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. 1992 Dec;458:27–40. doi: 10.1113/jphysiol.1992.sp019404

The effect of caged calcium release on the adaptation of the transduction current in chick hair cells.

T Kimitsuki 1, H Ohmori 1
PMCID: PMC1175142  PMID: 1284566

Abstract

1. Intracellular Ca2+ concentration ([Ca2+]i) was raised by photolysis of a caged calcium compound, nitr-5, and its effects on the mechano-electrical transduction (MET) current were studied by a whole-cell patch electrode voltage clamp technique in dissociated hair cells of a chick. Nitr-5 was loaded into the hair cell by incubation with the membrane-permeable form of the compound (nitr-5 AM). 2. Photolysis of nitr-5 by ultraviolet (UV) light irradiation induced outward currents at -50 mV when recorded with a KCl-based intracellular medium without Ca2+ chelating compounds. The average amplitude of the photo-activated outward current was 115 +/- 82 pA (mean +/- S.D., n = 5). 3. The MET current generated at -50 mV showed a decay after step displacement of the hair bundle. This adaptation was accelerated after UV exposure of the cell. The adaptation was further accelerated by hyperpolarization of the membrane and was eliminated in 20-100 microM Ca2+ extracellular media. 4. The displacement-response relationship was shifted towards the positive direction after the UV irradiation. 5. The recovery of the transducer current after step displacement of the hair bundle was accelerated after UV irradiation, for both the inward-going MET current recorded at -50 mV and the outward-going MET current at +54 mV. However, the adaptation was not observed at positive membrane potentials even after the photolysis of nitr-5. 6. The extent of MET current decay was reduced or disappeared in 20-100 microM Ca2+ extracellular media and the offset time course was prolonged at the membrane potential of -50 mV. The current decay was not observed even after the photo-release of intracellular Ca2+ in 50-100 microM Ca2+ extracellular media. 7. These results (paragraphs 3-6) suggest that the MET current adaptation is accelerated by the increase of [Ca2+]i, and that Ca2+ ions entering through MET channels are essential in the development of adaptation. 8. The adaptation of the MET current was reversibly reduced in a dihydrostreptomycin (DHSM, 20-50 microM) medium. The time course of the adaptation changes lagged the changes in the MET current amplitude. 9. The adaptation developed or disappeared with a delay of 10-20 s after the introduction of either the normal-Ca2+ (2.5 mM) or the low-Ca2+ (50-100 microM) extracellular medium, respectively. These delays in the development and the subsidence of adaptation suggest a presence of a Ca2+ buffer site intracellularly between the adaptative site and the MET channel.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ashmore J. F., Ohmori H. Control of intracellular calcium by ATP in isolated outer hair cells of the guinea-pig cochlea. J Physiol. 1990 Sep;428:109–131. doi: 10.1113/jphysiol.1990.sp018203. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Assad J. A., Hacohen N., Corey D. P. Voltage dependence of adaptation and active bundle movement in bullfrog saccular hair cells. Proc Natl Acad Sci U S A. 1989 Apr;86(8):2918–2922. doi: 10.1073/pnas.86.8.2918. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bosher S. K., Warren R. L. Very low calcium content of cochlear endolymph, an extracellular fluid. Nature. 1978 Jun 1;273(5661):377–378. doi: 10.1038/273377a0. [DOI] [PubMed] [Google Scholar]
  4. Corey D. P., Hudspeth A. J. Ionic basis of the receptor potential in a vertebrate hair cell. Nature. 1979 Oct 25;281(5733):675–677. doi: 10.1038/281675a0. [DOI] [PubMed] [Google Scholar]
