Determination of resting free calcium in barnacle muscle using modified aequorins, buffered calcium injections, and simultaneous image-intensified video microscopy

1995 ◽  
Vol 16 (5) ◽  
pp. 499-507 ◽  
Author(s):  
Ellis B. Ridgway ◽  
Albert M. Gordon



1987 ◽  
Vol 252 (4) ◽  
pp. C441-C449 ◽  
Author(s):  
L. A. Levy ◽  
E. Murphy ◽  
R. E. London

Fluorine 19 nuclear magnetic resonance (NMR) studies of intracellular fluorinated calcium chelators provide a useful strategy for the determination of cytosolic free calcium levels in cells and perfused organs. However, the fluorinated chelator with the highest affinity for calcium ions which has been described to date. 1,2-bis-(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), exhibits a dissociation constant (Kd) value 5- to 10-fold greater than the intracellular calcium concentration levels in most cell types, thus limiting the ability of fluorine NMR to report these concentrations reliably. We have consequently designed and synthesized several fluorinated calcium chelators with higher affinity for calcium. The best of these, 2-(2-amino-4-methyl-5-fluorophenoxy)-methyl-8 aminoquinidine-N,N,N',N'-tetraacetic acid (quinMF), has a Kd value approximately 10 times lower than that of 5FBAPTA. Several of the newly synthesized indicators have different chemical shifts for the calcium complexed and uncomplexed chelators to allow the simultaneous use of two indicators. In addition to providing information about the level of cytosolic free calcium, chelators containing a quinoline ring exhibit considerable sensitivity to magnesium levels and hence have potential application for the determination of cytosolic-magnesium concentrations. Application of these chelators is illustrated by determination of the cytosolic-free calcium level in erythrocytes. Use of quinMF, the chelator with the lowest Kd value, gives a calcium value of 25-30 nM.



The Analyst ◽  
1990 ◽  
Vol 115 (5) ◽  
pp. 605 ◽  
Author(s):  
Jacobus F. van Staden ◽  
Ancel van Rensburg


2000 ◽  
Vol 19 (3/4) ◽  
pp. 96-102
Author(s):  
A. M. Koorts ◽  
M. Viljoen ◽  
M. C. Kruger

A large number of fluorescent calcium indicators are available for the determination of intracellular free calcium concentrations. The best known of these is fura-2. However, the employment of fura-2, amongst others, for the determination of intracellular free calcium is not problem-free.



1990 ◽  
Vol 68 (11) ◽  
pp. 1932-1936 ◽  
Author(s):  
Byron Kratochvil ◽  
Xi-Wen He

A two-wavelength method was applied to the determination of free, ionic calcium with Arsenazo III in solutions containing calcium-binding ligands. By this procedure impurities in the indicator can be corrected for, thereby allowing the use of commercial indicator preparations with purities as low as 80%. Only a 1:1 complex with a conditional log stability constant of 4.28 ± 0.13 at pH 4.6 and ionic strength 0.1 was found under the conditions studied. Key words: free metal ion determination, calcium ion speciation, spectrophotometry, arsenazo III, ion increment method for speciation.



1980 ◽  
Vol 26 (6) ◽  
pp. 781-781
Author(s):  
Brian W Renoe ◽  
Jay M McDonald ◽  
Jack H Ladenson

Abstract Vol. 25 p 1766: Second paragraph, line four, the reference numbers cited should be (5-11); numbers of all subsequent citations above 10 in text should be increased by one, to correspond with the list of references. p 1828: In Figure 2, the label on the ordinate is not clear. It reads “counts/10 s × 10−3.” p 1930: Under “Determination of Concentrations in Human Plasma,” the injection of dihydroergotamine should be 0.5 mL of a 1 g/L solution. p 1931: Nine to 12 determinations of binding in the absence of nonradioactive standard were also used to construct the standard curves. p 1932: In the paragraph preceding Results and in the caption to Figure 3, the amount of compound 2 is 0.5 mg, not 1 mg. p 2020: In the preparation of phosphate buffer, the second sentence should read: “Dissolve 2.84 g of sodium diphosphate in 100 mL of de-ionized water (solution 2).” p 2021: In the section on extraction of serum under Procedures, the 10 µL of internal standard and 200 µL of sample should be added to 200 µL of phosphate buffer. Vol. 26 p99: In the caption for Figure 3A, read “r = 0.99,” not “r = 0.09.” p. 176: The sample volume referred to in the fourth paragraph of column three should be 0.15 µL, not “150 mL.” p 193: Add to reference list: 8. Goutte-Coussieu, C., Habrioux, G., Eichenberger, D., and Jayle, M. F., Rapid fluorometry of estrogens in nonpregnancy urine, with use of chloroform extraction and purification by anion-exchange chromatography. Clin. Chem. 25, 230 (1979). 9. Jarrige, P., Purification et propriétés des sulfatases du suc d’Helix pomatia. Bull. Soc. Chim. Biol. (Paris) 7-8,761 (1963). 10. Ittrich, G., Untersuchungen über Extraktion des roten Kober-Farbstoffs durch organische Lösungsmittel zur Ostrogenbestimmung im Harn. Acta Endocrinol. (Copenhagen) 35, 34 (1960). 11. Adessi, G., Lallier, J. C., Goutte-Coussieu, C., and Jayle, M. F., Méthode de dosage automatique par spectrofluorimétrie des estrogénes urinaires au cours et en dehors de la grossesse. Ann. Biol. Clin. 37, 89 (1979). 12. Schöller, R., Contrôle de Qualité en Hormonologie. I.-Stéroides Urinaires. Editions Sepe, Paris-Fresnes, 1976, p 51. p. 354: In Table 1, last line, columns 2 and 4, substitute “0.12” for “0.16.”



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