Enhanced loading of Fura-2/AM calcium indicator dye in adult rodent brain slices via a microfluidic oxygenator

• A microfluidic oxygenator is used to deliver constant oxygen to rodent brain slices.
• Device improves loading efficiency of calcium indicator Fura-2/AM into cells of slice.
• Loading in slices from 1-year old mice was achieved.
• Technique significantly expands the age range for which calcium studies are possible.

A microfluidic oxygenator is used to deliver constant oxygen to rodent brain slices, enabling the loading of the cell-permeant calcium indicator Fura-2/AM into cells of adult brain slices. When compared to traditional methods, our microfluidic oxygenator improves loading efficiency, measured by the number of loaded cells per unit area, for all tested age groups. Loading in slices from 1-year-old mice was achieved, which has not been possible with current bulk loading methods. This technique significantly expands the age range for which calcium studies are possible without cellular injection. This technique will facilitate opportunities for the study of calcium signaling of aging and long term stress related diseases. Moreover, it should be applicable to other membrane-permeant physiological indicator varieties.