Abstract
The effect of prednisolone on the endocochlear DC potential (EP) was studied. Prednisolone given at 10 mg/kg produced a depression of the endocochlear DC potential followed by a recovery. The EP decreased to 64.6±13.3 % of the initial value within 30 minutes and then recovered. It reached 70.7±13.9 % within 1 hour, 83.6±18.4 % within 2 hours, 90.7±11.5 % within 3 hours and 93.6±11.5 % within 4 hours. The pattern of the EP depression resembled that of the cochlear microphonics after the injection of 10 mg/kg prednisolone. It appears that prednisolone acts to the stria vascularis and causes a depression of EP. The depression of CM would be due to the second effect occurring after the changes in the stria vascularis. Prednisolone would promote the reabsorption of the endolymphatic sodium. The EP would be a potential necessary for the maintenance of the normal concentration of sodium and potassium ions in the endolymph.
