• Ruben, Robert J. (PI)
  • Iwasa, K. (PI)
  • Braida, Louis (PI)
  • Fuchs, Paul (PI)
  • Montgomery, Allen (PI)
  • Iwasa, K. (PI)

Project: Research project


The fast mechanical response of the mammalian auditory outer hair cell is
believed to be the cellular basis of the positive feedback mechanism
required for the fine tuning process of the hearing organ. We showed that
the fast mechanical response of the cell is membrane potential dependent.
We found that a simplified membrane model can describe the elastic property
of the cell and were able to evaluate the force produced by the cell for
the first time. It turned out that the efficiency is 0.5 nN/Mv for a
single cell, and this indicates that the mechanical feedback resulting this
effect is of the same order of magnitude as the mechanical signal on the
cellular level. In the process of investigating what kind of physiological
signals cause athe fast response, we demonstrated that the lateral wall can
also be a mechano-receptor in addition to the stereocilia. We observed
macroscopic current produced by osmotic stress, attributable to stretch-
activated potassium channels. The endocochlear potential, which is the main energy source of the mechano-
electrical transduction in the inner ear, is attributed to the marginal
cell of stria vascularis. With the whole-cell recording method, we found
that an inward current of the marginal cell is blocked by micromolar
concentration of amiloride. This is suggestive that the cell has
amiloride-sensitive sodium channel similar to other epithelium cells such
as the ones in the kidney. This current can, at least partially, account
for the unusually positive membrane potential of the marginal cell, and
thereby the endocochlear potential.
Effective start/end date7/1/776/30/93


  • National Institutes of Health: $15,000.00


Hearing Loss
Medical Genetics
Hearing Disorders
Molecular Biology
Animal Models


  • Medicine(all)
  • Neuroscience(all)