Evidence that GABA is not the afferent transmitter in the cochlea.

The GABA antagonists picrotoxin, bicuculline and bicuculline-methochloride, when applied intracochlearly, do not affect the compound action potential of the cochlear nerve. It is therefore concluded that these drugs do not interfere with afferent synaptic transmission, and therefore that GABA is not the afferent transmitter. With very high doses, picrotoxin as well as bicuculline-methochloride partially block the efferent synapses. This effect is most likely to be unspecific, but shows that with the technique used the agents can reach the synaptic site.