Methylprednisolone has been shown clinically to have beneficial effects on certain types of hearing loss. In the current study, compound action potential (CAP) thresholds, endocochlear potentials (EPs), and potassium concentration (CK+) values in the endolymph were determined under conditions of transient asphyxia (45 seconds) and methylprednisolone treatment (24 hours) in bilateral adrenalectomized rats. Treatment with methylprednisolone significantly reduced the effect of transient asphyxia on CAP thresholds as compared with nontreated animals. Methylprednisolone did not alter the dramatic short-term reduction in the EPs produced by anoxia. Potassium concentrations in treated adrenalectomized rats were significantly lower before transient asphyxia than in nontreated adrenalectomized rats. In the nontreated rats, transient asphyxia induced a reduction in CK+ levels that was not seen in the methylprednisolone-treated animals. The data support the clinical application of methylprednisolone for certain forms of hearing loss and for potassium imbalance in the endolymph.
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