two-photon laser-scanning microscopy (TPLSM) to motion-sensitive visual interneurons of the fly to study Ca(2+) dynamics in vivo at a higher spatial and temporal resolution than possible with conventional fluorescence microscopy. Based on a custom-built two-photon microscope, we performed line scans to measure changes in presynaptic Ca(2+) concentrations elicited ... More
Rate of release of Ca2+ following laser photolysis of the DM-nitrophen-Ca2+ complex.
AuthorsMcCray JA, Fidler-Lim N, Ellis-Davies GC, Kaplan JH
JournalBiochemistry
PubMed ID1390672
'The determination of the rate of release of Ca2+ by pulsed photolysis of the photolabile chelator DM-nitrophen is important for its use in time-resolved physiological studies: the rate of substrate or effector release should be faster than the processes they initiate. Flash photolysis of DM-nitrophen using a 50-ns pulse from ... More
Submicroscopic calcium signals as fundamental events of excitation--contraction coupling in guinea-pig cardiac myocytes.
AuthorsLipp P, Niggli E
JournalJ Physiol
PubMed ID8730580
'1. Subcellularly localized Ca2+ signals have been proposed to represent elementary events of cardiac Ca2+ signalling (Ca2+ sparks), whereby an individual sarcolemmal L-type Ca2+ channel locally controls opening of a single (or a few) Ca2+ release channels in the sarcoplasmic reticulum (SR). 2. To investigate directly the elementary nature of ... More
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
Calcium sensitivity of glutamate release in a calyx-type terminal.
AuthorsBollmann JH, Sakmann B, Borst JG
JournalScience
PubMed ID10937999
'Synaptic efficacy critically depends on the presynaptic intracellular calcium concentration ([Ca2+]i). We measured the calcium sensitivity of glutamate release in a rat auditory brainstem synapse by laser photolysis of caged calcium. A rise in [Ca2+]i to 1 micromolar readily evoked release. An increase to >30 micromolar depleted the releasable vesicle ... More
Membrane capacitance changes induced by thrombin and calcium in single endothelial cells cultured from human umbilical vein.
AuthorsCarter TD, Zupancic G, Smith SM, Wheeler-Jones C, Ogden D
JournalJ Physiol
PubMed ID9824722
'1. Vesicular secretion from single human umbilical vein endothelial cells (HUVECs) was monitored by changes in membrane capacitance (Cm). Secretion was evoked by dialysis with strongly buffered intracellular free Ca2+ concentrations ([Ca2+]i), flash photolysis of Ca2+-loaded DM-nitrophen or caged InsP3, or by thrombin. [Ca2+]i was monitored spectrofluorimetrically with furaptra. The ... More
Activation of single cardiac and skeletal ryanodine receptor channels by flash photolysis of caged Ca2+.
AuthorsGyörke S, Vélez P, Suárez-Isla B, Fill M
JournalBiophys J
PubMed ID8075325
'Single ryanodine-sensitive sarcoplasmic reticulum (SR) Ca2+ release channels isolated from rabbit skeletal and canine cardiac muscle were reconstituted in planar lipid bilayers. Single channel activity was measured in simple solutions (no ATP or Mg2+) with 250 mM symmetrical Cs+ as charge carrier. A laser flash was used to photolyze caged-Ca2+ ... More
The role of Ca2+ feedback in shaping InsP3-evoked Ca2+ signals in mouse pancreatic acinar cells.
AuthorsKidd JF, Fogarty KE, Tuft RA, Thorn P
JournalJ Physiol
PubMed ID10517811
'1. Cytosolic Ca2+ has been proposed to act as both a positive and a negative feedback signal on the inositol trisphosphate (InsP3) receptor. However, it is unclear how this might affect the Ca2+ response in vivo. 2. Mouse pancreatic acinar cells were whole-cell patch clamped to record the Ca2+-dependent chloride ... More
Kinetic studies of Ca2+ binding and Ca2+ clearance in the cytosol of adrenal chromaffin cells.
AuthorsXu T, Naraghi M, Kang H, Neher E
JournalBiophys J
PubMed ID9199815
'The Ca2+ binding kinetics of fura-2, DM-nitrophen, and the endogenous Ca2+ buffer, which determine the time course of Ca2+ changes after photolysis of DM-nitrophen, were studied in bovine chromaffin cells. The in vivo Ca2+ association rate constants of fura-2, DM-nitrophen, and the endogenous Ca2+ buffer were measured to be 5.17 ... More
A fast activating presynaptic reuptake current during serotonergic transmission in identified neurons of Hirudo.
AuthorsBruns D, Engert F, Lux HD
JournalNeuron
PubMed ID8386524
'An electrogenic serotonin (5-HT) uptake process was characterized in the serotonergic Retzius-P cell synapse of the leech, and the simultaneous activation of this presynaptic reuptake and the postsynaptic response was monitored during evoked transmitter release. A presynaptic, Na(+)-dependent inward current upon application of 5-HT was isolated at membrane potentials between ... More
Role of Ca2+ in determining the rate of tension development and relaxation in rat skinned myocardium.
