Lowering extracellular calcium decreases the length of isolated outer hair cells.
Transduction by the inner hair cells is hypothesized to be modulated through a change in the length of the outer hair cells (OHC). It has been suggested that the slow change occurring in OHC length is mediated by an actin-myosin system requiring Ca2+ and ATP. This study was designed to systematically examine the effects of lowering extracellular Ca2+ on OHC length. OHCs were isolated from guinea pig cochleae, mechanically dissociated and dispersed, and placed in a Hank's balanced salt solution (HBS). Exposing the cells to a Ca(2+)-free HBS supplemented with 200 microns EDTA produced a shortening in OHC length with a concomitant increase in cell width. The shortening was reversed successfully by bathing the cells in 8 mM Ca2+. We speculate that the decrease in length due to lowering extracellular Ca2+ may be caused by a relaxation of a circumferential contractile mechanism which is thought to cause elongation of intact OHCs (Slepecky, 1989; Dulon et al., 1990).
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Kresge Hearing Research Laboratoy of the South, Department of Otorhinolaryngology and Biocommunication, Louisiana State University Medical Center, New Orleans 70112-2234.
Fallon
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Winbery
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Bobbin
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D000818:Animals; D001696:Biomechanical Phenomena; D002118:Calcium / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D010477:Perfusion
D002118:Calcium