Author's present address D. J. Jagger: Department of Physiology, University of Auckland, Private Bag 92109, Auckland, New Zealand.
Calcium signalling mediated by the α9 acetylcholine receptor in a cochlear cell line from the Immortomouse
Article first published online: 13 AUG 2004
The Journal of Physiology
Volume 527, Issue 1, pages 49–54, August 2000
How to Cite
Jagger, D. J., Griesinger, C. B., Rivolta, M. N., Holley, M. C. and Ashmore, J. F. (2000), Calcium signalling mediated by the α9 acetylcholine receptor in a cochlear cell line from the Immortomouse. The Journal of Physiology, 527: 49–54. doi: 10.1111/j.1469-7793.2000.t01-1-00049.x
- Issue published online: 13 AUG 2004
- Article first published online: 13 AUG 2004
- (Received 8 May 2000; accepted after revision 16 June 2000)
- 1We have investigated the characteristics of the α9 acetylcholine receptor (α9AChR) expressed in hair cell precursors in an immortalized cell line UB/OC-2 developed from the organ of Corti of the transgenic H-2Kb-tsA58 mouse (the Immortomouse) using both calcium imaging and whole-cell recording.
- 2Ratiometric measurements of fura-2 fluorescence revealed an increase of intracellular calcium concentration in cells when challenged with 10 μM ACh. The calcium increase was seen in 66 % of the cells grown at 39 °C in differentiated conditions. A smaller fraction (34 %) of cells grown at 33 °C in proliferative conditions responded.
- 3Caffeine (10 mM) elevated cell calcium. In the absence of caffeine, the majority of imaged cells responded only once to ACh. A small proportion (< 2 % of the total) responded with an increase in intracellular calcium to multiple ACh presentations. Pretreatment with caffeine inhibited all calcium responses to ACh.
- 4In whole-cell tight-seal recordings 10 μM ACh activated an inward, non-selective cation current. The reversal potential of the ACh-activated inward current was dependent on the extracellular calcium concentration with an estimated PCa/PNa of 80 for the α9 receptor at physiological calcium levels.
- 5The data indicate that ACh activates a calcium-permeable channel α9AChR in UB/OC-2 cells and that the channel has a significantly higher calcium permeability than other AChRs. The results indicate that the α9AChR may be able to elevate intracellular calcium levels in hair cells both directly and via store release.