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Johnson, Stuart L, Marcotti, Walter and Kros, Corné J (2005) Increase in efficiency and reduction in Ca2+ dependence of exocytosis during development of mouse inner hair cells. Journal of Physiology, 563 (1). pp. 177-191. ISSN 0022-3751
Full text not available from this repository.Abstract
Developmental changes in the coupling between Ca2+ entry and exocytosis were studied in mouse inner hair cells (IHCs) which, together with the afferent endings, form the primary synapse of the mammalian auditory system. Ca2+ currents (ICa) and changes in membrane capacitance (¿Cm) were recorded using whole-cell voltage clamp from cells maintained at body temperature, using physiological (1.3 mM) extracellular Ca2+. The magnitudes of both ICa and ¿Cm increased with maturation from embryonic stages until postnatal day 6 (P6). Subsequently, ICa gradually declined to a steady level of about -100 pA from P13 while the Ca2+-induced ¿Cm remained relatively constant, indicating a developmental increase in the Ca2+ efficiency of exocytosis. Although the size of ICa changed during development, its activation properties did not, suggesting the presence of a homogeneous population of Ca2+ channels in IHCs throughout development. The Ca2+ dependence of exocytosis changed with maturation from a fourth power relation in immature cells to an approximately linear relation in mature cells. This change applies to the release of both a readily releasable pool (RRP) and a slower secondary pool of vesicles, implying a common release mechanism for these two kinetically distinct pools that becomes modified during development. The increased Ca2+ efficiency and linear Ca2+ dependence of mature IHC exocytosis, especially over the physiological range of intracellular Ca2+, could improve the high-fidelity transmission of both brief and long-lasting stimulation. These properties make the mature cell ideally suited for fine intensity discrimination over a wide dynamic range.
| Item Type: | Article |
|---|---|
| Additional Information: | All experiments done in the Kros lab, mostly by Kros¿s DPhil student Johnson with some contributions from Kros¿s postdoc Marcotti. Kros planned and oversaw the work and is corresponding author. |
| Schools and Departments: | School of Life Sciences > Neuroscience |
| Depositing User: | Corne Kros |
| Date Deposited: | 06 Feb 2012 18:30 |
| Last Modified: | 23 Mar 2012 11:13 |
| URI: | http://sro.sussex.ac.uk/id/eprint/16833 |