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Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH
Mixture interactions between sour and salt taste modalities were investigated in rats by direct measurement of intracellular pH (pH(i)) and Na(+) activity ([Na(+)](i)) in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) nerve recordings. Stimulating the lingual surface with...
Autores principales: | , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
2002
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229570/ https://www.ncbi.nlm.nih.gov/pubmed/12451050 http://dx.doi.org/10.1085/jgp.20028656 |
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author | Lyall, Vijay Alam, Rammy I. Phan, Tam-Hao T. Russell, Oneal F. Malik, Shahbaz A. Heck, Gerard L. DeSimone, John A. |
author_facet | Lyall, Vijay Alam, Rammy I. Phan, Tam-Hao T. Russell, Oneal F. Malik, Shahbaz A. Heck, Gerard L. DeSimone, John A. |
author_sort | Lyall, Vijay |
collection | PubMed |
description | Mixture interactions between sour and salt taste modalities were investigated in rats by direct measurement of intracellular pH (pH(i)) and Na(+) activity ([Na(+)](i)) in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) nerve recordings. Stimulating the lingual surface with NaCl solutions adjusted to pHs ranging between 2.0 and 10.3 increased the magnitude of NaCl CT responses linearly with increasing external pH (pH(o)). At pH 7.0, the epithelial sodium channel (ENaC) blocker, benzamil, decreased NaCl CT responses and inhibited further changes in CT responses induced by varying pH(o) to 2.0 or 10.3. At constant pH(o), buffering NaCl solutions with potassium acetate/acetic acid (KA/AA) or HCO(3) (−)/CO(2) inhibited NaCl CT responses relative to CT responses obtained with NaCl solutions buffered with HEPES. The carbonic anhydrase blockers, MK-507 and MK-417, attenuated the inhibition of NaCl CT responses in HCO(3) (−)/CO(2) buffer, suggesting a regulatory role for pH(i). In polarized TRCs step changes in apical pH(o) from 10.3 to 2.0 induced a linear decrease in pH(i) that remained within the physiological range (slope = 0.035; r(2) = 0.98). At constant pH(o), perfusing the apical membrane with Ringer's solutions buffered with KA/AA or HCO(3) (−)/CO(2) decreased resting TRC pH(i), and MK-507 or MK-417 attenuated the decrease in pH(i) in TRCs perfused with HCO(3) (−)/CO(2) buffer. In parallel experiments, TRC [Na(+)](i) decreased with (a) a decrease in apical pH, (b) exposing the apical membrane to amiloride or benzamil, (c) removal of apical Na(+), and (d) acid loading the cells with NH(4)Cl or sodium acetate at constant pH(o). Diethylpyrocarbonate and Zn(2+), modification reagents for histidine residues in proteins, attenuated the CO(2)-induced inhibition of NaCl CT responses and the pH(i)-induced inhibition of apical Na(+) influx in TRCs. We conclude that TRC pH(i) regulates Na(+)-influx through amiloride-sensitive apical ENaCs and hence modulates NaCl CT responses in acid/salt mixtures. |
format | Text |
id | pubmed-2229570 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2002 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22295702008-04-16 Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH Lyall, Vijay Alam, Rammy I. Phan, Tam-Hao T. Russell, Oneal F. Malik, Shahbaz A. Heck, Gerard L. DeSimone, John A. J Gen Physiol Article Mixture interactions between sour and salt taste modalities were investigated in rats by direct measurement of intracellular pH (pH(i)) and Na(+) activity ([Na(+)](i)) in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) nerve recordings. Stimulating the lingual surface with NaCl solutions adjusted to pHs ranging between 2.0 and 10.3 increased the magnitude of NaCl CT responses linearly with increasing external pH (pH(o)). At pH 7.0, the epithelial sodium channel (ENaC) blocker, benzamil, decreased NaCl CT responses and inhibited further changes in CT responses induced by varying pH(o) to 2.0 or 10.3. At constant pH(o), buffering NaCl solutions with potassium acetate/acetic acid (KA/AA) or HCO(3) (−)/CO(2) inhibited NaCl CT responses relative to CT responses obtained with NaCl solutions buffered with HEPES. The carbonic anhydrase blockers, MK-507 and MK-417, attenuated the inhibition of NaCl CT responses in HCO(3) (−)/CO(2) buffer, suggesting a regulatory role for pH(i). In polarized TRCs step changes in apical pH(o) from 10.3 to 2.0 induced a linear decrease in pH(i) that remained within the physiological range (slope = 0.035; r(2) = 0.98). At constant pH(o), perfusing the apical membrane with Ringer's solutions buffered with KA/AA or HCO(3) (−)/CO(2) decreased resting TRC pH(i), and MK-507 or MK-417 attenuated the decrease in pH(i) in TRCs perfused with HCO(3) (−)/CO(2) buffer. In parallel experiments, TRC [Na(+)](i) decreased with (a) a decrease in apical pH, (b) exposing the apical membrane to amiloride or benzamil, (c) removal of apical Na(+), and (d) acid loading the cells with NH(4)Cl or sodium acetate at constant pH(o). Diethylpyrocarbonate and Zn(2+), modification reagents for histidine residues in proteins, attenuated the CO(2)-induced inhibition of NaCl CT responses and the pH(i)-induced inhibition of apical Na(+) influx in TRCs. We conclude that TRC pH(i) regulates Na(+)-influx through amiloride-sensitive apical ENaCs and hence modulates NaCl CT responses in acid/salt mixtures. The Rockefeller University Press 2002-12 /pmc/articles/PMC2229570/ /pubmed/12451050 http://dx.doi.org/10.1085/jgp.20028656 Text en Copyright © 2002, The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Article Lyall, Vijay Alam, Rammy I. Phan, Tam-Hao T. Russell, Oneal F. Malik, Shahbaz A. Heck, Gerard L. DeSimone, John A. Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title | Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title_full | Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title_fullStr | Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title_full_unstemmed | Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title_short | Modulation of Rat Chorda Tympani NaCl Responses and Intracellular Na(+) Activity in Polarized Taste Receptor Cells by pH |
title_sort | modulation of rat chorda tympani nacl responses and intracellular na(+) activity in polarized taste receptor cells by ph |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229570/ https://www.ncbi.nlm.nih.gov/pubmed/12451050 http://dx.doi.org/10.1085/jgp.20028656 |
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