Joseph Santos-Sacchi PhD

Professor of Surgery (Otolaryngology), of Cellular and Molecular Physiology and of Neurobiology

Research Interests

Mammalian inner ear

Research Summary

The exquisite sensitivity and frequency resolving power of the mammalian inner ear depends upon interactions between the two receptor cells of the organ of Corti, inner (IHC) and outer (OHC) hair cells. While inner hair cells appear to function solely as receptors of acoustic information, OHC’s function both as receptors and effectors, producing motile responses as a function of transmembrane potential fluctuations.

These motile responses modify the mechanical input to the inner hair cells which receive the majority of afferent innervation, thereby enhancing the gross frequency tuning afforded by basilar membrane mechanics. Dr. Joseph Santos-Sacchi studies the effector role of the OHC with electrophysiological (patch clamp) and displacement measurement techniques using isolated OHCs from the guinea pig. He also works on the motor protein (prestin) responsible for the cells’ mechanical activity, utilizing mutational analysis and expression systems to understand how it works.

Selected Publications

  • Santos-Sacchi J. Determination of cell capacitance using the exact empirical solution of ∂Y/∂Cm and its phase angle. Biophys J, 87:714-27, 2004.
  • Santos-Sacchi J, Song L, Zheng J, Nuttall AL. Control of mammalian cochlear amplification by chloride anions. J Neurosci, 26(15):3992-8, 2006.
  • Bai JP, Navaratnam D, Samaranayake H, Santos-Sacchi J. En block C-terminal charge cluster reversals in prestin (SLC26A5): effects on voltage-dependent electromechanical activity. Neurosci Lett, 404(3):270-5, 2006.
  • Abe T, Kakehata S, Kitani R, Maruya S, Navaratnam D, Santos-Sacchi J, Shinkawa H. Developmental expression of the outer hair cell motor prestin in the mouse. J Membr Biol, 215(1):49-56, 2007.
  • Rybalchenko V and Santos-Sacchi J. Anion control of voltage sensing by the motor protein prestin in outer hair cells. Biophysical J, 95(9):4439-47, 2008.
  • Santos-Sacchi J, Navarrete E, Song L. Fast electromechanical amplification in the lateral membrane of the outer hair cell. Biophysical J, 96(2):739-47, 2009.
  • Bai J-P, Surguchev A, Montoya S, Aronson PS, Santos-Sacchi J, Navaratnam D. Prestin’s anion transport and voltage sensing capabilities are independent. Biophysical J, 96(8):3179-86, 2009.

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