title: Monitoring intracellular calcium ion dynamics in hair cell populations with Fluo-4 AM.
abstract: We optimized Fluo-4 AM loading of chicken cochlea to report hair-bundle Ca(2+) signals in populations of hair cells. The bundle Ca(2+) signal reported the physiological state of the bundle and cell; extruding cells had very high bundle Fluo-4 fluorescence, cells with intact bundles and tip links had intermediate fluorescence, and damaged cells with broken tip links had low fluorescence. Moreover, Fluo-4 fluorescence in the bundle correlated with Ca(2+) entry through transduction channels; mechanically activating transduction channels increased the Fluo-4 signal, while breaking tip links with Ca(2+) chelators or blocking Ca(2+) entry through transduction channels each caused bundle and cell-body Fluo-4 fluorescence to decrease. These results show that when tip links break, bundle and soma Ca(2+) decrease, which could serve to stimulate the hair cell's tip-link regeneration process. Measurement of bundle Ca(2+) with Fluo-4 AM is therefore a simple method for assessing mechanotransduction in hair cells and permits an increased understanding of the interplay of tip links, transduction channels, and Ca(2+) signaling in the hair cell.
authors.affiliation: Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Kateri J
authors.initials: KJ
authors.lastname: Spinelli
authors.forename: Peter G
authors.initials: PG
authors.lastname: Gillespie
mesh_terms: D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002645:Chickens; D003051:Cochlea / Q000378:metabolism*; D006198:Hair Cells, Auditory / Q000502:physiology*; D040542:Mechanotransduction, Cellular; D018408:Patch-Clamp Techniques; D014966:Xanthenes / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; C409648:Fluo 4; D014966:Xanthenes; D002118:Calcium