title: Frequency perception and cell injury in the semicircular canal caused by gentamicin.
abstract: OBJECTIVE
  The frequency characteristics of the vestibular organ have gained notice in recent years, but the morphologic basis was unknown. This study investigated the gentamicin-induced damage of frequency-selective perception of the horizontal semicircular canal and its morphologic basis.
  
  
  METHODS
  Eighty guinea pigs were randomly divided into four groups, one control group and three experimental groups. The experimental animals received gentamicin subcutaneously for 1 to 3 weeks. Short-latency vestibular evoked potentials evoked by 0.5 and 10 Hz step rotation stimuli following drug administration were recorded, and then the crista ampullaris of the horizontal semicircular canals was investigated by scanning and transmission electron microscopy.
  
  
  RESULTS
  Damage to hair cells of the crista ampullaris is concentrated at the apex area first and then extends to the peripheral area of the vestibular crista ampullaris when the gentamicin administration time increased. When only the hair cells at the apex area are damaged, the high-frequency (10 Hz) rotation perception of the crista ampullaris of the horizontal semicircular canal was injured, but perceptions to 0.5 Hz step rotation stimulation remained normal.
  
  
  CONCLUSIONS
  Gentamicin mainly affects the high-frequency perception function of the crista ampullaris of the horizontal semicircular canal. The hair cells at the central apex area of the crista ampullaris might be responsible for high-frequency rotation perception function.
authors.affiliation: Department of Otolaryngology, Taian Central Hospital, Taian, Shandong Province, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Wu-qing
authors.initials: WQ
authors.lastname: Wang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000633:toxicity*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005839:Gentamicins / Q000633:toxicity*; D006168:Guinea Pigs; D054777:Hair Cells, Ampulla / Q000187:drug effects / Q000473:pathology; D007279:Injections, Subcutaneous; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010898:Pitch Perception / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D012665:Semicircular Canals / Q000187:drug effects* / Q000473:pathology; D054776:Semicircular Ducts / Q000187:drug effects / Q000473:pathology; D058585:Vestibular Evoked Myogenic Potentials / Q000187:drug effects; D014724:Vestibular Function Tests
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins