Presynaptic Ca(2+) influx at the inhibitor of the crayfish neuromuscular junction: a photometric study at a high time resolution.
AuthorsVyshedskiy A, Lin JW
JournalJ Neurophysiol
PubMed ID10634895
'Presynaptic calcium influx at the inhibitor of the crayfish neuromuscular junction was investigated by measuring fluorescence transients generated by calcium-sensitive dyes. This approach allowed us to correlate presynaptic calcium influx with transmitter release at a high time resolution. Systematic testing of the calcium indicators showed that only low-affinity dyes, with ... More
Light dependence of calcium and membrane potential measured in blowfly photoreceptors in vivo.
AuthorsOberwinkler J, Stavenga DG
JournalJ Gen Physiol
PubMed ID9689022
'Light adaptation in insect photoreceptors is caused by an increase in the cytosolic Ca2+ concentration. To better understand this process, we measured the cytosolic Ca2+ concentration in vivo as a function of adapting light intensity in the white-eyed blowfly mutant chalky. We developed a technique to measure the cytosolic Ca2+ ... More
Stimulation-evoked increases in cytosolic [Ca(2+)] in mouse motor nerve terminals are limited by mitochondrial uptake and are temperature-dependent.
AuthorsDavid G, Barrett EF
JournalJ Neurosci
PubMed ID11007886
'Increases in cytosolic [Ca(2+)] evoked by trains of action potentials (20-100 Hz) were recorded from mouse and lizard motor nerve terminals filled with a low-affinity fluorescent indicator, Oregon Green BAPTA 5N. In mouse terminals at near-physiological temperatures (30-38 degrees C), trains of action potentials at 25-100 Hz elicited increases in ... More
Direct measurement of SR release flux by tracking 'Ca2+ spikes' in rat cardiac myocytes.
AuthorsSong LS, Sham JS, Stern MD, Lakatta EG, Cheng H
JournalJ Physiol
PubMed ID9769413
'1. Ca2+ release flux across the sarcoplasmic reticulum (SR) during cardiac excitation-contraction coupling was investigated using a novel fluorescence method. Under whole-cell voltage-clamp conditions, rat ventricular myocytes were dialysed with a high concentration of EGTA (4.0 mM, 150 nM free Ca2+), to minimize the residence time of released Ca2+ in ... More
Activation of trypsinogen in large endocytic vacuoles of pancreatic acinar cells.
'The intracellular activation of trypsinogen, which is both pH- and calcium-dependent, is an important early step in the development of acute pancreatitis. The cellular compartment in which trypsinogen activation occurs currently is unknown. We therefore investigated the site of intracellular trypsinogen activation by using an established cellular model of acute ... More
Coupling of calcium homeostasis to axonal sodium in axons of mouse optic nerve.
AuthorsVerbny Y, Zhang CL, Chiu SY
JournalJ Neurophysiol
PubMed ID12163532
'Axonal populations in neonatal and mature optic nerves were selectively stained with calcium dyes for analysis of calcium homeostasis and its possible coupling to axonal Na. Repetitive nerve stimulation causes a rise in axonal [Ca(2+)](i) the posttetanus recovery of which is impeded by increasing the number of action potentials in ... More
Comparison between the predictions of diffusion-reaction models and localized Ca2+ transients in amphibian skeletal muscle fibers.
AuthorsNovo D, DiFranco M, Vergara JL
JournalBiophys J
PubMed ID12885654
'We developed a three-dimensional cylindrical diffusion-reaction model of a single amphibian myofibril in which Ca(2+) release occurred only at the Z-line. The model incorporated diffusion of Ca(2+), Mg(2+), and all relevant buffer species, as well as the kinetic binding reactions between the buffers and appropriate ions. Model data was blurred ... More
Mitochondrial clearance of cytosolic Ca(2+) in stimulated lizard motor nerve terminals proceeds without progressive elevation of mitochondrial matrix [Ca(2+)].
