Tip-link independent mechanotransduction in cochlear outer hair cells?

When a static deflection is superimposed on a sinusoidal displacement of the hair bundle, abolition of the phasic receptor current is observed. Simultaneously, the total current was maximized or minimized depending on the direction of stimulation. in response to negative, inhibitory displacements, some cells exhibited not only a reduction of the phasic receptor current but an additional reduction of current. This indicates the existence of mechanosensitive channels, being only sensitive to these extremely slow hair-bundle displacements. This so-called DC-shift appears to be very similar to the DC-shift that was described in response to application of dihydrostreptomycin (DHSM). In addition to this finding, many isolated OHCs did not react to sinusoidal mechanical stimulation, but showed modulated current flow when stereocilia were statically deflected. If both the pharmacological black by DHSM and the tonic mechanosensitivity are the responses of transducer channels, having lost their tip links during the isolation procedure, this indicates the presence of tip-link independent gating of hair-cell transduction channels.