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.
Calcium Indicator (Cell-Impermeant Salts, Dextran Conjugates) Specifications: • Label (Ex/Em): Calcium Green™ -1 (506/531 nm) • Fluorescence intensity increase upon binding Ca2+: ~14 fold • Dextran size: 3,000 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.