The Electrogenic Sodium Bicarbonate Cotransporter NBCe1 Is a High-Affinity Bicarbonate Carrier in Cortical Astrocytes

Theparambil, Shefeeq M.; Ruminot, Ivan; Schneider, Hans-Peter; Shull, Gary E.; Deitmer, Joachim W.

Abstract

The electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4) is a robust regulator of intracellular H+ and a significant base carrier in many cell types. Using wild-type (WT) and NBCe1-deficient (NBC-KO) mice, we have studied the role of NBCe1 in cortical astrocytes in culture and in situ by monitoring intracellular H+ using the H+-sensitive dye BCECF [2',7' -bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein] in wide-field and confocal microscopy. Adding 0.1-3 mM HCO3- to an O-2-gassed, HEPES-buffered saline solution lowered the intracellular H+ concentration with a K-m of 0.65 mM HCO3- in WT astrocytes, but slowly raised [H+](1) in NBCe1-KO astrocytes. HumanNBCe1 heterologously expressed in Xenopus oocytes could be activated by adding 1-3mM HCO3-, and even by residual HCO3- in a nominally CO2/HCO3--free saline solution. Our results demonstrate a surprisingly high apparent bicarbonate sensitivity mediated by NBCe1 in cortical astrocytes, suggesting that NBCe1 may operate over a wide bicarbonate concentration in these cells.

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Título según WOS: ID WOS:000330360700009 Not found in local WOS DB
Título de la Revista: JOURNAL OF NEUROSCIENCE
Volumen: 34
Número: 4
Editorial: SOC NEUROSCIENCE
Fecha de publicación: 2014
Página de inicio: 1148
Página final: 1157
DOI:

10.1523/JNEUROSCI.2377-13.2014

Notas: ISI