Dysfunctions of energy releasing and consuming processes of the cochlea

Features of energy production and utilization in the cochlea are discussed, with special attention given to the effects of various interferences upon these mechanisms, both with respect to electrophysiologic parameters and with respect to changes in steady state levels of selected metabolites. As a specific example the influence of ethacrynic acid upon the energy metabolism of the stria vascularis is considered. ATP and phosphocreatine concentrations were determined at control conditions and following intoxication with ethacrynic acid using the endolymphatic potential as monitor of functional damage. At the maximum depression of the endolymphatic potential phosphocreatine levels in the stria vascularis were normal and ATP levels slightly reduced; furthermore, if ethacrynic acid intoxicated ears were subjected to the additional stress of ischemia, the decline of both electrophysiologic indicators and high energy phosphates proceeded at a much slower rate. The findings were interpreted as showing that ethacrynic acid reduces the rate of energy consumption, with no significant effects on energy production.