Although human pannexins (PanX) are homologous to gap junction molecules, their physiological function in vertebrates remains poorly understood. Our results demonstrate that overexpression of PanX1 results in the formation of Ca(2+)-permeable gap junction channels between adjacent cells, thus, allowing direct intercellular Ca(2+) diffusion and facilitating intercellular Ca(2+) wave propagation. More ... More
Hypoxia induces an increase in intracellular magnesium via transient receptor potential melastatin 7 (TRPM7) channels in rat hippocampal neurons in vitro.
AuthorsZhang J, Zhao F, Zhao Y, Wang J, Pei L, Sun N, Shi J,
JournalJ Biol Chem
PubMed ID21487014
TRPM7, a divalent cation channel, plays an important role in neurons damaged from cerebral ischemia due to permitting intracellular calcium overload. This study aimed to explore whether magnesium was transported via a TRPM7 channel into the intracellular space of rat hippocampal neurons after 1 h of oxygen-glucose deprivation (OGD) and ... More
Effects of serum amyloid a and lysophosphatidylcholine on intracellular calcium concentration in human coronary artery smooth muscle cells.
Serum amyloid A (SAA), an acute-phase protein, and lysophosphatidylcholine (LPC), an oxidized LDL component, contribute to the physiological processes of atherosclerosis and cardiovascular disease. However, the effects of SAA/LPC on human coronary artery smooth muscle cells (hCASMCs) have not been fully investigated. Therefore, we examined the effects of SAA/LPC on ... More
Cellular mechanisms of vasopressin and endothelin to mobilize [Mg2+]i in vascular smooth muscle cells.
AuthorsOkada K, Ishikawa S, Saito T
JournalAm J Physiol
PubMed ID1415672
The present study was undertaken to examine the effects of arginine vasopressin (AVP) and endothelin-1 (ET-1) on cytosolic free Mg2+ ([Mg2+]i) in cultured rat vascular smooth muscle cells (VSMC). [Mg2+]i was measured using the fluorescence indicator dye mag-fura-2. AVP and ET-1 at a concentration of 1 x 10(-9) M or ... More
Elevation of extracellular magnesium rapidly raises intracellular free Mg<sup>2+</sup> in human aortic endothelial cells: is extracellular Mg<sup>2+</sup> a regulatory cation?
AuthorsZhang A, Altura BT, Altura BM
JournalFront Biosci
PubMed ID9195896
Cadherins mediate intercellular mechanical signaling in fibroblasts by activation of stretch-sensitive calcium-permeable channels.
AuthorsKo KS, Arora PD, McCulloch CA
JournalJ Biol Chem
PubMed ID11466312
'Cells in mechanically active environments form extensive, cadherin-mediated intercellular junctions that are important in tissue remodeling and differentiation. Currently, it is unknown whether adherens junctions in connective tissue fibroblasts transmit mechanical signals and coordinate multicellular adaptations to physical forces. We hypothesized that cadherins mediate intercellular mechanotransduction by activating calcium-permeable, stretch-sensitive ... More
Direct measurement of free Ca in organelles of gastric epithelial cells.
AuthorsHofer AM, Machen TE
JournalAm J Physiol
PubMed ID7943242
'When loaded as the acetoxymethyl ester (AM) derivative, the fluorescent probe mag-fura 2 accumulates in both the cytoplasm and the subcellular compartments. The relatively high dissociation constant of this dye for Ca (53 microM) permits the measurement of changes in the free concentration of this ion in a variety of ... More
Na+-dependent release of Mg2+ from an intracellular pool in rat sublingual mucous acini.
AuthorsZhang GH, Melvin JE
JournalJ Biol Chem
PubMed ID8910560
'Muscarinic stimulation induces release of Mg2+ from an intracellular pool in rat sublingual mucous acini (Zhang, G. H., and Melvin, J. E. (1992) J. Biol. Chem. 267, 20721-20727). In the present study we examined the interdependence of Mg2+ mobilization on intracellular Na+ and Ca2+ by monitoring the intracellular free concentrations ... More
Matrix free Mg2+ changes with metabolic state in isolated heart mitochondria.
AuthorsJung DW, Apel L, Brierley GP
JournalBiochemistry
PubMed ID2361136
'The concentration of free Mg2+ in the matrix of isolated heart mitochondria has been monitored by using the fluorescent probe furaptra (mag-fura-2). Beef heart mitochondria respiring in a KCl medium in the absence of external Mg2+ maintain free matrix Mg2+ near 0.50 mM. Addition of Pi under these conditions decreases ... More
Magnesium homeostasis in cardiac cells.
AuthorsFreudenrich CC, Murphy E, Liu S, Lieberman M
JournalMol Cell Biochem
PubMed ID1461262
'Several aspects of Mg2+ homeostasis were investigated in cultured chicken heart cells using the fluorescent Mg2+ indicator, FURAPTRA. The concentration of cytosolic Mg2+ ([Mg2+]i) is 0.48 +/- 0.03 mM (n = 31). To test whether a putative Na/Mg exchange mechanism controls [Mg2+]i below electrochemical equilibrium, we manipulated the Na+ gradient ... More
Intralymphocyte free magnesium and calcium and insulin tolerance test in a group of essential hypertensive patients.
AuthorsDelva P, Pastori C, Montesi G, Degan M, Micciolo R, Paluani F, Lechi A
JournalLife Sci
PubMed ID9952286
'In order to assess the links which are claimed to exist between peripheral insulin resistance and intracellular magnesium and calcium concentrations, we measured free intralymphocyte magnesium (Mg(i)) and calcium (Ca(i)) concentrations as well as the rate constant of plasma glucose disappearance (K(itt)) after insulin injection (insulin tolerance test: ITT) in ... More
Modulation of Mg2+ efflux from rat ventricular myocytes studied with the fluorescent indicator furaptra.
AuthorsTursun P, Tashiro M, Konishi M
JournalBiophys J
PubMed ID15626700
'The fluorescent Mg(2+) indicator furaptra (mag-fura-2) was introduced into single ventricular myocytes by incubation with its acetoxy-methyl ester form. The ratio of furaptra's fluorescence intensity at 382 and 350 nm was used to estimate the apparent cytoplasmic [Mg(2+)] ([Mg(2+)](i)). In Ca(2+)-free extracellular conditions (0.1 mM EGTA) at 25 degrees C, ... More
Coordination between Ca2+ release and subsequent re-uptake in the sarcoplasmic reticulum.
AuthorsSaiki Y, Ikemoto N
JournalBiochemistry
PubMed ID10074365
'We here report the results of our recent effort to produce, in the isolated sarcoplasmic reticulum (SR), a biphasic Ca2+ release and Ca2+ re-uptake transient and to resolve the kinetic relationship between Ca2+ release and re-uptake of the released Ca2+. Ca2+ release from the SR was induced by polylysine (the ... More
AM-loading of fluorescent Ca2+ indicators into intact single fibers of frog muscle.