AuthorsDavid G
JournalJ Neurosci
PubMed ID10460256
'This study used fluorescent indicator dyes to measure changes in cytosolic and mitochondrial [Ca(2+)] produced by physiological stimulation of lizard motor nerve terminals. During repetitive action potential discharge at 10-50 Hz, the increase in average cytosolic [Ca(2+)] reached plateau at levels that increased with increasing stimulus frequency. This stabilization of ... More
An apoplastic Ca2+ sensor regulates internal Ca2+ release in aequorin-transformed tobacco cells.
AuthorsCessna SG, Low PS
JournalJ Biol Chem
PubMed ID11139570
'Removal of Ca(2+) from tobacco suspension cell medium has two immediate effects on cytosolic Ca(2+) fluxes: (i) externally derived Ca(2+) influx (occurring in response to cold shock or hypo-osmotic shock) is inhibited, and (ii) organellar Ca(2+) release (induced by a fungally derived defense elicitor, caffeine, or hypo-osmotic shock) is elevated. ... More
Extrusion of Ca2+ from mouse motor terminal mitochondria via a Na+-Ca2+ exchanger increases post-tetanic evoked release.
AuthorsGarcía-Chacón LE, Nguyen KT, David G, Barrett EF
JournalJ Physiol
PubMed ID16613870
'Mitochondria sequester much of the Ca2+ that enters motor nerve terminals during repetitive stimulation at frequencies exceeding 10-20 Hz. We studied the post-stimulation extrusion of Ca2+ from mitochondria by measuring changes in matrix [Ca2+] with fluorescent indicators loaded into motor terminal mitochondria in the mouse levator auris longus muscle. Trains ... More
The Psi(m) depolarization that accompanies mitochondrial Ca2+ uptake is greater in mutant SOD1 than in wild-type mouse motor terminals.
AuthorsNguyen KT, García-Chacón LE, Barrett JN, Barrett EF, David G,
JournalProc Natl Acad Sci U S A
PubMed ID19174508
'The electrical gradient across the mitochondrial inner membrane (Psi(m)) is established by electron transport chain (ETC) activity and permits mitochondrial Ca(2+) sequestration. Using rhodamine-123, we determined how repetitive nerve stimulation (100 Hz) affects Psi(m) in motor terminals innervating mouse levator auris muscles. Stimulation-induced Psi(m) depolarizations in wild-type (WT) terminals were ... More
Characterization of the calcium release domains during excitation-contraction coupling in skeletal muscle fibres.
AuthorsDiFranco M, Novo D, Vergara JL
JournalPflugers Arch
PubMed ID11907817
'The spatiotemporal properties of the Ca2+ release process in skeletal muscle fibres were determined using a confocal spot detection system. The low-affinity, fluorescent Ca2+ indicator Oregon Green 488 BAPTA-5N (OGB-5N) was used to record localized, action potential-induced fluorescence signals from consecutive locations separated by 200 nm within a single sarcomere. ... 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
Phenylalanine fluorescence studies of calcium binding to N-domain fragments of Paramecium calmodulin mutants show increased calcium affinity correlates with increased disorder.
AuthorsVanScyoc WS, Shea MA
JournalProtein Sci
PubMed ID11514666
'Calmodulin (CaM) is a ubiquitous, essential calcium-binding protein that regulates diverse protein targets in response to physiological calcium fluctuations. Most high-resolution structures of CaM-target complexes indicate that the two homologous domains of CaM are equivalent partners in target recognition. However, mutations between calcium-binding sites I and II in the N-domain ... More
Ca(2+)-dependent activation of Cl(-) currents in Xenopus oocytes is modulated by voltage.
AuthorsCallamaras N, Parker I
JournalAm J Physiol Cell Physiol
PubMed ID10751316
'Ca(2+)-activated Cl(-) currents (I(Cl,Ca)) were examined using fluorescence confocal microscopy to monitor intracellular Ca(2+) liberation evoked by flash photolysis of caged inositol 1,4, 5-trisphosphate (InsP(3)) in voltage-clamped Xenopus oocytes. Currents at +40 mV exhibited a steep dependence on InsP(3) concentration ([InsP(3)]), whereas currents at -140 mV exhibited a higher threshold ... More
alpha-Latrotoxin releases calcium in frog motor nerve terminals.
