Akikazu Ito

Effect of Increased Perilymphatic Pressure on Endocochlear Potential

A study was done to determine how increased fluid pressure in the inner ear influences cochlear blood flow. Hydrostatic pressure was applied to the scala vestibuli or scala tympani in guinea pigs. Endocochlear potential, which is sensitive to the lack of oxygen, was measured through the round window membrane or through the stria vascularis. Cochlear blood flow was confirmed by intravenous injection of India ink. When the perilymphatic pressure was raised to a relatively high level, endocochlear potential decreased, in a similar way as in response to anoxia, because of the cessation of the cochlear blood flow. This change was completely reversible upon applications of pressure for brief periods of time. We consider that the cochlear blood flow ceases when the fluid pressure reaches the level of intracochlear arterial pressure.

Blood flow of the round window.

ZusammenfassungFilmaufnahmen des Blutstroms am runden Fenster zeigen, daß der Blutstrom von Mittel- und Innenohr in diesem Abschnitt getrennt betrachtet werden kann. So läßt sich der Blutstrom im Innenohr durch die Membran des runden Fensters beobachten, ohne daß eine Operation am Innenohr nötig ist.SummaryMotion pictures of the blood flow of the round window in guinea pigs were taken. In this part the blood flow of the inner ear could be distinguished from that of the middle ear. Our motion pictures show that the blood flow of the inner ear can be observed through the round window membrane without an operation on the inner ear.