Presynaptic calcium signals and transmitter release are modulated by calcium-activated potassium channels.
AuthorsRobitaille R, Charlton MP
JournalJ Neurosci
PubMed ID1370323
'The regulation of synaptic transmission by Ca(2+)-activated potassium (gKca) channels was investigated at the frog neuromuscular junction (nmj). Charybdotoxin (CTX), a blocker of certain types of gKca channels, induced a twofold increase of transmitter release. Similar results were obtained with purified natural toxin, synthetic toxin, and recombinant toxin. Apamin, a ... More
Calcium buffer injections block fucoid egg development by facilitating calcium diffusion.
AuthorsSpeksnijder JE, Miller AL, Weisenseel MH, Chen TH, Jaffe LF
JournalProc Natl Acad Sci U S A
PubMed ID2505254
'The polarity of fucoid eggs is fixed either when tip growth starts or a bit earlier. A steady flow of calcium ions into the incipient tip is thought to establish a high calcium zone that is needed for its localization and formation. To test this hypothesis, we have injected seven ... More
Endogenously expressed Trp1 is involved in store-mediated Ca2+ entry by conformational coupling in human platelets.
AuthorsRosado JA, Brownlow SL, Sage SO
JournalJ Biol Chem
PubMed ID12196544
'Physical interaction between transient receptor potential (Trp) channels and inositol 1,4,5-trisphosphate receptors (IP(3)Rs) has been presented as a candidate mechanism for the activation of store-mediated Ca(2+) entry. The role of a human homologue of Drosophila transient receptor potential channel, hTrp1, in the conduction of store-mediated Ca(2+) entry was examined in ... More
The role of intracellular Ca2+ in the regulation of the plasma membrane Ca2+ permeability of unstimulated rat lymphocytes.
AuthorsMason MJ, Mahaut-Smith MP, Grinstein S
JournalJ Biol Chem
PubMed ID1828246
'The mechanism responsible for the increase in cytosolic free Ca2+ concentration ([Ca2+]i) during mitogenic stimulation of lymphocytes has been widely investigated. By contrast, little is known about the processes underlying Ca2+i homeostasis in resting (unstimulated) cells. It has been suggested that [Ca2+]i is an important determinant of the rate of ... More
Increased aggregation and secretion responses of human platelets when loaded with the calcium fluorescent probes quin2 and fura-2.
AuthorsLanza F, Beretz A, Kubina M, Cazenave JP
JournalThromb Haemost
PubMed ID3672425
'Incorporation into human platelets of the calcium fluorescent indicators quin2 or fura-2 at low concentrations used to measure intracellular free calcium leads to the potentiation of the effects of agonists on platelets. This was shown by increased aggregatory and secretory responses of quin2 or fura-2 loaded platelets after stimulation with ... More
Calcium mobilization is required for nuclear vesicle fusion in vitro: implications for membrane traffic and IP3 receptor function.
AuthorsSullivan KM, Busa WB, Wilson KL
JournalCell
PubMed ID8391933
'We studied the fusion of nuclear vesicles bound to chromatin in Xenopus egg extracts. Fusion was inhibited by 5 mM BAPTA, a Ca2+ buffer that suppresses cytosolic [Ca2+] gradients. The BAPTA-inhibited step in fusion was biochemically distinct from, and occurred later than, the GTP gamma S-sensitive step mediated by the ... More
Effects of intracellular calcium chelation on voltage-dependent and calcium-dependent currents in cat neocortical neurons.
AuthorsSchwindt PC, Spain WJ, Crill WE
JournalNeuroscience
PubMed ID1316566
'Large neurons from layer V in a slice preparation of cat sensorimotor cortex were impaled with microelectrodes containing KCl plus different concentrations of the Ca2+ chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N'',N''-tetra-acetic acid (BAPTA) or two of its derivatives. Impalement with electrodes containing high BAPTA (200 mM) quickly abolished Ca(2+)-dependent afterhyperpolarizations. Spike parameters were normal, ... More
On the dissociation constants of BAPTA-type calcium buffers.
AuthorsPethig R, Kuhn M, Payne R, Adler E, Chen TH, Jaffe LF
JournalCell Calcium
PubMed ID2515001
'We have determined or redetermined the calcium dissociation constants of seven BAPTA-type buffers with KD''s in the range from 0.4 microM to about 20 mM in 300 mM KCl. These include four newly synthesized ones: 5-nitro BAPTA; 5,5''-dinitro BAPTA; 5-methyl-5''-nitro BAPTA; and 5-methyl-5''-formyl BAPTA. Moreover, we tabulate dissociation constants or ... More
New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures.
AuthorsTsien RY
JournalBiochemistry
PubMed ID6770893
A new family of high-affinity buffers and optical indicators for Ca2+ is rationally designed and synthesized. The parent compound is 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a relative of the well-known chelator EGTA [ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] in which methylene links between oxygen and nitrogen are replaced by benzene rings. BAPTA and ... More
Mycobacterium tuberculosis phagosomes exhibit altered calmodulin-dependent signal transduction: contribution to inhibition of phagosome-lysosome fusion and intracellular survival in human macrophages.
AuthorsMalik ZA, Iyer SS, Kusner DJ
JournalJ Immunol
PubMed ID11207296
Mycobacterium tuberculosis successfully parasitizes macrophages by disrupting the maturation of its phagosome, creating an intracellular compartment with endosomal rather than lysosomal characteristics. We have recently demonstrated that live M. tuberculosis infect human macrophages in the absence of an increase in cytosolic Ca(2+) ([Ca(2+)](c)), which correlates with inhibition of phagosome-lysosome fusion ... More
Physiological [Ca2+]i level and pump-leak turnover in intact red cells measured using an incorporated Ca chelator.
