Abstract
Functioning of the membrane motor of the outer hair cell is tightly associated with transfer of charge across the membrane. To obtain further insights into the motor mechanism, we examined kinetics of charge transfer across the membrane in two different modes. One is to monitor charge transfer induced by changes in the membrane potential as an excess membrane capacitance. The other is to measure spontaneous flip-flops of charges across the membrane under voltage-clamp conditions as current noise. The noise spectrum of current was inverse Lorentzian, and the capacitance was Lorentzian, as theoretically expected. The characteristic frequency of the capacitance was approximately 10 kHz, and that for current noise was approximately 30 kHz. The difference in the characteristic frequencies seems to reflect the difference in the modes of mechanical movement associated with the two physical quantities.
Full Text
The Full Text of this article is available as a PDF (107.3 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adachi M., Iwasa K. H. Electrically driven motor in the outer hair cell: effect of a mechanical constraint. Proc Natl Acad Sci U S A. 1999 Jun 22;96(13):7244–7249. doi: 10.1073/pnas.96.13.7244. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ashmore J. F. A fast motile response in guinea-pig outer hair cells: the cellular basis of the cochlear amplifier. J Physiol. 1987 Jul;388:323–347. doi: 10.1113/jphysiol.1987.sp016617. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ashmore J. F. Forward and reverse transduction in the mammalian cochlea. Neurosci Res Suppl. 1990;12:S39–S50. doi: 10.1016/0921-8696(90)90007-p. [DOI] [PubMed] [Google Scholar]
- Brownell W. E., Bader C. R., Bertrand D., de Ribaupierre Y. Evoked mechanical responses of isolated cochlear outer hair cells. Science. 1985 Jan 11;227(4683):194–196. doi: 10.1126/science.3966153. [DOI] [PubMed] [Google Scholar]
- Dallos P., Evans B. N. High-frequency motility of outer hair cells and the cochlear amplifier. Science. 1995 Mar 31;267(5206):2006–2009. doi: 10.1126/science.7701325. [DOI] [PubMed] [Google Scholar]
- Fidler N., Fernandez J. M. Phase tracking: an improved phase detection technique for cell membrane capacitance measurements. Biophys J. 1989 Dec;56(6):1153–1162. doi: 10.1016/S0006-3495(89)82762-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Frank G., Hemmert W., Gummer A. W. Limiting dynamics of high-frequency electromechanical transduction of outer hair cells. Proc Natl Acad Sci U S A. 1999 Apr 13;96(8):4420–4425. doi: 10.1073/pnas.96.8.4420. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gale J. E., Ashmore J. F. Charge displacement induced by rapid stretch in the basolateral membrane of the guinea-pig outer hair cell. Proc Biol Sci. 1994 Mar 22;255(1344):243–249. doi: 10.1098/rspb.1994.0035. [DOI] [PubMed] [Google Scholar]
- Housley G. D., Ashmore J. F. Ionic currents of outer hair cells isolated from the guinea-pig cochlea. J Physiol. 1992 Mar;448:73–98. doi: 10.1113/jphysiol.1992.sp019030. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Iwasa K. H. Current noise spectrum and capacitance due to the membrane motor of the outer hair cell: theory. Biophys J. 1997 Dec;73(6):2965–2971. doi: 10.1016/S0006-3495(97)78325-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Iwasa K. H. Effect of stress on the membrane capacitance of the auditory outer hair cell. Biophys J. 1993 Jul;65(1):492–498. doi: 10.1016/S0006-3495(93)81053-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kakehata S., Santos-Sacchi J. Membrane tension directly shifts voltage dependence of outer hair cell motility and associated gating charge. Biophys J. 1995 May;68(5):2190–2197. doi: 10.1016/S0006-3495(95)80401-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Santos-Sacchi J., Dilger J. P. Whole cell currents and mechanical responses of isolated outer hair cells. Hear Res. 1988 Sep 15;35(2-3):143–150. doi: 10.1016/0378-5955(88)90113-x. [DOI] [PubMed] [Google Scholar]
- Santos-Sacchi J. Reversible inhibition of voltage-dependent outer hair cell motility and capacitance. J Neurosci. 1991 Oct;11(10):3096–3110. doi: 10.1523/JNEUROSCI.11-10-03096.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]