AuthorsTsang CW, Elrick DB, Charlton MP
JournalJ Neurosci
PubMed ID11102474
'alpha-Latrotoxin (alpha-LTX) is a neurotoxin that accelerates spontaneous exocytosis independently of extracellular Ca(2+). Although alpha-LTX increases spontaneous transmitter release at synapses, the mechanism is unknown. We tested the hypothesis that alpha-LTX causes transmitter release by mobilizing intracellular Ca(2+) in frog motor nerve terminals. Transmitter release was measured electrophysiologically and with ... More
Patch-clamp recording of charge movement, Ca(2+) current, and Ca(2+) transients in adult skeletal muscle fibers
AuthorsWang ZM, Messi ML, Delbono O
JournalBiophys J
PubMed ID10545370
'Intramembrane charge movement (Q), Ca(2+) conductance (G(m)) through the dihydropyridine-sensitive L-type Ca(2+) channel (DHPR) and intracellular Ca(2+) fluorescence (F) have been recorded simultaneously in flexor digitorum brevis muscle fibers of adult mice, using the whole-cell configuration of the patch-clamp technique. The voltage distribution of Q was fitted to a Boltzmann ... More
SERCA pump optimizes Ca2+ release by a mechanism independent of store filling in smooth muscle cells.
AuthorsGómez-Viquez L, Guerrero-Serna G, García U, Guerrero-Hernández A
JournalBiophys J
PubMed ID12829491
'Thapsigargin-sensitive sarco/endoplasmic reticulum Ca(2+) pumps (SERCAs) are involved in maintaining and replenishing agonist-sensitive internal stores. Although it has been assumed that release channels act independently of SERCA pumps, there are data suggesting the opposite. Our aim was to study the relationship between SERCA pumps and the release channels in smooth ... More
Extracellular Ca2+ depletion contributes to fast activity-dependent modulation of synaptic transmission in the brain.
AuthorsRusakov DA, Fine A
JournalNeuron
PubMed ID12546823
'Synaptic activation is associated with rapid changes in intracellular Ca(2+), while the extracellular Ca(2+) level is generally assumed to be constant. Here, using a novel optical method to measure changes in extracellular Ca(2+) at high spatial and temporal resolution, we find that brief trains of synaptic transmission in hippocampal area ... More
Photo-physical properties of Ca2+-indicator dyes suitable for two-photon fluorescence-lifetime recordings.
AuthorsWilms CD, Eilers J,
JournalJ Microsc
PubMed ID17371443
We analyzed the suitability of various Ca2+-indicator dyes for quantitative two-photon fluorescence-lifetime imaging. Although fura-2, fluo-3, BTC and calcein did not show useful Ca2+-dependent lifetime changes, calcium orange, calcium green-1, oregon green-2 and -5N, as well as magnesium green allowed to quantify the Ca2+-free and Ca2+-bound dye fractions by a ... More
Low-affinity Ca2+ indicators compared in measurements of skeletal muscle Ca2+ transients.
AuthorsHollingworth S, Gee KR, Baylor SM,
JournalBiophys J
PubMed ID19804716
The low-affinity fluorescent Ca(2+) indicators OGB-5N, Fluo-5N, fura-5N, Rhod-5N, and Mag-fluo-4 were evaluated for their ability to accurately track the kinetics of the spatially averaged free Ca(2+) transient (Delta[Ca(2+)]) in skeletal muscle. Frog single fibers were injected with one of the above indicators and, usually, furaptra (previously shown to rapidly ... More
Light evokes Ca2+ spikes in the axon terminal of a retinal bipolar cell.