AuthorsSaeki Y, Kobayashi T, Yasuda S, Nishimura S, Sugiura S, Yamashita H, Sugi H
JournalJ Mol Cell Cardiol
PubMed ID15010276
'To clarify the roles of Ca2+ and crossbridge kinetics in determining the cardiac contraction profile, we analyzed the rate of tension development following nitrophenyl-EGTA photolysis and the rate of relaxation following diazo-2 photolysis in the absence and presence of phosphate (Pi, 5 mM) in rat skinned ventricular trabeculae. The rate ... More
Two-photon and UV-laser flash photolysis of the Ca2+ cage, dimethoxynitrophenyl-EGTA-4.
AuthorsDelPrincipe F, Egger M, Ellis-Davies GC, Niggli E
JournalCell Calcium
PubMed ID10191963
'We report efficient two-photon and UV-laser flash photolysis of dimethoxynitrophenyl-EGTA-4 (DMNPE-4), a newly-developed photolabile Ca(2+)-specific chelator. This compound exhibits good two-photon absorption at 705 nm, has a low Mg2+ affinity (approximately 7 mM), a Kd for Ca2+ of 19 nM, a quantum yield of 0.20 and changes its Ca2+ affinity ... More
Effect of Ca2+ binding on the profile structure of the sarcoplasmic reticulum membrane using time-resolved x-ray diffraction.
AuthorsDeLong LJ, Blasie JK
JournalBiophys J
PubMed ID8369405
'A number of studies have indicated that Ca(2+)-ATPase, the integral membrane protein of the sarcoplasmic reticulum (SR) membrane, undergoes some structural change upon Ca2+ binding to its high affinity binding sites (i.e., upon conversion of the E1 to the CaxE1 form of the enzyme). We have used x-ray diffraction to ... More
Multiple calcium-dependent processes related to secretion in bovine chromaffin cells.
AuthorsNeher E, Zucker RS
JournalNeuron
PubMed ID8427700
'We have used the caged calcium compound DM-nitrophen to investigate the kinetics of calcium-dependent secretion in bovine chromaffin cells. Perfusion with partially calcium-loaded nitrophen often caused a loading transient--slow secretion for up to 1 min due to displacement of Ca2+ by cytoplasmic Mg2+. Flash photolysis elicited 100 microM [Ca2+]i steps ... More
Astrocytic calcium signaling: mechanism and implications for functional brain imaging.
AuthorsWang X, Takano T, Nedergaard M,
JournalMethods Mol Biol
PubMed ID18839089
'Astrocytes are electrically non-excitable cells that, on a slow time scale of seconds, integrate synaptic transmission by dynamic increases in cytosolic Ca2+. A number of groups have recently shown that astrocytic Ca2+ signaling regulates vascular tones and that astrocytes play a central role in functional hyperemia by Ca2+ -dependent release ... More
Millisecond studies of secretion in single rat pituitary cells stimulated by flash photolysis of caged Ca2+.
AuthorsThomas P, Wong JG, Almers W
JournalEMBO J
PubMed ID8428588
'To study the final steps in the secretory pathway of rat pituitary melanotrophs, we have monitored changes in cell surface area due to exocytosis after flash photolysis of caged Ca2+. A step increase in cytosolic [Ca2+] to 45-125 microM triggers three phases of exocytic secretion. A small cohort of a ... More
Two-photon activation of caged calcium with submicron, submillisecond resolution.
AuthorsBrown EB, Webb WW
JournalMethods Enzymol
PubMed ID9661159
Controlling cell chemistry with caged compounds.
AuthorsAdams SR, Tsien RY
JournalAnnu Rev Physiol
PubMed ID8466191
Caged compounds and striated muscle contraction.
AuthorsHomsher E, Millar NC
JournalAnnu Rev Physiol
PubMed ID2139560
Photorelease techniques for raising or lowering intracellular Ca2+.
AuthorsZucker R
JournalMethods Cell Biol
PubMed ID8201983
Activation of ryanodine receptors by flash photolysis of caged Ca2+.
AuthorsLamb GD, Stephenson DG
JournalBiophys J
PubMed ID7756558
Flash photolysis of DM-nitrophen generates an extremely large [Ca2+] transient ("Ca2+ spike") at the start of each Ca2+ "step." The Ca2+ spike greatly increases the speed of activation of the ryanodine receptor channel ("supercharging") and could be responsible for apparent channel adaptation. ... More
Neurobiology with caged calcium.
AuthorsEllis-Davies GC,
JournalChem Rev
PubMed ID18447376
In this review, I give a brief outline of the wide variety of cells and cellular functions regulated by Ca2+. Using this basic biological context, I tell the history of the development of caged Ca2+ molecules from the perspective of the requirements of the experimental application of each photosensitive probe, ... More
Caged compounds: photorelease technology for control of cellular chemistry and physiology.
AuthorsEllis-Davies GC
JournalNat Methods
PubMed ID17664946
Caged compounds are light-sensitive probes that functionally encapsulate biomolecules in an inactive form. Irradiation liberates the trapped molecule, permitting targeted perturbation of a biological process. Uncaging technology and fluorescence microscopy are 'optically orthogonal': the former allows control, and the latter, observation of cellular function. Used in conjunction with other technologies ... More
Caged compounds: tools for illuminating neuronal responses and connections.