AuthorsZhao M, Hollingworth S, Baylor SM
JournalBiophys J
PubMed ID9168048
'The AM loading of a number of different fluorescent Ca2+ indicators was compared in intact single fibers of frog muscle. Among the 13 indicators studied, loading rates (the average increase in the fiber concentration of indicator per first 60 min of loading) varied approximately 100-fold, from approximately 3 microM/h to ... More
Apoptogenic ganglioside GD3 directly induces the mitochondrial permeability transition.
AuthorsKristal BS, Brown AM
JournalJ Biol Chem
PubMed ID10438487
'Early events in apoptotic cascades initiated by ceramides or by activation of the surface receptor CD95 (Fas/APO-1) include the formation of ganglioside GD3. GD3 appears to be both necessary and sufficient to propagate this lipid-mediated apoptotic pathway. Later events common to many apoptotic pathways include induction of the mitochondrial permeability ... More
[Peripheral insulin resistance and free intralymphocyte magnesium and calcium concentrations in patients with essential hypertension]
AuthorsDelva P, Pastori C, Montesi G, Degan M, Paluani F, Lechi A
JournalArch Mal Coeur Vaiss
PubMed ID9404425
'To ascertain the claimed links between peripheral insulin resistance and intracellular magnesium and calcium concentrations, we measured free intralymphocyte magnesium (Mg(i)) and calcium (Ca(i)) concentrations, as well as the rate constant of plasma glucose disappearance (K(itt)) after insulin injection (insulin tolerance test: ITT), in a group of 15 normotensive control ... More
Signal transduction during exocytosis in Limulus polyphemus granulocytes.
AuthorsSolon E, Gupta AP, Gaugler R
JournalDev Comp Immunol
PubMed ID9016385
'Bacterial lipopolysaccharide (LPS)-induced exocytosis is one of the primary immune responses of the Limulus granulocyte (GR). Exocytosis can be mediated by guanine nucleotide-binding protein (G-protein)-linked surface receptors that activate phospholipase C (PLC) to produce inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG). IP3 mobilizes intracellular Ca2+ ([Ca2+]i), which can lead to exocytosis. ... More
Ca2+ homeostasis in the agonist-sensitive internal store: functional interactions between mitochondria and the ER measured In situ in intact cells.
AuthorsLandolfi B, Curci S, Debellis L, Pozzan T, Hofer AM
JournalJ Cell Biol
PubMed ID9732284
'Mitochondria have a well-established capacity to detect cytoplasmic Ca2+ signals resulting from the discharge of ER Ca2+ stores. Conversely, both the buffering of released Ca2+ and ATP production by mitochondria are predicted to influence ER Ca2+ handling, but this complex exchange has been difficult to assess in situ using conventional ... More
Imaging of intracellular calcium stores in single permeabilized lens cells.
AuthorsChurchill GC, Louis CF
JournalAm J Physiol
PubMed ID9950770
'Intracellular Ca2+ stores in permeabilized sheep lens cells were imaged with mag-fura 2 to characterize their distribution and sensitivity to Ca2+-releasing agents. Inositol 1,4,5-trisphosphate (IP3) or cyclic ADP-ribose (cADPR) released Ca2+ from intracellular Ca2+ stores that were maintained by an ATP-dependent Ca2+ pump. The IP3 antagonist heparin inhibited IP3- but ... More
Mg2+ buffering in cultured chick ventricular myocytes: quantitation and modulation by Ca2+.
AuthorsKoss KL, Putnam RW, Grubbs RD
JournalAm J Physiol
PubMed ID8498485
'To characterize the Mg2+ buffering of cultured chick ventricular myocytes, cytosolic Mg2+ was increased by liberating Mg2+ normally chelated by ATP upon total depletion of ATP content. Because the total Mg content and cell volume remained constant during this time, the difference between the amount of Mg2+ liberated (2.7 mM) ... More
Lack of evidence for presenilins as endoplasmic reticulum Ca2+ leak channels.
AuthorsShilling D, Mak DO, Kang DE, Foskett JK,
JournalJ Biol Chem
PubMed ID22311977
'Familial Alzheimer disease (FAD) is linked to mutations in the presenilin (PS) homologs. FAD mutant PS expression has several cellular consequences, including exaggerated intracellular Ca(2+) ([Ca(2+)](i)) signaling due to enhanced agonist sensitivity and increased magnitude of [Ca(2+)](i) signals. The mechanisms underlying these phenomena remain controversial. It has been proposed that ... More
Heterogeneity of channel density in inositol-1,4,5-trisphosphate-sensitive Ca2+ stores.
AuthorsHirose K, Iino M
JournalNature
PubMed ID7997268
'Inositol-1,4,5-trisphosphate (InsP3)-induced Ca2+ release is a key mechanism for intracellular Ca2+ mobilization. The rate of Ca2+ release declines progressively with time until a higher concentration of InsP3 is added, which is referred to as the incremental detection mechanism. Two hypotheses have been postulated to explain these complex kinetics: (1) Ca2+ ... More
Simultaneous measurements of Ca2+ in the intracellular stores and the cytosol of hepatocytes during hormone-induced Ca2+ oscillations.
AuthorsChatton JY, Liu H, Stucki JW
JournalFEBS Lett
PubMed ID7615074
'Simultaneous Ca2+ measurements in the cytosol and intracellular stores (IS) of rat hepatocytes were performed using two Ca(2+)-sensitive probes (Fluo-3 and Mag-fura-2), and combined whole-cell patch clamp and fluorescence microscopy. A steady-state Ca2+ concentration of approximately 630 microM was estimated in the IS. alpha 1-Adrenergic stimulation induced periodic elevations of ... More
Free cadmium activity in renal epithelial cells is enhanced by Mg2+ depletion.
AuthorsQuamme GA
JournalKidney Int
PubMed ID1614037
'Free Cd2+ uptake was determined by fluorescence techniques with the use of mag-fura-2 in single epithelial MDCK cells. Cytosolic Cd2+ increased in a time-dependent and concentration-dependent manner following the addition of cadmium to the external solution. The increment in cytosolic Cd2+ was greater in magnesium-depleted cells relative to normal cells. ... More
Activation of the Na(+)-H+ exchanger modulates angiotensin II-stimulated Na(+)-dependent Mg2+ transport in vascular smooth muscle cells in genetic hypertension.
AuthorsTouyz RM, Schiffrin EL
JournalHypertension
PubMed ID10489391
'This study investigated the role of the Na(+)-H+ exchanger (NHE) on angiotensin II (Ang II)-induced activation of Na(+)-dependent Mg2+ transport in vascular smooth muscle cells (VSMCs) from Wistar-Kyoto rats (WKY; n=20) and spontaneously hypertensive rats (SHR; n=20). Intracellular free concentrations of Mg2+ ([Mg2+]i) and Na+ ([Na+]i) and intracellular pH (pHi) ... More
The endoplasmic reticulum is a glucose-modulated high-affinity sink for Ca2+ in mouse pancreatic beta-cells.
