Non-uniform mapping of stress-induced, motility-related charge movement inthe outer hair cell plasma membrane

There is a growing consensus that outer hair cell (OHC) electromotility und erlies the mammalian cochlear amplifier. This voltage-dependent motility is mirrored by a gating current, which along with motility can be altered by tension applied to the cell's plasma membrane. We used localized tension ap plication along the length of the OHC to induce gating currents from membra ne microdomains; with this information we mapped the distribution of the OH C's sensitivity to membrane stress before and after disrupting the cytoskel eton with intracellular Pronase. Mechanically induced gating currents, whic h were susceptible to salicylate, lanthanides and turgor pressure, evidence d a bell-shaped distribution that was restricted to the lateral membrane wh ere the electromotile response resides. After Pronase treatment, gating cur rents remained intact and restricted. These results confirm that the molecu lar motors are intrinsically and bi-directionally susceptible to voltage an d tension, and provide evidence for limited mobility of OHC motors within t he cell's lateral membrane.