AuthorsNerbonne JM
JournalCurr Opin Neurobiol
PubMed ID8794086
A number of new 'caged' intracellular second messengers and neurotransmitters have been developed using the photolabile o-nitrobenzyl group. This chemistry has also recently been exploited in novel ways, including the development of caged enzyme substrates and caged proteins. Although caged compounds continue to be used primarily for mechanistic (kinetic) studies ... More
Reaction-induced infrared difference spectroscopy for the study of protein reaction mechanisms.
AuthorsZscherp C, Barth A
JournalBiochemistry
PubMed ID11329252
This paper reviews state-of-the-art reaction-induced infrared difference spectroscopy of proteins. This technique enables detailed characterization of enzyme function on the level of single bonds of proteins, cofactors, or substrates. The following methods to initiate a reaction in the infrared sample are discussed: (i) light-induced difference spectroscopy, (ii) attenuated total reflection ... More
A new method for monitoring the kinetics of calcium binding to the sarcoplasmic reticulum Ca(2+)-ATPase employing the flash-photolysis of caged-calcium.
AuthorsDeLong LJ, Phillips CM, Kaplan JH, Scarpa A, Blasie JK
JournalJ Biochem Biophys Methods
PubMed ID2150968
The kinetics of Ca2+ binding to the high-affinity sites of the sarcoplasmic reticulum (SR) Ca2(+)-ATPase were directly investigated by continuously monitoring the extravesicular calcium concentration via the metallochromic indicator Arsenazo III following the release of Ca2+ from a photolabile caged-calcium molecule, 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis [(oxycarbony)methyl]-1,2-ethanediamine (DM-nitrophen), utilizing a pulsed Nd:YAG laser for ... More
Ca2+-sensitive and Ca2+-insensitive exocytosis in maize coleoptile protoplasts.
AuthorsThiel G, Sutter JU, Homann U
JournalPflugers Arch
PubMed ID10653175
Ca2+ and osmotic driven extension of the surface area of maize coleoptile protoplasts was investigated using capacitance measurements and photolysis of the caged compound DM-nitrophen. Protoplasts responded to an elevation of cytoplasmic Ca2+ (Ca(i)) with a rapid burst in capacitance reaching a maximal increase of 1.3+/-1.1% over the resting cell ... More
Development and application of caged calcium.
AuthorsEllis-Davies GC
JournalMethods Enzymol
PubMed ID12622152
Several caged calciums have been synthesized since 1986, and three are commercially available: DM-nitrophen, NP-EGTA, and nitr-5. Each of these caged compounds has uniquely useful properties, making the choice of which cage to use dependent on the specific experiment (i.e., the cell type and divalent cation requirements of the experiments ... More
Caged-Ca2+: a new agent allowing liberation of free Ca2+ in biological systems by photolysis.
AuthorsGrell E, Lewitzki E, Ruf H, Bamberg E, Ellis-Davies GC, Kaplan JH, de Weer P
JournalCell Mol Biol
PubMed ID2514999
The alkaline earth cation complexes of DM-nitrophen [1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis-[(oxycarbonyl) methyl]- 1,2-ethanediamine)] release the bound cation in the millisecond time range upon irradiation by a short UV-light pulse. This technique allows to generate cation (eg. Ca2+) concentration jumps or pulses in solution or in cellular systems. The physico-chemical properties of DM-nitrophen and ... More
Calcium ions are involved in Escherichia coli chemotaxis.
AuthorsTisa LS, Adler J
JournalProc Natl Acad Sci U S A
PubMed ID1465403
Escherichia coli regulates intracellular free Ca2+ at about 90 nM [Gangola, P. & Rosen, B. P. (1987) J. Biol. Chem. 262, 12570-12574]. To increase intracellular free Ca2+, nitr-5/Ca2+, a "caged" Ca2+ compound, was electroporated into cells and then its affinity for Ca2+ was reduced by exposure to 370-nm light. Upon ... More
Analysis of relations between NMDA receptors and GABA release at olfactory bulb reciprocal synapses.
AuthorsChen WR, Xiong W, Shepherd GM
JournalNeuron
PubMed ID10774730
In the mammalian olfactory bulb, signal processing is mediated by synaptic interactions between dendrites. Glutamate released from mitral cell dendrites excites dendritic spines of granule cells, which in turn release GABA back onto the mitral cell dendrites, forming a reciprocal synaptic pair. This feedback synaptic circuit was shown to be ... More
Target contact regulates the calcium responsiveness of the secretory machinery during synaptogenesis.
AuthorsZoran MJ, Doyle RT, Haydon PG
JournalNeuron
PubMed ID1670920
Neuron B19 of Helisoma is selective in synaptogenesis. Presynaptic mechanisms underlying this selectivity were tested. Acetylcholine-sensitive assay cells were micromanipulated into contact with B19 somata to assess its secretory state. Prior to appropriate muscle target contact, spontaneous synaptic currents were detected; however, action potential-evoked release of neurotransmitter was detected only ... More
Reconstitution of calcium-triggered membrane fusion using "reserve" granules.
