Uncaging calcium in neurons

Changes in intracellular free calcium concentration (Δ[Ca(2+)]i) driving physiological events such as neurotransmitter release or Ca(2+)-dependent currents can be monitored using Ca(2+)-sensitive fluorescent dyes. Although these dyes can correlate Δ[Ca(2+)]i with a physiological event, they cannot directly test for causality between changes in [Ca(2+)]i and that event. Photolabile Ca(2+) chelators are Ca(2+)-binding molecules that can alter and, to a certain extent, control [Ca(2+)]i in an inducible manner and with temporal and spatial resolution that surpasses microinjection or ionophore application. Here we discuss the properties of caged Ca(2+) compounds as well as some practical considerations for their use in neuronal cells, where they have proven particularly effective.