AuthorsTengholm A, Hellman B, Gylfe E
JournalJ Physiol
PubMed ID11158282
'The regulation of organelle free Ca2+ was analysed in individual mouse pancreatic beta-cells loaded with the fluorescent low-affinity indicator furaptra. Removal of the cytoplasmic indicator by controlled digitonin permeabilization of the plasma membrane resulted in a sudden increase of the 340 nm/380 nm fluorescence excitation ratio followed by a gradual ... More
Activity-dependent [Ca2+]i changes in guinea pig vagal motoneurons: relationship to the slow afterhyperpolarization.
AuthorsLasser-Ross N, Ross WN, Yarom Y
JournalJ Neurophysiol
PubMed ID9307116
'Vagal motoneurons in slices from the guinea-pig brain stem were injected with the fluorescent [Ca2+]i indicators fura-2, furaptra, or Calcium Green-1. Spike-induced fluorescence changes were measured in the soma and dendrites and simultaneously the long-lasting afterhyperpolarization was recorded with a sharp microelectrode in the soma. Na+ spikes or Ca2+ spikes ... More
Sarcoplasmic reticulum calcium release compared in slow-twitch and fast-twitch fibres of mouse muscle.
AuthorsBaylor SM, Hollingworth S
JournalJ Physiol
PubMed ID12813151
'Experiments were carried out to compare the amplitude and time course of Ca2+ release from the sarcoplasmic reticulum (SR) in intact slow-twitch and fast-twitch mouse fibres. Individual fibres within small bundles were injected with furaptra, a low-affinity, rapidly responding Ca2+ indicator. In response to a single action potential at 16 ... More
In vitro relationship between magnesium and insulin secretion.
AuthorsIshizuka J, Bold RJ, Townsend CM, Thompson JC
JournalMagnes Res
PubMed ID8054257
'Magnesium, the most abundant intracellular divalent cation, is known to play an essential role in many normal cell functions, such as fluid and electrolyte transport, enzyme activity, and cell proliferation. It is known that magnesium deficiency or hypomagnesaemia induces hyperinsulinism, while hypermagnesaemia inhibits insulin secretion: however, the mechanism controlling the ... More
Mechanisms of Mg(2+) transport in cultured ruminal epithelial cells.
AuthorsSchweigel M, Vormann J, Martens H
JournalAm J Physiol Gastrointest Liver Physiol
PubMed ID10712259
'Net Mg(2+) absorption from the rumen is mainly mediated by a transcellular pathway, with the greater part (62%) being electrically silent. To investigate this component of Mg(2+) transport, experiments were performed with isolated ruminal epithelial cells (REC). Using the fluorescent indicators mag-fura 2, sodium-binding benzofuran isophthalate, and 2'', 7''-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, we ... More
In situ characterization of nonmitochondrial Ca2+ stores in individual pancreatic beta-cells.
AuthorsTengholm A, Hagman C, Gylfe E, Hellman B
JournalDiabetes
PubMed ID9703321
'Free Ca2+ was measured in intracellular stores of individual mouse pancreatic beta-cells using dual-wavelength microfluorometry and the low-affinity Ca2+ indicator furaptra. Controlled permeabilization of the plasma membrane with 4 micromol/l digitonin revealed that 22% of the furaptra was trapped in intracellular nonnuclear compartments. When 3 mmol/l ATP and 200 nmol/l ... More
Elevation of extracellular magnesium rapidly raises intracellular free Mg2+ in human aortic endothelial cells: is extracellular Mg2+ a regulatory cation?
AuthorsZhang A, Altura BT, Altura BM
JournalFront Biosci
PubMed ID9206991
'Extracellular magnesium ions [Mg2+]o are known to regulate functions of endothelial cells, but whether [Mg2+]o can alter intracellular free ionized magnesium [Mg2+]i in these cells remains unknown. The present studies, using digital imaging microscopy and the Mg2+ fluorescent probe, mag-fura-2, determined effects of elevation of [Mg2+]o on [Mg2+]i in cultured ... More
Fluorescence probe study of the lumenal Ca2+ of the sarcoplasmic reticulum vesicles during Ca2+ uptake and Ca2+ release.
AuthorsSaiki Y, Ikemoto N
JournalBiochem Biophys Res Commun
PubMed ID9405254
'A limited amount of information is available about the lumenal Ca2+ kinetics of the sarcoplasmic reticulum (SR). Incubation of mag-fura-2AM permitted to incorporate a sufficient amount of the probe into the SR vesicles, as determined by Mn2+ quenching. Rapid changes in the lumenal [Ca2+] ([Ca2+]lum) during Ca2+ uptake and release ... More
Insulin increases intracellular magnesium transport in human platelets.
AuthorsHwang DL, Yen CF, Nadler JL
JournalJ Clin Endocrinol Metab
PubMed ID8445010
'Evidence suggests that magnesium (Mg) deficiency may play a key role in cardiovascular disease. In particular, Mg deficiency may lead to a potentiation of platelet aggregation. However, the factor(s) regulating intracellular-free Mg concentration ([Mg2+]i) in platelets is not known. We studied the effects of insulin on the changes of [Mg2+]i ... More
Regulation of intracellular magnesium in ascites cells: involvement of different regulatory pathways.
AuthorsWolf FI, Di Francesco A, Covacci V, Corda D, Cittadini A
JournalArch Biochem Biophys
PubMed ID8660698
'Extracellular ATP causes 40% stimulation of Mg2+ efflux from Ehrlich ascites tumor cells (EATC) incubated under 0-trans conditions. ATP also causes a threefold increase of arachidonic acid (AA) metabolite release from [3H]AA-preloaded EATC, indicating that, under these experimental conditions, it induces phospholipase A2 (PLA2) activation. ATP-induced Mg2+ efflux can be ... More
Unloading and refilling of two classes of spatially resolved endoplasmic reticulum Ca(2+) stores in astrocytes.
AuthorsGolovina VA, Blaustein MP
JournalGlia
PubMed ID10816603
'Signaling by two classes of endoplasmic reticulum (ER) Ca(2+) stores was studied in primary cultured rat astrocytes. Cytosolic and intra-ER Ca(2+) concentrations ([Ca(2+)](CYT) and [Ca(2+)](ER)) were measured with, respectively, Fura-2 and Furaptra, in separate experiments. The agonists, glutamate and ATP, released Ca(2+) primarily from cyclopiazonic acid (CPA)-sensitive ER Ca(2+) stores ... More
Insulin stimulates Mg2+ uptake in mouse distal convoluted tubule cells.
AuthorsDai LJ, Ritchie G, Bapty BW, Kerstan D, Quamme GA
JournalAm J Physiol
PubMed ID10600938
'Insulin has been shown to be a magnesium-conserving hormone acting, in part, through stimulation of magnesium absorption within the thick ascending limb. Although the distal convoluted tubule possesses the most insulin receptors, it is unclear what, if any, actions insulin has in the distal tubule. The effects of insulin were ... More
Differential effects of cyclosporin A and tacrolimus on magnesium influx in Caco2 cells.