AuthorsChestkov VV, Radko SP, Cho MS, Chrambach A, Vogel SS
JournalJ Biol Chem
PubMed ID9442095
Calcium-gated secretion of proteins involves the transfer of "reserve" granules, exocytotic vesicles that are cytoplasmic and, hence, plasma membrane-naive, from the cell interior to the surface membrane where they dock prior to fusion. Docking and subsequent priming steps are thought to require cytoplasmic factors. These steps are believed to induce ... More
Optical nanosensors for chemical analysis inside single living cells. 1. Fabrication, characterization, and methods for intracellular delivery of PEBBLE sensors.
AuthorsClark HA, Hoyer M, Philbert MA, Kopelman R
JournalAnal Chem
PubMed ID10565274
Spherical optical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding), have been produced in sizes including 20 and 200 nm in diameter. These sensors are fabricated in a microemulsion and consist of fluorescent indicators entrapped in a polyacrylamide matrix. A generalized polymerization method has been developed that permits production ... More
Turnover rate of the cardiac Na(+)-Ca2+ exchanger in guinea-pig ventricular myocytes.
AuthorsPowell T, Noma A, Shioya T, Kozlowski RZ
JournalJ Physiol
PubMed ID8145153
1. Single guinea-pig ventricular myocytes were voltage clamped using the whole-cell configuration of the patch-clamp technique and membrane current generated by the Na(+)-Ca2+ exchange mechanism recorded. 2. Rapid increases in cytosolic free calcium ([Ca2+]i) evoked by flash photolysis of either nitr-5 or DM-nitrophen resulted in current relaxations, arising from a ... More
Calcium waves in skinned cardiac myocytes evoked by two-photon excitation photolysis of caged calcium.
AuthorsKonishi M, Yamashita T, Nakayama S, Kokubun S
JournalJpn J Physiol
PubMed ID11282005
In rat ventricular myocytes chemically skinned with saponin, a local rise of [Ca2+] was achieved by two-photon excitation photolysis (TPP) of the caged Ca2+ compound 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis[(oxycarbonyl)methyl]-1,2-ethanediamine (DM-nitrophen). Confocal Ca2+ images, by use of fluo-3, were simultaneously collected. TPP of DM-nitrophen induced Ca2+ waves propagating over the myocyte, and the local ... More
Measurement of intracellular Ca2+ concentration using Indo-1 during simultaneous flash photolysis to release Ca2+ from DM-nitrophen.
AuthorsKirby MS, Hadley RW, Lederer WJ
JournalPflugers Arch
PubMed ID8058467
We have constructed a modular instrument to measure intracellular [Ca2+] ([Ca2+]i) in single isolated cells while simultaneously imposing step changes in [Ca2+]i using "caged Ca2+". By combining the outputs of a xenon arc lamp with a frequency-tripled (Nd:YAG) laser, the instrument can operate with low maintained illumination to measure [Ca2+]i ... More
Calcium dependence of exocytosis and endocytosis at the cochlear inner hair cell afferent synapse.
AuthorsBeutner D, Voets T, Neher E, Moser T
JournalNeuron
PubMed ID11301027
Release of neurotransmitter at the inner hair cell (IHC) afferent synapse is a fundamental step in translating sound into auditory nerve excitation. To study the Ca2+ dependence of the underlying vesicle fusion and subsequent endocytosis, we combined Ca2+ uncaging with membrane capacitance measurements in mouse IHCs. Rapid elevations in [Ca2+]i ... More
Detection of Ca(2+)-transients elicited by flash photolysis of DM-nitrophen with a fast calcium indicator.
AuthorsEscobar AL, Cifuentes F, Vergara JL
JournalFEBS Lett
PubMed ID7758592
A confocal spot detection optical setup was used to record fluorescence signals in response to calcium pulses, elicited by flash photolysis of DM-nitrophen, with the calcium indicators CaOrange-5N and Fluo-3. Our results yield the following conclusions: [Ca2+] changes are almost perfect spikes at pCa 9 and broader transients followed by ... More
Photo-released intracellular Ca2+ evokes reversible mechanical responses in supporting cells of the guinea-pig organ of Corti.
AuthorsDulon D, Blanchet C, Laffon E
JournalBiochem Biophys Res Commun
PubMed ID8024570
Loaded under whole cell patch-clamp configuration, the caged Ca2+ molecule DM-nitrophen was used to increase [Ca2+]i rapidly and reversibly in isolated Deiters cells of the organ of Corti. Photolysis of DM-nitrophen increased [Ca2+]i from resting concentrations of 20-50 nM to values above microM, as measured with the fluorescent indicator Fluo-3. ... More
Calcium diffusion coefficient in Myxicola axoplasm.
Authorsal-Baldawi NF, Abercrombie RF
JournalCell Calcium
PubMed ID8521456
Calcium diffusion coefficients were measured in Myxicola axoplasm and in agar controls by two independent techniques: one utilizing 45Ca, and one utilizing Ca-specific mini-electrodes. The lowest value, approximately 0.1 x 10(-6) cm2.s-1, was measured, using the mini-electrode technique, in axoplasm with intact Ca-sequestering organelles. With ATP-depleted axoplasm, diffusion coefficients of ... More
Calcium-dependent immediate feedback control of inositol 1,4,5-triphosphate-induced Ca2+ release.
