Fluo-3 is a fluorescence indicator of intracellular calcium (Ca 2+), developed by Roger Y. Tsien. [1] It is used to measure Ca 2+ inside living cells in flow cytometry, and confocal laser scanning microscopy using visible light excitation (compatible with argon laser sources operating at …

The Ca 2+ indicator fluo-3 (Figure 1) was developed by Tsien and colleagues for use with visible-light excitation sources in flow cytometry and confocal laser-scanning microscopy. Since being introduced in 1989, fluo-3 imaging has revealed the spatial dynamics of many elementary processes in calcium signaling.

Visible light–excitable Ca 2+ indicators offer several advantages over UV light–excitable indicators: The Ca 2+ indicator fluo-3 (Figure 19.3.1) was developed by Tsien and colleagues for use with visible-light excitation sources in flow cytometry and confocal laser-scanning microscopy.

Fluo-3, fluo-4 and their derivatives all exhibit large fluorescence intensity increases on binding Ca2+. Unlike the ultra -violet light–excited indicators fura-2 and indo-1, there is no accompanying spectral shift.

The cell-permeant dye fluo-3 AM is a visible lightexcitable, high affinity Ca2+ indicator. It is available in 1 mg amounts (F-1241), as a 1 mM solution (F-14218), in a high-throughtput screening amount (F-14242) and in our Fl.

Fluo-4 is essentially a brighter, more photostable derivative of fluo-3. Its Ca 2+ affinity is a little lower (K d ~345 nM) and its absorption maximum is shifted ~12 nm compared to fluo-3, making it more suitable for 488 excitation using an argon laser ( 43 - 45 ).

Fluo-3 is a calcium sensor that utilizes fluorescein as a fluorescent tag, with excitation and emission wavelengths near 505 nm and 530 nm, respectively. It has a 325 nM affinity for Ca2+ and shows a 40-fold increase in emission intensity upon calcium binding.

Mag-fura-2 (Table 1) can be used as a magnesium indicator or low afinity calcium indicator. We also provide a selection of fluorescent indicators for chloride and zinc (page 5), as well as pH indicators (pages 6-7).

Fluo-3 and related molecule Fluo3/AM are used as a fluorescence indicator of intracellular calcium (Ca2+). Fluo-3 may be use for flow cytometry and confocal laser scanning microscopy using visible light excitation (compatible with argon laser sources operating at 488 nm).

This application note describes the comparison of using fluo-3 & fluo-4, loaded into M1-transfected CHO-cells and how the FLIPR System is used to measure the calcium response to carbachol activation.