AuthorsGouadon E, Lecerf F, German-Fattal M,
JournalJ Pharm Pharm Sci
PubMed ID22974787
'Hypomagnesemia with urinary magnesium (Mg) wasting is a well acknowledged side effect of cyclosporin A (CsA) and tacrolimus (FK506) treatments. TRPM6, TRPM7 and MagT1 are involved in the active transcellular Mg transport processes in intestine and kidney. Since Mg homeostasis is tightly controlled by the dynamic action of intestinal absorption ... More
Transport of magnesium by two isoforms of the Na+-Ca2+ exchanger expressed in CCL39 fibroblasts.
AuthorsTashiro M, Konishi M, Iwamoto T, Shigekawa M, Kurihara S
JournalPflugers Arch
PubMed ID11041546
'Cytoplasmic concentrations of Ca2+ ([Ca2+]i) and Mg2+ ([Mg2+]i) were measured with fluorescent indicators in CCL39 cells, a cell line established from Chinese hamster lung fibroblasts, transfected with complementary deoxyribonucleic acid (cDNA) of the Na+-Ca2+ exchanger isolated either from canine heart (NCX1) or from rat brain (NCX3). Raising extracellular [Mg2+] to ... More
The endoplasmic reticulum can act as a functional Ca2+ store in all subcellular regions of the pancreatic acinar cell.
Authorsvan de Put FH, Elliott AC
JournalJ Biol Chem
PubMed ID9346920
'Stimulation of pancreatic acinar cells raises [Ca2+]i via Ca2+ release from inositol-1,4,5-trisphosphate (InsP3)-sensitive intracellular Ca2+ stores, generally considered to reside within the endoplasmic reticulum (ER). However, with physiological doses of cholinergic agonists, the [Ca2+]i increase is localized to the apical (secretory) pole of the cell, leading to suggestions that zymogen ... More
Calcium-sensitive fluorescent dyes can report increases in intracellular free zinc concentration in cultured forebrain neurons.
AuthorsCheng C, Reynolds IJ
JournalJ Neurochem
PubMed ID9832138
'High concentrations of Zn2+ are found in presynaptic terminals of excitatory neurons in the CNS. Zn2+ can be released during synaptic activity and modulate postsynaptic receptors, but little is known about the possibility that Zn2+ may enter postsynaptic cells and produce dynamic changes in the intracellular Zn2+ concentration ([Zn2+]i). We ... More
Transmembrane Mg2+ currents and intracellular free Mg2+ concentration in Paramecium tetraurelia.
AuthorsPreston RR
JournalJ Membr Biol
PubMed ID9636240
'The properties of Mg2+ conductances in Paramecium tetraurelia were investigated under two-electrode voltage clamp. When bathed in physiological Mg2+ concentrations (0.5 mm), depolarizing steps from rest elicited a prominent Mg2+-specific current (IMg) that has been noted previously. The dependence of this current on extracellular Mg2+ approximated that of Mg2+-induced backward ... More
Cytosolic ionized magnesium concentration in end-stage renal disease. Effect of hemodialysis.
AuthorsKaupke CJ, Zhou XJ, Vaziri ND
JournalASAIO J
PubMed ID8268611
'Chronic renal failure is known to raise serum magnesium concentration. However, its effect on intracellular free cytosolic magnesium concentration ([Mg2+]i) has not been clearly delineated. Likewise, whereas hemodialysis (HD) lowers serum magnesium concentration, its effect on [Mg2+]i is unknown. It should be noted that, based on other studies, [Mg2+]i is ... More
Excitation-calcium release uncoupling in aged single human skeletal muscle fibers.
AuthorsDelbono O, O'Rourke KS, Ettinger WH
JournalJ Membr Biol
PubMed ID8747553
'The biological mechanisms underlying decline in muscle power and fatigue with age are not completely understood. The contribution of alterations in the excitation-calcium release coupling in single muscle fibers was explored in this work. Single muscle fibers were voltage-clamped using the double Vaseline gap technique. The samples were obtained by ... More
Effects of rapid shortening on rate of force regeneration and myoplasmic [Ca2+] in intact frog skeletal muscle fibres.
AuthorsVandenboom R, Claflin DR, Julian FJ
JournalJ Physiol
PubMed ID9679172
'1. The effect of rapid shortening on rate of force regeneration (dF/dtR) was examined in single, intact frog (Rana temporaria) skeletal muscle fibres (3.0 C). Step releases leading to unloaded shortening were applied after 500 ms of stimulation, during the plateau of an isometric tetanus. Initial mean sarcomere length ranged ... More
Dynamics of intracellular free Mg2+ changes in a vascular smooth muscle cell line.
AuthorsQuamme GA, Dai LJ, Rabkin SW
JournalAm J Physiol
PubMed ID8342644
'Intracellular free Mg2+ concentration ([Mg2+]i) has been implicated in the pathogenesis of hypertension. It has been postulated that Mg2+ through its antagonistic effects on intracellular Ca2+ concentration may affect tension and contractility of vascular smooth muscle cells. An established cell line of rat thoracic aorta cells (A10) was cultured on ... More
Intracellular Mg2+ concentrations following metabolic inhibition in opossum kidney cells.
AuthorsLi HY, Dai LJ, Krieger C, Quamme GA
JournalBiochim Biophys Acta
PubMed ID7686402
'Intracellular magnesium is associated with intracellular ATP concentrations as Mg-ATP2- and is involved with many enzymes in energy utilization. Intracellular Mg2+ has also been postulated to be involved with various Ca2+ actions. We determined adenine nucleotide concentrations (ATP, ADP and AMP) by HPLC and the associated changes in intracellular free ... More
Lithium induced changes in intracellular free magnesium concentration in isolated rat ventricular myocytes.
AuthorsGow IF, Flatman PW, Ellis D
JournalMol Cell Biochem
PubMed ID10497887
'We have examined the effect of exposing isolated rat ventricular myocytes to lithium while measuring cytosolic free magnesium ([Mg2+]i) and calcium ([Ca2+]i) levels with the fluorescent, ion sensitive probes mag-fura-2 and fura-2. There was a significant rise in [Mg2+]i after a 5 min exposure to a solution in which 50% ... More
Arachidonic acid-activated Na+-dependent Mg2+ efflux in rat renal epithelial cells.
AuthorsIkari A, Nakajima K, Suketa Y, Harada H, Takagi K
JournalBiochim Biophys Acta
PubMed ID14643927
'Arachidonic acid (AA), a metabolite of membrane phospholipids, and its metabolites are increased in Mg2+ deficiency. We examined whether the extracellular Mg2+ concentration affects AA production and whether AA regulates a putative Na+-dependent Mg2+ efflux pathway in renal epithelial NRK-52E cells. We used the cells cultured in 5 mM Mg2+-containing ... More
AuthorsFreudenrich CC, Murphy E, Levy LA, London RE, Lieberman M
JournalAm J Physiol
PubMed ID1566808
'To assess the role of pH in cellular Mg homeostasis, cytosolic pH (pHi) was manipulated by the NH4Cl prepulse technique; pHi, cytosolic Mg2+ (Mgi), and cytosolic Ca2+ (Cai) were measured fluorometrically in single cultured embryonic chicken heart cells loaded with 2'',7''-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), FURAPTRA, and fura-2, respectively. The basal values obtained ... More
Interaction between secretin and nerve-mediated amylase secretion in the isolated exocrine rat pancreas.
