Sodium and Potassium Concentrations in the Endolymph and Perilymph of the Cat

Abstract

Inner ear fluid from the scala vestibuli, scala tympani, scala media, utricle, and cerebrospinal fluid were collected from 47 normal cats, and analyzed for sodium and potassium concentrations with a flame photometer. Each compartment was found to have its own different values for sodium and potassium concentration. Perilymph in the scala vestibuli possesses a lower sodium concentration than perilymph in the scala tympani; in potassium concentration the perilymph in the scala vestibuli shows a higher value than that of the scala tympani. Compared with cochlear endolymph, utricular endolymph contains a higher concentration of sodium and a lower concentration of potassium. These concentration differences, which are related to the characteristics of membrane transport in each compartment of inner ear fluid, are considered to be adequate to sustain normal biological conditions of the inner ear.