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The nature of the negative endocochlear potentials produced by anoxia and ethacrynic acid in the rat and guinea‐pig.
Author(s) -
Bosher S K
Publication year - 1979
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1979.sp012892
Subject(s) - endocochlear potential , endolymph , perilymph , chemistry , biophysics , guinea pig , nigericin , anatomy , inner ear , endocrinology , biochemistry , biology , membrane
1. The alterations in the Na+ and K+ concentrations of the cochlear endolymph and in the endocochlear potential were followed simultaneously by means of ion‐sensitive and conventional micro‐electrodes during simple anoxia, during anoxia after i.v. ethacrynic acid and after i.v. ethacrynic acid alone. The endolymphatic pH changes were measured separately and the effect of perilymphatic ethacrynic acid upon the endocochlear potential was investigated. 2. The over‐all Na+:K+ permeability ratio for the endolymph system was determined in individual animals for the first time using an indirect method. The normal mean values of 0.27 (rat) and 0.38 (guinea‐pig) were increased after ethacrynic acid. Permeability changes occurred during anoxia but were delayed in onset. 3. The negative endocochlear potentials in each situation behaved quantitatively like modified K+ diffusion potentials largely dependent upon the K+ and Na+ gradients between endolymph and perilymph.