Prestin and the dynamic stiffness of cochlear outer hair cells.
The outer hair cell (OHC) lateral wall is a unique trilaminate structure consisting of the plasma membrane, the cortical lattice, and subsurface cisternae. OHCs are capable of altering their length in response to transmembrane voltage change. This so-called electromotile response is presumed to result from conformational changes of membrane-bound protein molecules, named prestin. OHC motility is accompanied by axial stiffness changes when the membrane potential of the cell is altered. During length changes, intracellular anions (mainly Cl-) act as extrinsic voltage sensors. In this study, we inquired whether the motor proteins are responsible for the voltage-dependent axial stiffness of OHCs, and whether ACh, the neurotransmitter of efferent neurons, modulates the stiffness of the cortical lattice and/or the stiffness of the motor protein. The experiments were done on isolated guinea pig OHCs in the whole-cell voltage-clamp mode. Axial stiffness was determined by loading a fiber of known stiffness onto the apical surface of the cells. Voltage-dependent stiffness and cell motility disappeared, and the axial stiffness of the cells significantly decreased after removal of intracellular Cl-. The result suggests that the stiffness of the motor protein is a major contributor to the global axial stiffness of OHCs. ACh was found to affect both the motor protein and other lateral wall stiffness components.
He
David Z Z
DZ
Department of Biomedical Sciences, Creighton University Medical School, Omaha, Nebraska 68175, USA. hed@creighton.edu
Jia
Shuping
S
Dallos
Peter
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001696:Biomechanical Phenomena; D001703:Biophysics / Q000379:methods; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002469:Cell Separation; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D020409:Molecular Motor Proteins / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011506:Proteins / Q000378:metabolism*
D020409:Molecular Motor Proteins; C498722:Pres protein, Cavia porcellus; D011506:Proteins; D000109:Acetylcholine