Fig. 2.

ATP-evoked Ca²⁺ signaling in the LER of cochlear organotypic cultures from postnatal WT and PIPKIγ^+/− mice. (A) Samples of a representative false-color image sequence showing fura-2 fluorescence ratio changes (ΔR), encoded as shown by the color scale bar, recorded in a WT culture after delivery of a brief puff (50 ms) of ATP (4 μM) through a glass micropipette (white asterisk); time in seconds from puff offset is shown in the lower right corner of the corresponding frame. (Scale bar, 100 μm.) (B) Waveforms of Ca²⁺ responses obtained by averaging signals within the nine color-matched regions of interest shown over individual cells at increasing distance from micropipette opening in A. (C) propagation index, defined as the maximal area invaded by the intercellular Ca²⁺ wave divided by the area directly stimulated by the puff (pooled data); an index of 1 indicates no propagation; black asterisks indicate significant differences (ANOVA); error bars, SD. (D) Sample traces of Ca²⁺ responses obtained by averaging fura-2 ratio signals within 15 randomly selected cells in representative apical turn cultures from P5 WT and PIPKIγ^+/− mice during sustained application of extracellular ATP (200 nm, gray bars). (E) Frequency histograms of ATP-evoked [Ca²⁺]_i oscillations (events) in cultures from P5 WT and PIPKIγ^+/− mice (pooled data); in each graph, the solid black line (right ordinates) is the time integral of the corresponding frequency histogram and, as such, it tracks the mean number of events in the cell population from the onset of the ATP application.