Xenia A. Meshik*, Krzysztof L. Hyrc, Mark P. Goldberg**, Washington University School of Medicine, Dept. Neurology,
The Hope Center for Neurological Disorders, Alafi Neuroimaging Laboratory, Saint Louis, MO 63110.
1. Asante Calcium Red is a novel calcium indicator that combines visible light excitation with long emission wavelength and can be used as a single or dual emission wavelength (ratiometric) indicator.
2. The choice of imaging mode determines the magnitude of indicator response to changing calcium concentration with long excitation wavelength (543 nm) being the most dynamic.
3. Interestingly, Asante Calcium Red yields the most dynamic emission ratio when imaged using multi-photon excitation and, as such, might be well-suited for deep tissue calcium imaging.
4. Asante Calcium Red offers moderate affinity for calcium and is also sensitive to magnesium and zinc, none of which, however, is expected to significantly affect calcium dependent fluorescence of the indicator.
5. Thanks to its long emission wavelength, Asante Calcium Red might be used to measure intracellular free calcium concentrations in cells expression Green or Yellow Fluorescent Proteins, a task not easily attainable with most of the fluorescent calcium indicators.