DC Potentials of the Membranous Labyrinth

The endolymphatic DC potentials were measured in the utricle, saccule and cochlear duct of the membranous labyrinth of the guinea pig and compared with potassium analyses of the endolymph. The average utricular potential was found to be +4 mv, the saccular potential +1 mv, and the cochlear potential +65 mv. The average potassium concentration of utricular endolymph was 139 mEq/l.; that from the cochlea was similar. The cochlear DC potential is approximately 70 mv higher than that of the vestibule (utricle and saccule), whereas the high potassium and low sodium concentration of endolymph is similar throughout. It is concluded that the endolymphatic resting potential of the internal ear is not correlated with the potassium or the sodium concentration of the endolymph.