DC potentials in different cells of the stria vascularis measured in vitro

Fine glass microelectrodes were inserted into the stria vascularis (SV) from the endolymphatic side under conditions in vitro. DC potentials were recorded in individual cells of the SV. The electrophoretic dye marking technique was used for identification of cells with different DC potentials. Penetration of the luminal membrane of marginal cells (MC) was accompanied by an unstable transient negative potential of about -15 mV. When the electrode penetrated further into the MC, a positive potential of about +10 mV was recorded. In the basal cells (BC) of the SV a negative DC potential of approx. -45 mV was always measured. Addition of ouabain into the perfusion solution (10(-3) mol/l) abolished the positive potential of MC, whereas the negative potential of BC decreased to approximately one half of the original value. A higher positive potential (+17 mV) was found in the MC of animals which were exposed to noise twenty days before the recording. Results are discussed in the light of the knowledge about localization of different transporting systems within the SV cells.