Cargando…

Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule

The inner stripe of the outer medullary collecting tubule is a major distal nephron segment in urinary acidification. To examine the mechanism of basolateral membrane H+/OH-/HCO3- transport in this segment, cell pH was measured microfluorometrically in the inner stripe of the rabbit outer medullary...

Descripción completa

Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1990
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2216319/
https://www.ncbi.nlm.nih.gov/pubmed/2307960
_version_ 1782149133888389120
collection PubMed
description The inner stripe of the outer medullary collecting tubule is a major distal nephron segment in urinary acidification. To examine the mechanism of basolateral membrane H+/OH-/HCO3- transport in this segment, cell pH was measured microfluorometrically in the inner stripe of the rabbit outer medullary collecting tubule perfused in vitro using the pH-sensitive fluorescent dye, (2',7')-bis(carboxyethyl)-(5,6)- carboxyfluorescein. Decreasing peritubular pH from 7.4 to 6.8 (changing [HCO3-] from 25 to 5 mM) caused a cell acidification of 0.25 +/- 0.02 pH units, while a similar luminal change resulted in a smaller cell acidification of only 0.04 +/- 0.01 pH units. Total replacement of peritubular Cl- with gluconate caused cell pH to increase by 0.18 +/- 0.04 pH units, an effect inhibited by 100 microM peritubular DIDS and independent of Na+. Direct coupling between Cl- and base was suggested by the continued presence of peritubular Cl- removal-induced cell alkalinization under the condition of a cell voltage clamp (K(+)- valinomycin). In addition, 90% of basolateral membrane H+/OH-/HCO3- permeability was inhibited by complete removal of luminal and peritubular Cl-. Peritubular Cl(-)-induced cell pH changes were inhibited two-thirds by removal of exogenous CO2/HCO3- from the system. The apparent Km for peritubular Cl- determined in the presence of 25 mM luminal and peritubular [HCO3-] was 113.5 +/- 14.8 mM. These results demonstrate that the basolateral membrane of the inner stripe of the outer medullary collecting tubule possesses a stilbene-sensitive Cl- /HCO3- exchanger which mediates 90% of basolateral membrane H+/OH-/HCO3- permeability and may be regulated by physiologic Cl- concentrations.
format Text
id pubmed-2216319
institution National Center for Biotechnology Information
language English
publishDate 1990
publisher The Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-22163192008-04-23 Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule J Gen Physiol Articles The inner stripe of the outer medullary collecting tubule is a major distal nephron segment in urinary acidification. To examine the mechanism of basolateral membrane H+/OH-/HCO3- transport in this segment, cell pH was measured microfluorometrically in the inner stripe of the rabbit outer medullary collecting tubule perfused in vitro using the pH-sensitive fluorescent dye, (2',7')-bis(carboxyethyl)-(5,6)- carboxyfluorescein. Decreasing peritubular pH from 7.4 to 6.8 (changing [HCO3-] from 25 to 5 mM) caused a cell acidification of 0.25 +/- 0.02 pH units, while a similar luminal change resulted in a smaller cell acidification of only 0.04 +/- 0.01 pH units. Total replacement of peritubular Cl- with gluconate caused cell pH to increase by 0.18 +/- 0.04 pH units, an effect inhibited by 100 microM peritubular DIDS and independent of Na+. Direct coupling between Cl- and base was suggested by the continued presence of peritubular Cl- removal-induced cell alkalinization under the condition of a cell voltage clamp (K(+)- valinomycin). In addition, 90% of basolateral membrane H+/OH-/HCO3- permeability was inhibited by complete removal of luminal and peritubular Cl-. Peritubular Cl(-)-induced cell pH changes were inhibited two-thirds by removal of exogenous CO2/HCO3- from the system. The apparent Km for peritubular Cl- determined in the presence of 25 mM luminal and peritubular [HCO3-] was 113.5 +/- 14.8 mM. These results demonstrate that the basolateral membrane of the inner stripe of the outer medullary collecting tubule possesses a stilbene-sensitive Cl- /HCO3- exchanger which mediates 90% of basolateral membrane H+/OH-/HCO3- permeability and may be regulated by physiologic Cl- concentrations. The Rockefeller University Press 1990-02-01 /pmc/articles/PMC2216319/ /pubmed/2307960 Text en 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 Articles
Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title_full Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title_fullStr Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title_full_unstemmed Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title_short Basolateral membrane Na(+)-independent Cl-/HCO3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
title_sort basolateral membrane na(+)-independent cl-/hco3- exchange in the inner stripe of the rabbit outer medullary collecting tubule
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2216319/
https://www.ncbi.nlm.nih.gov/pubmed/2307960