It is not yet well understood the actions of salicylate on the auditory system. Our previous study has shown that injections of salicylate increases the spontaneous discharge rate of cochlear nerve fibers. This study was aimed to elucidate the effects of various doses of salicylate on the cochlear nerve by recording the compound action potentials (CAPs) which were evoked by electrical pulse applied to the cochlea through the round window membrane before and after intravenous injection of salicylate.
After injection of 100mg/kg, 200mg/kg and 400mg/kg of salicylate, the amplitude of CAPs was decreased significantly, while their latency was increased significantly only after injection of 400mg/kg of salicylate. These results suggest that intravenous injection of salicylate acts directly on the cochlear nerve and causes increase of its excitability and that the amplitude changes of CAPs are better indicaters than the latency changes of CAPs.