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Acta Physiologica 2006; Volume 186, Supplement 650
Joint Meeting of The German Society of Physiology and The Federation of European Physiological Societies 2006
3/26/2006-3/29/2006
Ludwig-Maximilians-University, Munich
FAST KINETICS OF SINGLE MECHANOTRANSDUCER CHANNELS IN MAMMALIAN OUTER HAIR CELLS BY AFM AND PATCH CLAMP
Abstract number: OT10-60
Langer1 M, Langer1 MG, Munkner1 S, Koitschev1 A, Fink1 S, Lehmann-Horn1 F
1Sensory Biophysics Group, Abteilung Angewandte Physiologie, Universitt Ulm
Perception of sound relies on transformation of incoming mechanical stimuli (sound) into electrical signals, called mechanoelectrical transduction (MET). The mechanosensitive molecular complex, located in the stereocilia of the hair cells, consists of at least a channel protein with a cation-nonselective pore region with a molecular gate and a link pulling at its gate. It is still unknown how the transduction channel can respond to applied forces within microseconds and how the transduction machinery overcomes the limit of channel gating noise. Here, single-channel currents in mammalian outer hair cells (OHC) were measured using patch clamp in response to displacement of individual stereocilia by atomic force microscopy (AFM). AFM stimulation of single stereocilia yielded intrinsic channel gating with continuous transitions between open and closed state rather than step-like responses. This observation suggests a gate flickering between open and closed state with rate constants far beyond the recording bandwidth of 3 kHz. Observed current responses likely reflect the mean open probability of the transduction channel rather than transitions between open and closed state at full bandwidth. Assuming a gating noise equally distributed over very large channel gating bandwidth (exceeding the upper frequency limit of hearing) the current noise level would reduce, improving the signal to noise ratio and the
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Acta Physiologica 2006; Volume 186, Supplement 650 :OT10-60