Fig. 2.

Rapid recovery of mechanical properties in hair bundles of the bullfrog’s sacculus. (A) While a 10-Hz sinusoidal stimulus of amplitude 100 nm (top trace) was delivered to the base of a flexible glass fiber, a pulse of iontophoretic current (bottom trace) released EDTA. The hair bundle’s movement (middle trace) increased immediately after iontophoresis, but returned toward the initial value over a few seconds. (B) For the record shown in A, the decline in the amplitude of hair bundle oscillation after the iontophoretic pulse followed an exponential relation (red line) with a time constant of 1,910 ms. (C) To the left in each pair of images in the top row are individual frames of a movie of a spontaneously oscillating hair bundle (Movie S1) representing the unperturbed bundle (Initial), the same bundle after exposure to EDTA (Exposed), and finally the bundle after transient displacement in the negative direction (Recovered). To the right are three images, each obtained by subtracting the original frame from the subsequent frame. The Initial and Recovered images reveal spontaneous hair bundle motion, which is absent in the Exposed image. The time course of the hair bundle’s position in the movie (upper trace) shows suppression of the spontaneous oscillations during iontophoretic application of EDTA (lower trace) and their recovery after the bundle was pushed in the negative direction (between the red arrowheads).