Inhibitory Effects of Heavy Metal Ions on Endolymphatic DC Potential and Cochlear Microphonics in the Guinea Pig
Endocochlear DC potential (EP) and cochlear microphonics (CM) were investigated in the guinea pig under the influence of the following heavy metal ions; manganese, nickel, cobalt, cadmium and lanthanum. The scala tympani and scala vestibuli were perfused with control and test solutions. CM decreased gradually to 50-80%, but EP showed no change after perfusion with a solution containing 1 mM of metal ions. At a concentration of 10 mM, EP decreased from +80 mV to +11-+48 mV and CM decreased to 15-55%. These decreases in EP and CM were irreversible, and perfusion of the area with the standard solution for 20 min had no effect.