The effect of taurine on calcium homeostasis of isolated cochlear spiral ganglion neurons under normal and ototoxic conditions was investigated using fluo-3 calcium imaging. Sole application of taurine (15 mM) induced an increase in intracelluar Ca(2+) concentration ([Ca(2+)](i)), which was largely inhibited either by the application of an L-type calcium-channel blocker nifedipine or a calcium-free medium. Preincubation with 1 mM gentamicin induced an inhibition of the high K(+)-evoked elevation of [Ca(2+)](i). Short-term exposure to taurine prevented this inhibition. The results suggested that taurine at this concentration was able to increase [Ca(2+)](i) mainly by calcium influx through L-type calcium channels in isolated spiral ganglion neurons and to antagonize gentamicin-induced inhibition of calcium elevation evoked by high K(+) by its calcium homeostatic effect.