AuthorsProtti DA, Flores-Herr N, von Gersdorff H
JournalNeuron
PubMed ID10707985
Bipolar cells in the vertebrate retina have been characterized as nonspiking interneurons. Using patch-clamp recordings from goldfish retinal slices, we find, however, that the morphologically well-defined Mb1 bipolar cell is capable of generating spikes. Surprisingly, in dark-adapted retina, spikes were reliably evoked by light flashes and had a long (1-2 ... More
An interdomain linker increases the thermostability and decreases the calcium affinity of the calmodulin N-domain.
AuthorsSorensen BR, Faga LA, Hultman R, Shea MA
JournalBiochemistry
PubMed ID11771998
A hydrophobic core is a widely accepted determinant of protein stability. However, regulatory proteins undergoing ligand-induced conformational switching may expose interior residues to solvent and cannot afford to be extremely rigid. Optimizing the energetic balance between stability and binding is challenging. The addition of five interdomain residues to rat and ... More
Amphetamine selectively blocks inhibitory glutamate transmission in dopamine neurons.
AuthorsPaladini CA, Fiorillo CD, Morikawa H, Williams JT
JournalNat Neurosci
PubMed ID11224544
Amphetamine is a highly addictive psychostimulant that promotes the release of the catecholamines dopamine and norepinephrine. Amphetamine-induced release of dopamine in the midbrain inhibits the activity of dopamine neurons through activation of D2 dopamine autoreceptors. Here we show that amphetamine may also excite dopamine neurons through modulation of glutamate neurotransmission. ... 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
Calcium uptake via endocytosis with rapid release from acidifying endosomes.
AuthorsGerasimenko JV, Tepikin AV, Petersen OH, Gerasimenko OV
JournalCurr Biol
PubMed ID9843688
A number of specific cellular Ca2+ uptake pathways have been described in many different cell types [1] [2] [3].The possibility that substantial quantities of Ca2+ could be imported via endocytosis has essentially been ignored, although it has been recognized that endosomes can store Ca2+ [4] [5]. Exocrine cells can release ... More
Depolarization-induced slow calcium transients activate early genes in skeletal muscle cells.
AuthorsCarrasco MA, Riveros N, Ríos J, Müller M, Torres F, Pineda J, Lantadilla S, Jaimovich E
JournalAm J Physiol Cell Physiol
PubMed ID12529240
The signaling mechanisms by which skeletal muscle electrical activity leads to changes in gene expression remain largely undefined. We have reported that myotube depolarization induces calcium signals in the cytosol and nucleus via inositol 1,4,5-trisphosphate (IP(3)) and phosphorylation of both ERK1/2 and cAMP-response element-binding protein (CREB). We now describe the ... More
Distinct ion channel classes are expressed on the outer nuclear envelope of T- and B-lymphocyte cell lines.
AuthorsFranco-Obregón A, Wang HW, Clapham DE
JournalBiophys J
PubMed ID10866948
The outer nuclear membrane, endoplasmic reticulum, and mitochondrial membrane ion channels are poorly understood, although they are important in the control of compartmental calcium levels, cell division, and apoptosis. Few direct recordings of these ion channels have been made because of the difficulty of accessing these intracellular membranes. Using patch-clamp ... More
Localized detection of action potential-induced presynaptic calcium transients at a Xenopus neuromuscular junction.
AuthorsDiGregorio DA, Vergara JL
JournalJ Physiol
PubMed ID9457637
1. Action potential (AP)-induced fluorescence transients were measured, using Ca2+ indicators and a spot-detection method, at single nerve terminals of a cultured Xenopus neuromuscular junction preparation with simultaneous measurement of neurotransmitter release. 2. Transients obtained using the low affinity Ca2+ indicator Oregon Green 488 BAPTA-5N (OGB-5N) exhibited rapid rising (t1/2 ... More
Potentiation of fractional sarcoplasmic reticulum calcium release by total and free intra-sarcoplasmic reticulum calcium concentration.