AuthorsWisdom DM, Camello PJ, Salido GM, Singh J
JournalExp Physiol
PubMed ID7529511
'This study investigates the effects of the gut peptide, secretin, on nerve-mediated and acetylcholine-evoked amylase secretion and calcium (Ca2+) and magnesium (Mg2+) mobilization in the in vitro rat pancreas. Both electrical field stimulation (EFS; 50 V, 20 Hz, 1 ms) and acetylcholine (ACh; 10(-6) M) caused marked increases in amylase ... More
Modulation of vascular smooth muscle cell growth by magnesium-role of mitogen-activated protein kinases.
AuthorsTouyz RM, Yao G
JournalJ Cell Physiol
PubMed ID14566962
'We tested the hypothesis that Mg(2+) influences growth of vascular smooth muscle cells (VSMCs) by modulating cell cycle activation through mitogen-activated protein (MAP) kinase-dependent pathways. Rat VSMCs were grown in culture medium containing normal Mg(2+) (1.02 mmol/L, control) and increasing concentrations of Mg(2+) (2-4 mmol/L) for 1-8 days. Effects of ... More
Technique for in situ measurement of calcium in intracellular inositol 1,4,5-trisphosphate-sensitive stores using the fluorescent indicator mag-fura-2.
AuthorsHofer AM, Machen TE
JournalProc Natl Acad Sci U S A
PubMed ID8464866
'Stimulation of cells with calcium-mobilizing agonists frequently results in inositol 1,4,5-trisphosphate (InsP3)-mediated discharge of Ca from an internal store. We report here a technique for directly monitoring Ca within this and other stores in gastric epithelial cells. This technique takes advantage of the propensity of the acetoxymethyl ester derivative of ... More
Light-induced increase in free Mg2+ concentration in spinach chloroplasts: measurement of free Mg2+ by using a fluorescent probe and necessity of stromal alkalinization.
AuthorsIshijima S, Uchibori A, Takagi H, Maki R, Ohnishi M
JournalArch Biochem Biophys
PubMed ID12646275
'Free Mg(2+) in chloroplasts may contribute to the regulation of photosynthetic enzymes, but adequate methodology for the determination of free Mg(2+) concentration ([Mg(2+)]) in chloroplasts has been lacking. We measured internal chloroplast [Mg(2+)] by using a Mg-sensitive fluorescent indicator, mag-fura-2. In intact, dark-kept spinach chloroplasts, internal [Mg(2+)] was estimated to ... More
A fluorescent indicator for measuring cytosolic free magnesium.
AuthorsRaju B, Murphy E, Levy LA, Hall RD, London RE
JournalAm J Physiol
PubMed ID2923192
'The previously developed chelator O-aminophenol-N,N,O-triacetic acid (APTRA) (L. A. Levy, E. Murphy, B. Raju, and R. E. London. Biochemistry 27: 4041-4048, 1988) has been modified to yield a fluorescent analogue which can be utilized as an intracellular probe for ionized Mg2+. The fluorescent analogue, FURAPTRA, with a magnesium dissociation constant ... More
Determination of ionized magnesium in platelets and correlation with selected variables.
AuthorsNiemela JE, Snader BM, Elin RJ
JournalClin Chem
PubMed ID8653901
'We describe a method for determining the intracellular ionized magnesium concentration ([Mg2+]i) in platelets by using the fluorescent probe FURAPTRA. We determined the dissociation constant (KD) of FURAPTRA for Mg2+ (2.26 +/- 0.29 mmol/L), within-day assay variability (CV = 6.8%), among-day intraindividual variability (CV = 11.0%), variability after a 4-h ... More
The physiologic concentration of inositol 1,4,5-trisphosphate in the oocytes of Xenopus laevis.
'To measure the concentration of inositol 1,4,5-trisphosphate ([IP3]) in small regions of single Xenopus oocytes, a biological detector cell was combined with capillary electrophoresis. This method is 10, 000 times more sensitive than all existing assays enabling subcellular measurement of [IP3] in Xenopus oocytes. Upon addition of lysophosphatidic acid to ... More
Myoplasmic free Mg2+ concentration during repetitive stimulation of single fibres from mouse skeletal muscle.
AuthorsWesterblad H, Allen DG
JournalJ Physiol
PubMed ID1464836
'1. The role of the myoplasmic free Mg2+ concentration ([Mg2+]i) in fatigue was studied in intact single fibres isolated from mouse skeletal muscle. Fatigue was produced by repeated tetanic stimulation. The fluorescent Mg2+ indicator furaptra was pressure injected into fibres. In vivo calibrations were performed to convert fluorescence signals into ... More
The regulation of intracellular Mg2+ in guinea-pig heart, studied with Mg(2+)-selective microelectrodes and fluorochromes.
AuthorsBuri A, Chen S, Fry CH, Illner H, Kickenweiz E, McGuigan JA, Noble D, Powell T, Twist VW
JournalExp Physiol
PubMed ID8471242
'Because of the reported presence of a Na(+)-Mg2+ exchanger in guinea-pig but not in ferret myocardium, the Mg2+ extrusion mechanism in guinea-pig myocardium has been reinvestigated using Mg(2+)- and Na(+)- selective microelectrodes and the fluorochromes mag-fura-2 and -5. The mean [Mg2+]i measured with microelectrodes in trabeculae or papillary muscles was ... More
Intrasynaptosomal free Mg2+ concentration measured with the fluorescent indicator mag-fura-2: modulation by Na+ gradient and by extrasynaptosomal ATP.
AuthorsGarcía-Martín E, Martín-Romero FJ, Gutiérrez-Merino C
JournalJ Neurochem
PubMed ID7595575
'Synaptosomes can be loaded with mag-fura-2 without significant perturbation of their ATP content by incubation for 10 min at 37 degrees C with 10 microM mag-fura-2 acetoxymethyl ester in Hanks''-HEPES buffer (pH 7.45). The intrasynaptosomal free Mg2+ concentration ([Mg2+]i) was found to be dependent on external Mg2+ concentration, increasing from ... More
Xestospongin C empties the ER calcium store but does not inhibit InsP3-induced Ca2+ release in cultured dorsal root ganglia neurones.
AuthorsSolovyova N, Fernyhough P, Glazner G, Verkhratsky A
JournalCell Calcium
PubMed ID12127062
'The action of Xestospongin C (XeC) on calcium concentration in the cytosol ([Ca2+]i) and within the lumen of endoplasmic reticulum (ER) ([Ca2+]L) was studied using cultured dorsal root ganglia (DRG) neurones. Application of 2.5 microM of XeC triggered a slow [Ca2+]i transient as measured by Fura-2 video-imaging. The kinetics and ... More
Presence of a novel influx pathway for Mg2+ in MDCK cells.
AuthorsQuamme GA, Dai LJ
JournalAm J Physiol
PubMed ID2399971
'Basal free Mg2+ concentration was 0.49 +/- 0.03 mM in normal single Madin-Darby canine kidney (MDCK) cells as measured by fluorescence with the aid of mag-fura-2. Accordingly, Mg2+ may enter the cell down a transmembrane electrical gradient. The present study describes some aspects of Mg2+ entry into the established MDCK ... More
Ionic selectivity of low-affinity ratiometric calcium indicators: mag-Fura-2, Fura-2FF and BTC.
