Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN AG-Seminar

Tuesday, 31.10.2006 16 c.t.

Single-channel recordings of voltage-gated calcium channels in vertebrate hair cells

by Dr. Adrian Contreras
from Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands

Location

Seminarraum Haus 2, 4. Stock (Bunsenstr.)

Abstract

Calcium (Ca) regulates multiple aspects of the physiology of inner ear hair cells. These include adaptation of mechanotransduction, non-linear hair bundle mechanics, and gating of Ca-dependent mechanisms that shape the receptor potential as well as neurotransmitter release. We employed low- and high-resolution electrophysiological recordings to demonstrate that hair cells express more than one Ca current subtype. We proved the efficacy of using single-channel patch-clamp recordings to determine the conductance of Ca channels in hair cells under near physiological conditions, and in so doing, demonstrated the conditions in which anomalous mole fraction effects of single Ca channels can be observed. Other physiologically relevant properties of Ca channels in hair cells such as inactivation and assembly of the channels into clusters were delineated. These studies unmasked an unexpected slow inactivation of the channels, which is only partly conferred by the channels interaction with its auxiliary subunits and synaptic proteins. Additionally, the Ca channels had a heterogeneous expression, from low- to high-density clusters. In this talk, I will discuss these findings and their relevance for understanding Ca-dependent functions in hair cells.

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