AuthorsIino M, Endo M
JournalNature
PubMed ID1331809
The temporal and spatial distribution of increases in intracellular Ca2+ concentration is an important factor in cellular signal transduction. Inositol 1,4,5-trisphosphate (InsP3) plays a key part in agonist-induced Ca2+ release, which can take place abruptly and in a confined space by a mechanism that is not fully understood. Here we ... More
Effects of photolabile calcium chelators on fluorescent calcium indicators.
AuthorsZucker RS
JournalCell Calcium
PubMed ID1540986
The fluorescence properties of the calcium indicators Fura-2 and Fluo-3 have been investigated in the presence of the 'caged calcium' photolabile chelators Nitr-5 and DM-nitrophen. The excitation spectra of dilute solutions of these indicators was distorted by the presence of photolabile chelators, owing to differential absorbance of excitation light by ... More
Does the use of DM-nitrophen, nitr-5, or diazo-2 interfere with the measurement of indo-1 fluorescence?
AuthorsHadley RW, Kirby MS, Lederer WJ, Kao JP
JournalBiophys J
PubMed ID8312490
Emission spectra of the photolabile Ca2+ chelators DM-nitrophen, nitr-5, and diazo-2 were studied alone, and in the presence of indo-1, to investigate potential interactions that would make the simultaneous manipulation and ratiometric measurement of the intracellular Ca2+ concentration difficult. Neither diazo-2 nor its photoproduct were found to be significantly fluorescent, ... More
Control of synaptic strength and timing by the release-site Ca2+ signal.
AuthorsBollmann JH, Sakmann B
JournalNat Neurosci
PubMed ID15750590
Transmitter release is triggered by highly localized, transient increases in the presynaptic Ca(2+) concentration ([Ca(2+)]). Rapidly decaying [Ca(2+)] elevations were generated using Ca(2+) uncaging techniques, and [Ca(2+)] was measured with a low-affinity Ca(2+) indicator in a giant presynaptic terminal, the calyx of Held, in rat brain slices. The rise time ... More
Cytoplasmic calcium buffer capacity determined with Nitr-5 and DM-nitrophen.
Authorsal-Baldawi NF, Abercrombie RF
JournalCell Calcium
PubMed ID8521455
We have examined intracellular calcium buffer capacity of cytoplasm from the giant axon of the marine invertebrate Myxicola infundibulum by photolytically releasing calcium from 'caged' compounds, while monitoring free calcium, [Ca2+], with Ca-sensing electrodes. In cytoplasm containing intact organelles, two features of the [Ca2+] response were seen upon light exposure: ... More
Optical single-channel analysis of the aerolysin pore in erythrocyte membranes.
AuthorsTschödrich-Rotter M, Kubitscheck U, Ugochukwu G, Buckley JT, Peters R
JournalBiophys J
PubMed ID8789089
Scanning microphotolysis (Scamp), a recently developed photobleaching technique, was used to analyze the transport of two small organic anions and one inorganic cation through single pores formed in human erythrocyte membranes by the channel-forming toxin aerolysin secreted by Aeromonas species. The transport rate constants of erythrocyte ghosts carrying a single ... More
Magnesium binding to DM-nitrophen and its effect on the photorelease of calcium.
AuthorsAyer RK, Zucker RS
JournalBiophys J
PubMed ID10585961
The effect of Mg(2+) on the process of Ca(2+) release from the caged Ca(2+) compound DM-nitrophen (NP) was studied in vitro by steady light UV photolysis of NP in the presence of Ca(2+) and Mg(2+). Ca(2+) release during photolysis and its relaxation/recovery after photolysis were monitored with the Ca(2+)-sensitive dye ... More
Inactivation and block of calcium channels by photo-released Ca2+ in dorsal root ganglion neurons.
AuthorsMorad M, Davies NW, Kaplan JH, Lux HD
JournalScience
PubMed ID2457253
Calcium channels are inactivated by voltage and intracellular calcium. To study the kinetics and the mechanism of calcium-induced inactivation of calcium channels, a "caged" calcium compound, dimethoxy-nitrophen was used to photo-release about 50 microM calcium ion within 0.2 millisecond in dorsal root ganglion neurons. When divalent cations were the charge ... More
The calcium concentration clamp: spikes and reversible pulses using the photolabile chelator DM-nitrophen.
AuthorsZucker RS
JournalCell Calcium
PubMed ID8458075
New procedures are described for producing brief transients and reversible elevations in [Ca] that can be used to quantitatively control the concentration of cytoplasmic calcium. If the photolabile calcium chelator DM-nitrophen, partially bound to calcium, is exposed to steady illumination, [Ca] can be raised from a few nM to up ... More
Calcium pump kinetics determined in single erythrocyte ghosts by microphotolysis and confocal imaging.
AuthorsKubitscheck U, Pratsch L, Passow H, Peters R
JournalBiophys J
PubMed ID7669907
The activity of the plasma membrane calcium pump was measured in single cells. Human red blood cell ghosts were loaded with a fluorescent calcium indicator and either caged calcium and ATP (protocol A) or caged ATP and calcium (protocol B). In a suitably modified laser scanning microscope either calcium or ... More
Adaptation of single cardiac ryanodine receptor channels.
AuthorsVélez P, Györke S, Escobar AL, Vergara J, Fill M
JournalBiophys J
PubMed ID9017196
Single cardiac ryanodine receptor (RyR) channel adaptation was previously defined with Ca2+ stimuli produced by flash photolysis of DM-nitrophen (caged-Ca+2). Photolysis of DM-nitrophen induced a very fast Ca+2 overshoot (Ca+2 spike) at the leading edge of the Ca+2 stimuli. It has been suggested that adaptation (tau approximately 1.3 s) may ... More
Voltage-independent calcium release in heart muscle.
AuthorsNiggli E, Lederer WJ
JournalScience
PubMed ID2173135
The Ca2+ that activates contraction in heart muscle is regulated as in skeletal muscle by processes that depend on voltage and intracellular Ca2+ and involve a positive feedback system. How the initial electrical signal is amplified in heart muscle has remained controversial, however. Analogous protein structures from skeletal muscle and ... More
Binding kinetics of calbindin-D(28k) determined by flash photolysis of caged Ca(2+)
AuthorsNägerl UV, Novo D, Mody I, Vergara JL
JournalBiophys J
PubMed ID11106608
We have used UV flash photolysis of DM-nitrophen in combination with model-based analysis of Oregon Green 488 BAPTA-5N fluorescence transients to study the kinetics of Ca(2+) binding to calbindin-D(28K). The experiments used saturated DM-nitrophen at a [Ca(2+)] of 1.5 microM. Under these conditions, UV laser flashes produced rapid steplike increases ... More
Gbetagamma acts at the C terminus of SNAP-25 to mediate presynaptic inhibition.
Presynaptic inhibition mediated by G protein-coupled receptors may involve a direct interaction between G proteins and the vesicle fusion machinery. The molecular target of this pathway is unknown. We demonstrate that Gbetagamma-mediated presynaptic inhibition in lamprey central synapses occurs downstream from voltage-gated Ca(2+) channels. Using presynaptic microinjections of botulinum toxins ... More
Specific inhibition of Na-Ca exchange function by antisense oligodeoxynucleotides.
AuthorsLipp P, Schwaller B, Niggli E
JournalFEBS Lett
PubMed ID7750570
The Na-Ca exchanger is essential for the Ca2+ homeostasis in many cell types. This transporter has been difficult to investigate because no specific inhibitor is available. We have synthesized an antisense oligodeoxynucleotide directed against the rat cardiac Na-Ca exchanger mRNA. To estimate the activity of the Na-Ca exchange in single ... More
Inhibitory actions of synthesised polyamine spider toxins and their analogues on Ca2+-activated Cl- currents recorded from cultured DRG neurones from neonatal rats.
AuthorsSutton KG, Stapleton SR, Scott RH
JournalNeurosci Lett
PubMed ID9718988
The whole cell variant of the patch clamp technique was used to investigate the actions of polyamine spider toxins and their analogues on high voltage-activated Ca2+ currents and Ca2+-activated Cl- currents (I(Cl(Ca))). The actions of synthesised FTX (putative natural toxin from the American funnel web spider), sFTX-3.3, Orn-FTX-3.3, Lys-FTX-3.3, and ... More
Ca2+ release from the phosphorylated and the unphosphorylated sarcoplasmic reticulum Ca2+ ATPase results in parallel structural changes. An infrared spectroscopic study.
AuthorsBarth A, Kreutz W, Mäntele W
JournalJ Biol Chem
PubMed ID9325264
Structural changes of the sarcoplasmic reticulum Ca2+-ATPase occurring in the reaction step involving phosphoenzyme conversion and Ca2+ release (Ca2E1-P --> E2-P) were followed using time-resolved infrared spectroscopy in H2O and 2H2O. The difference spectra measured between 1800 and 1500 cm-1 were almost identical to those of Ca2+ release from the ... More
Laser photolysis of caged calcium: rates of calcium release by nitrophenyl-EGTA and DM-nitrophen.
AuthorsEllis-Davies GC, Kaplan JH, Barsotti RJ
JournalBiophys J
PubMed ID8789118
Nitrophenyl-EGTA and DM-nitrophen are Ca2+ cages that release Ca2+ when cleaved upon illumination with near-ultraviolet light. Laser photolysis of nitrophenyl-EGTA produced transient intermediates that decayed biexponentially with rates of 500,000 s-1 and 100,000 s-1 in the presence of saturating Ca2+ and 290,000 s-1 and 68,000 s-1 in the absence of ... More
Polyamines decrease Ca(2+) sensitivity of tension and increase rates of activation in skinned cardiac myocytes.