AuthorsHyrc KL, Bownik JM, Goldberg MP
JournalCell Calcium
PubMed ID10756974
'Accurate measurement of elevated intracellular calcium levels requires indicators with low calcium affinity and high selectivity. We examined fluorescence spectral properties and ionic specificity of three low-affinity, ratiometric indicators structurally related to Fura-2: mag-Fura-2 (furaptra), Fura-2FF, and BTC. The indicators differed in respect to their excitation wavelengths, affinity for Ca2+ ... More
Magnesium relaxes arterial smooth muscle by decreasing intracellular Ca2+ without changing intracellular Mg2+.
AuthorsD'Angelo EK, Singer HA, Rembold CM
JournalJ Clin Invest
PubMed ID1602005
'Elevations in extracellular [Mg2+] ([Mg2+]o) relax vascular smooth muscle. We tested the hypothesis that elevated [Mg2+]o induces relaxation through reductions in myoplasmic [Ca2+] and myosin light chain phosphorylation without changing intracellular [Mg2+] ([Mg2+]i). Histamine stimulation of endothelium-free swine carotid medial tissues was associated with increases in both Fura 2- and ... More
Control of InsP3-induced Ca2+ oscillations in permeabilized blowfly salivary gland cells: contribution of mitochondria.
AuthorsZimmermann B
JournalJ Physiol
PubMed ID10856123
'Many agonists linked to the generation of inositol 1,4, 5-trisphosphate (InsP3) and release of Ca2+ from intracellular stores induce repetitive transients in cytosolic Ca2+ whose frequency increases over a certain range of agonist concentrations. In order to investigate the mechanisms underlying this frequency modulation, the fluorescent Ca2+ sensor mag-fura-2 was ... More
Cell metabolism affects selective vulnerability in PINK1-associated Parkinson's disease.
'Mitochondrial dysfunction plays a primary role in the pathogenesis of Parkinson''s disease (PD), particularly in autosomal recessive forms of the disease caused by mutations encoding PINK1. Although mitochondrial pathology can be demonstrated in many cell types, it is neurons that bear the brunt of cell death in PD. We studied ... More
The amplitude and time course of the myoplasmic free [Ca2+] transient in fast-twitch fibers of mouse muscle.
AuthorsHollingworth S, Zhao M, Baylor SM
JournalJ Gen Physiol
PubMed ID8923269
'Bundles of 10-100 fibers were dissected from the extensor digitorum longus muscle of mouse, mounted in an apparatus for optical recording, and stretched to long sarcomere length (> or = 3.6 microns). One fiber within the bundle was microinjected with furaptra, a fluorescent indicator that responds rapidly to changes in ... More
'Intracellular magnesium concentration ([Mg2+]i) of cultured dorsal root ganglion (DRG) neurons was measured using the magnesium indicator Mag-Fura-2/AM. [Mg2+]i was 0.48 +/- 0.08 mM (mean +/- SEM, n = 23) at rest, and it increased 3-fold by depolarization with a 60-mM K+ solution. The [Mg2+]i increase was observed in the ... More
Malaria parasites solve the problem of a low calcium environment.
AuthorsCamacho P
JournalJ Cell Biol
PubMed ID12695494
'The parasite responsible for malaria, Plasmodium falciparum, spends much of its life in the RBC under conditions of low cytosolic Ca2+. This poses an interesting problem for a parasite that depends on a Ca2+ signaling system to carry out its vital functions. This long standing puzzle has now been resolved ... More
Secretagogue-evoked changes in intracellular free magnesium concentrations in rat pancreatic acinar cells.
AuthorsLennard R, Singh J
JournalJ Physiol
PubMed ID1770445
'1. This study employs the fluorescent dye Mag-Fura-2 acetoxymethyl ester (AM) to measure intracellular free magnesium concentration [Mg2+]i in isolated rat pancreatic acinar cells. Initially a number of protocols were investigated to develop optimal loading conditions for the dye Mag-Fura-2 AM. The procedure yielding cells which showed minimal dye loss ... More
Sodium gradient-dependent transport of magnesium in rat ventricular myocytes.
AuthorsTashiro M, Konishi M
JournalAm J Physiol Cell Physiol
PubMed ID11078711
'Cytoplasmic concentration of Mg(2+) ([Mg(2+)](i)) was measured with a fluorescent indicator furaptra in ventricular myocytes enzymatically dissociated from rat hearts (25 degrees C). To study Mg(2+) transport across the cell membrane, cells were treated with ionomycin in Ca(2+)-free (0.1 mM EGTA) and high-Mg(2+) (10 mM) conditions to facilitate passive Mg(2+) ... More
Determination of free Mg2+ in isolated heart mitochondria using fluorescent probes.
AuthorsJung DW, Brierley GP
JournalMagnes Trace Elem
PubMed ID1844548
'The concentration of free Mg2+ in the matrix of isolated heart mitochondria has been monitored using the fluorescent probe furaptra. The techniques used for loading, calibrating and using furaptra fluorescence to monitor matrix free Mg2+ are described. Furaptra is loaded as the membrane-permeable acetoxymethyl ester which is hydrolyzed to the ... More
Extracellular Mg2+ regulates intracellular Mg2+ and its subcellular compartmentation in fission yeast, Schizosaccharomyces pombe.
AuthorsZhang A, Cheng TP, Wu XY, Altura BT, Altura BM
JournalCell Mol Life Sci
PubMed ID9117998
'Effects of extracellular magnesium ions ([Mg2+]o) on intracellular free Mg2+ ([Mg2+]i) and its subcellular distribution in single fission yeast cells, Schizosaccharomyces pombe, were studied with digital-imaging microscopy and an Mg2+ fluorescent probe (mag-fura-2). Using 0.44 mM [Mg2+]o, [Mg2+]i in yeast cells was 0.91 +/- 0.08 mM. Elevation of [Mg2+]o to ... More
PGE2 stimulates Mg2+ uptake in mouse distal convoluted tubule cells.
AuthorsDai LJ, Bapty B, Ritchie G, Quamme GA
JournalAm J Physiol
PubMed ID9815142
'Prostaglandins have diverse effects on renal electrolyte reabsorption, inhibiting NaCl absorption in the thick ascending limb and modulating sodium and calcium transport in cortical collecting cells. It is unclear what effect, if any, prostaglandins have on tubular magnesium handling. The effects of prostaglandin E2 (PGE2) were studied on immortalized mouse ... More
Kinesin dependent, rapid, bi-directional transport of ER sub-compartment in dendrites of hippocampal neurons.
AuthorsBannai H, Inoue T, Nakayama T, Hattori M, Mikoshiba K
JournalJ Cell Sci
PubMed ID14676272
'Although spatially restricted Ca2+ release from the endoplasmic reticulum (ER) through intracellular Ca2+ channels plays important roles in various neuronal activities, the accurate distribution and dynamics of ER in the dendrite of living neurons still remain unknown. To elucidate these, we expressed fluorescent protein-tagged ER proteins in cultured mouse hippocampal ... More
Competition between lithium and magnesium ions for the G-protein transducin in the guanosine 5'-diphosphate bound conformation.
