Excess plasma membrane and effects of ionic amphipaths on mechanics of outer hair cell lateral wall

2002 ◽  
Vol 282 (5) ◽  
pp. C1076-C1086 ◽  
Author(s):  
Noriko Morimoto ◽  
Robert M. Raphael ◽  
Anders Nygren ◽  
William E. Brownell
Keyword(s):  
Plasma Membrane ◽  
Hydraulic Conductivity ◽  
Hair Cell ◽  
Outer Hair Cell ◽  
Lateral Wall ◽  
Micropipette Aspiration ◽  
Membrane Mechanics ◽  
Time Required ◽  
The Impact ◽  
Membrane Reservoir

The interaction between the outer hair cell (OHC) lateral wall plasma membrane and the underlying cortical lattice was examined by a morphometric analysis of cell images during cell deformation. Vesiculation of the plasma membrane was produced by micropipette aspiration in control cells and cells exposed to ionic amphipaths that alter membrane mechanics. An increase of total cell and vesicle surface area suggests that the plasma membrane possesses a membrane reservoir. Chlorpromazine (CPZ) decreased the pressure required for vesiculation, whereas salicylate (Sal) had no effect. The time required for vesiculation was decreased by CPZ, indicating that CPZ decreases the energy barrier required for vesiculation. An increase in total volume is observed during micropipette aspiration. A deformation-induced increase in hydraulic conductivity is also seen in response to micropipette-applied fluid jet deformation of the lateral wall. Application of CPZ and/or Sal decreased this strain-induced hydraulic conductivity. The impact of ionic amphipaths on OHC plasma membrane and lateral wall mechanics may contribute to their effects on OHC electromotility and hearing.

Effects of Salicylate on Plasma Membrane Mechanics

2005 ◽  
Vol 94 (3) ◽  
pp. 2105-2110 ◽  
Author(s):  
Sergey A. Ermilov ◽  
David R. Murdock ◽  
Dania El-Daye ◽  
William E. Brownell ◽  
Bahman Anvari
Keyword(s):  
Hearing Loss ◽  
Plasma Membrane ◽  
Optical Tweezers ◽  
Outer Hair Cell ◽  
Control Cell ◽  
Lateral Wall ◽  
Membrane Mechanics ◽  
Cell Plasma Membrane ◽  
Hek Cells ◽  
Cell Plasma

High concentrations of the amphipathic drug salicylate (Sal) block outer hair cell (OHC) electromotility resulting in reversible hearing loss. We used optical tweezers to study the effects of Sal on the mechanics of the cell plasma membrane. Membrane tethers were formed from guinea pig OHCs and cultured human embryonic kidney (HEK) cells as controls. HEK cells are commonly used in functional expression studies of electromotility. Effective tether viscosity (ηeff), steady-state tethering force extrapolated to zero pulling rate Fss(0), and time constant for tether growth (τtg) were estimated from the measurements of the instantaneous tethering force at different tether pulling rates. Average values of ηeff, Fss(0), and τtg for the OHC lateral wall plasma membrane and control cell plasma membrane remained the same after Sal perfusion, which is consistent with the hypothesis that Sal-induced reversible hearing loss appears to be more the result of its competition with essential anions and less the result of a change in plasma membrane mechanics.

scholarly journals Outer Hair Cell Lateral Wall Structure Constrains the Mobility of Plasma Membrane Proteins

PLoS Genetics ◽  
2015 ◽  
Vol 11 (9) ◽  
pp. e1005500 ◽  
Author(s):  
Tetsuji Yamashita ◽  
Pierre Hakizimana ◽  
Siva Wu ◽  
Ahmed Hassan ◽  
Stefan Jacob ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Hair Cell ◽  
Outer Hair Cell ◽  
Lateral Wall ◽  
Wall Structure ◽  
Plasma Membrane Proteins

scholarly journals Micropipette aspiration on the outer hair cell lateral wall

1997 ◽  
Vol 72 (6) ◽  
pp. 2812-2819 ◽  
Author(s):  
P.S. Sit ◽  
A.A. Spector ◽  
A.J. Lue ◽  
A.S. Popel ◽  
W.E. Brownell
Keyword(s):  
Hair Cell ◽  
Outer Hair Cell ◽  
Lateral Wall ◽  
Micropipette Aspiration

scholarly journals 3D Ultrastructure of the Cochlear Outer Hair Cell Lateral Wall Revealed By Electron Tomography