AuthorsHarris SP, Patel JR, Marton LJ, Moss RL
JournalAm J Physiol Heart Circ Physiol
PubMed ID10993806
Owing in part to their interactions with membrane proteins, polyamines (e.g., spermine, spermidine, and putrescine) have been identified as potential modulators of membrane excitability and Ca(2+) homeostasis in cardiac myocytes. To investigate whether polyamines also affect cardiac myofilament proteins, we assessed the effects of polyamines on contractility using rat myocytes ... More
Multiple exocytotic pathways in pancreatic beta cells.
AuthorsTakahashi N, Kadowaki T, Yazaki Y, Miyashita Y, Kasai H
JournalJ Cell Biol
PubMed ID9214381
Ca2+-dependent exocytotic pathways in mouse pancreatic beta cells were investigated using both capacitance measurement and amperometric detection of vesicular contents. Serotonin was preloaded into large dense-core vesicles for the amperometry. Exocytosis was induced by rapid elevation of cytosolic Ca2+ concentrations using caged-Ca2+ compounds. Capacitance measurement revealed two major components of ... More
Determinants of relaxation rate in skinned frog skeletal muscle fibers.
AuthorsWahr PA, Johnson JD, Rall JA
JournalAm J Physiol
PubMed ID9611126
The influences of sarcomere uniformity and Ca2+ concentration on the kinetics of relaxation were examined in skinned frog skeletal muscle fibers induced to relax by rapid sequestration of Ca2+ by the photolysis of the Ca2+ chelator, diazo-2, at 10 degreesC. Compared with an intact fiber, diazo-2-induced relaxation exhibited a faster ... More
Calcium transients in astrocyte endfeet cause cerebrovascular constrictions.
AuthorsMulligan SJ, MacVicar BA
JournalNature
PubMed ID15356633
Cerebral blood flow (CBF) is coupled to neuronal activity and is imaged in vivo to map brain activation. CBF is also modified by afferent projection fibres that release vasoactive neurotransmitters in the perivascular region, principally on the astrocyte endfeet that outline cerebral blood vessels. However, the role of astrocytes in ... More
Photolytic manipulation of [Ca2+]i reveals slow kinetics of potassium channels underlying the afterhyperpolarization in hippocampal pyramidal neurons.
AuthorsSah P, Clements JD
JournalJ Neurosci
PubMed ID10233997
The identity of the potassium channel underlying the slow, apamin-insensitive component of the afterhyperpolarization current (sIAHP) remains unknown. We studied sIAHP in CA1 pyramidal neurons using simultaneous whole-cell recording, calcium fluorescence imaging, and flash photolysis of caged compounds. Intracellular calcium concentration ([Ca2+]i) peaked earlier and decayed more rapidly than sIAHP. ... More
Induction of filopodia by direct local elevation of intracellular calcium ion concentration.
AuthorsLau PM, Zucker RS, Bentley D
JournalJ Cell Biol
PubMed ID10366598
In neuronal growth cones, cycles of filopodial protrusion and retraction are important in growth cone translocation and steering. Alteration in intracellular calcium ion concentration has been shown by several indirect methods to be critically involved in the regulation of filopodial activity. Here, we investigate whether direct elevation of [Ca2+]i, which ... More
Regulation of ionic currents by protein kinase A and intracellular calcium in outer hair cells isolated from the guinea-pig cochlea.
AuthorsJagger DJ, Ashmore JF
JournalPflugers Arch
PubMed ID9914397
Two prominent potassium currents, termed IK and IK,n, and a cation current are found in outer hair cells (OHCs) of the guinea-pig cochlea. We report here whole-cell recordings which indicate that the currents are regulated by intracellular factors. 8-bromo-cAMP (500 microM), a membrane-permeable cAMP analogue, activated potassium currents in OHCs ... More
Photolysis of caged calcium in femtoliter volumes using two-photon excitation.
A new technique for the determination of the two-photon uncaging action cross section (deltau) of photolyzable calcium cages is described. This technique is potentially applicable to other caged species that can be chelated by a fluorescent indicator dye, as well as caged fluorescent compounds. The two-photon action cross sections of ... More
Molecular operations of the sodium-calcium exchanger revealed by conformation currents.
AuthorsNiggli E, Lederer WJ
JournalNature
PubMed ID2000135
The sodium-calcium exchanger is critical in the normal functioning of many cells. In heart muscle, it is the principal way by which the cells keep the concentration of intracellular calcium low, pumping out the Ca2+ that enters the cytosol through L-type Ca2+ channels. The exchanger may also contribute to the ... More
Effect of a 14-day hindlimb suspension on cytosolic Ca2+ concentration in rat portal vein myocytes.
Effects of a 14-day hindlimb suspension were examined on increases in cytosolic Ca2+ concentration ([Ca2+]i) evoked by vasoactive compounds and on Ca2+ channels in rat portal vein myocytes. The maximal increases in [Ca2+]i elicited by caffeine, norepinephrine, and angiotensin II were reduced by 30-50% in suspended rats, and complete recovery ... More
Do caged-Ca2+ compounds mimic the physiological stimulus for secretion?
AuthorsOberhauser AF, Robinson IM, Fernandez JM
JournalJ Physiol Paris
PubMed ID8520573
We measured the exocytotic response induced by a rapid and global increase in the concentration of Ca2+ or GTP gamma S (achieved by flash photolysis of caged compounds) in mast cells and chromaffin cells. Secretion was measured by following both cell membrane capacitance and amperometry. When Ca2+ was used to ... More
Estimation of the sarcoplasmic reticulum Ca2+ release flux underlying Ca2+ sparks.
