Intracellular calcium and outer hair cell electromotility

Brain Res. 2001 Dec 13;922(1):65-70. doi: 10.1016/s0006-8993(01)03150-x.


The influence of increased intracellular calcium level on outer hair cell (OHC) electromotility was examined by means of transcellular electrical stimulation in a partitioning microchamber. Electromotile activity was measured before and after application of the calcium ionophore ionomycin, which promotes the inflow of extracellular calcium, as well as its release from intracellular calcium stores. The ionomycin solvent, dimethyl sulphoxide (DMSO), by itself elicited a significant decrease in the magnitude of OHC electromotility. The DMSO effect was counteracted by 10 microM ionomycin and was reversed by 50 microM ionomycin. The increase in electromotility is partially mediated by a calmodulin-dependent mechanism, since W7, a calmodulin antagonist, attenuated the 50 microM ionomycin-induced motility increase. Our results suggest that the electromotility magnitude increase in isolated OHCs due to ionomycin is a calcium/calmodulin-dependent phenomenon.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / physiology*
  • Calmodulin / antagonists & inhibitors
  • Cell Movement / drug effects
  • Dimethyl Sulfoxide / pharmacology
  • Electric Stimulation
  • Enzyme Inhibitors / pharmacology
  • Guinea Pigs
  • Hair Cells, Auditory, Outer / drug effects
  • Hair Cells, Auditory, Outer / physiology*
  • In Vitro Techniques
  • Ionomycin / pharmacology
  • Ionophores / pharmacology
  • Signal Transduction / drug effects
  • Sulfonamides / pharmacology


  • Calmodulin
  • Enzyme Inhibitors
  • Ionophores
  • Sulfonamides
  • Ionomycin
  • W 7
  • Calcium
  • Dimethyl Sulfoxide