Effects of perilymphatic pressure, @entity1854 , and XXXX on cochlear fluid pH of @entity840 .

@entity840 @entity1854 @entity3158 @entity3157 @entity1341 @entity4982 @entity842 @entity3612
CONCLUSIONS: Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. OBJECTIVES: Cochlea fluid pH is highly dependent on the @entity3157 / @entity3158 buffer system. Cochlear blood flow (CBF) supplies @entity3612 and removes @entity3158 . It is speculated that cochlear blood flow changes might affect the balance of the @entity3157 / @entity3158 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF. The purpose of this study was to elucidate the effect of positive hydrostatic inner ear pressure and application of a vasodilator and vasoconstrictor of cochlear vessels on the pH of the endolymph and perilymph. METHODS: The authors performed animal physiological experiments on 30 @entity840 . Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, @entity842 donor ( @entity1854 ; @entity4982 ), and the vasoconstrictor, @entity1341 , were placed topically onto the round window of the @entity840 cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the @entity840 cochlea. During the topical application study, scala vestibuli perilymph pH (pHv) was also measured simultaneously in the second turn. RESULTS: The application of hydrostatic positive pressure caused a decrease in pHe and EP. Positive perilymphatic pressure caused the endolymph to become acidic pressure-dependently. Application of 3.0% @entity4982 evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% @entity1341 caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.