AuthorsShannon TR, Ginsburg KS, Bers DM
JournalBiophys J
PubMed ID10620297
Our aim was to measure the influence of sarcoplasmic reticulum (SR) calcium content ([Ca](SRT)) and free SR [Ca] ([Ca](SR)) on the fraction of SR calcium released during voltage clamp steps in isolated rabbit ventricular myocytes. [Ca](SRT), as measured by caffeine application, was progressively increased by conditioning pulses. Sodium was absent ... More
Calsenilin reverses presenilin-mediated enhancement of calcium signaling.
AuthorsLeissring MA, Yamasaki TR, Wasco W, Buxbaum JD, Parker I, LaFerla FM
JournalProc Natl Acad Sci U S A
PubMed ID10900016
Most cases of autosomal-dominant familial Alzheimer's disease are linked to mutations in the presenilin genes (PS1 and PS2). In addition to modulating beta-amyloid production, presenilin mutations also produce highly specific and selective alterations in intracellular calcium signaling. Although the molecular mechanisms underlying these changes are not known, one candidate molecular ... More
Thermodynamically irreversible gating of ryanodine receptors in situ revealed by stereotyped duration of release in Ca(2+) sparks.
AuthorsWang SQ, Song LS, Xu L, Meissner G, Lakatta EG, Ríos E, Stern MD, Cheng H
JournalBiophys J
PubMed ID12080116
For a single or a group of Markov channels gating reversibly, distributions of open and closed times should be the sum of positively weighted decaying exponentials. Violation of this microscopic reversibility has been demonstrated previously on a number of occasions at the single channel level, and has been attributed to ... More
Identification of a ryanodine receptor in rat heart mitochondria.
AuthorsBeutner G, Sharma VK, Giovannucci DR, Yule DI, Sheu SS
JournalJ Biol Chem
PubMed ID11297554
Recent studies have shown that, in a wide variety of cells, mitochondria respond dynamically to physiological changes in cytosolic Ca(2+) concentrations ([Ca(2+)](c)). Mitochondrial Ca(2+) uptake occurs via a ruthenium red-sensitive calcium uniporter and a rapid mode of Ca(2+) uptake. Surprisingly, the molecular identity of these Ca(2+) transport proteins is still ... More
Calcium imaging demonstrates colocalization of calcium influx and extrusion in fly photoreceptors.
AuthorsOberwinkler J, Stavenga DG
JournalProc Natl Acad Sci U S A
PubMed ID10900015
During illumination, Ca(2+) enters fly photoreceptor cells through light-activated channels that are located in the rhabdomere, the compartment specialized for phototransduction. From the rhabdomere, Ca(2+) diffuses into the cell body. We visualize this process by rapidly imaging the fluorescence in a cross section of a photoreceptor cell injected with a ... More
Evidence that mitochondria buffer physiological Ca2+ loads in lizard motor nerve terminals.
AuthorsDavid G, Barrett JN, Barrett EF
JournalJ Physiol
PubMed ID9547381
1. Changes in cytosolic and mitochondrial [Ca2+] produced by brief trains of action potentials were measured in motor nerve terminals using a rapidly scanning confocal microscope. Cytosolic [Ca2+] was measured using ionophoretically injected Oregon Green BAPTA 5N (OG-5N). Mitochondrial [Ca2+] was measured using rhod-2, bath loaded as dihydrorhod-2. 2. In ... More
Development and dissipation of Ca(2+) gradients in adrenal chromaffin cells.
AuthorsMarengo FD, Monck JR
JournalBiophys J
PubMed ID11023887
We used pulsed laser imaging to measure the development and dissipation of Ca(2+) gradients evoked by the activation of voltage-sensitive Ca(2+) channels in adrenal chromaffin cells. Ca(2+) gradients appeared rapidly (<5 ms) upon membrane depolarization and dissipated over several hundred milliseconds after membrane repolarization. Dissipation occurred with an initial fast ... More
Timing of Ca(2+) release from intracellular stores and the electrical response of Limulus ventral photoreceptors to dim flashes.
