Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/936944
- Potassium accumulation between type I hair cells and calyx terminals in mouse crista
McPherson, Angela E.;
Donne, Scott W.;
Callister, Robert J.;
Brichta, Alan M.
- The University of Newcastle. Faculty of Health, School of Biomedical Sciences and Pharmacy
- The mode of synaptic transmission in the vestibular periphery, between type I hair cells and their associated calyx terminal, has been the subject of much debate. The close and extensive apposition of pre- and post-synaptic elements has led some to suggest potassium (K⁺) accumulates in the intercellular space and even plays a role in synaptic transmission. During patch clamp recordings from isolated and embedded hair cells in a semi-intact preparation of the mouse cristae, we noted marked differences in whole-cell currents. Embedded type I hair cells show a prominent droop during steady-state activation as well as a dramatic collapse in tail currents. Responses to a depolarizing voltage step (-124 to +16 mV) in embedded, but not isolated, hair cells resulted in a>40 mV shift of the K⁺ equilibrium potential and a rise in effective K⁺ concentration (>50 mM) in the intercellular space. Together these data suggest K⁺ accumulation in the intercellular space accounts for the different responses in isolated and embedded type I hair cells. To test this notion, we exposed the preparation to hyperosmotic solutions to enlarge the intercellular space. As predicted, the K⁺ accumulation effects were reduced; however, a fit of our data with a classic diffusion model suggested K⁺ permeability, rather than the intercellular space, had been altered by the hyperosmotic change. These results support the notion that under depolarizing conditions Substantial K⁺ accumulation occurs in the space between type I hair cells and calyx. The extent of K⁺ accumulation during normal synaptic transmission, however, remains to be determined.
- Experimental Brain Research Vol. 210, Issue 3-4, p. 607-621
- Publisher Link
type I hair cell;
- Resource Type
- journal article