Abstract
Ethacrynic acid (EA: 30mg/kg, not effective itself for threshold change of guinea pig's cochlea) potentiated markedly the ototoxicity of gentamicin (GM: 150mg/kg) injected 90 min before the treatment of EA. GM was detected mainly in the outer hair cells (OHC) of the cochlea 3 to 24h after EA injection with a gradient of concentration toward basal turn. When put into a sound proof room immediately after EA injection, animals showed no significant threshold shift at all frequencies until 24h, although GM appeared in the basal OHCs even at that time. Furthermore, we found the initial GM uptake around the basal body of OHC. These findings suggest that GM uptake is potentiated by the hair cell activation due to sound stimulation.