AuthorsSrinivasan C, Toon J, Amari L, Abukhdeir AM, Hamm H, Geraldes CF, Ho YK, Mota de Freitas D
JournalJ Inorg Biochem
PubMed ID15134914
'Li(+) is the most effective drug used to treat bipolar disorder; however, its exact mechanism of action has yet to be elucidated. One hypothesis is that Li(+) competes with Mg2+ for the Mg2+ binding sites on guanine-nucleotide binding proteins (G-proteins). Using 7Li T1 relaxation measurements and fluorescence spectroscopy with the ... More
Ca2+ sensitivity of phospholipid scrambling in human red cell ghosts.
AuthorsWoon LA, Holland JW, Kable EP, Roufogalis BD
JournalCell Calcium
PubMed ID10456228
'The phospholipids in plasma membranes of erythrocytes, as well as platelets, lymphocytes and other cells are asymmetrically distributed, with sphingomyelin and phosphatidylcholine residing predominantly in the outer leaflet of the bilayer, and phosphatidylserine and phosphatidylethanolamine in the inner leaflet. It is known that Ca2+ can disrupt the phospholipid asymmetry by ... 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
Fluorescent monitoring of Jurkatt cell intracellular magnesium during metabolic poisoning.
AuthorsCarroll RG, Thomas JM
JournalShock
PubMed ID7735953
'Divalent cation movement characterizes the final common pathway of cellular death from ischemic or metabolic injury. The influx of calcium is an essential step in cellular death. We hypothesized that intracellular magnesium levels may change during the progression to cellular death. Verapamil-sensitive changes in free ionized intracellular Mg2+ ([Mg2+[i) and ... More
Practical considerations for using mag-fura-2 to measure cytosolic free magnesium.
AuthorsGrubbs RD, Beltz PA, Koss KL
JournalMagnes Trace Elem
PubMed ID1844547
'The development of fluorescent ion-selective indicators for magnesium has provided valuable tools for measuring second-by-second changes in cytosolic magnesium activity. In the course of establishing appropriate protocols for using one of these indicators, mag-fura-2, to measure magnesium activity in BC3H-1 cells and chick ventricular myocytes, many potential pitfalls and limitations ... More
Gender-specific correlation of platelet ionized magnesium and serum low-density-lipoprotein cholesterol concentrations in apparently healthy subjects.
AuthorsNiemela JE, Csako G, Bui MN, Elin RJ
JournalJ Lab Clin Med
PubMed ID9011595
'We previously found an inverse correlation between platelet ionized magnesium concentration ((Mg2+)i) and serum total cholesterol concentration in normal male but not female subjects. In the present study, we determined the platelet (Mg2+)i by using a fluorescent ionized magnesium (Mg2+) indicator, FURAPTRA, and measured the serum concentrations of the following: ... More
Calcium-dependent neutrophil secretion: characterization and regulation by annexins.
AuthorsRosales JL, Ernst JD
JournalJ Immunol
PubMed ID9550422
'To gain direct access to the secretory machinery and study the regulation, mechanisms, and effectors of Ca2+-dependent neutrophil secretion, we developed an efficient and reproducible method of plasma membrane permeabilization using streptolysin O. We confirmed previous studies that permeabilized neutrophils secrete in response to calcium alone, but we also found ... More
Cytosolic free magnesium in cardiac myocytes: identification of a Mg2+ influx pathway.
AuthorsQuamme GA, Rabkin SW
JournalBiochem Biophys Res Commun
PubMed ID2322282
'Regulation of intracellular Mg2+ activity in the heart is not well characterized. Cardiac myocytes were prepared as primary cultures from 7 day old chick embryo hearts and intracellular Mg2+ concentration [( Mg2+]i) was determined in single ventricular cells with mag-fura-2. Basal [Mg2+]i was 0.48 +/- 0.03 mM in normal culture ... More
Modulation of oxidative phosphorylation by Mg2+ in rat heart mitochondria.
AuthorsRodríguez-Zavala JS, Moreno-Sánchez R
JournalJ Biol Chem
PubMed ID9525878
'The effect of varying the Mg2+ concentration on the 2-oxoglutarate dehydrogenase (2-OGDH) activity and the rate of oxidative phosphorylation of rat heart mitochondria was studied. The ionophore A23187 was used to modify the mitochondrial free Mg2+ concentration. Half-maximal stimulation (K0.5) of ATP synthesis by Mg2+ was obtained with 0.13 +/- ... More
Selection of fluorescent ion indicators for simultaneous measurements of pH and Ca2+.
AuthorsMartínez-Zaguilán R, Parnami G, Lynch RM
JournalCell Calcium
PubMed ID8983854
'The advent of fluorescent ion sensitive indicators has improved our understanding of the mechanisms involved in regulating pHi and [Ca2+]i homeostasis in living cells. However, changes in [Ca2+]i can alter pHi regulatory mechanisms and vice versa, making assignment of either ion to a particular physiological response complex. A further complication ... More
High magnesium concentration inhibits ligand-stimulated calcium influx and hormone secretion in rat pituitary lactotropes with involvement of intracellular free magnesium.
AuthorsKasahara K, Tasaka K, Masumoto N, Nishizaki T, Mizuki J, Tahara M, Miyake A, Tanizawa O
JournalBiochem Biophys Res Commun
PubMed ID8250951
'The effects of extracellular magnesium concentration ([Mg2+]ex) on thyrotropin-releasing hormone (TRH)-stimulated intracellular free calcium mobilization and prolactin secretion were investigated concomitantly with measurement of the intracellular free magnesium concentration ([Mg2+]i). TRH-stimulated intracellular free calcium mobilization was significantly inhibited when the medium was replaced by high Mg2+ medium ([Mg2+]ex = 10 ... 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
The effect of angiotensin II on platelet intracellular free magnesium and calcium ionic concentrations in essential hypertension.
AuthorsTouyz RM, Schiffrin EL
JournalJ Hypertens
PubMed ID8390527
'OBJECTIVE: To assess the effects of angiotensin II on intracellular free Mg2+ and Ca2+ concentrations in platelets from normotensive and hypertensive subjects. DESIGN AND METHODS: Seventeen normotensive, 25 untreated hypertensive and 18 treated hypertensive patients were studied. Intracellular Mg2+ concentrations were measured with the fluorescent dye mag-fura-2-acetyoxymethylester (AM) and intracellular ... More
On the relationship between matrix free Mg2+ concentration and total Mg2+ in heart mitochondria.
AuthorsJung DW, Panzeter E, Baysal K, Brierley GP
JournalBiochim Biophys Acta
PubMed ID9230923
'The matrix free magnesium ion concentration, [Mg2+]m, estimated using the fluorescent probe furaptra, averaged 0.67 mM in 15 preparations of beef heart mitochondria containing an average of 21 nmol total Mg2+ per mg protein. [Mg2+]m was compared with total Mg2+ during respiration-dependent uptake and efflux of Mg2+ and during osmotic ... More
Rapid mobilization of intracellular Mg2+ by bombesin in Swiss 3T3 cells: mobilization through external Ca(2+)- and tyrosine kinase-dependent mechanisms.
