title: Dihydrostreptomycin goes through the mechano-electric transduction channel in chick cochlear hair cells.
abstract: OBJECTIVE
  This study evaluated the ability of dihydrostreptomycin (DHSM) to go through the mechano-electric transduction (MET) channels in hair cells under physiological conditions.
  
  
  METHODS
  Tall hair cells were isolated from the chick basilar membrane (cochlea). Mechanical stimulation was applied by a glass rod attached to a piezoelectric bimorph, and MET currents were recorded with a whole-cell patch technique. The voltage-dependent block of DHSM to MET channel was estimated by calculating the relative conductances (the ratio of MET current in DHSM saline to DHSM-free saline) at various membrane potentials.
  
  
  CONCLUSIONS
  At membrane potentials between -100 and +50 mV, DHSM behaves as a voltage-dependent blocker according to a partial block model. At membrane potentials more negative than -100 mV, however, DHSM blocking decreased. This finding differed from the partial block model, but indicated that DHSM escaped through the channel pore into the cytoplasm by acting as a permeant channel blocker due to the large electrical driving force.
authors.affiliation: Department of Otolaryngology, Graduate School of Medical Sciences, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan. kimitaka@qent.med.kyushu-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kimitsuki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Wakasaki
authors.forename: Ayako
authors.initials: A
authors.lastname: Nawate
authors.forename: Noritaka
authors.initials: N
authors.lastname: Komune
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Takaiwa
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ohashi
authors.forename: Shizuo
authors.initials: S
authors.lastname: Komune
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D002645:Chickens; D003593:Cytoplasm / Q000378:metabolism; D004096:Dihydrostreptomycin Sulfate / Q000493:pharmacokinetics*; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects*; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000502:physiology; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D018408:Patch-Clamp Techniques
chemical_list: D000900:Anti-Bacterial Agents; D007473:Ion Channels; D004096:Dihydrostreptomycin Sulfate