Ca2+ indicator dyes

FIG. 3. Confocal images showing the location of the SR in live myocytes within an intact, small diameter (< 250 nm passive diameter), pressurized (70 mmHg) artery from the rat mesenteric artery arcade. The artery was loaded with Fluo-4 as the membrane-permeant acetoxymethyl ester. Some of this high-affinity, Ca2+ indicator dye is often sequestered in the SR (cf. Goldman et al 1990). The SR can then be readily visualized, especially when [Ca2+]CYx is low (as in the panels at 0 and 6.8 s), because the intra-SR dye is saturated with Ca2+, and fluoresces brightly. This artery was treated with 1.0 fim phenylephrine (PE), which caused the [Ca2+]CYT level to oscillate asynchronously in the cells seen in the centre of the panel. The cell outlines are clearly visible when [Ca2+]CYT tiscs, as in the panels at 3.4 and 10.2 s. Note that nearly all of the SR (the very bright areas, especially in the 0 and 3.4 s panels) lies parallel to, and immediately beneath the PL (from Miriel at al 1999, with permission). 

Fig. 8. R/Platelet in individual platelets adhering to polymer surfaces. HSB data were statistically confirmed to be different from PSt (P < 0.5), HSR (P < 0.5) and PHEMA (P < 0.5) after 40 s R/Platelet (an index of cytoplasmic free calcium concentration) is the ratio of fluorescence emission intensitie of a Ca2 + indicator dye (Fura 2) loaded in platelets when they are excited at 340 nm and 380 nm. (Reproduced from J Biomed Mater Res [Ref 84 Prevention of changes in platelet cytoplasmic free calcium levels by interaction with 2-hydroxyethyl methacrylate/styrene block copolymer surfaces] through the courtesy of John Wiley Sons, Inc.)...

Calcium oscillations observed with six cultured pancreatic p cells after a single infusion of 0.2 mM carbamoylcholine. Tire fluorescence intensity of the Ca2+ indicator dye fura 2, with excitation at 380 nm, was recorded versus time. From Pretki et al.ss... 

For example, the oscillatory change in intracellular [Ca2+] shown above was observed in pancreatic insulin-secreting P cells responding to stimulation by the agonist carbamoylcholine. The free [Ca2+] was evaluated from fluorescence measurements using the Ca2+ indicator dye fura 2 (From Prentki et alss). Oscillations in [Ca2+] have been observed... 

Calcium ion fluxes mediated by a variety of channels and ionophores into liposomes and cells have been studied by loading the vesicles with indicator dyes like arsenazo III (129) or quin-2 (130). The significantly higher calcium affinity of the fluorescence indicator fura-2 (131) was a major advancement in the detection of Ca2+ concentrations in small cells and liposomes (132-134). 

The studies reviewed above indicate that the SR in at least some smooth muscles appears to be subdivided into small, functionally independent compartments. By employing imaging methods with low-affinity Ca2+ dyes in intact, primary cultured arterial myocytes, we observed that RyR and L1SP3R are apparently associated with different SR subcompartments. 

Earlier techniques for measuring cytosolic free Ca2+ (1-2) such as the luminescent photoprotein aequorin, the absorbance dye arsenazo III and Ca2+-sensitive microelectrodes, all required microinjection or impalements, and were therefore applied mainly to giant cells. Later, photoproteins have been loaded with various reversible permeabilization procedures (3), but the largest expansion in the range of cell types in which Ca2+ signals can be quantified has come from the development of new fluorescent indicators that can be loaded using hydrolyzable esters. Currently four fluorescent indicators are used frequently quin-2, fura-2, indo-1 and fluo-3. 

Murexide, the ammonium salt of purpuric acid, was known for long to be a good indicator for Ca2+ in aqueous solution (74). The chemical composition of the dye is as follows ... 

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