Premium
Characterization of the Kv channels of mouse carotid body chemoreceptor cells and their role in oxygen sensing
Author(s) -
PérezGarcía M. Teresa,
Colinas Olaia,
MiguelVelado Eduardo,
MorenoDomínguez Alejandro,
LópezLópez José Ramón
Publication year - 2004
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 - 10.1113/jphysiol.2004.062281
Subject(s) - carotid body , chemoreceptor , immunocytochemistry , biophysics , glomus cell , green fluorescent protein , patch clamp , microbiology and biotechnology , biology , chemistry , electrophysiology , biochemistry , endocrinology , gene , neuroscience , receptor
As there are wide interspecies variations in the molecular nature of the O 2 ‐sensitive Kv channels in arterial chemoreceptors, we have characterized the expression of these channels and their hypoxic sensitivity in the mouse carotid body (CB). CB chemoreceptor cells were obtained from a transgenic mouse expressing green fluorescent protein (GFP) under the control of tyrosine hydroxylase (TH) promoter. Immunocytochemical identification of TH in CB cell cultures reveals a good match with GFP‐positive cells. Furthermore, these cells show an increase in [Ca 2+ ] i in response to low P O2 , demonstrating their ability to engender a physiological response. Whole‐cell experiments demonstrated slow‐inactivating K + currents with activation threshold around −30 mV and a bi‐exponential kinetic of deactivation (τ of 6.24 ± 0.52 and 32.85 ± 4.14 ms). TEA sensitivity of the currents identified also two different components (IC 50 of 17.8 ± 2.8 and 940.0 ± 14.7 μ m ). Current amplitude decreased reversibly in response to hypoxia, which selectively affected the fast deactivating component. Hypoxic inhibition was also abolished in the presence of low (10–50 μ m ) concentrations of TEA, suggesting that O 2 interacts with the component of the current most sensitive to TEA. The kinetic and pharmacological profile of the currents suggested the presence of Kv2 and Kv3 channels as their molecular correlates, and we have identified several members of these two subfamilies by single‐cell PCR and immunocytochemistry. This report represents the first functional and molecular characterization of Kv channels in mouse CB chemoreceptor cells, and strongly suggests that O 2 ‐sensitive Kv channels in this preparation belong to the Kv3 subfamily.