INTERACTION OF METHYLPREDNISOLONE AND TRANSIENT ASPHYXIA ON THE INNER-EAR OF THE ADRENALECTOMIZED RAT

Methylprednisolone has been shown clinically to have beneficial effect s on certain types of hearing loss, In the current study, compound act ion potential (CAP) thresholds, endocochlear potentials (EPs), and pot assium concentration (C-K(+)) values in the endolymph were determined under conditions of transient asphyxia (45 seconds) and methylpredniso lone treatment (24 hours) in bilateral adrenalectomized rats. Treatmen t with methylprednisolone significantly reduced the effect of transien t asphyxia on CAP thresholds as compared with nontreated animals, Meth ylprednisolone did not alter the dramatic shortterm reduction in the E Ps produced by anoxia, Potassium concentrations in treated adrenalecto mized rats were significantly lower before transient asphyxia than in nontreated adrenalectomized rats. In the nontreated rats, transient as phyxia induced a reduction in C-K(+) levels that was not seen in the m ethylprednisolone-treated animals. The data support the clinical appli cation of methylprednisolone for certain forms of hearing loss and for potassium imbalance in the endolymph.