title: Outer hair cells functionally and structurally deteriorate during reperfusion.
abstract: Transient ischemia of the cochlea was induced in 65 albino guinea pigs by pressing the labyrinthine artery, and the effects of cochlear reperfusion on cochlear potentials (endocochlear potential, compound action potential and cochlear microphonics (CM)) and structural changes in hair cells were examined. Although 15 min ischemia did not elevate the post-ischemic CM pseudo-threshold as compared with the pre-ischemic value, ischemia of 30 min or longer significantly elevated the CM pseudo-threshold. CM amplitude tended to progressively decrease during the reperfusion period in the animals subjected to 45 or 60 min ischemia. After transient ischemia, outer hair cells (OHCs) were swollen and exhibited alterations of the nucleus. Severer structural deterioration of OHCs was induced by 4 h reperfusion than ischemia itself when the ischemic period was 45 or 60 min. Perilymphatic perfusion of dimethylthiourea, a hydroxyl radical scavenger, partially ameliorated the elevation of the CM pseudo-thresholds and the structural changes of OHCs. These results indicate that cochlear reperfusion induces functional and structural deterioration of OHC probably by hydroxyl radical generation.
authors.affiliation: Department of Otolaryngology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Tabuchi
authors.forename: Shigeki
authors.initials: S
authors.lastname: Tsuji
authors.forename: Kazuya
authors.initials: K
authors.lastname: Fujihira
authors.forename: Keiko
authors.initials: K
authors.lastname: Oikawa
authors.forename: Akira
authors.initials: A
authors.lastname: Hara
authors.forename: Jun
authors.initials: J
authors.lastname: Kusakari
mesh_terms: D000200:Action Potentials; D000818:Animals; D001794:Blood Pressure; D003051:Cochlea / Q000098:blood supply* / Q000473:pathology; D003055:Cochlear Microphonic Potentials; D004056:Differential Threshold / Q000187:drug effects; D004594:Electrophysiology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D007511:Ischemia / Q000473:pathology / Q000503:physiopathology*; D008854:Microscopy, Electron; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000503:physiopathology*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D016166:Free Radical Scavengers; C038983:1,3-dimethylthiourea; D013890:Thiourea