Intracellular calcium changes by hyposmotic activation of cochlear outer hair cells in the guinea pig.
During continued exposure to a hypotonic solution, isolated outer hair cells (OHCs) from the guinea pig cochlea showed a regulatory volume decrease (RVD) after initial cell swelling. In the absence of extracellular Ca2+, RVD was significantly inhibited. Using Ca(2+)-sensitive dye fura-2, accompanying changes of the intracellular Ca2+ concentrations ([Ca2+]i) of OHC were investigated. Hyposmotic activation resulted in a [Ca2+]i increase associated with cell shortening and swelling. In a Ca(2+)-free solution, [Ca2+]i was not significantly increased during hyposmotic activation although shortening and swelling of the OHC was observed. These results suggest that the increase in [Ca2+]i during hyposmotic activation is mainly based on an influx or extracellular Ca2+ which precedes the RVD.
Harada
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Department of Otolaryngology, University of Tubingen, Germany.
Ernst
A
A
Zenner
H P
HP
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016257:Fura-2 / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D009995:Osmosis / Q000187:drug effects; D013997:Time Factors
D007038:Hypotonic Solutions; D002118:Calcium; D016257:Fura-2