Effect of asphyxia and aminooxyacetic acid on the slow potential evoked by crossed olivocochlear bundle stimulation

The action of asphyxia and aminooxyacetic acid (AOAA) on the crossed olivocochlear bundle (COCB), was investigated, in particular, the slow change evoked by COCB stimulation, often called the crossed olivocochlear potential (COCP). Terminating artificial respiration caused the COCP to fall within 2 min to 0.25 mV. It remained at this level for an additional 4 min before declining to zero. If artificial respiration was reinstated, before 3 min had elapsed, the COCP recovered completely within 5 min. Administration of AOAA (40 mg/kg, i.v.) produced a slow reduction in the endocochlear potential (EP) to about 10 mV in 60 min. The COCP initially declined after AOAA administration but fully recovered by the time the EP plateaued at 10 mV. The results with asphyxia could be explained solely by a reduction of the EP; however, in light of the different results observed with AOAA, one might hypothesize an additional action of asphyxia at the efferent nerve-ending-hair cell synapse.