A. Fridberger et M. Ulfendahl, ACUTE MECHANICAL OVERSTIMULATION OF ISOLATED OUTER HAIR-CELLS CAUSES CHANGES IN INTRACELLULAR CALCIUM LEVELS WITHOUT SHAPE CHANGES, Acta oto-laryngologica, 116(1), 1996, pp. 17-24
Impaired auditory function following acoustic overstimulation, or nois
e, is mainly reported to be accompanied by cellular changes such as da
mage to the sensory hair bundles, but changes in the cell bodies of th
e outer hair cells have also been described. To investigate more close
ly the immediate cellular responses to overstimulation, isolated guine
a pig outer hair cells were subjected to a 200 Hz oscillating water je
t producing intense mechanical stimulation. The water jet was aimed at
the cell body of the isolated outer hair cell. Cell shape changes wer
e studied using video microscopy, and intracellular calcium concentrat
ion changes were monitored by means of the fluorescent calcium indicat
or Fluo-3. Cells exposed to a high-intensity stimulus showed surprisin
gly small light-microscopical alterations. The cytoplasmic calcium con
centration increased in most cells, although some cells appeared very
resistant to the mechanical stress. No correlation could be found betw
een the calcium concentration changes and the cell length. The changes
in calcium concentration reported here are suggested to be involved i
n the long-term pathogenesis of noise-induced hair cell damage.