Figure 3

KCl-evoked Ca²⁺ spikes in GL15 cells. The graph shows the trace of intracellular Ca²⁺ variations in a single cell responding to extracellular 50 mM KCl pulses (arrows). The solid trace represents the [Ca²⁺]_i variations found in 100% (n = 60) of the differentiated tested cells. The trace in the box represents the [Ca²⁺]_i variations found in 70% (n = 47) of the undifferentiated cells. Time (s=seconds) is indicated on the abscissa; the ordinate gives the normalized fluorescence value (f/f₀).