Effect of Potassium Deficiency on Cochlear Potentials and Cation Content in Endolymph

The scala vestibuli and/or scala tympani in guinea pigs were perfused with K+-free modified Ringer's solution. Cochlear microphonics (CM), summating potential (SP), action potential (AP), and endocochlear potential (EP) were recorded from the basal turn of the cochlea before, during, and after the perfusion. Perfusion of both scala vestibuli and tympani with the normal Ringer's did not result in appreciable changes in the cochlear potentials or Na and K content in the endolymph. Perfusion of the perilymphatic space with K+-free Ringer's caused significant suppression of EP and AP. The CM was also reduced in magnitude and accompanied by increase of the positive SP. These changes were reversible by washing with normal Ringer's. The measurement of K and Na content in the endolymph indicated that the K deficiency in the perilymph brought about significant increase of Na content and decrease of K content. The role of K ions in the perilymph for the generation of EP is discussed. [Work supported by a Public Health Service grant].