Tip-link integrity and mechanical transduction in vertebrate hair cells.
An attractive hypothesis for hair-cell transduction is that fine, filamentous "tip links" pull directly on mechanically sensitive ion channels located at the tips of the stereocilia. We tested the involvement of tip links in the transduction process by treating bundles with a BAPTA-buffered, low-Ca2+ saline (10(-9) M). BAPTA abolished the transduction current in a few hundred milliseconds. BAPTA treatment for a few seconds eliminated the tip links observed by either scanning or transmission electron microscopy. BAPTA also eliminated the voltage-dependent movement and caused a positive bundle displacement of 133 nm, in quantitative agreement with a model for regulation of tension. We conclude that tip links convey tension to the transduction channels of hair cells.
Assad
J A
JA
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
Shepherd
G M
GM
Corey
D P
DP
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002923:Cilia / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D003902:Detergents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology; D011892:Rana catesbeiana
D003902:Detergents; D011092:Polyethylene Glycols; D004533:Egtazic Acid; D017830:Octoxynol; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium