Labeled calcium indicators are molecules that exhibit an increase in fluorescence upon binding Ca²⁺. They have uses in many calcium signaling investigations, including measuring intracellular Ca²⁺, following Ca²⁺ influx and release, and multiphoton excitation imaging of Ca²⁺ in living tissues. Cells may be loaded with the AM ester forms of these calcium indicators by adding the dissolved indicator directly to dishes containing cultured cells. The fluorescence signal from these cells is generally measured using fluorescence microscopy, fluorescence microplate assays, or flow cytometry.

Learn more about ion indicators including calcium, potassium, pH, and membrane potential indicators ›

Calcium Indicator (AM Ester) Specifications:
• Label (Ex/Em): Calcium Orange™ (549/576 nm)
• Fluorescence intensity increase upon binding Ca²⁺ : ∼3 fold
• Exhibit fluorescence increase upon binding Ca²⁺ with little shift in wavelength

Spectral Characteristics of Molecular Probes™ Calcium Indicators
These probes are excited by visible light, and because the energy required for excitation is low, the potential for cellular photodamage is reduced. Commonly used laser-based instruments (i.e., confocal laser scanning microscopes) are able to efficiently excite these indicators, and their emissions are in regions of the spectrum where cellular autofluorescence and scattering backgrounds are often less of a problem.

More Choices for Fluorescent Calcium Indicators
We offer a large selection of Molecular Probes™ calcium indicators for use in various experimental scenarios, for example dextran versions for reduced leakage and compartmentalization and BAPTA conjugates for detecting high-amplitude calcium transients. For more information, review Fluorescent Ca²⁺ Indicators Excited with Visible Light—Section 19.3 in the Molecular Probes™ Handbook.

For UV-excitable Ca²⁺ indicators, protein-based Ca²⁺ indicators, conjugates of Ca²⁺ indicators, and for fluorescence-based indicators of other metal ions (i.e., Mg²⁺, Zn²⁺) review Indicators for Ca²⁺, Mg²⁺, Zn²⁺ and Other Metal Ions—Chapter 19 in the Molecular Probes™ Handbook.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.