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Functional brainstem expression of T‐type calcium channel subunit alpha1H but not alpha1G maintaining sympathetic tone generation in neonatal B6 mice
Author(s) -
Su ChunKuei,
Fan YuPei,
Chen ChienChang
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.623.3
Subject(s) - brainstem , chemistry , calcium channel , medicine , protein subunit , spinal cord , endocrinology , t type calcium channel , l type calcium channel , wild type , voltage dependent calcium channel , biophysics , calcium , neuroscience , biology , biochemistry , gene , mutant
T‐type calcium channel (T‐channel) is a low‐voltage‐activated channel allowing calcium influx in the voltage range near resting membrane potentials. Functional expression of T‐channel currents only requires alpha1 subunits, including alpha1G, alpha1H, and alpha1I. We investigated whether T‐channel subunits differentially regulate sympathetic tone generation. Wild type B6 mice and the mice of T‐channel subunit alpha1G or alpha1H knock out were used to prepare the brainstem‐spinal cord‐splanchnic nerve that could spontaneously generate sympathetic nerve discharge (SND) under optimal in vitro conditions. Amounts of SND generated from each mouse group were normalized to the ambient current noise and expressed in units of signal/noise ratio for comparisons across experiments. Comparable amounts of SND were generated in the intact preparations of wild type and alpha1G knock out mice. However, significantly less amounts of SND (~40% of the amount of wild type or alpha1G) were generated in the intact preparations of alpha1H knock out. After removal of the synaptic drives originated in the brainstem by cervical cord transections, the amounts of spinally originated SND were largely comparable across mice with different genetic backgrounds. These findings suggest that a functional expression of alpha1H T‐channel subunits in the brainstem is essential for the maintenance of SND genesis in neonatal B6 mice.