Figure 3.

Effects of butanedione monoxime and gentamicin on electrically evoked hair-bundle movements. (A) Under control conditions, a hair bundle oscillated spontaneously and responded to electrical stimulation at 100 Hz (Upper). In the presence of 20 mM butanedione monoxime, the same bundle produced a comparable electrical response without spontaneous oscillation (Lower). The high-frequency spikes of bundle motion in the latter record might reflect the residual activity of myosin molecules. (B) A spontaneously active hair bundle responded well under control conditions to 30-Hz electrical stimulation (Upper). The electrical response was blocked when the same bundle was exposed to gentamicin (Lower), whose iontophoretic application is indicated beneath the recording. Drug exposure offset the bundle in the positive direction, an indication of blockage in the open-channel state.