Figure 4.

Partial block of utricular [Ca²⁺]_i transients by 50μM 2-APB at P3. (A) Resting G5 fluorescence, F₀. (B) Spontaneous ΔF/F₀ modulation (green) in the control condition. (C) ΔF/F₀ modulation (red) after bath application of 50μM 2-APB. (D) Spontaneous ΔF/F₀ modulation (blue) after washout of 2-APB. (E) Merge (B–D) showing modulation in the control condition (green), in the presence of 2-APB (red), and after washout (blue). The red channel was amplified to allow visualization of small ΔF/F₀ in the presence of 2-APB. 50μM 2-APB reversibly blocked spontaneous activity in SCs. Cells that continued to respond in the presence of 2-APB were located near the base of HCs at P3. (F) Example transients in the presence of 2-APB, and (G) average waveforms in the control condition and in the presence of 2-APB. (H) Population statistics summarizing the action of 2-APB on the exponential rise time, half width, and decay time of ΔF/F₀ transients. Spontaneous transients in the control condition are shown as fast events (Group 1) and slow events (Group 2) as in Figure 3. All events in the presence of 2-APB were slow and indistinguishable on the basis of kinetics.