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Endolymphatic sodium homeostasis by Reissner's membrane.
Neuroscience. 2003; 119(1):3-8.N

Abstract

Cochlear sensory transduction depends on active extrusion of sodium ion (Na(+)) from the luminal fluid, endolymph. Reissner's membrane epithelium forms much of the barrier between cochlear endolymph and perilymph and we hypothesized that Reissner's membrane might be responsible for this function. We found that Reissner's membrane isolated from gerbil produced a short circuit current (I(sc)) directed into the apical side, consistent with cation absorption and/or anion secretion. I(sc) was inhibited by amiloride analogs in the potency sequence benzamil>amiloride>>ethylisopropylamiloride, consistent with Na(+) absorption through an epithelial sodium channel in the apical cell membrane. I(sc) was also inhibited by an inhibitor of Na(+),K(+)-ATPase, ouabain, and by the K(+) channel blockers Ba(2+), 4-aminopyridine and quinine but not tetraethylammonium nor glibenclamide, consistent with the presence of a voltage-activated K(+) channel. Bumetanide, an inhibitor of the Na(+),2Cl(-),K(+)-cotransporter, had no effect on I(sc). Contrary to previous hypotheses, no evidence was found for electrogenic secretion of Cl(-) under control of cAMP since neither forskolin nor genistein affected I(sc) when Na(+) absorption was blocked. These results provide the first direct evidence that Reissner's membrane contributes to normal cochlear function by absorption of Na(+) from endolymph.

Authors+Show Affiliations

Kansas State University, Department of Anatomy and Physiology, 126 Coles Hall, 1600 Denison Ave., Manhattan, KS 66506-5802, USA.No affiliation info available

Pub Type(s)

Comparative Study
Letter
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

12763062

Citation

Lee, J H., and D C. Marcus. "Endolymphatic Sodium Homeostasis By Reissner's Membrane." Neuroscience, vol. 119, no. 1, 2003, pp. 3-8.
Lee JH, Marcus DC. Endolymphatic sodium homeostasis by Reissner's membrane. Neuroscience. 2003;119(1):3-8.
Lee, J. H., & Marcus, D. C. (2003). Endolymphatic sodium homeostasis by Reissner's membrane. Neuroscience, 119(1), 3-8.
Lee JH, Marcus DC. Endolymphatic Sodium Homeostasis By Reissner's Membrane. Neuroscience. 2003;119(1):3-8. PubMed PMID: 12763062.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Endolymphatic sodium homeostasis by Reissner's membrane. AU - Lee,J H, AU - Marcus,D C, PY - 2003/5/24/pubmed PY - 2003/7/29/medline PY - 2003/5/24/entrez SP - 3 EP - 8 JF - Neuroscience JO - Neuroscience VL - 119 IS - 1 N2 - Cochlear sensory transduction depends on active extrusion of sodium ion (Na(+)) from the luminal fluid, endolymph. Reissner's membrane epithelium forms much of the barrier between cochlear endolymph and perilymph and we hypothesized that Reissner's membrane might be responsible for this function. We found that Reissner's membrane isolated from gerbil produced a short circuit current (I(sc)) directed into the apical side, consistent with cation absorption and/or anion secretion. I(sc) was inhibited by amiloride analogs in the potency sequence benzamil>amiloride>>ethylisopropylamiloride, consistent with Na(+) absorption through an epithelial sodium channel in the apical cell membrane. I(sc) was also inhibited by an inhibitor of Na(+),K(+)-ATPase, ouabain, and by the K(+) channel blockers Ba(2+), 4-aminopyridine and quinine but not tetraethylammonium nor glibenclamide, consistent with the presence of a voltage-activated K(+) channel. Bumetanide, an inhibitor of the Na(+),2Cl(-),K(+)-cotransporter, had no effect on I(sc). Contrary to previous hypotheses, no evidence was found for electrogenic secretion of Cl(-) under control of cAMP since neither forskolin nor genistein affected I(sc) when Na(+) absorption was blocked. These results provide the first direct evidence that Reissner's membrane contributes to normal cochlear function by absorption of Na(+) from endolymph. SN - 0306-4522 UR - https://www.unboundmedicine.com/medline/citation/12763062/Endolymphatic_sodium_homeostasis_by_Reissner's_membrane_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0306452203001040 DB - PRIME DP - Unbound Medicine ER -