ELECTROCHEMICAL POTENTIALS AND POTASSIUM CONCENTRATION PROFILES RECORDED FROM PERILYMPH, ENDOLYMPH AND ASSOCIATED INNER-EAR TISSUES IN ADRENALECTOMIZED RATS

This study evaluated the electrochemical potentials and potassium conc entration (C-K+) profiles in the perilymph, endolymph, marginal cells, and spiral ligament of adrenalectomized rats in which endogenous cort icosteroids had been removed. Electrochemical potentials recorded at t he four cochlear sites were not affected by adrenalectomy (ADX). C-Kwas greater in the endolymph of the ADX animals as compared to control animals. Additionally, there was an increase of C-K+ in the marginal cells, perilymph, and spiral ligament tissues of the ADX animals as co mpared to control animals, although the observed increases were not st atistically significant. In a previous study (Ma et al,, 1995a), it wa s found that potassium levels in the blood plasma of ADX animals were higher than those identified in normal rats; thus, ADX may have a syst emic effect on C-K+ that is detectable in both tissues and fluids with in the cochlea. Even though C-K+ was elevated within the cochlea in th e ADX model, the functional response of the inner ear, as assessed ele ctrophysiologically, was not altered.