NOISE-INDUCED TRANSIENT MICROLESIONS IN THE CELL-MEMBRANES OF AUDITORY HAIR-CELLS

Several types of nonauditory cells recover from transitory mechanicall y induced microlesions in their cell membranes. We report evidence tha t hair cells in the auditory papilla of the alligator lizard suffered similar membrane wounding when exposed to noise loud enough to induce a temporary threshold shift. Lucifer yellow, a molecular marker that d oes not normally penetrate through the cell membrane into the cytoplas m, was introduced into the extracellular fluid bathing the basolateral membrane of the hair cells. We assessed the effect of loud noise on t he function of the ear by measuring compound action potentials of the auditory nerve before exposure to the noise, immediately after cessati on of the noise, and after recovering overnight. Hair cells that were exposed to the noise took up much more Lucifer yellow than hair cells that were not exposed. We propose that the Lucifer yellow entered the hair cells via noise-induced lesions in their cell membranes, and that the cells were able to survive and recover functionally. (C) 1998 Els evier Science B.V.