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 physically loaded with the cell-impermeant salt forms of these dextran-conjugated indicators using patch pipette, microinjection, or our Influx pinocyte-loading reagent. The fluorescence signal from these cells is measured using fluorescence microscopy. The dextran forms of our calcium indicators show a dramatic reduction in both leakage and compartmentalization compared to the AM ester forms.

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

Calcium Indicator (Cell-Impermeant Salts, Dextran Conjugates) Specifications:
• Label (Ex/Em): Oregon Green™ 488 BAPTA-1 (494/523 nm)
• Fluorescence intensity increase upon binding Ca²⁺: ∼14 fold
• Dextran size: 10,000 MW
• 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.