Possible Ca2+-dependent mechanism of apical outer hair cell modulation within the cochlea of the guinea pig |
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Authors: | Ulf-Rüdiger Heinrich J Maurer Wolf Mann |
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Institution: | (1) ENT Department, University of Mainz, Langenbeckstrasse 1, D-55131 Mainz, Germany, DE |
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Abstract: | Calcium ions were precipitated with potassium antimonate after injection of the inorganic calcium channel blocker MnCl2 or the inorganic potassium channel blockers BaCl2 or CsCl into the perilymph of the scala vestibuli of the guinea pig. The spatial distribution of the formed histochemical
reaction products within the organ of Corti was studied by energy-filtering transmission-electron microscopy. Compared with
untreated control ears, the number of the formed precipitates drastically increased at the extracellular side of the lamina
reticularis after application of the various inorganic channel blockers. The apical side of the outer hair cells and the intervening
Deiter cells were covered by a thick layer of calcium precipitates, whereas the number of histochemical reaction products
was clearly reduced in the nearby acellular tectorial membrane. The high calcium content within the formed reaction products
at the lamina reticularis could be demonstrated by elemental mapping and by electron energy-loss spectroscopy. To ascertain
the alterations in the amounts of the calcium precipitates within the tectorial membrane after application of the various
inorganic channel blockers, the precipitate densities were determined semiquantitatively by an image processing system and
the values obtained compared with those of untreated control specimens. The observed histochemical results are in good agreement
with published electrophysiological findings concerning the spatial distribution of ion channels located at the apical outer
hair cell membrane. The detected alterations in the spatial distribution of calcium precipitates might correspond to calcium-dependent
processes involved in outer hair cell modulation.
Received: 4 November 1996 / Accepted: 28 October 1997 |
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Keywords: | Calcium antagonists Calcium channel blocker Cochlea Electron energy-loss spectroscopy (EELS) Electron spectroscopic imaging (ESI) Hair cells Signal transduction Guinea pig |
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