Patch clamped responses from outer hair cells in the intact adult organ of Corti.

ABSTRACT

Outer hair cells (OHCs) from the mammalian cochlea act as both sensory cells and motor cells. We report here whole-cell tight seal recordings of OHC activity in their natural embedding tissue, the intact organ of Corti, using a temporal bone preparation. The mean cell resting potential, -76 +/- 4 mV (n = 19) and input conductance (10 +/- 3 nS at -70 mV) of third turn hair cells were significantly lower than have been found in isolated cells. Two main K+ currents in the cell were identified. One current, activated positive to -100 mV, was reduced by 5 mM BaCl2. The other current, activated above -40 mV, was reduced by 100 microM 4-aminopyridine (4-AP) and by 30 mM tetraethylammonium (TEA). Both of these currents have been also identified in recordings reported from isolated cells. On stepping to different membrane potentials, cells imaged in the organ of Corti changed length by an amount large enough to cause visible distortions in neighbouring cells. By quantifying such distortions we estimate that the forces generated by OHCs can account for the enhanced response to sound required by the cochlear amplifier.