抄録
The change in the potential of the scala vestibuli and in the cochlear microphonics were investigated at various intralabyrinthine pressure. In this study, the intralabyrinthine pressure were increased by blowing the physiological saline solution into the scala vestibuli and by inward pushing of the stapes.
The potential of the scala vestbuli was observed to rise nearly 1mV. in a few seconds when the positive pressure was applied to the scala vestibuli by injecting the saline solution; and reduced very slowly, showing hysterisis-like response, on withdrawal of the pressure. The change of the potential was well maintained as long as the pressure was applied.
Potential elevation was also observed when the stapes was pushed into the cochlea. The value of the elevation was in the range between 100 and 250 microvolts, and it was approximately 1/4 0f the magnitude of the cochlear microphonics induced by stapes vibration, the amplitude of which was eqalized to the displacement of stapes pushing.
Judging from the relation between the potential elevation and the intralabyrinthine pressure, it was revealed that the curve of the potential elevation had a capacitative character.
The microphonic response showed the transient decrease in its amplitued when positive pressure was applied to the scala vestbuli. After 0.2 seconds, the decreased amplitude of the microphonics recovered to the value before pressure increase. At this time, the potential of the scala vestibuli was still elevating as stated above.
From the results, it was concluded as follows:
The Reissner's membrane had high impedance to DC and low to AC. It was verified that it had a suitable character to correspond to the resistance-capacitance coupling circuit. The cochlea had a visco-elastic character with its local relaxation, and it showed functional stability against intralaby-rinthine pressure change. The pressure difference between the scala vestibuli and scala tympani was assumed to be mainly compensated by the downward movement of the basilar membrane.
