title: How are the inner hair cells and auditory nerve fibers activated without the mediation of the outer hair cells and the cochlear amplifier?
abstract: The present study was designed to assess whether, in the presence of a depression of the cochlear amplifier i.e. a sensorineural hearing loss (SNHL), the inner hair cells (IHCs) require the presence of a normal endocochlear potential for transduction. An SNHL was induced by injecting salicylic acid (which binds to the motor protein prestin in the outer hair cells), and then furosemide (which depresses the endocochlear potential) was injected. Furosemide did not cause an additional elevation of the threshold of the auditory nerve brainstem evoked response (ABR) over that induced by the salicylic acid injection. Exposure to noise was also used to induce a SNHL in other mice, and then furosemide was injected. Here too furosemide did not cause an additional ABR threshold elevation over that induced by the noise. These results show that the IHCs (and the auditory nerve) can be excited in the presence of a SNHL (i.e. without the cochlear amplifier) and in the absence of an endocochlear potential. Possible mechanisms of excitation in such a state are discussed.
authors.affiliation: Speech & Hearing Center, Institute for Medical Research - Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem.
authors.forename: Cahtia
authors.initials: C
authors.lastname: Adelman
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Weinberger
authors.forename: Haim
authors.initials: H
authors.lastname: Sohmer
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000378:metabolism; D003056:Cochlear Nerve / Q000378:metabolism; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem; D005665:Furosemide / Q000633:toxicity; D006198:Hair Cells, Auditory / Q000378:metabolism*; D006319:Hearing Loss, Sensorineural / Q000473:pathology*; D008297:Male; D051379:Mice; D009412:Nerve Fibers / Q000378:metabolism; D009622:Noise; D020156:Salicylic Acid / Q000378:metabolism / Q000633:toxicity; D000076988:Sulfate Transporters
chemical_list: D027321:Anion Transport Proteins; C498719:SLC26A5 protein, human; D000076988:Sulfate Transporters; D005665:Furosemide; D020156:Salicylic Acid