title: Neurotrophin-3 modifies potassium currents in isolated inner hair cells from guinea-pig cochlea.
abstract: OBJECTIVE
  Neurotrophins elicited short-term glutamate release from the presynaptic locus. The aim of this study was to investigate short-term effects of neurotrophin-3 (NT-3) on the membrane current of inner hair cells (IHCs).
  
  
  METHODS
  IHCs were isolated from the guinea-pig cochlea. Membrane currents were measured by conventional whole-cell voltage-clamp recordings. NT-3 was dissolved in a standard external solution and applied to the IHCs under pressure using pipettes.
  
  
  RESULTS
  Six out of eight IHCs demonstrated a suppression of K currents by extracellular application of NT-3. At +60 mV, the amplitudes of the outward current in the control and NT-3 solutions were 5.6+/-1.3 and 4.2+/-1.0 nA, respectively. NT-3 suppression was voltage-independent. One cell showed an immediate suppression with NT-3 and the following potentiation during washing with standard saline.
  
  
  CONCLUSIONS
  NT-3 suppressed the amplitude of K current on IHCs, suggesting that neurotrophins are capable of potentiating the hair cells' excitability. Neurotrophins may have a therapeutic value in the prevention and treatment of hearing impairment caused by inner ear damage.
authors.affiliation: Department of Otorhinolaryngology, Miyazaki Medical College, 5200 Kihara, Kiyotake-cho, Japan. kimituki@fc.miyazaki-med.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kimitsuki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakashima
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kawano
authors.forename: Shizuo
authors.initials: S
authors.lastname: Komune
mesh_terms: D000818:Animals; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D020933:Neurotrophin 3 / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*
chemical_list: D020933:Neurotrophin 3; D015221:Potassium Channels