title: Permeability to sodium ions of the endolymph-perilymph barrier.
abstract: The endocochlear potential and Na+ activity in the endolymph were simultaneously measured with a double-barreled Na+ selective liquid membrane electrode. The modified Na+ conductance and permeability coefficient of the endolymph-perilymph barrier were calculated from the rate of change in the endolymph Na+ concentration relative to the Na+ electrochemical gradient across the barrier during permanent anoxia. In normal guinea pigs the Na+ conductance of the endolymph-perilymph barrier is approximately 5 times less than its K+ conductance. Exposure to noise or treatment with kanamycin suppresses the cochlear microphonics but does not result in significant alterations in the Na+ permeability of the endolymph-perilymph barrier. It is likely that the Na+ permeability of the endolymph-perilymph barrier is not involved in the physiological processes which lead to the cochlear damage produced by noise or kanamycin.
mesh_terms: D000200:Action Potentials; D000818:Animals; D002463:Cell Membrane Permeability; D003055:Cochlear Microphonic Potentials; D004553:Electric Conductivity; D004710:Endolymph / Q000503:physiopathology*; D006168:Guinea Pigs; D034381:Hearing Loss / Q000139:chemically induced / Q000503:physiopathology; D006317:Hearing Loss, Noise-Induced / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D007612:Kanamycin / Q000009:adverse effects; D007761:Labyrinthine Fluids / Q000503:physiopathology*; D008564:Membrane Potentials; D010498:Perilymph / Q000503:physiopathology*; D012964:Sodium / Q000378:metabolism*
chemical_list: D007612:Kanamycin; D012964:Sodium