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Expression pattern of T‐type Ca 2+ channels in embryonic chick nodose ganglion neurons
Author(s) -
Pachuau Judith,
MartinCaraballo Miguel
Publication year - 2007
Publication title -
developmental neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.716
H-Index - 129
eISSN - 1932-846X
pISSN - 1932-8451
DOI - 10.1002/dneu.20563
Subject(s) - nodose ganglion , biology , patch clamp , medicine , ion channel , neuroscience , electrophysiology , microbiology and biotechnology , endocrinology , biophysics , stimulation , vagus nerve , biochemistry , receptor
In this study we have characterized the functional expression of T‐type Ca 2+ channels in developing chick nodose neurons, a population of placode‐derived sensory neurons innervating the heart and various visceral organs. Voltage‐gated Ca 2+ currents were measured using whole cell patch clamp recordings in neurons acutely isolated between embryonic day (E) 7 and E20, prior to hatching. E7 nodose neurons express relatively large high voltage‐activated (HVA) Ca 2+ currents. HVA current density progressively increases between E7 and E17. T‐type Ca 2+ currents were restricted to a few nodose neurons between E7 and E10 but were present in ∼60% of nodose neurons by E17. T‐type Ca 2+ channels regulate the response of nodose neurons to injection of hyperpolarizing currents, but do not have any effect on the action potential waveform. Nickel ions blocked T‐type Ca 2+ currents in a concentration‐dependent manner with an IC 50 of 17 μM. The high sensitivity of T‐type Ca 2+ channels to nickel blockade combined with sequencing of a partial cDNA suggests that T‐type Ca 2+ currents are generated by α1H subunits in chick nodose neurons. Steady‐state activation and inactivation kinetics were similar to those previously reported for other α1H channels in mammalian neurons. Semi‐quantitative PCR analysis indicates that α1H mRNA was present in chick nodose neurons by E7, suggesting that the functional expression of T‐type Ca 2+ channels involves a posttranscriptional mechanism. These findings demonstrate a distinct pattern of T‐type Ca 2+ channel functional expression in placode‐derived neurons when compared with CNS neurons. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007