AuthorsIshijima S, Tatibana M
JournalJ Biochem (Tokyo)
PubMed ID8089090
'We examined the effects of growth factors on intracellular free Mg2+ concentrations ([Mg2+]i) in single Swiss 3T3 fibroblasts, using microfluorometry of a Mg(2+)-sensitive dye mag-fura-2. We had already noted an increase in [Mg2+]i after exposure to bombesin for 30-60 min [Ishijima, S., Sonoda, T., & Tatibana, M. (1991) Am. J. ... More
Free magnesium concentration in salamander photoreceptor outer segments.
AuthorsChen C, Nakatani K, Koutalos Y
JournalJ Physiol
PubMed ID14500766
'Magnesium ions (Mg2+) play an important role in biochemical functions. In vertebrate photoreceptor outer segments, numerous reactions utilize MgGTP and MgATP, and Mg2+ also regulates several of the phototransduction enzymes. Although Mg2+ can pass through light-sensitive channels under certain conditions, no clear extrusion mechanism has been identified and removing extracellular ... More
Endogenous calcium buffering in motoneurones of the nucleus hypoglossus from mouse.
AuthorsLips MB, Keller BU
JournalJ Physiol
PubMed ID9679167
'1. Simultaneous patch clamp and rapid microfluorometric calcium measurements were performed on sixty-five motoneurones in slices of the nucleus hypoglossus in the brainstem of 2- to 6-day-old mice. 2. Hypoglossal motoneurones were particularly vulnerable to mechanical or metabolic stress during isolation of in vitro slice preparations. Therefore, experimental conditions were ... More
Abnormal intracellular calcium homeostasis in sympathetic neurons from young prehypertensive rats.
AuthorsLi D, Lee CW, Buckler K, Parekh A, Herring N, Paterson DJ,
JournalHypertension
PubMed ID22252398
'Hypertension is associated with cardiac noradrenergic hyperactivity, although it is not clear whether this precedes or follows the development of hypertension itself. We hypothesized that Ca(2+) homeostasis in postganglionic sympathetic neurons is impaired in spontaneously hypertensive rats (SHRs) and may occur before the development of hypertension. The depolarization-induced rise in ... More
Ca(2+) dynamics in the lumen of the endoplasmic reticulum in sensory neurons: direct visualization of Ca(2+)-induced Ca(2+) release triggered by physiological Ca(2+) entry.
AuthorsSolovyova N, Veselovsky N, Toescu EC, Verkhratsky A
JournalEMBO J
PubMed ID11847110
'In cultured rat dorsal root ganglia neurons, we measured membrane currents, using the patch-clamp whole-cell technique, and the concentrations of free Ca(2+) in the cytosol ([Ca(2+)](i)) and in the lumen of the endoplasmic reticulum (ER) ([Ca(2+)](L)), using high- (Fluo-3) and low- (Mag-Fura-2) affinity Ca(2+)-sensitive fluorescent probes and video imaging. Resting ... More
Ethanol and glutamate effects on intracellular magnesium.
AuthorsWilson WR, Phillips KS, Leslie SW
JournalAlcohol
PubMed ID9401666
'Acutely dissociated rat brain cells were loaded with the magnesium-sensitive fluorescent dye furaptra. Stimulation with varying concentrations of GLU + 1 microM GLY produced a concentration-dependent increase in free intracellular magnesium ([Mg2+]i) that was not dependent on the presence of extracellular Mg2+. Ethanol (50 mM) did not significantly inhibit GLU/GLY-stimulated ... More
Lack of effect of transmembrane gradient of magnesium and sodium on regulation of cytosolic free magnesium concentration in rat lymphocytes.
AuthorsSasaki N, Oshima T, Matsuura H, Yoshimura M, Yashiki M, Higashi Y, Ishioka N, Nakano Y, Kojima R, Kambe M, Kajiyama G
JournalBiochim Biophys Acta
PubMed ID9370254
'The regulation of the intracellular concentration of Mg2+ ([Mg2+]i) is not fully understood. The level of Mg in lymphocytes is a good predictor of total body Mg status. We measured [Mg2+]i and total Mg in rat lymphocytes by using, respectively, the fluorescent Mg2+ indicator mag-fura-2 and atomic absorption spectrophotometry. The ... More
Imaging of quantal calcium release in the inositol 1,4,5-trisphosphate-sensitive organelles of permeabilized HSY cells.
AuthorsTanimura A, Tojyo Y, Matsumoto Y
JournalCell Struct Funct
PubMed ID9706401
'The spatial characteristics of inositol 1,4,5-trisphosphate (IP3)-induced quantal Ca2+ release were examined by imaging Ca2+ concentrations within Ca2+ stores ([Ca2+]L) in permeabilized HSY cells. The image of mag-fura-2 fluorescent ratio with dual excitation (344 nm/360 nm) demonstrated that a sequential application of different concentrations of IP3 (0.1, 0.3, 10 microM) ... More
Intracellular Ca(2+) and Zn(2+) signals during monochloramine-induced oxidative stress in isolated rat colon crypts.
AuthorsCima RR, Dubach JM, Wieland AM, Walsh BM, Soybel DI
JournalAm J Physiol Gastrointest Liver Physiol
PubMed ID16002562
'During acute exacerbations of inflammatory bowel diseases, oxidants are generated through the interactions of bacteria in the lumen, activated granulocytes, and cells of the colon mucosa. In this study we explored the ability of one such class of oxidants, represented by monochloramine (NH(2)Cl), to serve as agonists of Ca(2+) and ... More
Decreased cellular Mg2+ concentrations in a subgroup of hypertensives--cell models for the pathogenesis of primary hypertension.
AuthorsKisters K, Tepel M, Spieker C, Dietl KH, Barenbrock M, Rahn KH, Zidek W
JournalJ Hum Hypertens
PubMed ID9249231
'A new method to determine total Mg2+ content in lymphocytes was developed, offering advantages for routine measurements as compared to fluorescence methods. Intracellular Mg2+ measurements were performed in lymphocytes of 18 untreated normotensive and 19 untreated essential hypertensive patients. Mg2+ content was referred to lymphocytic protein, which was determined according ... More
Glucose regulation of free Ca(2+) in the endoplasmic reticulum of mouse pancreatic beta cells.
AuthorsTengholm A, Hellman B, Gylfe E
JournalJ Biol Chem
PubMed ID10601240
'Free Ca(2+) was measured in organelles of individual mouse pancreatic beta cells loaded with the low affinity indicator furaptra. After removal of cytoplasmic indicator by controlled digitonin permeabilization the organelle Ca(2+) was located essentially in the endoplasmic reticulum (ER), >90% being sensitive to inhibition of sarco(endo)plasmic reticulum Ca(2+)-ATPases. The Ca(2+) ... More