Effect of hydrogen peroxide on potassium currents in inner hair cells isolated from guinea pig cochlea

Hydrogen peroxide (H₂O₂) is a ubiquitous reactive oxygen species that can induce several inner ear disorders. In this study, we recorded the potassium (K) currents in acutely isolated inner hair cells of guinea pig cochlea, and investigated the effects of H₂O₂. We also observed the morphological changes in inner hair cells induced by H ₂O₂. In the H₂O₂ solutions, the amplitude of outward K currents (I_K,f and I_K,s) clearly decreased after perfusion for approximately 15 min. Despite the decrease in outward currents, small inward currents (I_K,n) did not show any reduction. H₂O₂ induced morphological changes in the inner hair cells. All the inner hair cells in the H₂O₂ solutions showed shrinkage and granularity of the cell body and led to loss of viability. These results showed the vulnerability of inner hair cells to reactive oxygen species-induced inner ear disorders.