Pflügers Archiv

, Volume 444, Issue 1, pp 99–106

Voltage-dependent changes in specific membrane capacitance caused by prestin, the outer hair cell lateral membrane motor

  • Joseph Santos-Sacchi
  • Enrique Navarrete
Original Article

DOI: 10.1007/s00424-002-0804-2

Cite this article as:
Santos-Sacchi, J. & Navarrete, E. Pflügers Arch - Eur J Physiol (2002) 444: 99. doi:10.1007/s00424-002-0804-2

Abstract.

In the outer hair cell (OHC), membrane capacitance principally derives from two components – that associated with lateral membrane sensor/motor charge movement, and that proportional to the membrane surface area (Csa). We used measures of membrane capacitance to test a model hypothesis that OHC lateral membrane molecular motors, recently identified as the protein prestin, fluctuate between two area states. By measuring membrane capacitance in native OHCs or prestin-transfected HEK cells at extreme voltages (±200 mV) where motor-derived charge movement is small or absent, we observed that Csa depends on the state of the motors, or correspondingly on membrane voltage. Deiters cells or control HEK cells, which lack motors, do not show this dependence. We modeled the voltage-dependent change in Csa as a Boltzmann process with the same parameters that describe the charge movement of the motors' voltage sensors. Csa is 3.28±0.75 pF (mean ±SD; n=23) larger during extreme hyperpolarization, and the number of motors in OHCs and prestin-transfected HEK cells correlates with the magnitude of ΔCsa (r=0.78). Although these data are consistent with the area motor model, the corresponding area change, assuming 0.5 µF/cm2 under constant membrane thickness, is unphysiologically large, and indicates that the capacitance change must result from changes not only in lateral membrane area but also specific capacitance. Thus, we conclude that a conformational change in the lateral membrane motor, prestin, additionally alters the dielectric constant and/or thickness of the lateral plasma membrane.

Gating charge Membrane capacitance Motility 

Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Joseph Santos-Sacchi
    • 1
  • Enrique Navarrete
    • 1
  1. 1.Sections of Otolaryngology and Neurobiology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06510 USAUSA

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