Changes of perilymphatic glutamate and cochlear blood flow following ischemia

Dynamic changes of perilymphatic glutamate and cochlear blood How were meas ured simultaneously in the guinea pig following cochlear ischemia. Glutamat e was measured by the microdialysis technique with a probe inserted into th e scala tympani at the basal turn. Cochlear blood flow was monitored with a laser-Doppler probe on the lateral wall of the second cochlear turn. Both parameters were measured before and after electrocauterization of the anter ior inferior cerebellar artery and other vessels supplying the internal aud itory canal. In four animals, glutamate increased with a decline of cochlea r blood How and then decreased with recovery of blood How. Na normalization of glutamate was observed in seven animals with a persistent decrease of b lood now. The results of this study indicate that the glutamate regulating system in the cochlea is dependent on cochlear blood flow.