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A pH‐sensitive chloride current in the chemoreceptor cell of rat carotid body
Author(s) -
Petheo Gábor L.,
Molnár Zoltán,
Róka Attila,
Makara Judit K.,
Spät András
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00095.x
Subject(s) - chemoreceptor , extracellular , carotid body , chemistry , biophysics , membrane potential , patch clamp , chloride , reversal potential , acidosis , chloride channel , alkalosis , intracellular ph , biochemistry , medicine , endocrinology , electrophysiology , biology , receptor , organic chemistry
1 Cardiorespiratory response to acidosis is initiated by the carotid body. 2 The direct effect of extracellular pH (pH o ) on the chloride currents of isolated chemoreceptor cells of the rat carotid body was investigated using the whole‐cell patch‐clamp technique. 3 On applying intra‐ and extracellular solutions with a symmetrical high‐Cl − content and with the monovalent cations replaced with membrane‐impermeant ones, an inwardly rectifying Cl − current was found. 4 The current activated slowly and did not display any time‐dependent inactivation. Current activation was present at membrane potentials negative to 0 mV (pH o = 7.0). 5 The current was activated by extracellular acidosis and inhibited by alkalosis in the physiologically relevant pH range of 7.0‐7.8. 6 The current was reduced by 0.1 mM Cd 2+ to the level of the leak current and by 1 mM anthracene‐9‐carboxylic acid (9‐AC) to about 40 %, while 0.1 mM Ba 2+ had no effect. 7 Application of 1 mM 9‐AC caused a slow but statistically significant increase in the resting pH i (from a mean of 7.29 to 7.37 in 5 min) in clusters of chemoreceptor cells in CO 2 /HCO 3 − ‐buffered media as measured with carboxy‐SNARF‐1. 8 When membrane potential changes were estimated in the cell‐attached mode, 1 mM 9‐AC hyperpolarized three out of five tested cells (by 14 mV in average) incubated in CO 2 /HCO 3 − ‐buffered media. 9 In summary, chemoreceptor cells express an inwardly rectifying Cl − current, which is directly regulated by pH o . The current may participate in intracellular acidification and membrane depolarization during acidic challenge.