IX. Salicylate ototoxicity: A biochemical and electrophysiological study

Salicylate intoxication produces biochemical changes in endolymph and perilymph manifested by decreased malic dehydrogenase activity. There is hyperglycemia and elevation of glucose in endolymph and perilymph. Sodium, potassium and total protein concentrations of the inner ear fluids appear to be unaffected by acute salicylate intoxication. Two to three hours after a single intraperitoneal injection of sodium salicylate (350 mg/kg), the electrical activity of the cochlea, as recorded from the round window area shows an elevation in threshold of 20 to 24 decibels. In five cats, the N 1 action potential dropped 70%while the cochlear microphonic decreased 40%of their original voltages. These findings indicate that salicylate intoxication is accompanied by a decrease of both cochlear microphonics and neural potentials as well as changes in the biochemical composition of the inner ear fluids.