Effect of vestibular labyrinth destruction on endocochlear potential and potassium concentration of the cochlea

Partial labyrinthectomy can result in maintenance of hearing under certain circumstances, and the mechanism of the hearing impairment caused by labyrinthectomy is unclear. We hypothesized that disruption of the membranous labyrinth results in electrical leakage and electrolyte imbalance. This study investigated the change in cochlear function by measurement of endocochlear potential (EP) and potassium concentration ([K(+)]) caused by vestibular labyrinth destruction in the acute phase. Hartley guinea pigs underwent lateral semicircular canal (LSCC) transection with suctioning of the perilymph, ampullectomy, or destruction of the LSCC, superior SCC, and lateral part of the vestibule. The EP and [K(+)] were monitored using double-barreled ion-selective microelectrodes in the second turn of cochlea. The EP showed little to mild change after LSCC transectioning or ampullectomy, but declined variously and drastically after vestibulotomy. The EP did not recover but [K(+)] partially recovered after vestibulotomy. Disturbance of the mechanism of cochlear function caused by vestibular labyrinth destruction may involve reduction in the [K(+)] concentration in the endolymph. (C) 2009 Elsevier B.V. All rights reserved.