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Effects of CO2/HCO3- in perilymph on the endocochlear potential in guinea pigs.
J Physiol Sci. 2007 Feb; 57(1):15-22.JP

Abstract

The effect of CO(2)/HCO(3)(-) on the endocochlear potential (EP) was examined by using both ion-selective and conventional microelectrodes and the endolymphatic or perilymphatic perfusion technique. The main findings were as follows: (i) A decrease in the EP from approximately +75 to approximately +35 mV was produced by perilymphatic perfusion with CO(2)/HCO(3)(-)-free solution, which decrease was accompanied by an increase in the endolymphatic pH (DeltapH(e), approximately 0.4). (ii) Perilymphatic perfusion with a solution containing 20 mM NH(4)Cl produced a decrease in the EP (DeltaEP, approximately 20 mV) with an increase in the pH(e) (DeltapH(e), approximately 0.2), whereas switching the perfusion solution from the NH(4)Cl solution to a 5% CO(2)/25 mM HCO(3)(-) solution produced a gradual increase in the EP to the control level with the concomitant recovery of the pH(e). (iii) The perfusion with a solution of high or low HCO(3)(-) with a constant CO(2) level within 10 min produced no significant changes in the EP. (iv) Perfusion of the perilymph with 10 microg/ml nifedipine suppressed the transient asphyxia-induced decrease in EP slightly, but not significantly. (v) By contrast, the administration of 1 microg/ml nifedipine via the endolymph inhibited significantly the reduction in the EP induced by transient asphyxia or perilymphatic perfusion with CO(2)/HCO(3)(-)-free or 20 mM NH(4)Cl solution. These findings suggest that the effect of CO(2) removal from perilymphatic perfusion solution on the EP may be mediated by an increase in cytosolic Ca(2+) concentration induced by an elevation of cytosolic pH in endolymphatic surface cells.

Authors+Show Affiliations

Department of Physiology, Osaka Medical College, Osaka, 569-8686, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17169167

Citation

Nimura, Yoshitsugu, et al. "Effects of CO2/HCO3- in Perilymph On the Endocochlear Potential in Guinea Pigs." The Journal of Physiological Sciences : JPS, vol. 57, no. 1, 2007, pp. 15-22.
Nimura Y, Mori Y, Inui T, et al. Effects of CO2/HCO3- in perilymph on the endocochlear potential in guinea pigs. J Physiol Sci. 2007;57(1):15-22.
Nimura, Y., Mori, Y., Inui, T., Sohma, Y., Takenaka, H., & Kubota, T. (2007). Effects of CO2/HCO3- in perilymph on the endocochlear potential in guinea pigs. The Journal of Physiological Sciences : JPS, 57(1), 15-22.
Nimura Y, et al. Effects of CO2/HCO3- in Perilymph On the Endocochlear Potential in Guinea Pigs. J Physiol Sci. 2007;57(1):15-22. PubMed PMID: 17169167.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of CO2/HCO3- in perilymph on the endocochlear potential in guinea pigs. AU - Nimura,Yoshitsugu, AU - Mori,Yoshiaki, AU - Inui,Takaki, AU - Sohma,Yoshiro, AU - Takenaka,Hiroshi, AU - Kubota,Takahiro, Y1 - 2006/12/15/ PY - 2006/10/11/received PY - 2006/12/06/accepted PY - 2006/12/16/pubmed PY - 2007/5/11/medline PY - 2006/12/16/entrez SP - 15 EP - 22 JF - The journal of physiological sciences : JPS JO - J Physiol Sci VL - 57 IS - 1 N2 - The effect of CO(2)/HCO(3)(-) on the endocochlear potential (EP) was examined by using both ion-selective and conventional microelectrodes and the endolymphatic or perilymphatic perfusion technique. The main findings were as follows: (i) A decrease in the EP from approximately +75 to approximately +35 mV was produced by perilymphatic perfusion with CO(2)/HCO(3)(-)-free solution, which decrease was accompanied by an increase in the endolymphatic pH (DeltapH(e), approximately 0.4). (ii) Perilymphatic perfusion with a solution containing 20 mM NH(4)Cl produced a decrease in the EP (DeltaEP, approximately 20 mV) with an increase in the pH(e) (DeltapH(e), approximately 0.2), whereas switching the perfusion solution from the NH(4)Cl solution to a 5% CO(2)/25 mM HCO(3)(-) solution produced a gradual increase in the EP to the control level with the concomitant recovery of the pH(e). (iii) The perfusion with a solution of high or low HCO(3)(-) with a constant CO(2) level within 10 min produced no significant changes in the EP. (iv) Perfusion of the perilymph with 10 microg/ml nifedipine suppressed the transient asphyxia-induced decrease in EP slightly, but not significantly. (v) By contrast, the administration of 1 microg/ml nifedipine via the endolymph inhibited significantly the reduction in the EP induced by transient asphyxia or perilymphatic perfusion with CO(2)/HCO(3)(-)-free or 20 mM NH(4)Cl solution. These findings suggest that the effect of CO(2) removal from perilymphatic perfusion solution on the EP may be mediated by an increase in cytosolic Ca(2+) concentration induced by an elevation of cytosolic pH in endolymphatic surface cells. SN - 1880-6546 UR - https://www.unboundmedicine.com/medline/citation/17169167/Effects_of_CO2/HCO3__in_perilymph_on_the_endocochlear_potential_in_guinea_pigs_ L2 - http://joi.jlc.jst.go.jp/JST.JSTAGE/physiolsci/RP012006?from=PubMed DB - PRIME DP - Unbound Medicine ER -