  5. Corey D. P., Hudspeth A. J. Kinetics of the receptor current in bullfrog saccular hair cells. J Neurosci. 1983 May;3(5):962–976. doi: 10.1523/JNEUROSCI.03-05-00962.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Crawford A. C., Evans M. G., Fettiplace R. Activation and adaptation of transducer currents in turtle hair cells. J Physiol. 1989 Dec;419:405–434. doi: 10.1113/jphysiol.1989.sp017878. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Crawford A. C., Evans M. G., Fettiplace R. The actions of calcium on the mechano-electrical transducer current of turtle hair cells. J Physiol. 1991 Mar;434:369–398. doi: 10.1113/jphysiol.1991.sp018475. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Furukawa T., Matsuura S. Adaptive rundown of excitatory post-synaptic potentials at synapses between hair cells and eight nerve fibres in the goldfish. J Physiol. 1978 Mar;276:193–209. doi: 10.1113/jphysiol.1978.sp012228. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gurney A. M., Tsien R. Y., Lester H. A. Activation of a potassium current by rapid photochemically generated step increases of intracellular calcium in rat sympathetic neurons. Proc Natl Acad Sci U S A. 1987 May;84(10):3496–3500. doi: 10.1073/pnas.84.10.3496. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hacohen N., Assad J. A., Smith W. J., Corey D. P. Regulation of tension on hair-cell transduction channels: displacement and calcium dependence. J Neurosci. 1989 Nov;9(11):3988–3997. doi: 10.1523/JNEUROSCI.09-11-03988.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Howard J., Hudspeth A. J. Mechanical relaxation of the hair bundle mediates adaptation in mechanoelectrical transduction by the bullfrog's saccular hair cell. Proc Natl Acad Sci U S A. 1987 May;84(9):3064–3068. doi: 10.1073/pnas.84.9.3064. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hudspeth A. J., Corey D. P. Sensitivity, polarity, and conductance change in the response of vertebrate hair cells to controlled mechanical stimuli. Proc Natl Acad Sci U S A. 1977 Jun;74(6):2407–2411. doi: 10.1073/pnas.74.6.2407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hudspeth A. J. Extracellular current flow and the site of transduction by vertebrate hair cells. J Neurosci. 1982 Jan;2(1):1–10. doi: 10.1523/JNEUROSCI.02-01-00001.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Jaramillo F., Hudspeth A. J. Localization of the hair cell's transduction channels at the hair bundle's top by iontophoretic application of a channel blocker. Neuron. 1991 Sep;7(3):409–420. doi: 10.1016/0896-6273(91)90293-9. [DOI] [PubMed] [Google Scholar]
  15. Kao J. P., Harootunian A. T., Tsien R. Y. Photochemically generated cytosolic calcium pulses and their detection by fluo-3. J Biol Chem. 1989 May 15;264(14):8179–8184. [PubMed] [Google Scholar]
  16. Krishtal O. A., Pidoplichko V. I. A receptor for protons in the nerve cell membrane. Neuroscience. 1980;5(12):2325–2327. doi: 10.1016/0306-4522(80)90149-9. [DOI] [PubMed] [Google Scholar]
  17. Ohmori H. Gating properties of the mechano-electrical transducer channel in the dissociated vestibular hair cell of the chick. J Physiol. 1987 Jun;387:589–609. doi: 10.1113/jphysiol.1987.sp016590. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Ohmori H. Mechanical stimulation and Fura-2 fluorescence in the hair bundle of dissociated hair cells of the chick. J Physiol. 1988 May;399:115–137. doi: 10.1113/jphysiol.1988.sp017071. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Ohmori H. Mechano-electrical transduction currents in isolated vestibular hair cells of the chick. J Physiol. 1985 Feb;359:189–217. doi: 10.1113/jphysiol.1985.sp015581. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Ohmori H. Studies of ionic currents in the isolated vestibular hair cell of the chick. J Physiol. 1984 May;350:561–581. doi: 10.1113/jphysiol.1984.sp015218. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Poenie M., Alderton J., Steinhardt R., Tsien R. Calcium rises abruptly and briefly throughout the cell at the onset of anaphase. Science. 1986 Aug 22;233(4766):886–889. doi: 10.1126/science.3755550. [DOI] [PubMed] [Google Scholar]
  22. Rabié A., Thomasset M., Legrand C. Immunocytochemical detection of calcium-binding protein in the cochlear and vestibular hair cells of the rat. Cell Tissue Res. 1983;232(3):691–696. doi: 10.1007/BF00216440. [DOI] [PubMed] [Google Scholar]
  23. Shigemoto T., Ohmori H. Muscarinic agonists and ATP increase the intracellular Ca2+ concentration in chick cochlear hair cells. J Physiol. 1990 Jan;420:127–148. doi: 10.1113/jphysiol.1990.sp017904. [DOI] [PMC free article] [PubMed] [Google Scholar]

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