Confocal laser microscopical images of calcium distribution and intracellular organelles in the outer hair cell isolated from the guinea pig cochlea.
We report the use of a confocal laser fluorescence microscope to observe the distribution of cytosolic Ca2+ and the localization of intracellular organelles and cytoskeleton in the isolated outer hair cell (OHC). Membrane-bound Ca2+ stained by chlortetracycline was mainly seen in the subcuticular region, the infranuclear region, and the region adjacent to the lateral wall. In contrast, the central portion of the cytoplasm and nucleus were devoid of detectable fluorescence of membrane-associated Ca2+, but were relatively rich in free Ca2+. The cuticular plate showed a lack of both membrane-bound and free Ca2+. Fluorescent clusters of mitochondria and endoplasmic reticulum were predominantly seen in the infracuticular and infranuclear regions, and some were associated with the lateral wall. These two types of cytosolic organelles which fluoresced upon chlortetracycline treatment are therefore presumed to sequester calcium. The characteristic distribution of the endoplasmic reticulum was observed in coincidence with the infracuticular network of F-actin. The subsurface cistern, which was shown to be analogous to the endoplasmic reticulum in terms of its biological function, is likely to be the source of Ca2+ for the actin-mediated process.
Department of Otolaryngology, Tohoku University School of Medicine, Sendai, Japan.
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K
Ikeda
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T
Takasaka
D000199:Actins / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000032:analysis*; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000737:chemistry* / Q000648:ultrastructure; D066298:In Vitro Techniques; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000648:ultrastructure; D015388:Organelles / Q000648:ultrastructure*
D000199:Actins; D002118:Calcium