OUTER HAIR CELL MECHANICS ARE ALTERED BY DEVELOPMENTAL CHANGES IN LATERAL WALL PROTEIN CONTENT

Electromotile length change and force generation by outer hair cells is thought to be essential for a sensitive and sharply tuned mammalian cochlea. Outer hair cell stiffness is in turn important for effective transmission of force to the organ of Corti. Maturation of stiffness in outer hair cells during development may therefore be an important factor in the onset and maturation of hearing. We compared the mechanical properties of developing and adult gerbil outer hair cells using calibrated glass fibers. We found that specific compliance of outer hair cells increased dramatically up to the onset of hearing and decreased after that. We examined F-actin, spectrin and prestin synthesis in developing and adult gerbil outer hair cells. While the F-actin content of the lateral wall decreased progressively during postnatal development, both spectrin and prestin increased close to the onset of hearing. These results strongly support the hypothesis that the cortical lattice and the prestin content of the lateral wall membrane influence outer hair cell mechanical properties.