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Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs.
Acta Otolaryngol. 2015; 135(12):1219-24.AO

Abstract

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 HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 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 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig 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% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.

Authors+Show Affiliations

a Department of Otolaryngology, Teikyo University Chiba Medical Center , Chiba, Japan.a Department of Otolaryngology, Teikyo University Chiba Medical Center , Chiba, Japan.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

26327567

Citation

Suzuki, Masaaki, and Ryosuke Kotani. "Effects of Perilymphatic Pressure, Sodium Nitroprusside, and Bupivacaine On Cochlear Fluid pH of Guinea Pigs." Acta Oto-laryngologica, vol. 135, no. 12, 2015, pp. 1219-24.
Suzuki M, Kotani R. Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs. Acta Otolaryngol. 2015;135(12):1219-24.
Suzuki, M., & Kotani, R. (2015). Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs. Acta Oto-laryngologica, 135(12), 1219-24. https://doi.org/10.3109/00016489.2015.1077392
Suzuki M, Kotani R. Effects of Perilymphatic Pressure, Sodium Nitroprusside, and Bupivacaine On Cochlear Fluid pH of Guinea Pigs. Acta Otolaryngol. 2015;135(12):1219-24. PubMed PMID: 26327567.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs. AU - Suzuki,Masaaki, AU - Kotani,Ryosuke, Y1 - 2015/09/01/ PY - 2015/9/2/entrez PY - 2015/9/4/pubmed PY - 2016/8/10/medline KW - Endolymph potential KW - cochlea fluids KW - pH SP - 1219 EP - 24 JF - Acta oto-laryngologica JO - Acta Otolaryngol. VL - 135 IS - 12 N2 - 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 HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 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 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig 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% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes. SN - 1651-2251 UR - https://www.unboundmedicine.com/medline/citation/26327567/Effects_of_perilymphatic_pressure_sodium_nitroprusside_and_bupivacaine_on_cochlear_fluid_pH_of_guinea_pigs_ L2 - http://www.tandfonline.com/doi/full/10.3109/00016489.2015.1077392 DB - PRIME DP - Unbound Medicine ER -