Volume regulation in guinea pig outer hair cells and the role of intracellular calcium.
Single outer hair cells (OHCs) isolated from the guinea pig cochlea showed a regulatory volume decrease (RVD) after the initial cells swelling despite continued exposure to a hypotonic solution. The accompanying change of the intracellular Ca2+ concentration ([Ca2+]i) in the OHCs was investigated using the Ca(2+)-sensitive dye fura-2. Hyposmotic activation led to a [Ca2+]i increase which was accompanied by cell shortening and swelling. In a nominally Ca(2+)-free solution, however, [Ca2+]i was not significantly increased during hyposmotic activation although shortening and swelling of the OHCs were observed. These results suggest that the increase in [Ca2+]i during hyposmotic activation is mainly based on an influx of extracellular Ca2+.
Harada
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N
Department of Otolaryngology, University of Tübingen, Germany.
Ernst
A
A
Zenner
H P
HP
D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology*; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000502:physiology*; D007424:Intracellular Fluid / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology*
D015220:Calcium Channels; D015221:Potassium Channels; D002118:Calcium