Indicator calcium

Notes. (1) The usefulness of the HHSNNA indicator for the titration of calcium depends upon the fact that the pH of the solution is sufficiently high to ensure the quantitative precipitation of the magnesium as hydroxide and that calcium forms a more stable complex with EDTA than does magnesium. The EDTA does not react with magnesium [present as Mg(OH)2] until all the free calcium and the calcium-indicator complex have been complexed by the EDTA. If the indicator is added before the potassium hydroxide, a satisfactory end-point is not obtained because magnesium salts form a lake with the indicator as the pH increases and the magnesium indicator-lake is co-precipitated with the magnesium hydroxide. 

Blinks, J. R. (1990). Use of photoproteins as intracellular calcium indicators. Environ. Health Perspect 84 75-81. 

Blinks, J. R., et al. (1978). Practical aspects of the use of aequorin as a calcium indicator Assay, preparation, microinjection, and interpretation of signals. Method. Enzymol. 57 292-328. 

Illarionov, B. A., et al. (2000). Recombinant obelin cloning and expression of cDNA, purification, and characterization as a calcium indicator. Method. Enzymol. 305 223-249. 

Kihara, Y., and Morgan, J. P. (1989). A comparative study of three methods for intracellular loading of the calcium indicator aequorin in ferret papillary muscles. Biochem. Biophys. Res. Commun. 162 402—407. 

Morgan, J. P., DeFeo, T. T., and Morgan, K. G. (1984). A chemical procedure for loading the calcium indicator aequorin into mammalian working myocardium. Pfluegers Arch. 400 338-340. 

The calcium indicator Fura2, which has not been discussed in detail in this manuscript, has been widely used as an intracellular calcium indicator (see Ref. 15 and also Cobbold, P.H. Rink, T.J. Biochem. J. 1987, 248, 313-328. 

Previous studies indicate that osmotic gradients promote membrane fusion, while hyperosmotic conditions inhibit membrane fusion during exocytosis. Consistent with this idea is the observation that the release of lysosomal enzymes from rabbit neutrophils, induced by the chemotactic peptide J -formylmethionyl-leucyl-phenylalanine (FMLP), is inhibited almost 80% in a 700-mosmol/kg medium. Inhibition is immediate (within 10 s), increases with osmolality, and is independent of the osmoticant. Neutrophils loaded with the calcium indicator indo-1 exhibit an FMLP-induced calcium signal that is inhibited by hyperosmolality. Hyperosmolality (700 mosmol/kg) increases basal calcium levels and reduces the peak of the calcium signal elicited by FMLP at concentrations ranging from 10 ° to 10 M. 

Isolated chromaffin cells were maintained in suspension culture and loaded with the fluorescent calcium indicator Fura 2 as previously described (28). 2 x 10 cells/ml were added into a cuvette containing standard buffer without (dotted line) or with (full line) 2 mM calcium. At the arrow, 10" M pardaxin was added. A rise in was... 

RY Tsien. (1980). New calcium indicators and buffers with high selectivity against magnesium and protons Design, synthesis, and properties of prototype structures. Biochemistry 19 2396-2404. 

The adsorption of nonionic polyacrylamide is also increased in the presence of calcium, indicating specific interaction of calcium and the polymer. 

In a recent article by Dyatlov et al. (1998), a method for the determination of Pb+2 and Ca+2 in intracellular fluids was described. In this method, a fluorescent, calcium indicator (fluo-3) was used. 

Mank M, Griesbeck O (2008) Genetically encoded calcium indicators. Chem Rev 108 1550-1564... 

In calcium chelators Indo-1 (17) and Fura-3 (18b) (Figure 2.9),(18) the fluoropho-res have donor-acceptor stilbene-like structures rigidified so as to avoid photoisomerization. Based on the same principle, Fura-2 (18a)a8) is one of the most popular calcium indicator for microscopy of individual cells because, in contrast to Quin-2 (see Section 2.2.5.), the excitation spectrum is blue shifted on cation binding, thus allowing intensity-ratio measurements. On the other hand, there is almost no shift of the emission spectrum, which can be interpreted along the same line as DCM-crown (see earlier in this section). 

For practical applications it is better to use fluorescent probes excitable at high wavelengths, so that autofluorescence of the sample (especially biological samples) does not interfere. Calcium indicators based on fluorescein and rhodamine fluorophores(70) fulfill this requirement and are thus more convenient for fluorescence... 

Fluorescent Calcium Indicators in Current Use in Molecular Biology... 

Most of the fluorescent calcium indicators and their cell-permeant acetoxymethyl (AM) esters are variations of the nonfluorescent calcium chelator BAPTA and have been proposed by Tsien/134-1365 Among them Fura-2 and Indo-1 (Figure 5.22) are particularly used formeasuring Ca2+in single cells by imaging or flow cytometry/65... 

A Ca +-binding protein isolated from jellyfish Aequorea sp.) that is frequently used as a chemiluminescent calcium indicator.Aequorin contains a hydrophobic prosthetic group, coelenterazine. Investigators have been able to express the transfected gene recombinantly in a number of cells, and upon addition of the cofactor, one can measure intracellular calcium concentration. See Fura-2... 

The ash is analysed qualitatively the presence of lead, manganese and calcium indicates the presence in the varnish of resinates, that of sodium carbonate in considerable amount would indicate that the varnish contains soap, whilst boric acid or borates would show the presence of lac rendered soluble by these substances. 

Vomdran, C. et al. (1995) New fluorescent calcium indicators designed for cytosolic retention or measuring calcium near membranes, Biophys. J. 69, 2112-2124. 

The method used for determination of PolyP, which is based on the Mn2+-induced quenching of the fluorescence of the calcium indicator Fura-2, has been described (Lorenz et al., 1997a). The effect of Mn2+ ions on the Fura-2 fluorescence is gradually removed in the presence of increasing PolyPs concentrations this allows the quantification of PolyPs isolated from tissues or cells. The described method has some advantages when compared with the conventional detection procedures based on the metachromatic effect. It can be applied to the determination of pyrophosphate, tripolyphosphate and other short-chain PolyPs not detectable by toluidine blue (Lorenz et al., 1997a). 

S04-dominated water with concentrations of more than 2300 mg/1, and containing equivalent concentrations of calcium, indicates that gypsum or anhydrite is present in the aquifer rocks. 

Extracellular calcium is required to give maximum LH stimulated steroidogenesis in isolated Leydig cells [15,18]. Using the intracellular fluorescent calcium indicator, Quin 2, it has been shown that lowering the extracellular calcium concentration from 2.5 mM to 1.1 xM lowered the LH stimulated intracellular calcium concentrations from 300-500 nM to only 52 nM. These studies showed that LH increases intracellular calcium and that this increase is dependent mainly on extracellular levels of calcium. Cyclic AMP analogues were also shown to increase intracellular calcium to the same concentrations as those obtained with LH, indicating that cyclic AMP is one of the mediators of LH action on calcium mobilization [15]. 

The ability of selected experimental agents to potentiate glutamate receptor-mediated response was determined using fluorescent calcium indicator dyes and by measuring glutamate-evoked efflux of calcium into GluR4-transfected HEK293 cells. 

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