Action of Glutamate in the Cat Labyrinth

Abstract
Glutamate solutions of either 50 m M applied on the membranous labyrinth or 1 m M perfused into the lateral canal in cats increased spontaneous and stimulus-evoked activity of vestibular neurons. Kainic acid (10−4 M) perfused into the labyrinth produced a depolarizing action on vestibular afferents. These results indicate that glutamate could be an excitatory neurotransmitter at the synapse between vestibular hair cells and afferent nerve fibers in the cat.