AuthorsPayne R, Demas J
JournalJ Gen Physiol
PubMed ID10828247
Light-induced release of Ca(2+) from stores in Limulus ventral photoreceptors was studied using confocal fluorescence microscopy and the Ca(2+) indicator dyes, Oregon green-5N and fluo-4. Fluorescence was collected from a spot within 4 microm of the microvillar membrane. A dual-flash protocol was used to reconstruct transient elevations of intracellular free ... More
Presynaptic mitochondrial calcium sequestration influences transmission at mammalian central synapses.
AuthorsBillups B, Forsythe ID
JournalJ Neurosci
PubMed ID12122046
Beyond their role in generating ATP, mitochondria have a high capacity to sequester calcium. The interdependence of these functions and limited access to presynaptic compartments makes it difficult to assess the role of sequestration in synaptic transmission. We addressed this important question using the calyx of Held as a model ... More
One calcium ion may suffice to open the tetrameric cardiac ryanodine receptor in rat ventricular myocytes.
AuthorsFan JS, Palade P
JournalJ Physiol
PubMed ID10200424
1. The release of Ca2+ from sarcoplasmic reticulum in response to Ca2+ entering through L-type Ca2+ channels was studied in isolated voltage clamped rat ventricular myocytes at room temperature using the fluorescent Ca2+ indicators fluo-3 and Oregon Green 488 Bapta 5N. 2. Depolarizations to positive potentials elicited fluo-3 Ca2+ transients ... More
Stimulation-induced changes in [Ca2+] in lizard motor nerve terminals.
AuthorsDavid G, Barrett JN, Barrett EF
JournalJ Physiol
PubMed ID9350620
1. Motor axons were injected ionophoretically with one of five Ca(2+)-sensitive dyes (fluo-3, Calcium Green-2, Calcium Green-5N, fluo-3FF and Oregon Green BAPTA-5N). Changes in fluorescence (delta F/Frest) within motor terminal boutons following a single action potential and brief stimulus trains were monitored with high temporal resolution using a confocal microscope. ... More
Calcium binding to calmodulin mutants monitored by domain-specific intrinsic phenylalanine and tyrosine fluorescence.
AuthorsVanScyoc WS, Sorensen BR, Rusinova E, Laws WR, Ross JB, Shea MA
JournalBiophys J
PubMed ID12414709
Cooperative calcium binding to the two homologous domains of calmodulin (CaM) induces conformational changes that regulate its association with and activation of numerous cellular target proteins. Calcium binding to the pair of high-affinity sites (III and IV in the C-domain) can be monitored by observing calcium-dependent changes in intrinsic tyrosine ... More
Calcium release domains in mammalian skeletal muscle studied with two-photon imaging and spot detection techniques.
AuthorsGómez J, Neco P, DiFranco M, Vergara JL
JournalJ Gen Physiol
PubMed ID16735751
The spatiotemporal characteristics of the Ca(2+) release process in mouse skeletal muscle were investigated in enzymatically dissociated fibers from flexor digitorum brevis (FDB) muscles, using a custom-made two-photon microscope with laser scanning imaging (TPLSM) and spot detection capabilities. A two-microelectrode configuration was used to electrically stimulate the muscle fibers, to ... More
Obesity induces preadipocyte CD36 expression promoting inflammation via the disruption of lysosomal calcium homeostasis and lysosome function.
Authors
JournalEBioMedicine
PubMed ID32516742
Slow calcium waves mediate furrow microtubule reorganization and germ plasm compaction in the early zebrafish embryo.
Authors
JournalDevelopment
PubMed ID29632136
Ca2+ entry through NaV channels generates submillisecond axonal Ca2+ signaling.
Authors
JournalElife
PubMed ID32553116
Enhanced enzymatic production of cholesteryl 6'-acylglucoside impairs lysosomal degradation for the intracellular survival of Helicobacter pylori.