Acute effects of gentamicin on the ionic currents of semicircular canal hair cells in the frog

► Extra- and intracellular gentamicin (1 mM) decreases the Ca2+ current, ICa, of hair cells of the frog semicircular canals. ► The effect of gentamicin is fast and apparently operates by reducing the number of available Ca2+ channels. ► Reduction of ICa decreases IKCa, which plays a major role in controlling the hair cell membrane potential. ► Other potassium currents, such as IKV and IA, are unaffected by the treatment. ► Functional impairment develops much earlier than the biochemical events leading to cell apoptosis.