Molecular motor and electrokinetic contributions to outer hair cell electromotility.

The outer hair cell of the inner ear is believed to be responsible for the high sensitivity and selectivity of mammalian hearing. Molecular motors are generally believed to cause the electrically-driven length change (electromotility) of the outer hair cell. It has been suggested that electrokinetic effects might also play a significant role in electromotility, along with the molecular motors. This paper describes a new technique that can be used to experimentally determine the percentage of the electromotile response that is caused by electrokinetic effects. The technique is based on the novel idea that molecular motor activity cannot in itself generate a net force on the cell, but that electrokinetic effects can. Our method is the first that can separate molecular motor behavior from electrokinetic behavior, during experiments on the outer hair cell.