OUTER HAIR CELL LENGTH CHANGES IN AN EXTERNAL ELECTRIC-FIELD .1. THE ROLE OF INTRACELLULAR ELECTRO-OSMOTICALLY GENERATED PRESSURE-GRADIENTS

Brownell et al. [Science 227, 194-196 (1985)] observed that an isolate d, cylindrically shaped cochlear outer hair cell can change its length when an electric field is applied. In their experiments, the cell was fixed at one end, and located between two electrodes which lie on the cell axis but were positioned far from the cell. Kachar et al. [Natur e 322, 365-368 (1986)] had suggested that the cell's electrically evok ed elongation could be caused by pressure gradients resulting from ele ctro-osmosis of the intracellular fluid. A mathematical model is devel oped which predicts the length change that would result from electro-o smotically generated pressure gradients inside the cell. Estimated par ameter values are included to demonstrate that the pressures generated by electro-osmosis inside the cell would result in elongations that a re at least two orders of magnitude below the experimentally measured values. (C) 1995 Acoustical Society of America.