| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Physiological Laboratory, University of Cambridge.
1. Mechano-electrical transducer currents evoked by deflections of the hair bundle were recorded in turtle isolated hair cells under whole-cell voltage clamp. The outcome of perfusing with solutions of reduced Ca2+ concentration was investigated. 2. The transducer current was roughly doubled by lowering the concentration of divalent cations from normal (2.2 mM-Mg2+, 2.8 mM-Ca2+) to 0 Mg2+, 0.5 mM-Ca2+. No significant effects on the current's kinetics or reversal potential, or on the current-displacement relationship, were noted. 3. If the Ca2+ concentration was lowered to 50 microM (with no Mg2+), there was about a threefold increase in the maximum current but other changes, including loss of adaptation and a decreased slope and negative shift in the current-displacement relationship, were also observed. As a result, more than half the peak transducer current became activated at the resting position of the hair bundle compared to about a tenth in the control solution. 4. The extra changes manifest during perfusion with 50 microM-Ca2+ had also been seen when the cell was held at positive potentials near the Ca2+ equilibrium potential. This supports the view that some consequences of reduced external Ca2+ stem from a decline in its intracellular concentration. 5. With 20 microM-Ca2+, a standing inward current developed and the cell became unresponsive to mechanical stimuli, which may be explained by the transducer channels being fully activated at the resting position of the bundle. 6. The results are interpreted in terms of a dual action of Ca2+: an external block of the transducer channel which reduces the maximum current, and an intracellular effect on the position and slope of the current-displacement relationship; the latter effect can be modelled by internal Ca2+ stabilizing one of the closed states of the channel. 7. During perfusion with 1 microM-Ca2+, the holding current transiently increased but then returned to near its control level. There was a concomitant irreversible loss of sensitivity to hair bundle displacements which we suggest is due to rupture of the mechanical linkages to the transducer channel. 8. Following treatment with 1 microM-Ca2+, single-channel currents with an amplitude of -9 pA at -85 mV were sometimes visible in the whole-cell recording. The probability of such channels being open could be modulated by small deflections of the hair bundle which indicates that they may be the mechano-electrical transducer channels or conductance about 100 pS. 9. Open- and closed-time distributions for the channel were fitted by single exponentials, the mean open time at rest being approximately 1 ms. The mean open time was increased and the mean closed time decreased for movements of the hair bundle towards the kinocilium.(ABSTRACT TRUNCATED AT 400 WORDS)
This article has been cited by other articles:
|
|
 |
|
  M. Beurg, J.-H. Nam, A. Crawford, and R. Fettiplace The Actions of Calcium on Hair Bundle Mechanics in Mammalian Cochlear Hair Cells Biophys. J., April 1, 2008; 94(7): 2639 - 2653. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. A. Ghanem, K. D. Breneman, R. D. Rabbitt, and H. M. Brown Ionic Composition of Endolymph and Perilymph in the Inner Ear of the Oyster Toadfish, Opsanus tau Biol. Bull., February 1, 2008; 214(1): 83 - 90. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Waguespack, F. T. Salles, B. Kachar, and A. J. Ricci Stepwise Morphological and Functional Maturation of Mechanotransduction in Rat Outer Hair Cells J. Neurosci., December 12, 2007; 27(50): 13890 - 13902. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-Y. Tinevez, F. Julicher, and P. Martin Unifying the Various Incarnations of Active Hair-Bundle Motility by the Vertebrate Hair Cell Biophys. J., December 1, 2007; 93(11): 4053 - 4067. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Wangemann, K. Nakaya, T. Wu, R. J. Maganti, E. M. Itza, J. D. Sanneman, D. G. Harbidge, S. Billings, and D. C. Marcus Loss of cochlear HCO3- secretion causes deafness via endolymphatic acidification and inhibition of Ca2+ reabsorption in a Pendred syndrome mouse model Am J Physiol Renal Physiol, May 1, 2007; 292(5): F1345 - F1353. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Mammano, M. Bortolozzi, S. Ortolano, and F. Anselmi Ca2+ Signaling in the Inner Ear Physiology, April 1, 2007; 22(2): 131 - 144. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Jia, P. Dallos, and D. Z. Z. He Mechanoelectric Transduction of Adult Inner Hair Cells J. Neurosci., January 31, 2007; 27(5): 1006 - 1014. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. E. Farris, G. B. Wells, and A. J. Ricci Steady-State Adaptation of Mechanotransduction Modulates the Resting Potential of Auditory Hair Cells, Providing an Assay for Endolymph [Ca2+] J. Neurosci., November 29, 2006; 26(48): 12526 - 12536. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Beurg, M. G. Evans, C. M. Hackney, and R. Fettiplace A Large-Conductance Calcium-Selective Mechanotransducer Channel in Mammalian Cochlear Hair Cells J. Neurosci., October 25, 2006; 26(43): 10992 - 11000. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. P. Corey What is the hair cell transduction channel? J. Physiol., October 1, 2006; 576(1): 23 - 28. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. J. Kennedy, M. G. Evans, A. C. Crawford, and R. Fettiplace Depolarization of cochlear outer hair cells evokes active hair bundle motion by two mechanisms. J. Neurosci., March 8, 2006; 26(10): 2757 - 2766. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Xue and E. H. Peterson Hair Bundle Heights in the Utricle: Differences Between Macular Locations and Hair Cell Types J Neurophysiol, January 1, 2006; 95(1): 171 - 186. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Marcotti, S. M. van Netten, and C. J. Kros The aminoglycoside antibiotic dihydrostreptomycin rapidly enters mouse outer hair cells through the mechano -electrical transducer channels J. Physiol., September 1, 2005; 567(2): 505 - 521. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Ricci, H. J. Kennedy, A. C. Crawford, and R. Fettiplace The Transduction Channel Filter in Auditory Hair Cells J. Neurosci., August 24, 2005; 25(34): 7831 - 7839. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Nagata, A. Duggan, G. Kumar, and J. Garcia-Anoveros Nociceptor and Hair Cell Transducer Properties of TRPA1, a Channel for Pain and Hearing J. Neurosci., April 20, 2005; 25(16): 4052 - 4061. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. D. Rabbitt, R. Boyle, G. R. Holstein, and S. M. Highstein Hair-Cell Versus Afferent Adaptation in the Semicircular Canals J Neurophysiol, January 1, 2005; 93(1): 424 - 436. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. A. Manley, U. Sienknecht, and C. Koppl Calcium Modulates the Frequency and Amplitude of Spontaneous Otoacoustic Emissions in the Bobtail Skink J Neurophysiol, November 1, 2004; 92(5): 2685 - 2693. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Bashtanov, R. J. Goodyear, G. P. Richardson, and I. J. Russell The mechanical properties of chick (Gallus domesticus) sensory hair bundles: relative contributions of structures sensitive to calcium chelation and subtilisin treatment J. Physiol., August 15, 2004; 559(1): 287 - 299. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. E. Farris, C. L. LeBlanc, J. Goswami, and A. J. Ricci Probing the pore of the auditory hair cell mechanotransducer channel in turtle J. Physiol., August 1, 2004; 558(3): 769 - 792. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. van Netten, T. Dinklo, W. Marcotti, and C. J. Kros Channel gating forces govern accuracy of mechano-electrical transduction in hair cells PNAS, December 23, 2003; 100(26): 15510 - 15515. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. Vollrath and R. A. Eatock Time Course and Extent of Mechanotransducer Adaptation in Mouse Utricular Hair Cells: Comparison With Frog Saccular Hair Cells J Neurophysiol, October 1, 2003; 90(4): 2676 - 2689. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Martin, D. Bozovic, Y. Choe, and A. J. Hudspeth Spontaneous Oscillation by Hair Bundles of the Bullfrog's Sacculus J. Neurosci., June 1, 2003; 23(11): 4533 - 4548. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Bozovic and A. J. Hudspeth Hair-bundle movements elicited by transepithelial electrical stimulation of hair cells in the sacculus of the bullfrog PNAS, February 4, 2003; 100(3): 958 - 963. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Ricci Differences in Mechano-Transducer Channel Kinetics Underlie Tonotopic Distribution of Fast Adaptation in Auditory Hair Cells J Neurophysiol, April 1, 2002; 87(4): 1738 - 1748. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Ricci, A. C. Crawford, and R. Fettiplace Mechanisms of Active Hair Bundle Motion in Auditory Hair Cells J. Neurosci., January 1, 2002; 22(1): 44 - 52. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A. Dumont, U. Lins, A. G. Filoteo, J. T. Penniston, B. Kachar, and P. G. Gillespie Plasma Membrane Ca2+-ATPase Isoform 2a Is the PMCA of Hair Bundles J. Neurosci., July 15, 2001; 21(14): 5066 - 5078. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Boyer, J. J. Art, C. J. Dechesne, J. Lehouelleur, J. Vautrin, and A. Sans Contribution of the Plasmalemma to Ca2+ Homeostasis in Hair Cells J. Neurosci., April 15, 2001; 21(8): 2640 - 2650. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. P. Hamill and B. Martinac Molecular Basis of Mechanotransduction in Living Cells Physiol Rev, April 1, 2001; 81(2): 685 - 740. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Hudspeth, Y. Choe, A. D. Mehta, and P. Martin Putting ion channels to work: Mechanoelectrical transduction, adaptation, and amplification by hair cells PNAS, October 24, 2000; 97(22): 11765 - 11772. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Ricci, A. C. Crawford, and R. Fettiplace Active Hair Bundle Motion Linked to Fast Transducer Adaptation in Auditory Hair Cells J. Neurosci., October 1, 2000; 20(19): 7131 - 7142. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y.-C. Wu, A. J. Ricci, and R. Fettiplace Two Components of Transducer Adaptation in Auditory Hair Cells J Neurophysiol, November 1, 1999; 82(5): 2171 - 2181. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Goodyear and G. Richardson The Ankle-Link Antigen: an Epitope Sensitive to Calcium Chelation Associated with the Hair-Cell Surface and the Calycal Processes of Photoreceptors J. Neurosci., May 15, 1999; 19(10): 3761 - 3772. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Choe, M. O. Magnasco, and A. J. Hudspeth A model for amplification of hair-bundle motion by cyclical binding of Ca2+ to mechanoelectrical-transduction channels PNAS, December 22, 1998; 95(26): 15321 - 15326. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Ricci, Y-C. Wu, and R. Fettiplace The Endogenous Calcium Buffer and the Time Course of Transducer Adaptation in Auditory Hair Cells J. Neurosci., October 15, 1998; 18(20): 8261 - 8277. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Meyer, D. N. Furness, H.-P. Zenner, C. M. Hackney, and A. W. Gummer Evidence for Opening of Hair-Cell Transducer Channels after Tip-Link Loss J. Neurosci., September 1, 1998; 18(17): 6748 - 6756. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Neurosci., August 15, 1998; 18(16): np - 0. [Full Text] [PDF]
|
|
|
|
|
|
E. A. Lumpkin and A. J. Hudspeth Regulation of Free Ca2+ Concentration in Hair-Cell Stereocilia J. Neurosci., August 15, 1998; 18(16): 6300 - 6318. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. N. Yamoah, E. A. Lumpkin, R. A. Dumont, P. J. S. Smith, A. J. Hudspeth, and P. G. Gillespie Plasma Membrane Ca2+-ATPase Extrudes Ca2+ from Hair Cell Stereocilia J. Neurosci., January 15, 1998; 18(2): 610 - 624. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Holt, D. P. Corey, and R. A. Eatock Mechanoelectrical Transduction and Adaptation in Hair Cells of the Mouse Utricle, a Low-Frequency Vestibular Organ J. Neurosci., November 15, 1997; 17(22): 8739 - 8748. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. E. Marquis and A. J. Hudspeth Effects of extracellular Ca2+ concentration on hair-bundle stiffness and gating-spring integrity in hair cells PNAS, October 28, 1997; 94(22): 11923 - 11928. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. A. Lumpkin, R. E. Marquis, and A. J. Hudspeth The selectivity of the hair cell's mechanoelectrical-transduction channel promotes Ca2+ flux at low Ca2+ concentrations PNAS, September 30, 1997; 94(20): 10997 - 11002. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y.-d. Zhao, E. N. Yamoah, and P. G. Gillespie Regeneration of broken tip links and restoration of mechanical transduction in hair cells PNAS, December 24, 1996; 93(26): 15469 - 15474. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
