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

Hydrogen peroxide (H(2)O(2)) 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 H(2)O(2). We also observed the morphological changes in inner hair cells induced by H(2)O(2). In the H(2)O(2) 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. H(2)O(2) induced morphological changes in the inner hair cells. All the inner hair cells in the H(2)O(2) 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. NeuroReport 21:1045-1049 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.