2019 ◽  
Author(s):  
William Jeffrey Triffo ◽  
Hildur Palsdottir ◽  
David Gene Morgan ◽  
Kent L. McDonald ◽  
Robert M. Raphael ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Hair Cell ◽  
Actin Filaments ◽  
Computational Models ◽  
Outer Hair Cell ◽  
Electron Tomography ◽  
3D Structure ◽  
Lateral Wall ◽  
Outer Hair Cells ◽  
Unique Type

AbstractOuter hair cells in the mammalian cochlea display a unique type of voltage-induced mechanical movement, termed electromotility, which amplifies auditory signals and contributes to the sensitivity and frequency selectivity of mammalian hearing. Electromotility occurs in the outer hair cell (OHC) lateral wall, and it is not fully understood how the supramolecular architecture of the lateral wall enables this unique form of cellular motility. Employing electron tomography of high-pressure frozen and freeze-substituted OHCs, we visualized the 3D structure and organization of the membrane and cytoskeletal components of the OHC lateral wall. The subsurface cisterna (SSC) is a highly prominent feature, and we report that the SSC membranes and lumen possess hexagonally ordered arrays of particles that endow the SSC with a previously unrealized anisotropic structural rigidity. We also find the SSC is tightly connected to adjacent actin filaments by short filamentous protein connections spaced at regular intervals. Pillar proteins that join the plasma membrane to the cytoskeleton appear as variable structures considerably thinner than actin filaments and significantly more flexible than actin-SSC links. The structurally rich organization and rigidity of the SSC coupled with apparently weaker mechanical connections between the plasma membrane and cytoskeleton reveal that the membrane-cytoskeletal architecture of the OHC lateral wall is more complex than previously appreciated. These observations are important for our understanding of OHC mechanics and need to be considered in computational models of OHC electromotility that incorporate subcellular features.

Modeling the Mechanics of Tethers Pulled From the Cochlear Outer Hair Cell Membrane

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Kristopher R. Schumacher ◽  
Aleksander S. Popel ◽  
Bahman Anvari ◽  
William E. Brownell ◽  
Alexander A. Spector
Keyword(s):  
Cell Membrane ◽  
Hair Cell ◽  
Outer Hair Cell ◽  
Lateral Wall ◽  
Outer Hair Cells ◽  
The Body ◽  
Computational Method ◽  
Membrane Properties ◽  
Bending Modulus ◽  
Sound Amplification

Cell membrane tethers are formed naturally (e.g., in leukocyte rolling) and experimentally to probe membrane properties. In cochlear outer hair cells, the plasma membrane is part of the trilayer lateral wall, where the membrane is attached to the cytoskeleton by a system of radial pillars. The mechanics of these cells is important to the sound amplification and frequency selectivity of the ear. We present a modeling study to simulate the membrane deflection, bending, and interaction with the cytoskeleton in the outer hair cell tether pulling experiment. In our analysis, three regions of the membrane are considered: the body of a cylindrical tether, the area where the membrane is attached and interacts with the cytoskeleton, and the transition region between the two. By using a computational method, we found the shape of the membrane in all three regions over a range of tether lengths and forces observed in experiments. We also analyze the effects of biophysical properties of the membrane, including the bending modulus and the forces of the membrane adhesion to the cytoskeleton. The model’s results provide a better understanding of the mechanics of tethers pulled from cell membranes.

scholarly journals Fluorescence-Imaged Microdeformation of the Outer Hair Cell Lateral Wall

1998 ◽  
Vol 18 (1) ◽  
pp. 48-58 ◽  
Author(s):  
John S. Oghalai ◽  
Alpen A. Patel ◽  
Takashi Nakagawa ◽  
William E. Brownell
Keyword(s):  
Hair Cell ◽  
Outer Hair Cell ◽  
Lateral Wall

Mechanosensitive Channels in the Lateral Wall Can Enhance the Cochlear Outer Hair Cell Frequency Response

2005 ◽  
Vol 33 (8) ◽  
pp. 991-1002 ◽  
Author(s):  
Alexander A. Spector ◽  
Aleksander S. Popel ◽  
Ruth Anne Eatock ◽  
William E. Brownell
Keyword(s):  
Hair Cell ◽  
Frequency Response ◽  
Outer Hair Cell ◽  
Lateral Wall ◽  
Mechanosensitive Channels ◽  
Cell Frequency
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