Effects of various vanadium compounds on cochlear potentials.

The effects of vanadium compounds, sodium vanadate, ammonium vanadate, potassium vanadate, vanadium oxysulfate, vanadium acetylacetonate, and vanadium trichloride, on endocochlear potential (EP) and cochlear microphonic potential (CM) were examined in the guinea pig cochlea. The perilymphatic space was perfused for 30 min with 1 mM solution of each compound and changes of EP, CM, and negative EP were observed. Upon perfusion with pentavalent vanadium solutions, such as sodium vanadate, ammonium vanadate, and potassium vanadate, the EP showed an overshoot at the beginning of perfusion and then a gradual decrease, while the CM showed only a gradual decrease. The other compounds had no effects on EP and CM. Since the negative EP showed no differences due to perfusion of any compound, it is concluded that the vanadate compounds have inhibitory effects on EP primarily, and on CM only secondarily. The chemical mechanism of the effects of vanadates was discussed concerning the function of the stria vascularis and also its participation in acute hearing loss.