AuthorsLew VL, Tsien RY, Miner C, Bookchin RM
JournalNature
PubMed ID6283392
The physiological actions of Ca2+ as a trigger and second messenger depend on the maintenance of large inward resting Ca2+ gradients across the cell plasma membrane. An ATP-fuelled Ca-pump, originally discovered and still best characterized in human red cells, is now believed to mediate resting Ca2+ extrusion in most animal ... More
Pollen tube growth is coupled to the extracellular calcium ion flux and the intracellular calcium gradient: effect of BAPTA-type buffers and hypertonic media.
AuthorsPierson ES, Miller DD, Callaham DA, Shipley AM, Rivers BA, Cresti M, Hepler PK
JournalPlant Cell
PubMed ID7866026
Lily pollen tubes possess a steep, tip-focused intracellular Ca2+ gradient and a tip-directed extracellular Ca2+ influx. Ratiometric ion imaging revealed that the gradient extends from above 3.0 microM at the apex to approximately 0.2 microM within 20 microns from the tip, while application of the Ca(2+)-specific vibrating electrode indicated that ... More
Calcium buffer injections inhibit cytokinesis in Xenopus eggs.
A slow cortical wave of high calcium accompanies the elongation of cleavage furrows in medaka fish eggs as well as in Xenopus eggs. We explored the role of such waves by injecting calcium buffers into Xenopus eggs at various times before and during first and second cleavage. Injection earlier than ... More
Detection of coexisting fluid phospholipid phases by equilibrium Ca2+ binding: peptide-poor L alpha and peptide-rich HII phase coexistence in gramicidin A'/phospholipid dispersions.
AuthorsDibble AR, Feigenson GW
JournalBiochemistry
PubMed ID7524658
The isothermal phase behavior of three gramicidin A'/phospholipid mixtures was investigated by an equilibrium Ca(2+)-binding technique. The phospholipid component was 1,2-dioleoyl-sn-glycero-3-phosphoserine (DOPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS), or POPS/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at a constant mole ratio of 1/4. The bulk aqueous free Ca2+ concentration, [Ca2+]*f, in equilibrium with one or two gramicidin A'/phospholipid fluid ... More
Lymphocyte adhesion-dependent calcium signaling in human endothelial cells.
AuthorsPfau S, Leitenberg D, Rinder H, Smith BR, Pardi R, Bender JR
JournalJ Cell Biol
PubMed ID7533170
Vascular endothelial cells (ECs) can undergo dramatic phenotypic and functional alterations in response to humoral and cellular stimuli. These changes promote endothelial participation in the inflammatory response through active recruitment of immune effector cells, increased vascular permeability, and alteration in vascular tone. In an attempt to define early events in ... More
Phagosome-lysosome fusion is a calcium-independent event in macrophages.
AuthorsZimmerli S, Majeed M, Gustavsson M, Stendahl O, Sanan DA, Ernst JD
JournalJ Cell Biol
PubMed ID8567729
Phagosome-lysosome membrane fusion is a highly regulated event that is essential for intracellular killing of microorganisms. Functionally, it represents a form of polarized regulated secretion, which is classically dependent on increases in intracellular ionized calcium ([Ca2+]i). Indeed, increases in [Ca2+]i are essential for phagosome-granule (lysosome) fusion in neutrophils and for ... More
Calcium buffer injections delay cleavage in Xenopus laevis blastomeres.
AuthorsSnow P, Nuccitelli R
JournalJ Cell Biol
PubMed ID8320261
Microinjection of calcium buffers into the two-cell Xenopus laevis embryo delays cell division in a dose-dependent manner. Four calcium buffers in the BAPTA series with different affinities for calcium were used to distinguish between a localized calcium gradient regulating cleavage and the global calcium concentration regulating this event. DibromoBAPTA (Kd ... More
Presynaptic calcium signals during neurotransmitter release: detection with fluorescent indicators and other calcium chelators.
AuthorsAugustine GJ, Adler EM, Charlton MP, Hans M, Swandulla D, Zipser K
JournalJ Physiol Paris
PubMed ID1364192
Synthetic calcium buffers, including fluorescent calcium indicators, were microinjected into squid 'giant' presynaptic nerve terminals to investigate the calcium signal that triggers neurotransmitter secretion. Digital imaging methods, applied in conjunction with the fluorescent calcium indicator dye fura-2, reveal that transient rises in presynaptic calcium concentration are associated with action potentials. ... More
Characterization of oscillations in cytosolic free Ca2+ concentration and measurement of cytosolic Na+ concentration changes evoked by angiotensin II and vasopressin in individual rat aortic smooth muscle cells. Use of microfluorometry and digital imaging.
Dual wavelength microfluorometry was used to characterize the changes in cytosolic free Ca2+ concentration [( Ca2+]i) in individual cultured rat aortic vascular smooth muscle cells (VSMC). Angiotensin II (ANG II) at 10(-8) M induced a transient rise in [Ca2+]i from 43 +/- 2 to 245 +/- 23 nM, lasting for ... More
Stimulation and priming of protein kinase C translocation by a Ca2+ transient-independent mechanism. Studies in human neutrophils challenged with platelet-activating factor and other receptor agonists.
AuthorsO'Flaherty JT, Redman JF, Jacobson DP, Rossi AG
JournalJ Biol Chem
PubMed ID2174881
N-Formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4 stimulate human polymorphonuclear neutrophils (PMN) to translocate protein kinase C from the cytosol to plasmalemma as judged by their abilities to increase PMN binding of and receptor numbers for [3H]phorbol dibutyrate [( 3H]PDB) (O'Flaherty, J.T., Jacobson, D.P., Redman, J.F., and Rossi, A.G. (1990) J. Biol. ... More