AuthorsSoeller C, Cannell MB
JournalBiophys J
PubMed ID11964229
Using a combination of experimental and numerical approaches, we have tested two different approaches to calculating the sarcoplasmic reticulum (SR) Ca2+ release flux, which gives rise to cardiac muscle Ca2+ sparks. By using two-photon excited spot photolysis of DM-Nitrophen, known Ca2+ release flux time courses were generated to provide the ... More
Calcium signalling in cardiac muscle: refractoriness revealed by coherent activation.
AuthorsDelPrincipe F, Egger M, Niggli E
JournalNat Cell Biol
PubMed ID10559957
Contraction of cardiac myocytes is governed by calcium-ion (Ca2+ )-induced Ca2+ release (CICR) from the sarcoplasmic reticulum through Ca2+-release channels. Ca2+ release occurs by concerted activation of numerous elementary Ca2+ events, 'Ca2+ sparks', that are triggered and locally controlled by Ca2+ influx into the cell through plasmalemmal L-type Ca2+ channels. ... More
Tools for flash-photolysis experiments on voltage-clamped muscle fibre segments.
AuthorsSchuhmeier RP, Tewes S, Szentesi P, Melzer W
JournalPflugers Arch
PubMed ID10650992
An experimental set-up is described that allows the combination of rapid transmembrane voltage changes and photometric calcium recording with the fast photochemical turnover of substances applied externally or intracellularly to cut skeletal muscle fibres. It consists of a double-vaseline-gap system, designed for use with a xenon-flash-lamp device and a dual-wavelength ... More
Mechanisms governing dendritic gamma-aminobutyric acid (GABA) release in the rat olfactory bulb.
AuthorsIsaacson JS
JournalProc Natl Acad Sci U S A
PubMed ID11120892
In the olfactory bulb, synaptic transmission between dendrites plays an important role in the processing of olfactory information. Glutamate released from the dendrites of principal mitral cells excites the dendritic spines of granule cells, which in turn release gamma-aminobutyric acid (GABA) back onto mitral cell dendrites. Slow N-methyl-d-aspartate (NMDA) receptors ... More
Evidence for the load-dependent mechanical efficiency of individual myosin heads in skeletal muscle fibers activated by laser flash photolysis of caged calcium in the presence of a limited amount of ATP.
AuthorsSugi H, Iwamoto H, Akimoto T, Ushitani H
JournalProc Natl Acad Sci U S A
PubMed ID9482875
Although a contracting muscle regulates its energy output depending on the load imposed on it ("Fenn effect"), the mechanism underlying the load-dependent energy output remains obscure. To explore the possibility that the mechanical efficiency, with which chemical energy derived from ATP hydrolysis is converted into mechanical work, of individual myosin ... More
The regulatory light chains of myosin modulate cross-bridge cycling in skeletal muscle.
AuthorsSzczesna D, Zhao J, Potter JD
JournalJ Biol Chem
PubMed ID8617809
We investigated the kinetics of Ca2+ activation of skeletal muscle contraction elicited by the photolysis of caged Ca2+. Previously we showed that partial extraction of the 18-kDa regulatory light chains (RLCs) of myosin decreased the rate of force development and was subsequently increased by approximately 20% following reconstitution with RLCs ... More
Neurohumoral and metabolic effects of short-term dietary NaCl restriction in men. Relationship to salt-sensitivity status.
AuthorsEgan BM, Weder AB, Petrin J, Hoffman RG
JournalAm J Hypertens
PubMed ID1676891
Published observations suggest that not everyone benefits from severe dietary NaCl restriction, since blood pressure responses appear heterogeneous and adverse metabolic effects may occur. We studied the cardiovascular, neurohumoral, and metabolic effects of 7 day periods of 20 v 200 mEq/day NaCl diets in 27 men. Twelve subjects were salt ... More
Pulsed laser imaging of Ca(2+) influx in a neuroendocrine terminal.
AuthorsFisher TE, Fernandez JM
JournalJ Neurosci
PubMed ID10460251
The surge of Ca(2+) that triggers vesicle fusion is shaped by the distribution of Ca(2+) channels and the physical relationship between those channels and the exocytotic apparatus. Although channels and the release apparatus are thought to be tightly associated at fast synapses, the arrangement at neuroendocrine cells is less clear. ... More
Voltage and Ca(2+) dependence of pre-steady-state currents of the Na-Ca exchanger generated by Ca(2+) concentration jumps.
AuthorsKappl M, Nagel G, Hartung K
JournalBiophys J
PubMed ID11606276
The Ca(2+) concentration and voltage dependence of the relaxation kinetics of the Na-Ca exchanger after a Ca(2+) concentration jump was measured in excised giant membrane patches from guinea pig heart. Ca(2+) concentration jumps on the cytoplasmic side were achieved by laser flash-induced photolysis of DM-nitrophen. In the Ca-Ca exchange mode ... More